OpenZFS restructuring - move platform specific sources

Move platform specific Linux source under module/os/linux/
and update the build system accordingly.  Additional code
restructuring will follow to make the common code fully
portable.
    
Reviewed-by: Jorgen Lundman <[email protected]>
Reviewed-by: Igor Kozhukhov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Matthew Macy <[email protected]>
Closes #9206 

22 files changed, 9942 insertions, 0 deletions

diff --git a/module/os/linux/spl/Makefile.in b/module/os/linux/spl/Makefile.in
new file mode 100644
index 000000000..a29c36a2a
--- /dev/null
+++ b/module/os/linux/spl/Makefile.in
@@ -0,0 +1,18 @@
+$(MODULE)-objs += ../os/linux/spl/spl-atomic.o
+$(MODULE)-objs += ../os/linux/spl/spl-condvar.o
+$(MODULE)-objs += ../os/linux/spl/spl-cred.o
+$(MODULE)-objs += ../os/linux/spl/spl-err.o
+$(MODULE)-objs += ../os/linux/spl/spl-generic.o
+$(MODULE)-objs += ../os/linux/spl/spl-kmem.o
+$(MODULE)-objs += ../os/linux/spl/spl-kmem-cache.o
+$(MODULE)-objs += ../os/linux/spl/spl-kobj.o
+$(MODULE)-objs += ../os/linux/spl/spl-kstat.o
+$(MODULE)-objs += ../os/linux/spl/spl-proc.o
+$(MODULE)-objs += ../os/linux/spl/spl-procfs-list.o
+$(MODULE)-objs += ../os/linux/spl/spl-taskq.o
+$(MODULE)-objs += ../os/linux/spl/spl-thread.o
+$(MODULE)-objs += ../os/linux/spl/spl-tsd.o
+$(MODULE)-objs += ../os/linux/spl/spl-vmem.o
+$(MODULE)-objs += ../os/linux/spl/spl-vnode.o
+$(MODULE)-objs += ../os/linux/spl/spl-xdr.o
+$(MODULE)-objs += ../os/linux/spl/spl-zlib.o
diff --git a/module/os/linux/spl/README.md b/module/os/linux/spl/README.md
new file mode 100644
index 000000000..57f635aed
--- /dev/null
+++ b/module/os/linux/spl/README.md
@@ -0,0 +1,16 @@
+The Solaris Porting Layer, SPL, is a Linux kernel module which provides a
+compatibility layer used by the [ZFS on Linux](http://zfsonlinux.org) project.
+
+# Installation
+
+The latest version of the SPL is maintained as part of this repository.
+Only when building ZFS version 0.7.x or earlier must an external SPL release
+be used.  These releases can be found at:
+
+  * Version 0.7.x: https://github.com/zfsonlinux/spl/tree/spl-0.7-release  
+  * Version 0.6.5.x: https://github.com/zfsonlinux/spl/tree/spl-0.6.5-release  
+
+# Release
+
+The SPL is released under a GPLv2 license.  
+For more details see the NOTICE and THIRDPARTYLICENSE files; `UCRL-CODE-235197`
diff --git a/module/os/linux/spl/THIRDPARTYLICENSE.gplv2 b/module/os/linux/spl/THIRDPARTYLICENSE.gplv2
new file mode 100644
index 000000000..d159169d1
--- /dev/null
+++ b/module/os/linux/spl/THIRDPARTYLICENSE.gplv2
@@ -0,0 +1,339 @@
+                    GNU GENERAL PUBLIC LICENSE
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+    but WITHOUT ANY WARRANTY; without even the implied warranty of
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+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
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+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
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+library.  If this is what you want to do, use the GNU Lesser General
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diff --git a/module/os/linux/spl/THIRDPARTYLICENSE.gplv2.descrip b/module/os/linux/spl/THIRDPARTYLICENSE.gplv2.descrip
new file mode 100644
index 000000000..78535a8ee
--- /dev/null
+++ b/module/os/linux/spl/THIRDPARTYLICENSE.gplv2.descrip
@@ -0,0 +1 @@
+COMPATIBILITY LAYER FOR OPENZFS ON LINUX
diff --git a/module/os/linux/spl/spl-atomic.c b/module/os/linux/spl/spl-atomic.c
new file mode 100644
index 000000000..47ed1886e
--- /dev/null
+++ b/module/os/linux/spl/spl-atomic.c
@@ -0,0 +1,36 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Atomic Implementation.
+ */
+
+#include <sys/atomic.h>
+
+#ifdef ATOMIC_SPINLOCK
+/* Global atomic lock declarations */
+DEFINE_SPINLOCK(atomic32_lock);
+DEFINE_SPINLOCK(atomic64_lock);
+
+EXPORT_SYMBOL(atomic32_lock);
+EXPORT_SYMBOL(atomic64_lock);
+#endif /* ATOMIC_SPINLOCK */
diff --git a/module/os/linux/spl/spl-condvar.c b/module/os/linux/spl/spl-condvar.c
new file mode 100644
index 000000000..3cc33da62
--- /dev/null
+++ b/module/os/linux/spl/spl-condvar.c
@@ -0,0 +1,461 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Credential Implementation.
+ */
+
+#include <sys/condvar.h>
+#include <sys/time.h>
+#include <sys/sysmacros.h>
+#include <linux/hrtimer.h>
+#include <linux/compiler_compat.h>
+#include <linux/mod_compat.h>
+
+#include <linux/sched.h>
+
+#ifdef HAVE_SCHED_SIGNAL_HEADER
+#include <linux/sched/signal.h>
+#endif
+
+#define	MAX_HRTIMEOUT_SLACK_US	1000
+unsigned int spl_schedule_hrtimeout_slack_us = 0;
+
+static int
+param_set_hrtimeout_slack(const char *buf, zfs_kernel_param_t *kp)
+{
+	unsigned long val;
+	int error;
+
+	error = kstrtoul(buf, 0, &val);
+	if (error)
+		return (error);
+
+	if (val > MAX_HRTIMEOUT_SLACK_US)
+		return (-EINVAL);
+
+	error = param_set_uint(buf, kp);
+	if (error < 0)
+		return (error);
+
+	return (0);
+}
+
+module_param_call(spl_schedule_hrtimeout_slack_us, param_set_hrtimeout_slack,
+	param_get_uint, &spl_schedule_hrtimeout_slack_us, 0644);
+MODULE_PARM_DESC(spl_schedule_hrtimeout_slack_us,
+	"schedule_hrtimeout_range() delta/slack value in us, default(0)");
+
+void
+__cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg)
+{
+	ASSERT(cvp);
+	ASSERT(name == NULL);
+	ASSERT(type == CV_DEFAULT);
+	ASSERT(arg == NULL);
+
+	cvp->cv_magic = CV_MAGIC;
+	init_waitqueue_head(&cvp->cv_event);
+	init_waitqueue_head(&cvp->cv_destroy);
+	atomic_set(&cvp->cv_waiters, 0);
+	atomic_set(&cvp->cv_refs, 1);
+	cvp->cv_mutex = NULL;
+}
+EXPORT_SYMBOL(__cv_init);
+
+static int
+cv_destroy_wakeup(kcondvar_t *cvp)
+{
+	if (!atomic_read(&cvp->cv_waiters) && !atomic_read(&cvp->cv_refs)) {
+		ASSERT(cvp->cv_mutex == NULL);
+		ASSERT(!waitqueue_active(&cvp->cv_event));
+		return (1);
+	}
+
+	return (0);
+}
+
+void
+__cv_destroy(kcondvar_t *cvp)
+{
+	ASSERT(cvp);
+	ASSERT(cvp->cv_magic == CV_MAGIC);
+
+	cvp->cv_magic = CV_DESTROY;
+	atomic_dec(&cvp->cv_refs);
+
+	/* Block until all waiters are woken and references dropped. */
+	while (cv_destroy_wakeup(cvp) == 0)
+		wait_event_timeout(cvp->cv_destroy, cv_destroy_wakeup(cvp), 1);
+
+	ASSERT3P(cvp->cv_mutex, ==, NULL);
+	ASSERT3S(atomic_read(&cvp->cv_refs), ==, 0);
+	ASSERT3S(atomic_read(&cvp->cv_waiters), ==, 0);
+	ASSERT3S(waitqueue_active(&cvp->cv_event), ==, 0);
+}
+EXPORT_SYMBOL(__cv_destroy);
+
+static void
+cv_wait_common(kcondvar_t *cvp, kmutex_t *mp, int state, int io)
+{
+	DEFINE_WAIT(wait);
+	kmutex_t *m;
+
+	ASSERT(cvp);
+	ASSERT(mp);
+	ASSERT(cvp->cv_magic == CV_MAGIC);
+	ASSERT(mutex_owned(mp));
+	atomic_inc(&cvp->cv_refs);
+
+	m = READ_ONCE(cvp->cv_mutex);
+	if (!m)
+		m = xchg(&cvp->cv_mutex, mp);
+	/* Ensure the same mutex is used by all callers */
+	ASSERT(m == NULL || m == mp);
+
+	prepare_to_wait_exclusive(&cvp->cv_event, &wait, state);
+	atomic_inc(&cvp->cv_waiters);
+
+	/*
+	 * Mutex should be dropped after prepare_to_wait() this
+	 * ensures we're linked in to the waiters list and avoids the
+	 * race where 'cvp->cv_waiters > 0' but the list is empty.
+	 */
+	mutex_exit(mp);
+	if (io)
+		io_schedule();
+	else
+		schedule();
+
+	/* No more waiters a different mutex could be used */
+	if (atomic_dec_and_test(&cvp->cv_waiters)) {
+		/*
+		 * This is set without any lock, so it's racy. But this is
+		 * just for debug anyway, so make it best-effort
+		 */
+		cvp->cv_mutex = NULL;
+		wake_up(&cvp->cv_destroy);
+	}
+
+	finish_wait(&cvp->cv_event, &wait);
+	atomic_dec(&cvp->cv_refs);
+
+	/*
+	 * Hold mutex after we release the cvp, otherwise we could dead lock
+	 * with a thread holding the mutex and call cv_destroy.
+	 */
+	mutex_enter(mp);
+}
+
+void
+__cv_wait(kcondvar_t *cvp, kmutex_t *mp)
+{
+	cv_wait_common(cvp, mp, TASK_UNINTERRUPTIBLE, 0);
+}
+EXPORT_SYMBOL(__cv_wait);
+
+void
+__cv_wait_io(kcondvar_t *cvp, kmutex_t *mp)
+{
+	cv_wait_common(cvp, mp, TASK_UNINTERRUPTIBLE, 1);
+}
+EXPORT_SYMBOL(__cv_wait_io);
+
+int
+__cv_wait_io_sig(kcondvar_t *cvp, kmutex_t *mp)
+{
+	cv_wait_common(cvp, mp, TASK_INTERRUPTIBLE, 1);
+
+	return (signal_pending(current) ? 0 : 1);
+}
+EXPORT_SYMBOL(__cv_wait_io_sig);
+
+int
+__cv_wait_sig(kcondvar_t *cvp, kmutex_t *mp)
+{
+	cv_wait_common(cvp, mp, TASK_INTERRUPTIBLE, 0);
+
+	return (signal_pending(current) ? 0 : 1);
+}
+EXPORT_SYMBOL(__cv_wait_sig);
+
+#if defined(HAVE_IO_SCHEDULE_TIMEOUT)
+#define	spl_io_schedule_timeout(t)	io_schedule_timeout(t)
+#else
+
+struct spl_task_timer {
+	struct timer_list timer;
+	struct task_struct *task;
+};
+
+static void
+__cv_wakeup(spl_timer_list_t t)
+{
+	struct timer_list *tmr = (struct timer_list *)t;
+	struct spl_task_timer *task_timer = from_timer(task_timer, tmr, timer);
+
+	wake_up_process(task_timer->task);
+}
+
+static long
+spl_io_schedule_timeout(long time_left)
+{
+	long expire_time = jiffies + time_left;
+	struct spl_task_timer task_timer;
+	struct timer_list *timer = &task_timer.timer;
+
+	task_timer.task = current;
+
+	timer_setup(timer, __cv_wakeup, 0);
+
+	timer->expires = expire_time;
+	add_timer(timer);
+
+	io_schedule();
+
+	del_timer_sync(timer);
+
+	time_left = expire_time - jiffies;
+
+	return (time_left < 0 ? 0 : time_left);
+}
+#endif
+
+/*
+ * 'expire_time' argument is an absolute wall clock time in jiffies.
+ * Return value is time left (expire_time - now) or -1 if timeout occurred.
+ */
+static clock_t
+__cv_timedwait_common(kcondvar_t *cvp, kmutex_t *mp, clock_t expire_time,
+    int state, int io)
+{
+	DEFINE_WAIT(wait);
+	kmutex_t *m;
+	clock_t time_left;
+
+	ASSERT(cvp);
+	ASSERT(mp);
+	ASSERT(cvp->cv_magic == CV_MAGIC);
+	ASSERT(mutex_owned(mp));
+
+	/* XXX - Does not handle jiffie wrap properly */
+	time_left = expire_time - jiffies;
+	if (time_left <= 0)
+		return (-1);
+
+	atomic_inc(&cvp->cv_refs);
+	m = READ_ONCE(cvp->cv_mutex);
+	if (!m)
+		m = xchg(&cvp->cv_mutex, mp);
+	/* Ensure the same mutex is used by all callers */
+	ASSERT(m == NULL || m == mp);
+
+	prepare_to_wait_exclusive(&cvp->cv_event, &wait, state);
+	atomic_inc(&cvp->cv_waiters);
+
+	/*
+	 * Mutex should be dropped after prepare_to_wait() this
+	 * ensures we're linked in to the waiters list and avoids the
+	 * race where 'cvp->cv_waiters > 0' but the list is empty.
+	 */
+	mutex_exit(mp);
+	if (io)
+		time_left = spl_io_schedule_timeout(time_left);
+	else
+		time_left = schedule_timeout(time_left);
+
+	/* No more waiters a different mutex could be used */
+	if (atomic_dec_and_test(&cvp->cv_waiters)) {
+		/*
+		 * This is set without any lock, so it's racy. But this is
+		 * just for debug anyway, so make it best-effort
+		 */
+		cvp->cv_mutex = NULL;
+		wake_up(&cvp->cv_destroy);
+	}
+
+	finish_wait(&cvp->cv_event, &wait);
+	atomic_dec(&cvp->cv_refs);
+
+	/*
+	 * Hold mutex after we release the cvp, otherwise we could dead lock
+	 * with a thread holding the mutex and call cv_destroy.
+	 */
+	mutex_enter(mp);
+	return (time_left > 0 ? time_left : -1);
+}
+
+clock_t
+__cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time)
+{
+	return (__cv_timedwait_common(cvp, mp, exp_time,
+	    TASK_UNINTERRUPTIBLE, 0));
+}
+EXPORT_SYMBOL(__cv_timedwait);
+
+clock_t
+__cv_timedwait_io(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time)
+{
+	return (__cv_timedwait_common(cvp, mp, exp_time,
+	    TASK_UNINTERRUPTIBLE, 1));
+}
+EXPORT_SYMBOL(__cv_timedwait_io);
+
+clock_t
+__cv_timedwait_sig(kcondvar_t *cvp, kmutex_t *mp, clock_t exp_time)
+{
+	return (__cv_timedwait_common(cvp, mp, exp_time,
+	    TASK_INTERRUPTIBLE, 0));
+}
+EXPORT_SYMBOL(__cv_timedwait_sig);
+
+/*
+ * 'expire_time' argument is an absolute clock time in nanoseconds.
+ * Return value is time left (expire_time - now) or -1 if timeout occurred.
+ */
+static clock_t
+__cv_timedwait_hires(kcondvar_t *cvp, kmutex_t *mp, hrtime_t expire_time,
+    hrtime_t res, int state)
+{
+	DEFINE_WAIT(wait);
+	kmutex_t *m;
+	hrtime_t time_left;
+	ktime_t ktime_left;
+	u64 slack = 0;
+
+	ASSERT(cvp);
+	ASSERT(mp);
+	ASSERT(cvp->cv_magic == CV_MAGIC);
+	ASSERT(mutex_owned(mp));
+
+	time_left = expire_time - gethrtime();
+	if (time_left <= 0)
+		return (-1);
+
+	atomic_inc(&cvp->cv_refs);
+	m = READ_ONCE(cvp->cv_mutex);
+	if (!m)
+		m = xchg(&cvp->cv_mutex, mp);
+	/* Ensure the same mutex is used by all callers */
+	ASSERT(m == NULL || m == mp);
+
+	prepare_to_wait_exclusive(&cvp->cv_event, &wait, state);
+	atomic_inc(&cvp->cv_waiters);
+
+	/*
+	 * Mutex should be dropped after prepare_to_wait() this
+	 * ensures we're linked in to the waiters list and avoids the
+	 * race where 'cvp->cv_waiters > 0' but the list is empty.
+	 */
+	mutex_exit(mp);
+
+	ktime_left = ktime_set(0, time_left);
+	slack = MIN(MAX(res, spl_schedule_hrtimeout_slack_us * NSEC_PER_USEC),
+	    MAX_HRTIMEOUT_SLACK_US * NSEC_PER_USEC);
+	schedule_hrtimeout_range(&ktime_left, slack, HRTIMER_MODE_REL);
+
+	/* No more waiters a different mutex could be used */
+	if (atomic_dec_and_test(&cvp->cv_waiters)) {
+		/*
+		 * This is set without any lock, so it's racy. But this is
+		 * just for debug anyway, so make it best-effort
+		 */
+		cvp->cv_mutex = NULL;
+		wake_up(&cvp->cv_destroy);
+	}
+
+	finish_wait(&cvp->cv_event, &wait);
+	atomic_dec(&cvp->cv_refs);
+
+	mutex_enter(mp);
+	time_left = expire_time - gethrtime();
+	return (time_left > 0 ? NSEC_TO_TICK(time_left) : -1);
+}
+
+/*
+ * Compatibility wrapper for the cv_timedwait_hires() Illumos interface.
+ */
+static clock_t
+cv_timedwait_hires_common(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim,
+    hrtime_t res, int flag, int state)
+{
+	if (!(flag & CALLOUT_FLAG_ABSOLUTE))
+		tim += gethrtime();
+
+	return (__cv_timedwait_hires(cvp, mp, tim, res, state));
+}
+
+clock_t
+cv_timedwait_hires(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim, hrtime_t res,
+    int flag)
+{
+	return (cv_timedwait_hires_common(cvp, mp, tim, res, flag,
+	    TASK_UNINTERRUPTIBLE));
+}
+EXPORT_SYMBOL(cv_timedwait_hires);
+
+clock_t
+cv_timedwait_sig_hires(kcondvar_t *cvp, kmutex_t *mp, hrtime_t tim,
+    hrtime_t res, int flag)
+{
+	return (cv_timedwait_hires_common(cvp, mp, tim, res, flag,
+	    TASK_INTERRUPTIBLE));
+}
+EXPORT_SYMBOL(cv_timedwait_sig_hires);
+
+void
+__cv_signal(kcondvar_t *cvp)
+{
+	ASSERT(cvp);
+	ASSERT(cvp->cv_magic == CV_MAGIC);
+	atomic_inc(&cvp->cv_refs);
+
+	/*
+	 * All waiters are added with WQ_FLAG_EXCLUSIVE so only one
+	 * waiter will be set runnable with each call to wake_up().
+	 * Additionally wake_up() holds a spin_lock associated with
+	 * the wait queue to ensure we don't race waking up processes.
+	 */
+	if (atomic_read(&cvp->cv_waiters) > 0)
+		wake_up(&cvp->cv_event);
+
+	atomic_dec(&cvp->cv_refs);
+}
+EXPORT_SYMBOL(__cv_signal);
+
+void
+__cv_broadcast(kcondvar_t *cvp)
+{
+	ASSERT(cvp);
+	ASSERT(cvp->cv_magic == CV_MAGIC);
+	atomic_inc(&cvp->cv_refs);
+
+	/*
+	 * Wake_up_all() will wake up all waiters even those which
+	 * have the WQ_FLAG_EXCLUSIVE flag set.
+	 */
+	if (atomic_read(&cvp->cv_waiters) > 0)
+		wake_up_all(&cvp->cv_event);
+
+	atomic_dec(&cvp->cv_refs);
+}
+EXPORT_SYMBOL(__cv_broadcast);
diff --git a/module/os/linux/spl/spl-cred.c b/module/os/linux/spl/spl-cred.c
new file mode 100644
index 000000000..ea3e903f9
--- /dev/null
+++ b/module/os/linux/spl/spl-cred.c
@@ -0,0 +1,200 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Credential Implementation.
+ */
+
+#include <sys/cred.h>
+
+static int
+#ifdef HAVE_KUIDGID_T
+cr_groups_search(const struct group_info *group_info, kgid_t grp)
+#else
+cr_groups_search(const struct group_info *group_info, gid_t grp)
+#endif
+{
+	unsigned int left, right, mid;
+	int cmp;
+
+	if (!group_info)
+		return (0);
+
+	left = 0;
+	right = group_info->ngroups;
+	while (left < right) {
+		mid = (left + right) / 2;
+		cmp = KGID_TO_SGID(grp) -
+		    KGID_TO_SGID(GROUP_AT(group_info, mid));
+
+		if (cmp > 0)
+			left = mid + 1;
+		else if (cmp < 0)
+			right = mid;
+		else
+			return (1);
+	}
+	return (0);
+}
+
+/* Hold a reference on the credential */
+void
+crhold(cred_t *cr)
+{
+	(void) get_cred((const cred_t *)cr);
+}
+
+/* Free a reference on the credential */
+void
+crfree(cred_t *cr)
+{
+	put_cred((const cred_t *)cr);
+}
+
+/* Return the number of supplemental groups */
+int
+crgetngroups(const cred_t *cr)
+{
+	struct group_info *gi;
+	int rc;
+
+	gi = cr->group_info;
+	rc = gi->ngroups;
+#ifndef HAVE_GROUP_INFO_GID
+	/*
+	 * For Linux <= 4.8,
+	 * crgetgroups will only returns gi->blocks[0], which contains only
+	 * the first NGROUPS_PER_BLOCK groups.
+	 */
+	if (rc > NGROUPS_PER_BLOCK) {
+		WARN_ON_ONCE(1);
+		rc = NGROUPS_PER_BLOCK;
+	}
+#endif
+	return (rc);
+}
+
+/*
+ * Return an array of supplemental gids.  The returned address is safe
+ * to use as long as the caller has taken a reference with crhold().
+ *
+ * Linux 4.9 API change, group_info changed from 2d array via ->blocks to 1d
+ * array via ->gid.
+ */
+gid_t *
+crgetgroups(const cred_t *cr)
+{
+	struct group_info *gi;
+	gid_t *gids = NULL;
+
+	gi = cr->group_info;
+#ifdef HAVE_GROUP_INFO_GID
+	gids = KGIDP_TO_SGIDP(gi->gid);
+#else
+	if (gi->nblocks > 0)
+		gids = KGIDP_TO_SGIDP(gi->blocks[0]);
+#endif
+	return (gids);
+}
+
+/* Check if the passed gid is available in supplied credential. */
+int
+groupmember(gid_t gid, const cred_t *cr)
+{
+	struct group_info *gi;
+	int rc;
+
+	gi = cr->group_info;
+	rc = cr_groups_search(gi, SGID_TO_KGID(gid));
+
+	return (rc);
+}
+
+/* Return the effective user id */
+uid_t
+crgetuid(const cred_t *cr)
+{
+	return (KUID_TO_SUID(cr->euid));
+}
+
+/* Return the real user id */
+uid_t
+crgetruid(const cred_t *cr)
+{
+	return (KUID_TO_SUID(cr->uid));
+}
+
+/* Return the saved user id */
+uid_t
+crgetsuid(const cred_t *cr)
+{
+	return (KUID_TO_SUID(cr->suid));
+}
+
+/* Return the filesystem user id */
+uid_t
+crgetfsuid(const cred_t *cr)
+{
+	return (KUID_TO_SUID(cr->fsuid));
+}
+
+/* Return the effective group id */
+gid_t
+crgetgid(const cred_t *cr)
+{
+	return (KGID_TO_SGID(cr->egid));
+}
+
+/* Return the real group id */
+gid_t
+crgetrgid(const cred_t *cr)
+{
+	return (KGID_TO_SGID(cr->gid));
+}
+
+/* Return the saved group id */
+gid_t
+crgetsgid(const cred_t *cr)
+{
+	return (KGID_TO_SGID(cr->sgid));
+}
+
+/* Return the filesystem group id */
+gid_t
+crgetfsgid(const cred_t *cr)
+{
+	return (KGID_TO_SGID(cr->fsgid));
+}
+
+EXPORT_SYMBOL(crhold);
+EXPORT_SYMBOL(crfree);
+EXPORT_SYMBOL(crgetuid);
+EXPORT_SYMBOL(crgetruid);
+EXPORT_SYMBOL(crgetsuid);
+EXPORT_SYMBOL(crgetfsuid);
+EXPORT_SYMBOL(crgetgid);
+EXPORT_SYMBOL(crgetrgid);
+EXPORT_SYMBOL(crgetsgid);
+EXPORT_SYMBOL(crgetfsgid);
+EXPORT_SYMBOL(crgetngroups);
+EXPORT_SYMBOL(crgetgroups);
+EXPORT_SYMBOL(groupmember);
diff --git a/module/os/linux/spl/spl-err.c b/module/os/linux/spl/spl-err.c
new file mode 100644
index 000000000..3c0bb71c0
--- /dev/null
+++ b/module/os/linux/spl/spl-err.c
@@ -0,0 +1,124 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Error Implementation.
+ */
+
+#include <sys/sysmacros.h>
+#include <sys/cmn_err.h>
+
+/*
+ * It is often useful to actually have the panic crash the node so you
+ * can then get notified of the event, get the crashdump for later
+ * analysis and other such goodies.
+ * But we would still default to the current default of not to do that.
+ */
+/* BEGIN CSTYLED */
+unsigned int spl_panic_halt;
+module_param(spl_panic_halt, uint, 0644);
+MODULE_PARM_DESC(spl_panic_halt, "Cause kernel panic on assertion failures");
+/* END CSTYLED */
+
+void
+spl_dumpstack(void)
+{
+	printk("Showing stack for process %d\n", current->pid);
+	dump_stack();
+}
+EXPORT_SYMBOL(spl_dumpstack);
+
+int
+spl_panic(const char *file, const char *func, int line, const char *fmt, ...)
+{
+	const char *newfile;
+	char msg[MAXMSGLEN];
+	va_list ap;
+
+	newfile = strrchr(file, '/');
+	if (newfile != NULL)
+		newfile = newfile + 1;
+	else
+		newfile = file;
+
+	va_start(ap, fmt);
+	(void) vsnprintf(msg, sizeof (msg), fmt, ap);
+	va_end(ap);
+
+	printk(KERN_EMERG "%s", msg);
+	printk(KERN_EMERG "PANIC at %s:%d:%s()\n", newfile, line, func);
+	if (spl_panic_halt)
+		panic("%s", msg);
+
+	spl_dumpstack();
+
+	/* Halt the thread to facilitate further debugging */
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	while (1)
+		schedule();
+
+	/* Unreachable */
+	return (1);
+}
+EXPORT_SYMBOL(spl_panic);
+
+void
+vcmn_err(int ce, const char *fmt, va_list ap)
+{
+	char msg[MAXMSGLEN];
+
+	vsnprintf(msg, MAXMSGLEN, fmt, ap);
+
+	switch (ce) {
+	case CE_IGNORE:
+		break;
+	case CE_CONT:
+		printk("%s", msg);
+		break;
+	case CE_NOTE:
+		printk(KERN_NOTICE "NOTICE: %s\n", msg);
+		break;
+	case CE_WARN:
+		printk(KERN_WARNING "WARNING: %s\n", msg);
+		break;
+	case CE_PANIC:
+		printk(KERN_EMERG "PANIC: %s\n", msg);
+		spl_dumpstack();
+
+		/* Halt the thread to facilitate further debugging */
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		while (1)
+			schedule();
+	}
+} /* vcmn_err() */
+EXPORT_SYMBOL(vcmn_err);
+
+void
+cmn_err(int ce, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vcmn_err(ce, fmt, ap);
+	va_end(ap);
+} /* cmn_err() */
+EXPORT_SYMBOL(cmn_err);
diff --git a/module/os/linux/spl/spl-generic.c b/module/os/linux/spl/spl-generic.c
new file mode 100644
index 000000000..1deb2f444
--- /dev/null
+++ b/module/os/linux/spl/spl-generic.c
@@ -0,0 +1,757 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Generic Implementation.
+ */
+
+#include <sys/sysmacros.h>
+#include <sys/systeminfo.h>
+#include <sys/vmsystm.h>
+#include <sys/kobj.h>
+#include <sys/kmem.h>
+#include <sys/kmem_cache.h>
+#include <sys/vmem.h>
+#include <sys/mutex.h>
+#include <sys/rwlock.h>
+#include <sys/taskq.h>
+#include <sys/tsd.h>
+#include <sys/zmod.h>
+#include <sys/debug.h>
+#include <sys/proc.h>
+#include <sys/kstat.h>
+#include <sys/file.h>
+#include <linux/ctype.h>
+#include <sys/disp.h>
+#include <sys/random.h>
+#include <sys/strings.h>
+#include <linux/kmod.h>
+#include "zfs_gitrev.h"
+
+char spl_gitrev[64] = ZFS_META_GITREV;
+
+/* BEGIN CSTYLED */
+unsigned long spl_hostid = 0;
+EXPORT_SYMBOL(spl_hostid);
+/* BEGIN CSTYLED */
+module_param(spl_hostid, ulong, 0644);
+MODULE_PARM_DESC(spl_hostid, "The system hostid.");
+/* END CSTYLED */
+
+proc_t p0;
+EXPORT_SYMBOL(p0);
+
+/*
+ * Xorshift Pseudo Random Number Generator based on work by Sebastiano Vigna
+ *
+ * "Further scramblings of Marsaglia's xorshift generators"
+ * http://vigna.di.unimi.it/ftp/papers/xorshiftplus.pdf
+ *
+ * random_get_pseudo_bytes() is an API function on Illumos whose sole purpose
+ * is to provide bytes containing random numbers. It is mapped to /dev/urandom
+ * on Illumos, which uses a "FIPS 186-2 algorithm". No user of the SPL's
+ * random_get_pseudo_bytes() needs bytes that are of cryptographic quality, so
+ * we can implement it using a fast PRNG that we seed using Linux' actual
+ * equivalent to random_get_pseudo_bytes(). We do this by providing each CPU
+ * with an independent seed so that all calls to random_get_pseudo_bytes() are
+ * free of atomic instructions.
+ *
+ * A consequence of using a fast PRNG is that using random_get_pseudo_bytes()
+ * to generate words larger than 128 bits will paradoxically be limited to
+ * `2^128 - 1` possibilities. This is because we have a sequence of `2^128 - 1`
+ * 128-bit words and selecting the first will implicitly select the second. If
+ * a caller finds this behavior undesirable, random_get_bytes() should be used
+ * instead.
+ *
+ * XXX: Linux interrupt handlers that trigger within the critical section
+ * formed by `s[1] = xp[1];` and `xp[0] = s[0];` and call this function will
+ * see the same numbers. Nothing in the code currently calls this in an
+ * interrupt handler, so this is considered to be okay. If that becomes a
+ * problem, we could create a set of per-cpu variables for interrupt handlers
+ * and use them when in_interrupt() from linux/preempt_mask.h evaluates to
+ * true.
+ */
+static DEFINE_PER_CPU(uint64_t[2], spl_pseudo_entropy);
+
+/*
+ * spl_rand_next()/spl_rand_jump() are copied from the following CC-0 licensed
+ * file:
+ *
+ * http://xorshift.di.unimi.it/xorshift128plus.c
+ */
+
+static inline uint64_t
+spl_rand_next(uint64_t *s)
+{
+	uint64_t s1 = s[0];
+	const uint64_t s0 = s[1];
+	s[0] = s0;
+	s1 ^= s1 << 23; // a
+	s[1] = s1 ^ s0 ^ (s1 >> 18) ^ (s0 >> 5); // b, c
+	return (s[1] + s0);
+}
+
+static inline void
+spl_rand_jump(uint64_t *s)
+{
+	static const uint64_t JUMP[] =
+	    { 0x8a5cd789635d2dff, 0x121fd2155c472f96 };
+
+	uint64_t s0 = 0;
+	uint64_t s1 = 0;
+	int i, b;
+	for (i = 0; i < sizeof (JUMP) / sizeof (*JUMP); i++)
+		for (b = 0; b < 64; b++) {
+			if (JUMP[i] & 1ULL << b) {
+				s0 ^= s[0];
+				s1 ^= s[1];
+			}
+			(void) spl_rand_next(s);
+		}
+
+	s[0] = s0;
+	s[1] = s1;
+}
+
+int
+random_get_pseudo_bytes(uint8_t *ptr, size_t len)
+{
+	uint64_t *xp, s[2];
+
+	ASSERT(ptr);
+
+	xp = get_cpu_var(spl_pseudo_entropy);
+
+	s[0] = xp[0];
+	s[1] = xp[1];
+
+	while (len) {
+		union {
+			uint64_t ui64;
+			uint8_t byte[sizeof (uint64_t)];
+		}entropy;
+		int i = MIN(len, sizeof (uint64_t));
+
+		len -= i;
+		entropy.ui64 = spl_rand_next(s);
+
+		while (i--)
+			*ptr++ = entropy.byte[i];
+	}
+
+	xp[0] = s[0];
+	xp[1] = s[1];
+
+	put_cpu_var(spl_pseudo_entropy);
+
+	return (0);
+}
+
+
+EXPORT_SYMBOL(random_get_pseudo_bytes);
+
+#if BITS_PER_LONG == 32
+/*
+ * Support 64/64 => 64 division on a 32-bit platform.  While the kernel
+ * provides a div64_u64() function for this we do not use it because the
+ * implementation is flawed.  There are cases which return incorrect
+ * results as late as linux-2.6.35.  Until this is fixed upstream the
+ * spl must provide its own implementation.
+ *
+ * This implementation is a slightly modified version of the algorithm
+ * proposed by the book 'Hacker's Delight'.  The original source can be
+ * found here and is available for use without restriction.
+ *
+ * http://www.hackersdelight.org/HDcode/newCode/divDouble.c
+ */
+
+/*
+ * Calculate number of leading of zeros for a 64-bit value.
+ */
+static int
+nlz64(uint64_t x)
+{
+	register int n = 0;
+
+	if (x == 0)
+		return (64);
+
+	if (x <= 0x00000000FFFFFFFFULL) { n = n + 32; x = x << 32; }
+	if (x <= 0x0000FFFFFFFFFFFFULL) { n = n + 16; x = x << 16; }
+	if (x <= 0x00FFFFFFFFFFFFFFULL) { n = n +  8; x = x <<  8; }
+	if (x <= 0x0FFFFFFFFFFFFFFFULL) { n = n +  4; x = x <<  4; }
+	if (x <= 0x3FFFFFFFFFFFFFFFULL) { n = n +  2; x = x <<  2; }
+	if (x <= 0x7FFFFFFFFFFFFFFFULL) { n = n +  1; }
+
+	return (n);
+}
+
+/*
+ * Newer kernels have a div_u64() function but we define our own
+ * to simplify portability between kernel versions.
+ */
+static inline uint64_t
+__div_u64(uint64_t u, uint32_t v)
+{
+	(void) do_div(u, v);
+	return (u);
+}
+
+/*
+ * Implementation of 64-bit unsigned division for 32-bit machines.
+ *
+ * First the procedure takes care of the case in which the divisor is a
+ * 32-bit quantity. There are two subcases: (1) If the left half of the
+ * dividend is less than the divisor, one execution of do_div() is all that
+ * is required (overflow is not possible). (2) Otherwise it does two
+ * divisions, using the grade school method.
+ */
+uint64_t
+__udivdi3(uint64_t u, uint64_t v)
+{
+	uint64_t u0, u1, v1, q0, q1, k;
+	int n;
+
+	if (v >> 32 == 0) {			// If v < 2**32:
+		if (u >> 32 < v) {		// If u/v cannot overflow,
+			return (__div_u64(u, v)); // just do one division.
+		} else {			// If u/v would overflow:
+			u1 = u >> 32;		// Break u into two halves.
+			u0 = u & 0xFFFFFFFF;
+			q1 = __div_u64(u1, v);	// First quotient digit.
+			k  = u1 - q1 * v;	// First remainder, < v.
+			u0 += (k << 32);
+			q0 = __div_u64(u0, v);	// Seconds quotient digit.
+			return ((q1 << 32) + q0);
+		}
+	} else {				// If v >= 2**32:
+		n = nlz64(v);			// 0 <= n <= 31.
+		v1 = (v << n) >> 32;		// Normalize divisor, MSB is 1.
+		u1 = u >> 1;			// To ensure no overflow.
+		q1 = __div_u64(u1, v1);		// Get quotient from
+		q0 = (q1 << n) >> 31;		// Undo normalization and
+						// division of u by 2.
+		if (q0 != 0)			// Make q0 correct or
+			q0 = q0 - 1;		// too small by 1.
+		if ((u - q0 * v) >= v)
+			q0 = q0 + 1;		// Now q0 is correct.
+
+		return (q0);
+	}
+}
+EXPORT_SYMBOL(__udivdi3);
+
+/* BEGIN CSTYLED */
+#ifndef abs64
+#define	abs64(x)	({ uint64_t t = (x) >> 63; ((x) ^ t) - t; })
+#endif
+/* END CSTYLED */
+
+/*
+ * Implementation of 64-bit signed division for 32-bit machines.
+ */
+int64_t
+__divdi3(int64_t u, int64_t v)
+{
+	int64_t q, t;
+	q = __udivdi3(abs64(u), abs64(v));
+	t = (u ^ v) >> 63;	// If u, v have different
+	return ((q ^ t) - t);	// signs, negate q.
+}
+EXPORT_SYMBOL(__divdi3);
+
+/*
+ * Implementation of 64-bit unsigned modulo for 32-bit machines.
+ */
+uint64_t
+__umoddi3(uint64_t dividend, uint64_t divisor)
+{
+	return (dividend - (divisor * __udivdi3(dividend, divisor)));
+}
+EXPORT_SYMBOL(__umoddi3);
+
+/*
+ * Implementation of 64-bit unsigned division/modulo for 32-bit machines.
+ */
+uint64_t
+__udivmoddi4(uint64_t n, uint64_t d, uint64_t *r)
+{
+	uint64_t q = __udivdi3(n, d);
+	if (r)
+		*r = n - d * q;
+	return (q);
+}
+EXPORT_SYMBOL(__udivmoddi4);
+
+/*
+ * Implementation of 64-bit signed division/modulo for 32-bit machines.
+ */
+int64_t
+__divmoddi4(int64_t n, int64_t d, int64_t *r)
+{
+	int64_t q, rr;
+	boolean_t nn = B_FALSE;
+	boolean_t nd = B_FALSE;
+	if (n < 0) {
+		nn = B_TRUE;
+		n = -n;
+	}
+	if (d < 0) {
+		nd = B_TRUE;
+		d = -d;
+	}
+
+	q = __udivmoddi4(n, d, (uint64_t *)&rr);
+
+	if (nn != nd)
+		q = -q;
+	if (nn)
+		rr = -rr;
+	if (r)
+		*r = rr;
+	return (q);
+}
+EXPORT_SYMBOL(__divmoddi4);
+
+#if defined(__arm) || defined(__arm__)
+/*
+ * Implementation of 64-bit (un)signed division for 32-bit arm machines.
+ *
+ * Run-time ABI for the ARM Architecture (page 20).  A pair of (unsigned)
+ * long longs is returned in {{r0, r1}, {r2,r3}}, the quotient in {r0, r1},
+ * and the remainder in {r2, r3}.  The return type is specifically left
+ * set to 'void' to ensure the compiler does not overwrite these registers
+ * during the return.  All results are in registers as per ABI
+ */
+void
+__aeabi_uldivmod(uint64_t u, uint64_t v)
+{
+	uint64_t res;
+	uint64_t mod;
+
+	res = __udivdi3(u, v);
+	mod = __umoddi3(u, v);
+	{
+		register uint32_t r0 asm("r0") = (res & 0xFFFFFFFF);
+		register uint32_t r1 asm("r1") = (res >> 32);
+		register uint32_t r2 asm("r2") = (mod & 0xFFFFFFFF);
+		register uint32_t r3 asm("r3") = (mod >> 32);
+
+		/* BEGIN CSTYLED */
+		asm volatile(""
+		    : "+r"(r0), "+r"(r1), "+r"(r2),"+r"(r3)  /* output */
+		    : "r"(r0), "r"(r1), "r"(r2), "r"(r3));   /* input */
+		/* END CSTYLED */
+
+		return; /* r0; */
+	}
+}
+EXPORT_SYMBOL(__aeabi_uldivmod);
+
+void
+__aeabi_ldivmod(int64_t u, int64_t v)
+{
+	int64_t res;
+	uint64_t mod;
+
+	res =  __divdi3(u, v);
+	mod = __umoddi3(u, v);
+	{
+		register uint32_t r0 asm("r0") = (res & 0xFFFFFFFF);
+		register uint32_t r1 asm("r1") = (res >> 32);
+		register uint32_t r2 asm("r2") = (mod & 0xFFFFFFFF);
+		register uint32_t r3 asm("r3") = (mod >> 32);
+
+		/* BEGIN CSTYLED */
+		asm volatile(""
+		    : "+r"(r0), "+r"(r1), "+r"(r2),"+r"(r3)  /* output */
+		    : "r"(r0), "r"(r1), "r"(r2), "r"(r3));   /* input */
+		/* END CSTYLED */
+
+		return; /* r0; */
+	}
+}
+EXPORT_SYMBOL(__aeabi_ldivmod);
+#endif /* __arm || __arm__ */
+#endif /* BITS_PER_LONG */
+
+/*
+ * NOTE: The strtoxx behavior is solely based on my reading of the Solaris
+ * ddi_strtol(9F) man page.  I have not verified the behavior of these
+ * functions against their Solaris counterparts.  It is possible that I
+ * may have misinterpreted the man page or the man page is incorrect.
+ */
+int ddi_strtoul(const char *, char **, int, unsigned long *);
+int ddi_strtol(const char *, char **, int, long *);
+int ddi_strtoull(const char *, char **, int, unsigned long long *);
+int ddi_strtoll(const char *, char **, int, long long *);
+
+#define	define_ddi_strtoux(type, valtype)				\
+int ddi_strtou##type(const char *str, char **endptr,			\
+    int base, valtype *result)						\
+{									\
+	valtype last_value, value = 0;					\
+	char *ptr = (char *)str;					\
+	int flag = 1, digit;						\
+									\
+	if (strlen(ptr) == 0)						\
+		return (EINVAL);					\
+									\
+	/* Auto-detect base based on prefix */				\
+	if (!base) {							\
+		if (str[0] == '0') {					\
+			if (tolower(str[1]) == 'x' && isxdigit(str[2])) { \
+				base = 16; /* hex */			\
+				ptr += 2;				\
+			} else if (str[1] >= '0' && str[1] < 8) {	\
+				base = 8; /* octal */			\
+				ptr += 1;				\
+			} else {					\
+				return (EINVAL);			\
+			}						\
+		} else {						\
+			base = 10; /* decimal */			\
+		}							\
+	}								\
+									\
+	while (1) {							\
+		if (isdigit(*ptr))					\
+			digit = *ptr - '0';				\
+		else if (isalpha(*ptr))					\
+			digit = tolower(*ptr) - 'a' + 10;		\
+		else							\
+			break;						\
+									\
+		if (digit >= base)					\
+			break;						\
+									\
+		last_value = value;					\
+		value = value * base + digit;				\
+		if (last_value > value) /* Overflow */			\
+			return (ERANGE);				\
+									\
+		flag = 1;						\
+		ptr++;							\
+	}								\
+									\
+	if (flag)							\
+		*result = value;					\
+									\
+	if (endptr)							\
+		*endptr = (char *)(flag ? ptr : str);			\
+									\
+	return (0);							\
+}									\
+
+#define	define_ddi_strtox(type, valtype)				\
+int ddi_strto##type(const char *str, char **endptr,			\
+    int base, valtype *result)						\
+{									\
+	int rc;								\
+									\
+	if (*str == '-') {						\
+		rc = ddi_strtou##type(str + 1, endptr, base, result);	\
+		if (!rc) {						\
+			if (*endptr == str + 1)				\
+				*endptr = (char *)str;			\
+			else						\
+				*result = -*result;			\
+		}							\
+	} else {							\
+		rc = ddi_strtou##type(str, endptr, base, result);	\
+	}								\
+									\
+	return (rc);							\
+}
+
+define_ddi_strtoux(l, unsigned long)
+define_ddi_strtox(l, long)
+define_ddi_strtoux(ll, unsigned long long)
+define_ddi_strtox(ll, long long)
+
+EXPORT_SYMBOL(ddi_strtoul);
+EXPORT_SYMBOL(ddi_strtol);
+EXPORT_SYMBOL(ddi_strtoll);
+EXPORT_SYMBOL(ddi_strtoull);
+
+int
+ddi_copyin(const void *from, void *to, size_t len, int flags)
+{
+	/* Fake ioctl() issued by kernel, 'from' is a kernel address */
+	if (flags & FKIOCTL) {
+		memcpy(to, from, len);
+		return (0);
+	}
+
+	return (copyin(from, to, len));
+}
+EXPORT_SYMBOL(ddi_copyin);
+
+int
+ddi_copyout(const void *from, void *to, size_t len, int flags)
+{
+	/* Fake ioctl() issued by kernel, 'from' is a kernel address */
+	if (flags & FKIOCTL) {
+		memcpy(to, from, len);
+		return (0);
+	}
+
+	return (copyout(from, to, len));
+}
+EXPORT_SYMBOL(ddi_copyout);
+
+/*
+ * Read the unique system identifier from the /etc/hostid file.
+ *
+ * The behavior of /usr/bin/hostid on Linux systems with the
+ * regular eglibc and coreutils is:
+ *
+ *   1. Generate the value if the /etc/hostid file does not exist
+ *      or if the /etc/hostid file is less than four bytes in size.
+ *
+ *   2. If the /etc/hostid file is at least 4 bytes, then return
+ *      the first four bytes [0..3] in native endian order.
+ *
+ *   3. Always ignore bytes [4..] if they exist in the file.
+ *
+ * Only the first four bytes are significant, even on systems that
+ * have a 64-bit word size.
+ *
+ * See:
+ *
+ *   eglibc: sysdeps/unix/sysv/linux/gethostid.c
+ *   coreutils: src/hostid.c
+ *
+ * Notes:
+ *
+ * The /etc/hostid file on Solaris is a text file that often reads:
+ *
+ *   # DO NOT EDIT
+ *   "0123456789"
+ *
+ * Directly copying this file to Linux results in a constant
+ * hostid of 4f442023 because the default comment constitutes
+ * the first four bytes of the file.
+ *
+ */
+
+char *spl_hostid_path = HW_HOSTID_PATH;
+module_param(spl_hostid_path, charp, 0444);
+MODULE_PARM_DESC(spl_hostid_path, "The system hostid file (/etc/hostid)");
+
+static int
+hostid_read(uint32_t *hostid)
+{
+	uint64_t size;
+	struct _buf *file;
+	uint32_t value = 0;
+	int error;
+
+	file = kobj_open_file(spl_hostid_path);
+	if (file == (struct _buf *)-1)
+		return (ENOENT);
+
+	error = kobj_get_filesize(file, &size);
+	if (error) {
+		kobj_close_file(file);
+		return (error);
+	}
+
+	if (size < sizeof (HW_HOSTID_MASK)) {
+		kobj_close_file(file);
+		return (EINVAL);
+	}
+
+	/*
+	 * Read directly into the variable like eglibc does.
+	 * Short reads are okay; native behavior is preserved.
+	 */
+	error = kobj_read_file(file, (char *)&value, sizeof (value), 0);
+	if (error < 0) {
+		kobj_close_file(file);
+		return (EIO);
+	}
+
+	/* Mask down to 32 bits like coreutils does. */
+	*hostid = (value & HW_HOSTID_MASK);
+	kobj_close_file(file);
+
+	return (0);
+}
+
+/*
+ * Return the system hostid.  Preferentially use the spl_hostid module option
+ * when set, otherwise use the value in the /etc/hostid file.
+ */
+uint32_t
+zone_get_hostid(void *zone)
+{
+	uint32_t hostid;
+
+	ASSERT3P(zone, ==, NULL);
+
+	if (spl_hostid != 0)
+		return ((uint32_t)(spl_hostid & HW_HOSTID_MASK));
+
+	if (hostid_read(&hostid) == 0)
+		return (hostid);
+
+	return (0);
+}
+EXPORT_SYMBOL(zone_get_hostid);
+
+static int
+spl_kvmem_init(void)
+{
+	int rc = 0;
+
+	rc = spl_kmem_init();
+	if (rc)
+		return (rc);
+
+	rc = spl_vmem_init();
+	if (rc) {
+		spl_kmem_fini();
+		return (rc);
+	}
+
+	return (rc);
+}
+
+/*
+ * We initialize the random number generator with 128 bits of entropy from the
+ * system random number generator. In the improbable case that we have a zero
+ * seed, we fallback to the system jiffies, unless it is also zero, in which
+ * situation we use a preprogrammed seed. We step forward by 2^64 iterations to
+ * initialize each of the per-cpu seeds so that the sequences generated on each
+ * CPU are guaranteed to never overlap in practice.
+ */
+static void __init
+spl_random_init(void)
+{
+	uint64_t s[2];
+	int i;
+
+	get_random_bytes(s, sizeof (s));
+
+	if (s[0] == 0 && s[1] == 0) {
+		if (jiffies != 0) {
+			s[0] = jiffies;
+			s[1] = ~0 - jiffies;
+		} else {
+			(void) memcpy(s, "improbable seed", sizeof (s));
+		}
+		printk("SPL: get_random_bytes() returned 0 "
+		    "when generating random seed. Setting initial seed to "
+		    "0x%016llx%016llx.\n", cpu_to_be64(s[0]),
+		    cpu_to_be64(s[1]));
+	}
+
+	for_each_possible_cpu(i) {
+		uint64_t *wordp = per_cpu(spl_pseudo_entropy, i);
+
+		spl_rand_jump(s);
+
+		wordp[0] = s[0];
+		wordp[1] = s[1];
+	}
+}
+
+static void
+spl_kvmem_fini(void)
+{
+	spl_vmem_fini();
+	spl_kmem_fini();
+}
+
+static int __init
+spl_init(void)
+{
+	int rc = 0;
+
+	bzero(&p0, sizeof (proc_t));
+	spl_random_init();
+
+	if ((rc = spl_kvmem_init()))
+		goto out1;
+
+	if ((rc = spl_tsd_init()))
+		goto out2;
+
+	if ((rc = spl_taskq_init()))
+		goto out3;
+
+	if ((rc = spl_kmem_cache_init()))
+		goto out4;
+
+	if ((rc = spl_vn_init()))
+		goto out5;
+
+	if ((rc = spl_proc_init()))
+		goto out6;
+
+	if ((rc = spl_kstat_init()))
+		goto out7;
+
+	if ((rc = spl_zlib_init()))
+		goto out8;
+
+	return (rc);
+
+out8:
+	spl_kstat_fini();
+out7:
+	spl_proc_fini();
+out6:
+	spl_vn_fini();
+out5:
+	spl_kmem_cache_fini();
+out4:
+	spl_taskq_fini();
+out3:
+	spl_tsd_fini();
+out2:
+	spl_kvmem_fini();
+out1:
+	return (rc);
+}
+
+static void __exit
+spl_fini(void)
+{
+	spl_zlib_fini();
+	spl_kstat_fini();
+	spl_proc_fini();
+	spl_vn_fini();
+	spl_kmem_cache_fini();
+	spl_taskq_fini();
+	spl_tsd_fini();
+	spl_kvmem_fini();
+}
+
+module_init(spl_init);
+module_exit(spl_fini);
+
+MODULE_DESCRIPTION("Solaris Porting Layer");
+MODULE_AUTHOR(ZFS_META_AUTHOR);
+MODULE_LICENSE("GPL");
+MODULE_VERSION(ZFS_META_VERSION "-" ZFS_META_RELEASE);
diff --git a/module/os/linux/spl/spl-kmem-cache.c b/module/os/linux/spl/spl-kmem-cache.c
new file mode 100644
index 000000000..b39867b03
--- /dev/null
+++ b/module/os/linux/spl/spl-kmem-cache.c
@@ -0,0 +1,1780 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <sys/kmem.h>
+#include <sys/kmem_cache.h>
+#include <sys/shrinker.h>
+#include <sys/taskq.h>
+#include <sys/timer.h>
+#include <sys/vmem.h>
+#include <sys/wait.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/prefetch.h>
+
+/*
+ * Within the scope of spl-kmem.c file the kmem_cache_* definitions
+ * are removed to allow access to the real Linux slab allocator.
+ */
+#undef kmem_cache_destroy
+#undef kmem_cache_create
+#undef kmem_cache_alloc
+#undef kmem_cache_free
+
+
+/*
+ * Linux 3.16 replaced smp_mb__{before,after}_{atomic,clear}_{dec,inc,bit}()
+ * with smp_mb__{before,after}_atomic() because they were redundant. This is
+ * only used inside our SLAB allocator, so we implement an internal wrapper
+ * here to give us smp_mb__{before,after}_atomic() on older kernels.
+ */
+#ifndef smp_mb__before_atomic
+#define	smp_mb__before_atomic(x) smp_mb__before_clear_bit(x)
+#endif
+
+#ifndef smp_mb__after_atomic
+#define	smp_mb__after_atomic(x) smp_mb__after_clear_bit(x)
+#endif
+
+/*
+ * Cache expiration was implemented because it was part of the default Solaris
+ * kmem_cache behavior.  The idea is that per-cpu objects which haven't been
+ * accessed in several seconds should be returned to the cache.  On the other
+ * hand Linux slabs never move objects back to the slabs unless there is
+ * memory pressure on the system.  By default the Linux method is enabled
+ * because it has been shown to improve responsiveness on low memory systems.
+ * This policy may be changed by setting KMC_EXPIRE_AGE or KMC_EXPIRE_MEM.
+ */
+/* BEGIN CSTYLED */
+unsigned int spl_kmem_cache_expire = KMC_EXPIRE_MEM;
+EXPORT_SYMBOL(spl_kmem_cache_expire);
+module_param(spl_kmem_cache_expire, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_expire, "By age (0x1) or low memory (0x2)");
+
+/*
+ * Cache magazines are an optimization designed to minimize the cost of
+ * allocating memory.  They do this by keeping a per-cpu cache of recently
+ * freed objects, which can then be reallocated without taking a lock. This
+ * can improve performance on highly contended caches.  However, because
+ * objects in magazines will prevent otherwise empty slabs from being
+ * immediately released this may not be ideal for low memory machines.
+ *
+ * For this reason spl_kmem_cache_magazine_size can be used to set a maximum
+ * magazine size.  When this value is set to 0 the magazine size will be
+ * automatically determined based on the object size.  Otherwise magazines
+ * will be limited to 2-256 objects per magazine (i.e per cpu).  Magazines
+ * may never be entirely disabled in this implementation.
+ */
+unsigned int spl_kmem_cache_magazine_size = 0;
+module_param(spl_kmem_cache_magazine_size, uint, 0444);
+MODULE_PARM_DESC(spl_kmem_cache_magazine_size,
+	"Default magazine size (2-256), set automatically (0)");
+
+/*
+ * The default behavior is to report the number of objects remaining in the
+ * cache.  This allows the Linux VM to repeatedly reclaim objects from the
+ * cache when memory is low satisfy other memory allocations.  Alternately,
+ * setting this value to KMC_RECLAIM_ONCE limits how aggressively the cache
+ * is reclaimed.  This may increase the likelihood of out of memory events.
+ */
+unsigned int spl_kmem_cache_reclaim = 0 /* KMC_RECLAIM_ONCE */;
+module_param(spl_kmem_cache_reclaim, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_reclaim, "Single reclaim pass (0x1)");
+
+unsigned int spl_kmem_cache_obj_per_slab = SPL_KMEM_CACHE_OBJ_PER_SLAB;
+module_param(spl_kmem_cache_obj_per_slab, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_obj_per_slab, "Number of objects per slab");
+
+unsigned int spl_kmem_cache_obj_per_slab_min = SPL_KMEM_CACHE_OBJ_PER_SLAB_MIN;
+module_param(spl_kmem_cache_obj_per_slab_min, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_obj_per_slab_min,
+	"Minimal number of objects per slab");
+
+unsigned int spl_kmem_cache_max_size = SPL_KMEM_CACHE_MAX_SIZE;
+module_param(spl_kmem_cache_max_size, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_max_size, "Maximum size of slab in MB");
+
+/*
+ * For small objects the Linux slab allocator should be used to make the most
+ * efficient use of the memory.  However, large objects are not supported by
+ * the Linux slab and therefore the SPL implementation is preferred.  A cutoff
+ * of 16K was determined to be optimal for architectures using 4K pages.
+ */
+#if PAGE_SIZE == 4096
+unsigned int spl_kmem_cache_slab_limit = 16384;
+#else
+unsigned int spl_kmem_cache_slab_limit = 0;
+#endif
+module_param(spl_kmem_cache_slab_limit, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_slab_limit,
+	"Objects less than N bytes use the Linux slab");
+
+/*
+ * This value defaults to a threshold designed to avoid allocations which
+ * have been deemed costly by the kernel.
+ */
+unsigned int spl_kmem_cache_kmem_limit =
+	((1 << (PAGE_ALLOC_COSTLY_ORDER - 1)) * PAGE_SIZE) /
+	SPL_KMEM_CACHE_OBJ_PER_SLAB;
+module_param(spl_kmem_cache_kmem_limit, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_cache_kmem_limit,
+	"Objects less than N bytes use the kmalloc");
+
+/*
+ * The number of threads available to allocate new slabs for caches.  This
+ * should not need to be tuned but it is available for performance analysis.
+ */
+unsigned int spl_kmem_cache_kmem_threads = 4;
+module_param(spl_kmem_cache_kmem_threads, uint, 0444);
+MODULE_PARM_DESC(spl_kmem_cache_kmem_threads,
+	"Number of spl_kmem_cache threads");
+/* END CSTYLED */
+
+/*
+ * Slab allocation interfaces
+ *
+ * While the Linux slab implementation was inspired by the Solaris
+ * implementation I cannot use it to emulate the Solaris APIs.  I
+ * require two features which are not provided by the Linux slab.
+ *
+ * 1) Constructors AND destructors.  Recent versions of the Linux
+ *    kernel have removed support for destructors.  This is a deal
+ *    breaker for the SPL which contains particularly expensive
+ *    initializers for mutex's, condition variables, etc.  We also
+ *    require a minimal level of cleanup for these data types unlike
+ *    many Linux data types which do need to be explicitly destroyed.
+ *
+ * 2) Virtual address space backed slab.  Callers of the Solaris slab
+ *    expect it to work well for both small are very large allocations.
+ *    Because of memory fragmentation the Linux slab which is backed
+ *    by kmalloc'ed memory performs very badly when confronted with
+ *    large numbers of large allocations.  Basing the slab on the
+ *    virtual address space removes the need for contiguous pages
+ *    and greatly improve performance for large allocations.
+ *
+ * For these reasons, the SPL has its own slab implementation with
+ * the needed features.  It is not as highly optimized as either the
+ * Solaris or Linux slabs, but it should get me most of what is
+ * needed until it can be optimized or obsoleted by another approach.
+ *
+ * One serious concern I do have about this method is the relatively
+ * small virtual address space on 32bit arches.  This will seriously
+ * constrain the size of the slab caches and their performance.
+ */
+
+struct list_head spl_kmem_cache_list;   /* List of caches */
+struct rw_semaphore spl_kmem_cache_sem; /* Cache list lock */
+taskq_t *spl_kmem_cache_taskq;		/* Task queue for aging / reclaim */
+
+static void spl_cache_shrink(spl_kmem_cache_t *skc, void *obj);
+
+SPL_SHRINKER_CALLBACK_FWD_DECLARE(spl_kmem_cache_generic_shrinker);
+SPL_SHRINKER_DECLARE(spl_kmem_cache_shrinker,
+	spl_kmem_cache_generic_shrinker, KMC_DEFAULT_SEEKS);
+
+static void *
+kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
+{
+	gfp_t lflags = kmem_flags_convert(flags);
+	void *ptr;
+
+	if (skc->skc_flags & KMC_KMEM) {
+		ASSERT(ISP2(size));
+		ptr = (void *)__get_free_pages(lflags, get_order(size));
+	} else {
+		ptr = __vmalloc(size, lflags | __GFP_HIGHMEM, PAGE_KERNEL);
+	}
+
+	/* Resulting allocated memory will be page aligned */
+	ASSERT(IS_P2ALIGNED(ptr, PAGE_SIZE));
+
+	return (ptr);
+}
+
+static void
+kv_free(spl_kmem_cache_t *skc, void *ptr, int size)
+{
+	ASSERT(IS_P2ALIGNED(ptr, PAGE_SIZE));
+
+	/*
+	 * The Linux direct reclaim path uses this out of band value to
+	 * determine if forward progress is being made.  Normally this is
+	 * incremented by kmem_freepages() which is part of the various
+	 * Linux slab implementations.  However, since we are using none
+	 * of that infrastructure we are responsible for incrementing it.
+	 */
+	if (current->reclaim_state)
+		current->reclaim_state->reclaimed_slab += size >> PAGE_SHIFT;
+
+	if (skc->skc_flags & KMC_KMEM) {
+		ASSERT(ISP2(size));
+		free_pages((unsigned long)ptr, get_order(size));
+	} else {
+		vfree(ptr);
+	}
+}
+
+/*
+ * Required space for each aligned sks.
+ */
+static inline uint32_t
+spl_sks_size(spl_kmem_cache_t *skc)
+{
+	return (P2ROUNDUP_TYPED(sizeof (spl_kmem_slab_t),
+	    skc->skc_obj_align, uint32_t));
+}
+
+/*
+ * Required space for each aligned object.
+ */
+static inline uint32_t
+spl_obj_size(spl_kmem_cache_t *skc)
+{
+	uint32_t align = skc->skc_obj_align;
+
+	return (P2ROUNDUP_TYPED(skc->skc_obj_size, align, uint32_t) +
+	    P2ROUNDUP_TYPED(sizeof (spl_kmem_obj_t), align, uint32_t));
+}
+
+/*
+ * Lookup the spl_kmem_object_t for an object given that object.
+ */
+static inline spl_kmem_obj_t *
+spl_sko_from_obj(spl_kmem_cache_t *skc, void *obj)
+{
+	return (obj + P2ROUNDUP_TYPED(skc->skc_obj_size,
+	    skc->skc_obj_align, uint32_t));
+}
+
+/*
+ * Required space for each offslab object taking in to account alignment
+ * restrictions and the power-of-two requirement of kv_alloc().
+ */
+static inline uint32_t
+spl_offslab_size(spl_kmem_cache_t *skc)
+{
+	return (1UL << (fls64(spl_obj_size(skc)) + 1));
+}
+
+/*
+ * It's important that we pack the spl_kmem_obj_t structure and the
+ * actual objects in to one large address space to minimize the number
+ * of calls to the allocator.  It is far better to do a few large
+ * allocations and then subdivide it ourselves.  Now which allocator
+ * we use requires balancing a few trade offs.
+ *
+ * For small objects we use kmem_alloc() because as long as you are
+ * only requesting a small number of pages (ideally just one) its cheap.
+ * However, when you start requesting multiple pages with kmem_alloc()
+ * it gets increasingly expensive since it requires contiguous pages.
+ * For this reason we shift to vmem_alloc() for slabs of large objects
+ * which removes the need for contiguous pages.  We do not use
+ * vmem_alloc() in all cases because there is significant locking
+ * overhead in __get_vm_area_node().  This function takes a single
+ * global lock when acquiring an available virtual address range which
+ * serializes all vmem_alloc()'s for all slab caches.  Using slightly
+ * different allocation functions for small and large objects should
+ * give us the best of both worlds.
+ *
+ * KMC_ONSLAB                       KMC_OFFSLAB
+ *
+ * +------------------------+       +-----------------+
+ * | spl_kmem_slab_t --+-+  |       | spl_kmem_slab_t |---+-+
+ * | skc_obj_size    <-+ |  |       +-----------------+   | |
+ * | spl_kmem_obj_t      |  |                             | |
+ * | skc_obj_size    <---+  |       +-----------------+   | |
+ * | spl_kmem_obj_t      |  |       | skc_obj_size    | <-+ |
+ * | ...                 v  |       | spl_kmem_obj_t  |     |
+ * +------------------------+       +-----------------+     v
+ */
+static spl_kmem_slab_t *
+spl_slab_alloc(spl_kmem_cache_t *skc, int flags)
+{
+	spl_kmem_slab_t *sks;
+	spl_kmem_obj_t *sko, *n;
+	void *base, *obj;
+	uint32_t obj_size, offslab_size = 0;
+	int i,  rc = 0;
+
+	base = kv_alloc(skc, skc->skc_slab_size, flags);
+	if (base == NULL)
+		return (NULL);
+
+	sks = (spl_kmem_slab_t *)base;
+	sks->sks_magic = SKS_MAGIC;
+	sks->sks_objs = skc->skc_slab_objs;
+	sks->sks_age = jiffies;
+	sks->sks_cache = skc;
+	INIT_LIST_HEAD(&sks->sks_list);
+	INIT_LIST_HEAD(&sks->sks_free_list);
+	sks->sks_ref = 0;
+	obj_size = spl_obj_size(skc);
+
+	if (skc->skc_flags & KMC_OFFSLAB)
+		offslab_size = spl_offslab_size(skc);
+
+	for (i = 0; i < sks->sks_objs; i++) {
+		if (skc->skc_flags & KMC_OFFSLAB) {
+			obj = kv_alloc(skc, offslab_size, flags);
+			if (!obj) {
+				rc = -ENOMEM;
+				goto out;
+			}
+		} else {
+			obj = base + spl_sks_size(skc) + (i * obj_size);
+		}
+
+		ASSERT(IS_P2ALIGNED(obj, skc->skc_obj_align));
+		sko = spl_sko_from_obj(skc, obj);
+		sko->sko_addr = obj;
+		sko->sko_magic = SKO_MAGIC;
+		sko->sko_slab = sks;
+		INIT_LIST_HEAD(&sko->sko_list);
+		list_add_tail(&sko->sko_list, &sks->sks_free_list);
+	}
+
+out:
+	if (rc) {
+		if (skc->skc_flags & KMC_OFFSLAB)
+			list_for_each_entry_safe(sko,
+			    n, &sks->sks_free_list, sko_list) {
+				kv_free(skc, sko->sko_addr, offslab_size);
+			}
+
+		kv_free(skc, base, skc->skc_slab_size);
+		sks = NULL;
+	}
+
+	return (sks);
+}
+
+/*
+ * Remove a slab from complete or partial list, it must be called with
+ * the 'skc->skc_lock' held but the actual free must be performed
+ * outside the lock to prevent deadlocking on vmem addresses.
+ */
+static void
+spl_slab_free(spl_kmem_slab_t *sks,
+    struct list_head *sks_list, struct list_head *sko_list)
+{
+	spl_kmem_cache_t *skc;
+
+	ASSERT(sks->sks_magic == SKS_MAGIC);
+	ASSERT(sks->sks_ref == 0);
+
+	skc = sks->sks_cache;
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+
+	/*
+	 * Update slab/objects counters in the cache, then remove the
+	 * slab from the skc->skc_partial_list.  Finally add the slab
+	 * and all its objects in to the private work lists where the
+	 * destructors will be called and the memory freed to the system.
+	 */
+	skc->skc_obj_total -= sks->sks_objs;
+	skc->skc_slab_total--;
+	list_del(&sks->sks_list);
+	list_add(&sks->sks_list, sks_list);
+	list_splice_init(&sks->sks_free_list, sko_list);
+}
+
+/*
+ * Reclaim empty slabs at the end of the partial list.
+ */
+static void
+spl_slab_reclaim(spl_kmem_cache_t *skc)
+{
+	spl_kmem_slab_t *sks, *m;
+	spl_kmem_obj_t *sko, *n;
+	LIST_HEAD(sks_list);
+	LIST_HEAD(sko_list);
+	uint32_t size = 0;
+
+	/*
+	 * Empty slabs and objects must be moved to a private list so they
+	 * can be safely freed outside the spin lock.  All empty slabs are
+	 * at the end of skc->skc_partial_list, therefore once a non-empty
+	 * slab is found we can stop scanning.
+	 */
+	spin_lock(&skc->skc_lock);
+	list_for_each_entry_safe_reverse(sks, m,
+	    &skc->skc_partial_list, sks_list) {
+
+		if (sks->sks_ref > 0)
+			break;
+
+		spl_slab_free(sks, &sks_list, &sko_list);
+	}
+	spin_unlock(&skc->skc_lock);
+
+	/*
+	 * The following two loops ensure all the object destructors are
+	 * run, any offslab objects are freed, and the slabs themselves
+	 * are freed.  This is all done outside the skc->skc_lock since
+	 * this allows the destructor to sleep, and allows us to perform
+	 * a conditional reschedule when a freeing a large number of
+	 * objects and slabs back to the system.
+	 */
+	if (skc->skc_flags & KMC_OFFSLAB)
+		size = spl_offslab_size(skc);
+
+	list_for_each_entry_safe(sko, n, &sko_list, sko_list) {
+		ASSERT(sko->sko_magic == SKO_MAGIC);
+
+		if (skc->skc_flags & KMC_OFFSLAB)
+			kv_free(skc, sko->sko_addr, size);
+	}
+
+	list_for_each_entry_safe(sks, m, &sks_list, sks_list) {
+		ASSERT(sks->sks_magic == SKS_MAGIC);
+		kv_free(skc, sks, skc->skc_slab_size);
+	}
+}
+
+static spl_kmem_emergency_t *
+spl_emergency_search(struct rb_root *root, void *obj)
+{
+	struct rb_node *node = root->rb_node;
+	spl_kmem_emergency_t *ske;
+	unsigned long address = (unsigned long)obj;
+
+	while (node) {
+		ske = container_of(node, spl_kmem_emergency_t, ske_node);
+
+		if (address < ske->ske_obj)
+			node = node->rb_left;
+		else if (address > ske->ske_obj)
+			node = node->rb_right;
+		else
+			return (ske);
+	}
+
+	return (NULL);
+}
+
+static int
+spl_emergency_insert(struct rb_root *root, spl_kmem_emergency_t *ske)
+{
+	struct rb_node **new = &(root->rb_node), *parent = NULL;
+	spl_kmem_emergency_t *ske_tmp;
+	unsigned long address = ske->ske_obj;
+
+	while (*new) {
+		ske_tmp = container_of(*new, spl_kmem_emergency_t, ske_node);
+
+		parent = *new;
+		if (address < ske_tmp->ske_obj)
+			new = &((*new)->rb_left);
+		else if (address > ske_tmp->ske_obj)
+			new = &((*new)->rb_right);
+		else
+			return (0);
+	}
+
+	rb_link_node(&ske->ske_node, parent, new);
+	rb_insert_color(&ske->ske_node, root);
+
+	return (1);
+}
+
+/*
+ * Allocate a single emergency object and track it in a red black tree.
+ */
+static int
+spl_emergency_alloc(spl_kmem_cache_t *skc, int flags, void **obj)
+{
+	gfp_t lflags = kmem_flags_convert(flags);
+	spl_kmem_emergency_t *ske;
+	int order = get_order(skc->skc_obj_size);
+	int empty;
+
+	/* Last chance use a partial slab if one now exists */
+	spin_lock(&skc->skc_lock);
+	empty = list_empty(&skc->skc_partial_list);
+	spin_unlock(&skc->skc_lock);
+	if (!empty)
+		return (-EEXIST);
+
+	ske = kmalloc(sizeof (*ske), lflags);
+	if (ske == NULL)
+		return (-ENOMEM);
+
+	ske->ske_obj = __get_free_pages(lflags, order);
+	if (ske->ske_obj == 0) {
+		kfree(ske);
+		return (-ENOMEM);
+	}
+
+	spin_lock(&skc->skc_lock);
+	empty = spl_emergency_insert(&skc->skc_emergency_tree, ske);
+	if (likely(empty)) {
+		skc->skc_obj_total++;
+		skc->skc_obj_emergency++;
+		if (skc->skc_obj_emergency > skc->skc_obj_emergency_max)
+			skc->skc_obj_emergency_max = skc->skc_obj_emergency;
+	}
+	spin_unlock(&skc->skc_lock);
+
+	if (unlikely(!empty)) {
+		free_pages(ske->ske_obj, order);
+		kfree(ske);
+		return (-EINVAL);
+	}
+
+	*obj = (void *)ske->ske_obj;
+
+	return (0);
+}
+
+/*
+ * Locate the passed object in the red black tree and free it.
+ */
+static int
+spl_emergency_free(spl_kmem_cache_t *skc, void *obj)
+{
+	spl_kmem_emergency_t *ske;
+	int order = get_order(skc->skc_obj_size);
+
+	spin_lock(&skc->skc_lock);
+	ske = spl_emergency_search(&skc->skc_emergency_tree, obj);
+	if (ske) {
+		rb_erase(&ske->ske_node, &skc->skc_emergency_tree);
+		skc->skc_obj_emergency--;
+		skc->skc_obj_total--;
+	}
+	spin_unlock(&skc->skc_lock);
+
+	if (ske == NULL)
+		return (-ENOENT);
+
+	free_pages(ske->ske_obj, order);
+	kfree(ske);
+
+	return (0);
+}
+
+/*
+ * Release objects from the per-cpu magazine back to their slab.  The flush
+ * argument contains the max number of entries to remove from the magazine.
+ */
+static void
+__spl_cache_flush(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flush)
+{
+	int i, count = MIN(flush, skm->skm_avail);
+
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+	ASSERT(skm->skm_magic == SKM_MAGIC);
+
+	for (i = 0; i < count; i++)
+		spl_cache_shrink(skc, skm->skm_objs[i]);
+
+	skm->skm_avail -= count;
+	memmove(skm->skm_objs, &(skm->skm_objs[count]),
+	    sizeof (void *) * skm->skm_avail);
+}
+
+static void
+spl_cache_flush(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flush)
+{
+	spin_lock(&skc->skc_lock);
+	__spl_cache_flush(skc, skm, flush);
+	spin_unlock(&skc->skc_lock);
+}
+
+static void
+spl_magazine_age(void *data)
+{
+	spl_kmem_cache_t *skc = (spl_kmem_cache_t *)data;
+	spl_kmem_magazine_t *skm = skc->skc_mag[smp_processor_id()];
+
+	ASSERT(skm->skm_magic == SKM_MAGIC);
+	ASSERT(skm->skm_cpu == smp_processor_id());
+	ASSERT(irqs_disabled());
+
+	/* There are no available objects or they are too young to age out */
+	if ((skm->skm_avail == 0) ||
+	    time_before(jiffies, skm->skm_age + skc->skc_delay * HZ))
+		return;
+
+	/*
+	 * Because we're executing in interrupt context we may have
+	 * interrupted the holder of this lock.  To avoid a potential
+	 * deadlock return if the lock is contended.
+	 */
+	if (!spin_trylock(&skc->skc_lock))
+		return;
+
+	__spl_cache_flush(skc, skm, skm->skm_refill);
+	spin_unlock(&skc->skc_lock);
+}
+
+/*
+ * Called regularly to keep a downward pressure on the cache.
+ *
+ * Objects older than skc->skc_delay seconds in the per-cpu magazines will
+ * be returned to the caches.  This is done to prevent idle magazines from
+ * holding memory which could be better used elsewhere.  The delay is
+ * present to prevent thrashing the magazine.
+ *
+ * The newly released objects may result in empty partial slabs.  Those
+ * slabs should be released to the system.  Otherwise moving the objects
+ * out of the magazines is just wasted work.
+ */
+static void
+spl_cache_age(void *data)
+{
+	spl_kmem_cache_t *skc = (spl_kmem_cache_t *)data;
+	taskqid_t id = 0;
+
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+
+	/* Dynamically disabled at run time */
+	if (!(spl_kmem_cache_expire & KMC_EXPIRE_AGE))
+		return;
+
+	atomic_inc(&skc->skc_ref);
+
+	if (!(skc->skc_flags & KMC_NOMAGAZINE))
+		on_each_cpu(spl_magazine_age, skc, 1);
+
+	spl_slab_reclaim(skc);
+
+	while (!test_bit(KMC_BIT_DESTROY, &skc->skc_flags) && !id) {
+		id = taskq_dispatch_delay(
+		    spl_kmem_cache_taskq, spl_cache_age, skc, TQ_SLEEP,
+		    ddi_get_lbolt() + skc->skc_delay / 3 * HZ);
+
+		/* Destroy issued after dispatch immediately cancel it */
+		if (test_bit(KMC_BIT_DESTROY, &skc->skc_flags) && id)
+			taskq_cancel_id(spl_kmem_cache_taskq, id);
+	}
+
+	spin_lock(&skc->skc_lock);
+	skc->skc_taskqid = id;
+	spin_unlock(&skc->skc_lock);
+
+	atomic_dec(&skc->skc_ref);
+}
+
+/*
+ * Size a slab based on the size of each aligned object plus spl_kmem_obj_t.
+ * When on-slab we want to target spl_kmem_cache_obj_per_slab.  However,
+ * for very small objects we may end up with more than this so as not
+ * to waste space in the minimal allocation of a single page.  Also for
+ * very large objects we may use as few as spl_kmem_cache_obj_per_slab_min,
+ * lower than this and we will fail.
+ */
+static int
+spl_slab_size(spl_kmem_cache_t *skc, uint32_t *objs, uint32_t *size)
+{
+	uint32_t sks_size, obj_size, max_size, tgt_size, tgt_objs;
+
+	if (skc->skc_flags & KMC_OFFSLAB) {
+		tgt_objs = spl_kmem_cache_obj_per_slab;
+		tgt_size = P2ROUNDUP(sizeof (spl_kmem_slab_t), PAGE_SIZE);
+
+		if ((skc->skc_flags & KMC_KMEM) &&
+		    (spl_obj_size(skc) > (SPL_MAX_ORDER_NR_PAGES * PAGE_SIZE)))
+			return (-ENOSPC);
+	} else {
+		sks_size = spl_sks_size(skc);
+		obj_size = spl_obj_size(skc);
+		max_size = (spl_kmem_cache_max_size * 1024 * 1024);
+		tgt_size = (spl_kmem_cache_obj_per_slab * obj_size + sks_size);
+
+		/*
+		 * KMC_KMEM slabs are allocated by __get_free_pages() which
+		 * rounds up to the nearest order.  Knowing this the size
+		 * should be rounded up to the next power of two with a hard
+		 * maximum defined by the maximum allowed allocation order.
+		 */
+		if (skc->skc_flags & KMC_KMEM) {
+			max_size = SPL_MAX_ORDER_NR_PAGES * PAGE_SIZE;
+			tgt_size = MIN(max_size,
+			    PAGE_SIZE * (1 << MAX(get_order(tgt_size) - 1, 1)));
+		}
+
+		if (tgt_size <= max_size) {
+			tgt_objs = (tgt_size - sks_size) / obj_size;
+		} else {
+			tgt_objs = (max_size - sks_size) / obj_size;
+			tgt_size = (tgt_objs * obj_size) + sks_size;
+		}
+	}
+
+	if (tgt_objs == 0)
+		return (-ENOSPC);
+
+	*objs = tgt_objs;
+	*size = tgt_size;
+
+	return (0);
+}
+
+/*
+ * Make a guess at reasonable per-cpu magazine size based on the size of
+ * each object and the cost of caching N of them in each magazine.  Long
+ * term this should really adapt based on an observed usage heuristic.
+ */
+static int
+spl_magazine_size(spl_kmem_cache_t *skc)
+{
+	uint32_t obj_size = spl_obj_size(skc);
+	int size;
+
+	if (spl_kmem_cache_magazine_size > 0)
+		return (MAX(MIN(spl_kmem_cache_magazine_size, 256), 2));
+
+	/* Per-magazine sizes below assume a 4Kib page size */
+	if (obj_size > (PAGE_SIZE * 256))
+		size = 4;  /* Minimum 4Mib per-magazine */
+	else if (obj_size > (PAGE_SIZE * 32))
+		size = 16; /* Minimum 2Mib per-magazine */
+	else if (obj_size > (PAGE_SIZE))
+		size = 64; /* Minimum 256Kib per-magazine */
+	else if (obj_size > (PAGE_SIZE / 4))
+		size = 128; /* Minimum 128Kib per-magazine */
+	else
+		size = 256;
+
+	return (size);
+}
+
+/*
+ * Allocate a per-cpu magazine to associate with a specific core.
+ */
+static spl_kmem_magazine_t *
+spl_magazine_alloc(spl_kmem_cache_t *skc, int cpu)
+{
+	spl_kmem_magazine_t *skm;
+	int size = sizeof (spl_kmem_magazine_t) +
+	    sizeof (void *) * skc->skc_mag_size;
+
+	skm = kmalloc_node(size, GFP_KERNEL, cpu_to_node(cpu));
+	if (skm) {
+		skm->skm_magic = SKM_MAGIC;
+		skm->skm_avail = 0;
+		skm->skm_size = skc->skc_mag_size;
+		skm->skm_refill = skc->skc_mag_refill;
+		skm->skm_cache = skc;
+		skm->skm_age = jiffies;
+		skm->skm_cpu = cpu;
+	}
+
+	return (skm);
+}
+
+/*
+ * Free a per-cpu magazine associated with a specific core.
+ */
+static void
+spl_magazine_free(spl_kmem_magazine_t *skm)
+{
+	ASSERT(skm->skm_magic == SKM_MAGIC);
+	ASSERT(skm->skm_avail == 0);
+	kfree(skm);
+}
+
+/*
+ * Create all pre-cpu magazines of reasonable sizes.
+ */
+static int
+spl_magazine_create(spl_kmem_cache_t *skc)
+{
+	int i;
+
+	if (skc->skc_flags & KMC_NOMAGAZINE)
+		return (0);
+
+	skc->skc_mag = kzalloc(sizeof (spl_kmem_magazine_t *) *
+	    num_possible_cpus(), kmem_flags_convert(KM_SLEEP));
+	skc->skc_mag_size = spl_magazine_size(skc);
+	skc->skc_mag_refill = (skc->skc_mag_size + 1) / 2;
+
+	for_each_possible_cpu(i) {
+		skc->skc_mag[i] = spl_magazine_alloc(skc, i);
+		if (!skc->skc_mag[i]) {
+			for (i--; i >= 0; i--)
+				spl_magazine_free(skc->skc_mag[i]);
+
+			kfree(skc->skc_mag);
+			return (-ENOMEM);
+		}
+	}
+
+	return (0);
+}
+
+/*
+ * Destroy all pre-cpu magazines.
+ */
+static void
+spl_magazine_destroy(spl_kmem_cache_t *skc)
+{
+	spl_kmem_magazine_t *skm;
+	int i;
+
+	if (skc->skc_flags & KMC_NOMAGAZINE)
+		return;
+
+	for_each_possible_cpu(i) {
+		skm = skc->skc_mag[i];
+		spl_cache_flush(skc, skm, skm->skm_avail);
+		spl_magazine_free(skm);
+	}
+
+	kfree(skc->skc_mag);
+}
+
+/*
+ * Create a object cache based on the following arguments:
+ * name		cache name
+ * size		cache object size
+ * align	cache object alignment
+ * ctor		cache object constructor
+ * dtor		cache object destructor
+ * reclaim	cache object reclaim
+ * priv		cache private data for ctor/dtor/reclaim
+ * vmp		unused must be NULL
+ * flags
+ *	KMC_KMEM	Force SPL kmem backed cache
+ *	KMC_VMEM        Force SPL vmem backed cache
+ *	KMC_SLAB        Force Linux slab backed cache
+ *	KMC_OFFSLAB	Locate objects off the slab
+ *	KMC_NOTOUCH	unsupported
+ *	KMC_NODEBUG	unsupported
+ *	KMC_NOHASH      unsupported
+ *	KMC_QCACHE	unsupported
+ *	KMC_NOMAGAZINE	unsupported
+ */
+spl_kmem_cache_t *
+spl_kmem_cache_create(char *name, size_t size, size_t align,
+    spl_kmem_ctor_t ctor, spl_kmem_dtor_t dtor, spl_kmem_reclaim_t reclaim,
+    void *priv, void *vmp, int flags)
+{
+	gfp_t lflags = kmem_flags_convert(KM_SLEEP);
+	spl_kmem_cache_t *skc;
+	int rc;
+
+	/*
+	 * Unsupported flags
+	 */
+	ASSERT0(flags & KMC_NOMAGAZINE);
+	ASSERT0(flags & KMC_NOHASH);
+	ASSERT0(flags & KMC_QCACHE);
+	ASSERT(vmp == NULL);
+
+	might_sleep();
+
+	skc = kzalloc(sizeof (*skc), lflags);
+	if (skc == NULL)
+		return (NULL);
+
+	skc->skc_magic = SKC_MAGIC;
+	skc->skc_name_size = strlen(name) + 1;
+	skc->skc_name = (char *)kmalloc(skc->skc_name_size, lflags);
+	if (skc->skc_name == NULL) {
+		kfree(skc);
+		return (NULL);
+	}
+	strncpy(skc->skc_name, name, skc->skc_name_size);
+
+	skc->skc_ctor = ctor;
+	skc->skc_dtor = dtor;
+	skc->skc_reclaim = reclaim;
+	skc->skc_private = priv;
+	skc->skc_vmp = vmp;
+	skc->skc_linux_cache = NULL;
+	skc->skc_flags = flags;
+	skc->skc_obj_size = size;
+	skc->skc_obj_align = SPL_KMEM_CACHE_ALIGN;
+	skc->skc_delay = SPL_KMEM_CACHE_DELAY;
+	skc->skc_reap = SPL_KMEM_CACHE_REAP;
+	atomic_set(&skc->skc_ref, 0);
+
+	INIT_LIST_HEAD(&skc->skc_list);
+	INIT_LIST_HEAD(&skc->skc_complete_list);
+	INIT_LIST_HEAD(&skc->skc_partial_list);
+	skc->skc_emergency_tree = RB_ROOT;
+	spin_lock_init(&skc->skc_lock);
+	init_waitqueue_head(&skc->skc_waitq);
+	skc->skc_slab_fail = 0;
+	skc->skc_slab_create = 0;
+	skc->skc_slab_destroy = 0;
+	skc->skc_slab_total = 0;
+	skc->skc_slab_alloc = 0;
+	skc->skc_slab_max = 0;
+	skc->skc_obj_total = 0;
+	skc->skc_obj_alloc = 0;
+	skc->skc_obj_max = 0;
+	skc->skc_obj_deadlock = 0;
+	skc->skc_obj_emergency = 0;
+	skc->skc_obj_emergency_max = 0;
+
+	/*
+	 * Verify the requested alignment restriction is sane.
+	 */
+	if (align) {
+		VERIFY(ISP2(align));
+		VERIFY3U(align, >=, SPL_KMEM_CACHE_ALIGN);
+		VERIFY3U(align, <=, PAGE_SIZE);
+		skc->skc_obj_align = align;
+	}
+
+	/*
+	 * When no specific type of slab is requested (kmem, vmem, or
+	 * linuxslab) then select a cache type based on the object size
+	 * and default tunables.
+	 */
+	if (!(skc->skc_flags & (KMC_KMEM | KMC_VMEM | KMC_SLAB))) {
+
+		if (spl_kmem_cache_slab_limit &&
+		    size <= (size_t)spl_kmem_cache_slab_limit) {
+			/*
+			 * Objects smaller than spl_kmem_cache_slab_limit can
+			 * use the Linux slab for better space-efficiency.
+			 */
+			skc->skc_flags |= KMC_SLAB;
+		} else if (spl_obj_size(skc) <= spl_kmem_cache_kmem_limit) {
+			/*
+			 * Small objects, less than spl_kmem_cache_kmem_limit
+			 * per object should use kmem because their slabs are
+			 * small.
+			 */
+			skc->skc_flags |= KMC_KMEM;
+		} else {
+			/*
+			 * All other objects are considered large and are
+			 * placed on vmem backed slabs.
+			 */
+			skc->skc_flags |= KMC_VMEM;
+		}
+	}
+
+	/*
+	 * Given the type of slab allocate the required resources.
+	 */
+	if (skc->skc_flags & (KMC_KMEM | KMC_VMEM)) {
+		rc = spl_slab_size(skc,
+		    &skc->skc_slab_objs, &skc->skc_slab_size);
+		if (rc)
+			goto out;
+
+		rc = spl_magazine_create(skc);
+		if (rc)
+			goto out;
+	} else {
+		unsigned long slabflags = 0;
+
+		if (size > (SPL_MAX_KMEM_ORDER_NR_PAGES * PAGE_SIZE)) {
+			rc = EINVAL;
+			goto out;
+		}
+
+#if defined(SLAB_USERCOPY)
+		/*
+		 * Required for PAX-enabled kernels if the slab is to be
+		 * used for copying between user and kernel space.
+		 */
+		slabflags |= SLAB_USERCOPY;
+#endif
+
+#if defined(HAVE_KMEM_CACHE_CREATE_USERCOPY)
+		/*
+		 * Newer grsec patchset uses kmem_cache_create_usercopy()
+		 * instead of SLAB_USERCOPY flag
+		 */
+		skc->skc_linux_cache = kmem_cache_create_usercopy(
+		    skc->skc_name, size, align, slabflags, 0, size, NULL);
+#else
+		skc->skc_linux_cache = kmem_cache_create(
+		    skc->skc_name, size, align, slabflags, NULL);
+#endif
+		if (skc->skc_linux_cache == NULL) {
+			rc = ENOMEM;
+			goto out;
+		}
+
+#if defined(HAVE_KMEM_CACHE_ALLOCFLAGS)
+		skc->skc_linux_cache->allocflags |= __GFP_COMP;
+#elif defined(HAVE_KMEM_CACHE_GFPFLAGS)
+		skc->skc_linux_cache->gfpflags |= __GFP_COMP;
+#endif
+		skc->skc_flags |= KMC_NOMAGAZINE;
+	}
+
+	if (spl_kmem_cache_expire & KMC_EXPIRE_AGE) {
+		skc->skc_taskqid = taskq_dispatch_delay(spl_kmem_cache_taskq,
+		    spl_cache_age, skc, TQ_SLEEP,
+		    ddi_get_lbolt() + skc->skc_delay / 3 * HZ);
+	}
+
+	down_write(&spl_kmem_cache_sem);
+	list_add_tail(&skc->skc_list, &spl_kmem_cache_list);
+	up_write(&spl_kmem_cache_sem);
+
+	return (skc);
+out:
+	kfree(skc->skc_name);
+	kfree(skc);
+	return (NULL);
+}
+EXPORT_SYMBOL(spl_kmem_cache_create);
+
+/*
+ * Register a move callback for cache defragmentation.
+ * XXX: Unimplemented but harmless to stub out for now.
+ */
+void
+spl_kmem_cache_set_move(spl_kmem_cache_t *skc,
+    kmem_cbrc_t (move)(void *, void *, size_t, void *))
+{
+	ASSERT(move != NULL);
+}
+EXPORT_SYMBOL(spl_kmem_cache_set_move);
+
+/*
+ * Destroy a cache and all objects associated with the cache.
+ */
+void
+spl_kmem_cache_destroy(spl_kmem_cache_t *skc)
+{
+	DECLARE_WAIT_QUEUE_HEAD(wq);
+	taskqid_t id;
+
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+	ASSERT(skc->skc_flags & (KMC_KMEM | KMC_VMEM | KMC_SLAB));
+
+	down_write(&spl_kmem_cache_sem);
+	list_del_init(&skc->skc_list);
+	up_write(&spl_kmem_cache_sem);
+
+	/* Cancel any and wait for any pending delayed tasks */
+	VERIFY(!test_and_set_bit(KMC_BIT_DESTROY, &skc->skc_flags));
+
+	spin_lock(&skc->skc_lock);
+	id = skc->skc_taskqid;
+	spin_unlock(&skc->skc_lock);
+
+	taskq_cancel_id(spl_kmem_cache_taskq, id);
+
+	/*
+	 * Wait until all current callers complete, this is mainly
+	 * to catch the case where a low memory situation triggers a
+	 * cache reaping action which races with this destroy.
+	 */
+	wait_event(wq, atomic_read(&skc->skc_ref) == 0);
+
+	if (skc->skc_flags & (KMC_KMEM | KMC_VMEM)) {
+		spl_magazine_destroy(skc);
+		spl_slab_reclaim(skc);
+	} else {
+		ASSERT(skc->skc_flags & KMC_SLAB);
+		kmem_cache_destroy(skc->skc_linux_cache);
+	}
+
+	spin_lock(&skc->skc_lock);
+
+	/*
+	 * Validate there are no objects in use and free all the
+	 * spl_kmem_slab_t, spl_kmem_obj_t, and object buffers.
+	 */
+	ASSERT3U(skc->skc_slab_alloc, ==, 0);
+	ASSERT3U(skc->skc_obj_alloc, ==, 0);
+	ASSERT3U(skc->skc_slab_total, ==, 0);
+	ASSERT3U(skc->skc_obj_total, ==, 0);
+	ASSERT3U(skc->skc_obj_emergency, ==, 0);
+	ASSERT(list_empty(&skc->skc_complete_list));
+
+	spin_unlock(&skc->skc_lock);
+
+	kfree(skc->skc_name);
+	kfree(skc);
+}
+EXPORT_SYMBOL(spl_kmem_cache_destroy);
+
+/*
+ * Allocate an object from a slab attached to the cache.  This is used to
+ * repopulate the per-cpu magazine caches in batches when they run low.
+ */
+static void *
+spl_cache_obj(spl_kmem_cache_t *skc, spl_kmem_slab_t *sks)
+{
+	spl_kmem_obj_t *sko;
+
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+	ASSERT(sks->sks_magic == SKS_MAGIC);
+
+	sko = list_entry(sks->sks_free_list.next, spl_kmem_obj_t, sko_list);
+	ASSERT(sko->sko_magic == SKO_MAGIC);
+	ASSERT(sko->sko_addr != NULL);
+
+	/* Remove from sks_free_list */
+	list_del_init(&sko->sko_list);
+
+	sks->sks_age = jiffies;
+	sks->sks_ref++;
+	skc->skc_obj_alloc++;
+
+	/* Track max obj usage statistics */
+	if (skc->skc_obj_alloc > skc->skc_obj_max)
+		skc->skc_obj_max = skc->skc_obj_alloc;
+
+	/* Track max slab usage statistics */
+	if (sks->sks_ref == 1) {
+		skc->skc_slab_alloc++;
+
+		if (skc->skc_slab_alloc > skc->skc_slab_max)
+			skc->skc_slab_max = skc->skc_slab_alloc;
+	}
+
+	return (sko->sko_addr);
+}
+
+/*
+ * Generic slab allocation function to run by the global work queues.
+ * It is responsible for allocating a new slab, linking it in to the list
+ * of partial slabs, and then waking any waiters.
+ */
+static int
+__spl_cache_grow(spl_kmem_cache_t *skc, int flags)
+{
+	spl_kmem_slab_t *sks;
+
+	fstrans_cookie_t cookie = spl_fstrans_mark();
+	sks = spl_slab_alloc(skc, flags);
+	spl_fstrans_unmark(cookie);
+
+	spin_lock(&skc->skc_lock);
+	if (sks) {
+		skc->skc_slab_total++;
+		skc->skc_obj_total += sks->sks_objs;
+		list_add_tail(&sks->sks_list, &skc->skc_partial_list);
+
+		smp_mb__before_atomic();
+		clear_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags);
+		smp_mb__after_atomic();
+		wake_up_all(&skc->skc_waitq);
+	}
+	spin_unlock(&skc->skc_lock);
+
+	return (sks == NULL ? -ENOMEM : 0);
+}
+
+static void
+spl_cache_grow_work(void *data)
+{
+	spl_kmem_alloc_t *ska = (spl_kmem_alloc_t *)data;
+	spl_kmem_cache_t *skc = ska->ska_cache;
+
+	(void) __spl_cache_grow(skc, ska->ska_flags);
+
+	atomic_dec(&skc->skc_ref);
+	smp_mb__before_atomic();
+	clear_bit(KMC_BIT_GROWING, &skc->skc_flags);
+	smp_mb__after_atomic();
+
+	kfree(ska);
+}
+
+/*
+ * Returns non-zero when a new slab should be available.
+ */
+static int
+spl_cache_grow_wait(spl_kmem_cache_t *skc)
+{
+	return (!test_bit(KMC_BIT_GROWING, &skc->skc_flags));
+}
+
+/*
+ * No available objects on any slabs, create a new slab.  Note that this
+ * functionality is disabled for KMC_SLAB caches which are backed by the
+ * Linux slab.
+ */
+static int
+spl_cache_grow(spl_kmem_cache_t *skc, int flags, void **obj)
+{
+	int remaining, rc = 0;
+
+	ASSERT0(flags & ~KM_PUBLIC_MASK);
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+	ASSERT((skc->skc_flags & KMC_SLAB) == 0);
+	might_sleep();
+	*obj = NULL;
+
+	/*
+	 * Before allocating a new slab wait for any reaping to complete and
+	 * then return so the local magazine can be rechecked for new objects.
+	 */
+	if (test_bit(KMC_BIT_REAPING, &skc->skc_flags)) {
+		rc = spl_wait_on_bit(&skc->skc_flags, KMC_BIT_REAPING,
+		    TASK_UNINTERRUPTIBLE);
+		return (rc ? rc : -EAGAIN);
+	}
+
+	/*
+	 * To reduce the overhead of context switch and improve NUMA locality,
+	 * it tries to allocate a new slab in the current process context with
+	 * KM_NOSLEEP flag. If it fails, it will launch a new taskq to do the
+	 * allocation.
+	 *
+	 * However, this can't be applied to KVM_VMEM due to a bug that
+	 * __vmalloc() doesn't honor gfp flags in page table allocation.
+	 */
+	if (!(skc->skc_flags & KMC_VMEM)) {
+		rc = __spl_cache_grow(skc, flags | KM_NOSLEEP);
+		if (rc == 0)
+			return (0);
+	}
+
+	/*
+	 * This is handled by dispatching a work request to the global work
+	 * queue.  This allows us to asynchronously allocate a new slab while
+	 * retaining the ability to safely fall back to a smaller synchronous
+	 * allocations to ensure forward progress is always maintained.
+	 */
+	if (test_and_set_bit(KMC_BIT_GROWING, &skc->skc_flags) == 0) {
+		spl_kmem_alloc_t *ska;
+
+		ska = kmalloc(sizeof (*ska), kmem_flags_convert(flags));
+		if (ska == NULL) {
+			clear_bit_unlock(KMC_BIT_GROWING, &skc->skc_flags);
+			smp_mb__after_atomic();
+			wake_up_all(&skc->skc_waitq);
+			return (-ENOMEM);
+		}
+
+		atomic_inc(&skc->skc_ref);
+		ska->ska_cache = skc;
+		ska->ska_flags = flags;
+		taskq_init_ent(&ska->ska_tqe);
+		taskq_dispatch_ent(spl_kmem_cache_taskq,
+		    spl_cache_grow_work, ska, 0, &ska->ska_tqe);
+	}
+
+	/*
+	 * The goal here is to only detect the rare case where a virtual slab
+	 * allocation has deadlocked.  We must be careful to minimize the use
+	 * of emergency objects which are more expensive to track.  Therefore,
+	 * we set a very long timeout for the asynchronous allocation and if
+	 * the timeout is reached the cache is flagged as deadlocked.  From
+	 * this point only new emergency objects will be allocated until the
+	 * asynchronous allocation completes and clears the deadlocked flag.
+	 */
+	if (test_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags)) {
+		rc = spl_emergency_alloc(skc, flags, obj);
+	} else {
+		remaining = wait_event_timeout(skc->skc_waitq,
+		    spl_cache_grow_wait(skc), HZ / 10);
+
+		if (!remaining) {
+			spin_lock(&skc->skc_lock);
+			if (test_bit(KMC_BIT_GROWING, &skc->skc_flags)) {
+				set_bit(KMC_BIT_DEADLOCKED, &skc->skc_flags);
+				skc->skc_obj_deadlock++;
+			}
+			spin_unlock(&skc->skc_lock);
+		}
+
+		rc = -ENOMEM;
+	}
+
+	return (rc);
+}
+
+/*
+ * Refill a per-cpu magazine with objects from the slabs for this cache.
+ * Ideally the magazine can be repopulated using existing objects which have
+ * been released, however if we are unable to locate enough free objects new
+ * slabs of objects will be created.  On success NULL is returned, otherwise
+ * the address of a single emergency object is returned for use by the caller.
+ */
+static void *
+spl_cache_refill(spl_kmem_cache_t *skc, spl_kmem_magazine_t *skm, int flags)
+{
+	spl_kmem_slab_t *sks;
+	int count = 0, rc, refill;
+	void *obj = NULL;
+
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+	ASSERT(skm->skm_magic == SKM_MAGIC);
+
+	refill = MIN(skm->skm_refill, skm->skm_size - skm->skm_avail);
+	spin_lock(&skc->skc_lock);
+
+	while (refill > 0) {
+		/* No slabs available we may need to grow the cache */
+		if (list_empty(&skc->skc_partial_list)) {
+			spin_unlock(&skc->skc_lock);
+
+			local_irq_enable();
+			rc = spl_cache_grow(skc, flags, &obj);
+			local_irq_disable();
+
+			/* Emergency object for immediate use by caller */
+			if (rc == 0 && obj != NULL)
+				return (obj);
+
+			if (rc)
+				goto out;
+
+			/* Rescheduled to different CPU skm is not local */
+			if (skm != skc->skc_mag[smp_processor_id()])
+				goto out;
+
+			/*
+			 * Potentially rescheduled to the same CPU but
+			 * allocations may have occurred from this CPU while
+			 * we were sleeping so recalculate max refill.
+			 */
+			refill = MIN(refill, skm->skm_size - skm->skm_avail);
+
+			spin_lock(&skc->skc_lock);
+			continue;
+		}
+
+		/* Grab the next available slab */
+		sks = list_entry((&skc->skc_partial_list)->next,
+		    spl_kmem_slab_t, sks_list);
+		ASSERT(sks->sks_magic == SKS_MAGIC);
+		ASSERT(sks->sks_ref < sks->sks_objs);
+		ASSERT(!list_empty(&sks->sks_free_list));
+
+		/*
+		 * Consume as many objects as needed to refill the requested
+		 * cache.  We must also be careful not to overfill it.
+		 */
+		while (sks->sks_ref < sks->sks_objs && refill-- > 0 &&
+		    ++count) {
+			ASSERT(skm->skm_avail < skm->skm_size);
+			ASSERT(count < skm->skm_size);
+			skm->skm_objs[skm->skm_avail++] =
+			    spl_cache_obj(skc, sks);
+		}
+
+		/* Move slab to skc_complete_list when full */
+		if (sks->sks_ref == sks->sks_objs) {
+			list_del(&sks->sks_list);
+			list_add(&sks->sks_list, &skc->skc_complete_list);
+		}
+	}
+
+	spin_unlock(&skc->skc_lock);
+out:
+	return (NULL);
+}
+
+/*
+ * Release an object back to the slab from which it came.
+ */
+static void
+spl_cache_shrink(spl_kmem_cache_t *skc, void *obj)
+{
+	spl_kmem_slab_t *sks = NULL;
+	spl_kmem_obj_t *sko = NULL;
+
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+
+	sko = spl_sko_from_obj(skc, obj);
+	ASSERT(sko->sko_magic == SKO_MAGIC);
+	sks = sko->sko_slab;
+	ASSERT(sks->sks_magic == SKS_MAGIC);
+	ASSERT(sks->sks_cache == skc);
+	list_add(&sko->sko_list, &sks->sks_free_list);
+
+	sks->sks_age = jiffies;
+	sks->sks_ref--;
+	skc->skc_obj_alloc--;
+
+	/*
+	 * Move slab to skc_partial_list when no longer full.  Slabs
+	 * are added to the head to keep the partial list is quasi-full
+	 * sorted order.  Fuller at the head, emptier at the tail.
+	 */
+	if (sks->sks_ref == (sks->sks_objs - 1)) {
+		list_del(&sks->sks_list);
+		list_add(&sks->sks_list, &skc->skc_partial_list);
+	}
+
+	/*
+	 * Move empty slabs to the end of the partial list so
+	 * they can be easily found and freed during reclamation.
+	 */
+	if (sks->sks_ref == 0) {
+		list_del(&sks->sks_list);
+		list_add_tail(&sks->sks_list, &skc->skc_partial_list);
+		skc->skc_slab_alloc--;
+	}
+}
+
+/*
+ * Allocate an object from the per-cpu magazine, or if the magazine
+ * is empty directly allocate from a slab and repopulate the magazine.
+ */
+void *
+spl_kmem_cache_alloc(spl_kmem_cache_t *skc, int flags)
+{
+	spl_kmem_magazine_t *skm;
+	void *obj = NULL;
+
+	ASSERT0(flags & ~KM_PUBLIC_MASK);
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+	ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
+
+	/*
+	 * Allocate directly from a Linux slab.  All optimizations are left
+	 * to the underlying cache we only need to guarantee that KM_SLEEP
+	 * callers will never fail.
+	 */
+	if (skc->skc_flags & KMC_SLAB) {
+		struct kmem_cache *slc = skc->skc_linux_cache;
+		do {
+			obj = kmem_cache_alloc(slc, kmem_flags_convert(flags));
+		} while ((obj == NULL) && !(flags & KM_NOSLEEP));
+
+		goto ret;
+	}
+
+	local_irq_disable();
+
+restart:
+	/*
+	 * Safe to update per-cpu structure without lock, but
+	 * in the restart case we must be careful to reacquire
+	 * the local magazine since this may have changed
+	 * when we need to grow the cache.
+	 */
+	skm = skc->skc_mag[smp_processor_id()];
+	ASSERT(skm->skm_magic == SKM_MAGIC);
+
+	if (likely(skm->skm_avail)) {
+		/* Object available in CPU cache, use it */
+		obj = skm->skm_objs[--skm->skm_avail];
+		skm->skm_age = jiffies;
+	} else {
+		obj = spl_cache_refill(skc, skm, flags);
+		if ((obj == NULL) && !(flags & KM_NOSLEEP))
+			goto restart;
+
+		local_irq_enable();
+		goto ret;
+	}
+
+	local_irq_enable();
+	ASSERT(obj);
+	ASSERT(IS_P2ALIGNED(obj, skc->skc_obj_align));
+
+ret:
+	/* Pre-emptively migrate object to CPU L1 cache */
+	if (obj) {
+		if (obj && skc->skc_ctor)
+			skc->skc_ctor(obj, skc->skc_private, flags);
+		else
+			prefetchw(obj);
+	}
+
+	return (obj);
+}
+EXPORT_SYMBOL(spl_kmem_cache_alloc);
+
+/*
+ * Free an object back to the local per-cpu magazine, there is no
+ * guarantee that this is the same magazine the object was originally
+ * allocated from.  We may need to flush entire from the magazine
+ * back to the slabs to make space.
+ */
+void
+spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj)
+{
+	spl_kmem_magazine_t *skm;
+	unsigned long flags;
+	int do_reclaim = 0;
+	int do_emergency = 0;
+
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+	ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
+
+	/*
+	 * Run the destructor
+	 */
+	if (skc->skc_dtor)
+		skc->skc_dtor(obj, skc->skc_private);
+
+	/*
+	 * Free the object from the Linux underlying Linux slab.
+	 */
+	if (skc->skc_flags & KMC_SLAB) {
+		kmem_cache_free(skc->skc_linux_cache, obj);
+		return;
+	}
+
+	/*
+	 * While a cache has outstanding emergency objects all freed objects
+	 * must be checked.  However, since emergency objects will never use
+	 * a virtual address these objects can be safely excluded as an
+	 * optimization.
+	 */
+	if (!is_vmalloc_addr(obj)) {
+		spin_lock(&skc->skc_lock);
+		do_emergency = (skc->skc_obj_emergency > 0);
+		spin_unlock(&skc->skc_lock);
+
+		if (do_emergency && (spl_emergency_free(skc, obj) == 0))
+			return;
+	}
+
+	local_irq_save(flags);
+
+	/*
+	 * Safe to update per-cpu structure without lock, but
+	 * no remote memory allocation tracking is being performed
+	 * it is entirely possible to allocate an object from one
+	 * CPU cache and return it to another.
+	 */
+	skm = skc->skc_mag[smp_processor_id()];
+	ASSERT(skm->skm_magic == SKM_MAGIC);
+
+	/*
+	 * Per-CPU cache full, flush it to make space for this object,
+	 * this may result in an empty slab which can be reclaimed once
+	 * interrupts are re-enabled.
+	 */
+	if (unlikely(skm->skm_avail >= skm->skm_size)) {
+		spl_cache_flush(skc, skm, skm->skm_refill);
+		do_reclaim = 1;
+	}
+
+	/* Available space in cache, use it */
+	skm->skm_objs[skm->skm_avail++] = obj;
+
+	local_irq_restore(flags);
+
+	if (do_reclaim)
+		spl_slab_reclaim(skc);
+}
+EXPORT_SYMBOL(spl_kmem_cache_free);
+
+/*
+ * The generic shrinker function for all caches.  Under Linux a shrinker
+ * may not be tightly coupled with a slab cache.  In fact Linux always
+ * systematically tries calling all registered shrinker callbacks which
+ * report that they contain unused objects.  Because of this we only
+ * register one shrinker function in the shim layer for all slab caches.
+ * We always attempt to shrink all caches when this generic shrinker
+ * is called.
+ *
+ * If sc->nr_to_scan is zero, the caller is requesting a query of the
+ * number of objects which can potentially be freed.  If it is nonzero,
+ * the request is to free that many objects.
+ *
+ * Linux kernels >= 3.12 have the count_objects and scan_objects callbacks
+ * in struct shrinker and also require the shrinker to return the number
+ * of objects freed.
+ *
+ * Older kernels require the shrinker to return the number of freeable
+ * objects following the freeing of nr_to_free.
+ *
+ * Linux semantics differ from those under Solaris, which are to
+ * free all available objects which may (and probably will) be more
+ * objects than the requested nr_to_scan.
+ */
+static spl_shrinker_t
+__spl_kmem_cache_generic_shrinker(struct shrinker *shrink,
+    struct shrink_control *sc)
+{
+	spl_kmem_cache_t *skc;
+	int alloc = 0;
+
+	/*
+	 * No shrinking in a transaction context.  Can cause deadlocks.
+	 */
+	if (sc->nr_to_scan && spl_fstrans_check())
+		return (SHRINK_STOP);
+
+	down_read(&spl_kmem_cache_sem);
+	list_for_each_entry(skc, &spl_kmem_cache_list, skc_list) {
+		if (sc->nr_to_scan) {
+#ifdef HAVE_SPLIT_SHRINKER_CALLBACK
+			uint64_t oldalloc = skc->skc_obj_alloc;
+			spl_kmem_cache_reap_now(skc,
+			    MAX(sc->nr_to_scan>>fls64(skc->skc_slab_objs), 1));
+			if (oldalloc > skc->skc_obj_alloc)
+				alloc += oldalloc - skc->skc_obj_alloc;
+#else
+			spl_kmem_cache_reap_now(skc,
+			    MAX(sc->nr_to_scan>>fls64(skc->skc_slab_objs), 1));
+			alloc += skc->skc_obj_alloc;
+#endif /* HAVE_SPLIT_SHRINKER_CALLBACK */
+		} else {
+			/* Request to query number of freeable objects */
+			alloc += skc->skc_obj_alloc;
+		}
+	}
+	up_read(&spl_kmem_cache_sem);
+
+	/*
+	 * When KMC_RECLAIM_ONCE is set allow only a single reclaim pass.
+	 * This functionality only exists to work around a rare issue where
+	 * shrink_slabs() is repeatedly invoked by many cores causing the
+	 * system to thrash.
+	 */
+	if ((spl_kmem_cache_reclaim & KMC_RECLAIM_ONCE) && sc->nr_to_scan)
+		return (SHRINK_STOP);
+
+	return (MAX(alloc, 0));
+}
+
+SPL_SHRINKER_CALLBACK_WRAPPER(spl_kmem_cache_generic_shrinker);
+
+/*
+ * Call the registered reclaim function for a cache.  Depending on how
+ * many and which objects are released it may simply repopulate the
+ * local magazine which will then need to age-out.  Objects which cannot
+ * fit in the magazine we will be released back to their slabs which will
+ * also need to age out before being release.  This is all just best
+ * effort and we do not want to thrash creating and destroying slabs.
+ */
+void
+spl_kmem_cache_reap_now(spl_kmem_cache_t *skc, int count)
+{
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+	ASSERT(!test_bit(KMC_BIT_DESTROY, &skc->skc_flags));
+
+	atomic_inc(&skc->skc_ref);
+
+	/*
+	 * Execute the registered reclaim callback if it exists.
+	 */
+	if (skc->skc_flags & KMC_SLAB) {
+		if (skc->skc_reclaim)
+			skc->skc_reclaim(skc->skc_private);
+		goto out;
+	}
+
+	/*
+	 * Prevent concurrent cache reaping when contended.
+	 */
+	if (test_and_set_bit(KMC_BIT_REAPING, &skc->skc_flags))
+		goto out;
+
+	/*
+	 * When a reclaim function is available it may be invoked repeatedly
+	 * until at least a single slab can be freed.  This ensures that we
+	 * do free memory back to the system.  This helps minimize the chance
+	 * of an OOM event when the bulk of memory is used by the slab.
+	 *
+	 * When free slabs are already available the reclaim callback will be
+	 * skipped.  Additionally, if no forward progress is detected despite
+	 * a reclaim function the cache will be skipped to avoid deadlock.
+	 *
+	 * Longer term this would be the correct place to add the code which
+	 * repacks the slabs in order minimize fragmentation.
+	 */
+	if (skc->skc_reclaim) {
+		uint64_t objects = UINT64_MAX;
+		int do_reclaim;
+
+		do {
+			spin_lock(&skc->skc_lock);
+			do_reclaim =
+			    (skc->skc_slab_total > 0) &&
+			    ((skc->skc_slab_total-skc->skc_slab_alloc) == 0) &&
+			    (skc->skc_obj_alloc < objects);
+
+			objects = skc->skc_obj_alloc;
+			spin_unlock(&skc->skc_lock);
+
+			if (do_reclaim)
+				skc->skc_reclaim(skc->skc_private);
+
+		} while (do_reclaim);
+	}
+
+	/* Reclaim from the magazine and free all now empty slabs. */
+	if (spl_kmem_cache_expire & KMC_EXPIRE_MEM) {
+		spl_kmem_magazine_t *skm;
+		unsigned long irq_flags;
+
+		local_irq_save(irq_flags);
+		skm = skc->skc_mag[smp_processor_id()];
+		spl_cache_flush(skc, skm, skm->skm_avail);
+		local_irq_restore(irq_flags);
+	}
+
+	spl_slab_reclaim(skc);
+	clear_bit_unlock(KMC_BIT_REAPING, &skc->skc_flags);
+	smp_mb__after_atomic();
+	wake_up_bit(&skc->skc_flags, KMC_BIT_REAPING);
+out:
+	atomic_dec(&skc->skc_ref);
+}
+EXPORT_SYMBOL(spl_kmem_cache_reap_now);
+
+/*
+ * This is stubbed out for code consistency with other platforms.  There
+ * is existing logic to prevent concurrent reaping so while this is ugly
+ * it should do no harm.
+ */
+int
+spl_kmem_cache_reap_active()
+{
+	return (0);
+}
+EXPORT_SYMBOL(spl_kmem_cache_reap_active);
+
+/*
+ * Reap all free slabs from all registered caches.
+ */
+void
+spl_kmem_reap(void)
+{
+	struct shrink_control sc;
+
+	sc.nr_to_scan = KMC_REAP_CHUNK;
+	sc.gfp_mask = GFP_KERNEL;
+
+	(void) __spl_kmem_cache_generic_shrinker(NULL, &sc);
+}
+EXPORT_SYMBOL(spl_kmem_reap);
+
+int
+spl_kmem_cache_init(void)
+{
+	init_rwsem(&spl_kmem_cache_sem);
+	INIT_LIST_HEAD(&spl_kmem_cache_list);
+	spl_kmem_cache_taskq = taskq_create("spl_kmem_cache",
+	    spl_kmem_cache_kmem_threads, maxclsyspri,
+	    spl_kmem_cache_kmem_threads * 8, INT_MAX,
+	    TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
+	spl_register_shrinker(&spl_kmem_cache_shrinker);
+
+	return (0);
+}
+
+void
+spl_kmem_cache_fini(void)
+{
+	spl_unregister_shrinker(&spl_kmem_cache_shrinker);
+	taskq_destroy(spl_kmem_cache_taskq);
+}
diff --git a/module/os/linux/spl/spl-kmem.c b/module/os/linux/spl/spl-kmem.c
new file mode 100644
index 000000000..824b5e89f
--- /dev/null
+++ b/module/os/linux/spl/spl-kmem.c
@@ -0,0 +1,556 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <sys/debug.h>
+#include <sys/sysmacros.h>
+#include <sys/kmem.h>
+#include <sys/vmem.h>
+#include <linux/mm.h>
+
+/*
+ * As a general rule kmem_alloc() allocations should be small, preferably
+ * just a few pages since they must by physically contiguous.  Therefore, a
+ * rate limited warning will be printed to the console for any kmem_alloc()
+ * which exceeds a reasonable threshold.
+ *
+ * The default warning threshold is set to sixteen pages but capped at 64K to
+ * accommodate systems using large pages.  This value was selected to be small
+ * enough to ensure the largest allocations are quickly noticed and fixed.
+ * But large enough to avoid logging any warnings when a allocation size is
+ * larger than optimal but not a serious concern.  Since this value is tunable,
+ * developers are encouraged to set it lower when testing so any new largish
+ * allocations are quickly caught.  These warnings may be disabled by setting
+ * the threshold to zero.
+ */
+/* BEGIN CSTYLED */
+unsigned int spl_kmem_alloc_warn = MIN(16 * PAGE_SIZE, 64 * 1024);
+module_param(spl_kmem_alloc_warn, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_alloc_warn,
+	"Warning threshold in bytes for a kmem_alloc()");
+EXPORT_SYMBOL(spl_kmem_alloc_warn);
+
+/*
+ * Large kmem_alloc() allocations will fail if they exceed KMALLOC_MAX_SIZE.
+ * Allocations which are marginally smaller than this limit may succeed but
+ * should still be avoided due to the expense of locating a contiguous range
+ * of free pages.  Therefore, a maximum kmem size with reasonable safely
+ * margin of 4x is set.  Kmem_alloc() allocations larger than this maximum
+ * will quickly fail.  Vmem_alloc() allocations less than or equal to this
+ * value will use kmalloc(), but shift to vmalloc() when exceeding this value.
+ */
+unsigned int spl_kmem_alloc_max = (KMALLOC_MAX_SIZE >> 2);
+module_param(spl_kmem_alloc_max, uint, 0644);
+MODULE_PARM_DESC(spl_kmem_alloc_max,
+	"Maximum size in bytes for a kmem_alloc()");
+EXPORT_SYMBOL(spl_kmem_alloc_max);
+/* END CSTYLED */
+
+int
+kmem_debugging(void)
+{
+	return (0);
+}
+EXPORT_SYMBOL(kmem_debugging);
+
+char *
+kmem_vasprintf(const char *fmt, va_list ap)
+{
+	va_list aq;
+	char *ptr;
+
+	do {
+		va_copy(aq, ap);
+		ptr = kvasprintf(kmem_flags_convert(KM_SLEEP), fmt, aq);
+		va_end(aq);
+	} while (ptr == NULL);
+
+	return (ptr);
+}
+EXPORT_SYMBOL(kmem_vasprintf);
+
+char *
+kmem_asprintf(const char *fmt, ...)
+{
+	va_list ap;
+	char *ptr;
+
+	do {
+		va_start(ap, fmt);
+		ptr = kvasprintf(kmem_flags_convert(KM_SLEEP), fmt, ap);
+		va_end(ap);
+	} while (ptr == NULL);
+
+	return (ptr);
+}
+EXPORT_SYMBOL(kmem_asprintf);
+
+static char *
+__strdup(const char *str, int flags)
+{
+	char *ptr;
+	int n;
+
+	n = strlen(str);
+	ptr = kmalloc(n + 1, kmem_flags_convert(flags));
+	if (ptr)
+		memcpy(ptr, str, n + 1);
+
+	return (ptr);
+}
+
+char *
+strdup(const char *str)
+{
+	return (__strdup(str, KM_SLEEP));
+}
+EXPORT_SYMBOL(strdup);
+
+void
+strfree(char *str)
+{
+	kfree(str);
+}
+EXPORT_SYMBOL(strfree);
+
+/*
+ * General purpose unified implementation of kmem_alloc(). It is an
+ * amalgamation of Linux and Illumos allocator design. It should never be
+ * exported to ensure that code using kmem_alloc()/kmem_zalloc() remains
+ * relatively portable.  Consumers may only access this function through
+ * wrappers that enforce the common flags to ensure portability.
+ */
+inline void *
+spl_kmem_alloc_impl(size_t size, int flags, int node)
+{
+	gfp_t lflags = kmem_flags_convert(flags);
+	int use_vmem = 0;
+	void *ptr;
+
+	/*
+	 * Log abnormally large allocations and rate limit the console output.
+	 * Allocations larger than spl_kmem_alloc_warn should be performed
+	 * through the vmem_alloc()/vmem_zalloc() interfaces.
+	 */
+	if ((spl_kmem_alloc_warn > 0) && (size > spl_kmem_alloc_warn) &&
+	    !(flags & KM_VMEM)) {
+		printk(KERN_WARNING
+		    "Large kmem_alloc(%lu, 0x%x), please file an issue at:\n"
+		    "https://github.com/zfsonlinux/zfs/issues/new\n",
+		    (unsigned long)size, flags);
+		dump_stack();
+	}
+
+	/*
+	 * Use a loop because kmalloc_node() can fail when GFP_KERNEL is used
+	 * unlike kmem_alloc() with KM_SLEEP on Illumos.
+	 */
+	do {
+		/*
+		 * Calling kmalloc_node() when the size >= spl_kmem_alloc_max
+		 * is unsafe.  This must fail for all for kmem_alloc() and
+		 * kmem_zalloc() callers.
+		 *
+		 * For vmem_alloc() and vmem_zalloc() callers it is permissible
+		 * to use __vmalloc().  However, in general use of __vmalloc()
+		 * is strongly discouraged because a global lock must be
+		 * acquired.  Contention on this lock can significantly
+		 * impact performance so frequently manipulating the virtual
+		 * address space is strongly discouraged.
+		 */
+		if ((size > spl_kmem_alloc_max) || use_vmem) {
+			if (flags & KM_VMEM) {
+				ptr = __vmalloc(size, lflags | __GFP_HIGHMEM,
+				    PAGE_KERNEL);
+			} else {
+				return (NULL);
+			}
+		} else {
+			ptr = kmalloc_node(size, lflags, node);
+		}
+
+		if (likely(ptr) || (flags & KM_NOSLEEP))
+			return (ptr);
+
+		/*
+		 * For vmem_alloc() and vmem_zalloc() callers retry immediately
+		 * using __vmalloc() which is unlikely to fail.
+		 */
+		if ((flags & KM_VMEM) && (use_vmem == 0))  {
+			use_vmem = 1;
+			continue;
+		}
+
+		/*
+		 * Use cond_resched() instead of congestion_wait() to avoid
+		 * deadlocking systems where there are no block devices.
+		 */
+		cond_resched();
+	} while (1);
+
+	return (NULL);
+}
+
+inline void
+spl_kmem_free_impl(const void *buf, size_t size)
+{
+	if (is_vmalloc_addr(buf))
+		vfree(buf);
+	else
+		kfree(buf);
+}
+
+/*
+ * Memory allocation and accounting for kmem_* * style allocations.  When
+ * DEBUG_KMEM is enabled the total memory allocated will be tracked and
+ * any memory leaked will be reported during module unload.
+ *
+ * ./configure --enable-debug-kmem
+ */
+#ifdef DEBUG_KMEM
+
+/* Shim layer memory accounting */
+#ifdef HAVE_ATOMIC64_T
+atomic64_t kmem_alloc_used = ATOMIC64_INIT(0);
+unsigned long long kmem_alloc_max = 0;
+#else  /* HAVE_ATOMIC64_T */
+atomic_t kmem_alloc_used = ATOMIC_INIT(0);
+unsigned long long kmem_alloc_max = 0;
+#endif /* HAVE_ATOMIC64_T */
+
+EXPORT_SYMBOL(kmem_alloc_used);
+EXPORT_SYMBOL(kmem_alloc_max);
+
+inline void *
+spl_kmem_alloc_debug(size_t size, int flags, int node)
+{
+	void *ptr;
+
+	ptr = spl_kmem_alloc_impl(size, flags, node);
+	if (ptr) {
+		kmem_alloc_used_add(size);
+		if (unlikely(kmem_alloc_used_read() > kmem_alloc_max))
+			kmem_alloc_max = kmem_alloc_used_read();
+	}
+
+	return (ptr);
+}
+
+inline void
+spl_kmem_free_debug(const void *ptr, size_t size)
+{
+	kmem_alloc_used_sub(size);
+	spl_kmem_free_impl(ptr, size);
+}
+
+/*
+ * When DEBUG_KMEM_TRACKING is enabled not only will total bytes be tracked
+ * but also the location of every alloc and free.  When the SPL module is
+ * unloaded a list of all leaked addresses and where they were allocated
+ * will be dumped to the console.  Enabling this feature has a significant
+ * impact on performance but it makes finding memory leaks straight forward.
+ *
+ * Not surprisingly with debugging enabled the xmem_locks are very highly
+ * contended particularly on xfree().  If we want to run with this detailed
+ * debugging enabled for anything other than debugging  we need to minimize
+ * the contention by moving to a lock per xmem_table entry model.
+ *
+ * ./configure --enable-debug-kmem-tracking
+ */
+#ifdef DEBUG_KMEM_TRACKING
+
+#include <linux/hash.h>
+#include <linux/ctype.h>
+
+#define	KMEM_HASH_BITS		10
+#define	KMEM_TABLE_SIZE		(1 << KMEM_HASH_BITS)
+
+typedef struct kmem_debug {
+	struct hlist_node kd_hlist;	/* Hash node linkage */
+	struct list_head kd_list;	/* List of all allocations */
+	void *kd_addr;			/* Allocation pointer */
+	size_t kd_size;			/* Allocation size */
+	const char *kd_func;		/* Allocation function */
+	int kd_line;			/* Allocation line */
+} kmem_debug_t;
+
+static spinlock_t kmem_lock;
+static struct hlist_head kmem_table[KMEM_TABLE_SIZE];
+static struct list_head kmem_list;
+
+static kmem_debug_t *
+kmem_del_init(spinlock_t *lock, struct hlist_head *table,
+    int bits, const void *addr)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct kmem_debug *p;
+	unsigned long flags;
+
+	spin_lock_irqsave(lock, flags);
+
+	head = &table[hash_ptr((void *)addr, bits)];
+	hlist_for_each(node, head) {
+		p = list_entry(node, struct kmem_debug, kd_hlist);
+		if (p->kd_addr == addr) {
+			hlist_del_init(&p->kd_hlist);
+			list_del_init(&p->kd_list);
+			spin_unlock_irqrestore(lock, flags);
+			return (p);
+		}
+	}
+
+	spin_unlock_irqrestore(lock, flags);
+
+	return (NULL);
+}
+
+inline void *
+spl_kmem_alloc_track(size_t size, int flags,
+    const char *func, int line, int node)
+{
+	void *ptr = NULL;
+	kmem_debug_t *dptr;
+	unsigned long irq_flags;
+
+	dptr = kmalloc(sizeof (kmem_debug_t), kmem_flags_convert(flags));
+	if (dptr == NULL)
+		return (NULL);
+
+	dptr->kd_func = __strdup(func, flags);
+	if (dptr->kd_func == NULL) {
+		kfree(dptr);
+		return (NULL);
+	}
+
+	ptr = spl_kmem_alloc_debug(size, flags, node);
+	if (ptr == NULL) {
+		kfree(dptr->kd_func);
+		kfree(dptr);
+		return (NULL);
+	}
+
+	INIT_HLIST_NODE(&dptr->kd_hlist);
+	INIT_LIST_HEAD(&dptr->kd_list);
+
+	dptr->kd_addr = ptr;
+	dptr->kd_size = size;
+	dptr->kd_line = line;
+
+	spin_lock_irqsave(&kmem_lock, irq_flags);
+	hlist_add_head(&dptr->kd_hlist,
+	    &kmem_table[hash_ptr(ptr, KMEM_HASH_BITS)]);
+	list_add_tail(&dptr->kd_list, &kmem_list);
+	spin_unlock_irqrestore(&kmem_lock, irq_flags);
+
+	return (ptr);
+}
+
+inline void
+spl_kmem_free_track(const void *ptr, size_t size)
+{
+	kmem_debug_t *dptr;
+
+	/* Ignore NULL pointer since we haven't tracked it at all */
+	if (ptr == NULL)
+		return;
+
+	/* Must exist in hash due to kmem_alloc() */
+	dptr = kmem_del_init(&kmem_lock, kmem_table, KMEM_HASH_BITS, ptr);
+	ASSERT3P(dptr, !=, NULL);
+	ASSERT3S(dptr->kd_size, ==, size);
+
+	kfree(dptr->kd_func);
+	kfree(dptr);
+
+	spl_kmem_free_debug(ptr, size);
+}
+#endif /* DEBUG_KMEM_TRACKING */
+#endif /* DEBUG_KMEM */
+
+/*
+ * Public kmem_alloc(), kmem_zalloc() and kmem_free() interfaces.
+ */
+void *
+spl_kmem_alloc(size_t size, int flags, const char *func, int line)
+{
+	ASSERT0(flags & ~KM_PUBLIC_MASK);
+
+#if !defined(DEBUG_KMEM)
+	return (spl_kmem_alloc_impl(size, flags, NUMA_NO_NODE));
+#elif !defined(DEBUG_KMEM_TRACKING)
+	return (spl_kmem_alloc_debug(size, flags, NUMA_NO_NODE));
+#else
+	return (spl_kmem_alloc_track(size, flags, func, line, NUMA_NO_NODE));
+#endif
+}
+EXPORT_SYMBOL(spl_kmem_alloc);
+
+void *
+spl_kmem_zalloc(size_t size, int flags, const char *func, int line)
+{
+	ASSERT0(flags & ~KM_PUBLIC_MASK);
+
+	flags |= KM_ZERO;
+
+#if !defined(DEBUG_KMEM)
+	return (spl_kmem_alloc_impl(size, flags, NUMA_NO_NODE));
+#elif !defined(DEBUG_KMEM_TRACKING)
+	return (spl_kmem_alloc_debug(size, flags, NUMA_NO_NODE));
+#else
+	return (spl_kmem_alloc_track(size, flags, func, line, NUMA_NO_NODE));
+#endif
+}
+EXPORT_SYMBOL(spl_kmem_zalloc);
+
+void
+spl_kmem_free(const void *buf, size_t size)
+{
+#if !defined(DEBUG_KMEM)
+	return (spl_kmem_free_impl(buf, size));
+#elif !defined(DEBUG_KMEM_TRACKING)
+	return (spl_kmem_free_debug(buf, size));
+#else
+	return (spl_kmem_free_track(buf, size));
+#endif
+}
+EXPORT_SYMBOL(spl_kmem_free);
+
+#if defined(DEBUG_KMEM) && defined(DEBUG_KMEM_TRACKING)
+static char *
+spl_sprintf_addr(kmem_debug_t *kd, char *str, int len, int min)
+{
+	int size = ((len - 1) < kd->kd_size) ? (len - 1) : kd->kd_size;
+	int i, flag = 1;
+
+	ASSERT(str != NULL && len >= 17);
+	memset(str, 0, len);
+
+	/*
+	 * Check for a fully printable string, and while we are at
+	 * it place the printable characters in the passed buffer.
+	 */
+	for (i = 0; i < size; i++) {
+		str[i] = ((char *)(kd->kd_addr))[i];
+		if (isprint(str[i])) {
+			continue;
+		} else {
+			/*
+			 * Minimum number of printable characters found
+			 * to make it worthwhile to print this as ascii.
+			 */
+			if (i > min)
+				break;
+
+			flag = 0;
+			break;
+		}
+	}
+
+	if (!flag) {
+		sprintf(str, "%02x%02x%02x%02x%02x%02x%02x%02x",
+		    *((uint8_t *)kd->kd_addr),
+		    *((uint8_t *)kd->kd_addr + 2),
+		    *((uint8_t *)kd->kd_addr + 4),
+		    *((uint8_t *)kd->kd_addr + 6),
+		    *((uint8_t *)kd->kd_addr + 8),
+		    *((uint8_t *)kd->kd_addr + 10),
+		    *((uint8_t *)kd->kd_addr + 12),
+		    *((uint8_t *)kd->kd_addr + 14));
+	}
+
+	return (str);
+}
+
+static int
+spl_kmem_init_tracking(struct list_head *list, spinlock_t *lock, int size)
+{
+	int i;
+
+	spin_lock_init(lock);
+	INIT_LIST_HEAD(list);
+
+	for (i = 0; i < size; i++)
+		INIT_HLIST_HEAD(&kmem_table[i]);
+
+	return (0);
+}
+
+static void
+spl_kmem_fini_tracking(struct list_head *list, spinlock_t *lock)
+{
+	unsigned long flags;
+	kmem_debug_t *kd;
+	char str[17];
+
+	spin_lock_irqsave(lock, flags);
+	if (!list_empty(list))
+		printk(KERN_WARNING "%-16s %-5s %-16s %s:%s\n", "address",
+		    "size", "data", "func", "line");
+
+	list_for_each_entry(kd, list, kd_list) {
+		printk(KERN_WARNING "%p %-5d %-16s %s:%d\n", kd->kd_addr,
+		    (int)kd->kd_size, spl_sprintf_addr(kd, str, 17, 8),
+		    kd->kd_func, kd->kd_line);
+	}
+
+	spin_unlock_irqrestore(lock, flags);
+}
+#endif /* DEBUG_KMEM && DEBUG_KMEM_TRACKING */
+
+int
+spl_kmem_init(void)
+{
+
+#ifdef DEBUG_KMEM
+	kmem_alloc_used_set(0);
+
+
+
+#ifdef DEBUG_KMEM_TRACKING
+	spl_kmem_init_tracking(&kmem_list, &kmem_lock, KMEM_TABLE_SIZE);
+#endif /* DEBUG_KMEM_TRACKING */
+#endif /* DEBUG_KMEM */
+
+	return (0);
+}
+
+void
+spl_kmem_fini(void)
+{
+#ifdef DEBUG_KMEM
+	/*
+	 * Display all unreclaimed memory addresses, including the
+	 * allocation size and the first few bytes of what's located
+	 * at that address to aid in debugging.  Performance is not
+	 * a serious concern here since it is module unload time.
+	 */
+	if (kmem_alloc_used_read() != 0)
+		printk(KERN_WARNING "kmem leaked %ld/%llu bytes\n",
+		    (unsigned long)kmem_alloc_used_read(), kmem_alloc_max);
+
+#ifdef DEBUG_KMEM_TRACKING
+	spl_kmem_fini_tracking(&kmem_list, &kmem_lock);
+#endif /* DEBUG_KMEM_TRACKING */
+#endif /* DEBUG_KMEM */
+}
diff --git a/module/os/linux/spl/spl-kobj.c b/module/os/linux/spl/spl-kobj.c
new file mode 100644
index 000000000..7019369bd
--- /dev/null
+++ b/module/os/linux/spl/spl-kobj.c
@@ -0,0 +1,86 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Kobj Implementation.
+ */
+
+#include <sys/kobj.h>
+
+struct _buf *
+kobj_open_file(const char *name)
+{
+	struct _buf *file;
+	vnode_t *vp;
+	int rc;
+
+	file = kmalloc(sizeof (_buf_t), kmem_flags_convert(KM_SLEEP));
+	if (file == NULL)
+		return ((_buf_t *)-1UL);
+
+	if ((rc = vn_open(name, UIO_SYSSPACE, FREAD, 0644, &vp, 0, 0))) {
+		kfree(file);
+		return ((_buf_t *)-1UL);
+	}
+
+	file->vp = vp;
+
+	return (file);
+} /* kobj_open_file() */
+EXPORT_SYMBOL(kobj_open_file);
+
+void
+kobj_close_file(struct _buf *file)
+{
+	VOP_CLOSE(file->vp, 0, 0, 0, 0, 0);
+	kfree(file);
+} /* kobj_close_file() */
+EXPORT_SYMBOL(kobj_close_file);
+
+int
+kobj_read_file(struct _buf *file, char *buf, unsigned size, unsigned off)
+{
+	ssize_t resid;
+
+	if (vn_rdwr(UIO_READ, file->vp, buf, size, (offset_t)off,
+	    UIO_SYSSPACE, 0, 0, 0, &resid) != 0)
+		return (-1);
+
+	return (size - resid);
+} /* kobj_read_file() */
+EXPORT_SYMBOL(kobj_read_file);
+
+int
+kobj_get_filesize(struct _buf *file, uint64_t *size)
+{
+	vattr_t vap;
+	int rc;
+
+	rc = VOP_GETATTR(file->vp, &vap, 0, 0, NULL);
+	if (rc)
+		return (rc);
+
+	*size = vap.va_size;
+
+	return (rc);
+} /* kobj_get_filesize() */
+EXPORT_SYMBOL(kobj_get_filesize);
diff --git a/module/os/linux/spl/spl-kstat.c b/module/os/linux/spl/spl-kstat.c
new file mode 100644
index 000000000..1f67bf157
--- /dev/null
+++ b/module/os/linux/spl/spl-kstat.c
@@ -0,0 +1,770 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Kstat Implementation.
+ */
+
+#include <linux/seq_file.h>
+#include <sys/kstat.h>
+#include <sys/vmem.h>
+#include <sys/cmn_err.h>
+#include <sys/sysmacros.h>
+
+static kmutex_t kstat_module_lock;
+static struct list_head kstat_module_list;
+static kid_t kstat_id;
+
+static int
+kstat_resize_raw(kstat_t *ksp)
+{
+	if (ksp->ks_raw_bufsize == KSTAT_RAW_MAX)
+		return (ENOMEM);
+
+	vmem_free(ksp->ks_raw_buf, ksp->ks_raw_bufsize);
+	ksp->ks_raw_bufsize = MIN(ksp->ks_raw_bufsize * 2, KSTAT_RAW_MAX);
+	ksp->ks_raw_buf = vmem_alloc(ksp->ks_raw_bufsize, KM_SLEEP);
+
+	return (0);
+}
+
+void
+kstat_waitq_enter(kstat_io_t *kiop)
+{
+	hrtime_t new, delta;
+	ulong_t wcnt;
+
+	new = gethrtime();
+	delta = new - kiop->wlastupdate;
+	kiop->wlastupdate = new;
+	wcnt = kiop->wcnt++;
+	if (wcnt != 0) {
+		kiop->wlentime += delta * wcnt;
+		kiop->wtime += delta;
+	}
+}
+EXPORT_SYMBOL(kstat_waitq_enter);
+
+void
+kstat_waitq_exit(kstat_io_t *kiop)
+{
+	hrtime_t new, delta;
+	ulong_t wcnt;
+
+	new = gethrtime();
+	delta = new - kiop->wlastupdate;
+	kiop->wlastupdate = new;
+	wcnt = kiop->wcnt--;
+	ASSERT((int)wcnt > 0);
+	kiop->wlentime += delta * wcnt;
+	kiop->wtime += delta;
+}
+EXPORT_SYMBOL(kstat_waitq_exit);
+
+void
+kstat_runq_enter(kstat_io_t *kiop)
+{
+	hrtime_t new, delta;
+	ulong_t rcnt;
+
+	new = gethrtime();
+	delta = new - kiop->rlastupdate;
+	kiop->rlastupdate = new;
+	rcnt = kiop->rcnt++;
+	if (rcnt != 0) {
+		kiop->rlentime += delta * rcnt;
+		kiop->rtime += delta;
+	}
+}
+EXPORT_SYMBOL(kstat_runq_enter);
+
+void
+kstat_runq_exit(kstat_io_t *kiop)
+{
+	hrtime_t new, delta;
+	ulong_t rcnt;
+
+	new = gethrtime();
+	delta = new - kiop->rlastupdate;
+	kiop->rlastupdate = new;
+	rcnt = kiop->rcnt--;
+	ASSERT((int)rcnt > 0);
+	kiop->rlentime += delta * rcnt;
+	kiop->rtime += delta;
+}
+EXPORT_SYMBOL(kstat_runq_exit);
+
+static int
+kstat_seq_show_headers(struct seq_file *f)
+{
+	kstat_t *ksp = (kstat_t *)f->private;
+	int rc = 0;
+
+	ASSERT(ksp->ks_magic == KS_MAGIC);
+
+	seq_printf(f, "%d %d 0x%02x %d %d %lld %lld\n",
+	    ksp->ks_kid, ksp->ks_type, ksp->ks_flags,
+	    ksp->ks_ndata, (int)ksp->ks_data_size,
+	    ksp->ks_crtime, ksp->ks_snaptime);
+
+	switch (ksp->ks_type) {
+		case KSTAT_TYPE_RAW:
+restart:
+			if (ksp->ks_raw_ops.headers) {
+				rc = ksp->ks_raw_ops.headers(
+				    ksp->ks_raw_buf, ksp->ks_raw_bufsize);
+				if (rc == ENOMEM && !kstat_resize_raw(ksp))
+					goto restart;
+				if (!rc)
+					seq_puts(f, ksp->ks_raw_buf);
+			} else {
+				seq_printf(f, "raw data\n");
+			}
+			break;
+		case KSTAT_TYPE_NAMED:
+			seq_printf(f, "%-31s %-4s %s\n",
+			    "name", "type", "data");
+			break;
+		case KSTAT_TYPE_INTR:
+			seq_printf(f, "%-8s %-8s %-8s %-8s %-8s\n",
+			    "hard", "soft", "watchdog",
+			    "spurious", "multsvc");
+			break;
+		case KSTAT_TYPE_IO:
+			seq_printf(f,
+			    "%-8s %-8s %-8s %-8s %-8s %-8s "
+			    "%-8s %-8s %-8s %-8s %-8s %-8s\n",
+			    "nread", "nwritten", "reads", "writes",
+			    "wtime", "wlentime", "wupdate",
+			    "rtime", "rlentime", "rupdate",
+			    "wcnt", "rcnt");
+			break;
+		case KSTAT_TYPE_TIMER:
+			seq_printf(f,
+			    "%-31s %-8s "
+			    "%-8s %-8s %-8s %-8s %-8s\n",
+			    "name", "events", "elapsed",
+			    "min", "max", "start", "stop");
+			break;
+		default:
+			PANIC("Undefined kstat type %d\n", ksp->ks_type);
+	}
+
+	return (-rc);
+}
+
+static int
+kstat_seq_show_raw(struct seq_file *f, unsigned char *p, int l)
+{
+	int i, j;
+
+	for (i = 0; ; i++) {
+		seq_printf(f, "%03x:", i);
+
+		for (j = 0; j < 16; j++) {
+			if (i * 16 + j >= l) {
+				seq_printf(f, "\n");
+				goto out;
+			}
+
+			seq_printf(f, " %02x", (unsigned char)p[i * 16 + j]);
+		}
+		seq_printf(f, "\n");
+	}
+out:
+	return (0);
+}
+
+static int
+kstat_seq_show_named(struct seq_file *f, kstat_named_t *knp)
+{
+	seq_printf(f, "%-31s %-4d ", knp->name, knp->data_type);
+
+	switch (knp->data_type) {
+		case KSTAT_DATA_CHAR:
+			knp->value.c[15] = '\0'; /* NULL terminate */
+			seq_printf(f, "%-16s", knp->value.c);
+			break;
+		/*
+		 * NOTE - We need to be more careful able what tokens are
+		 * used for each arch, for now this is correct for x86_64.
+		 */
+		case KSTAT_DATA_INT32:
+			seq_printf(f, "%d", knp->value.i32);
+			break;
+		case KSTAT_DATA_UINT32:
+			seq_printf(f, "%u", knp->value.ui32);
+			break;
+		case KSTAT_DATA_INT64:
+			seq_printf(f, "%lld", (signed long long)knp->value.i64);
+			break;
+		case KSTAT_DATA_UINT64:
+			seq_printf(f, "%llu",
+			    (unsigned long long)knp->value.ui64);
+			break;
+		case KSTAT_DATA_LONG:
+			seq_printf(f, "%ld", knp->value.l);
+			break;
+		case KSTAT_DATA_ULONG:
+			seq_printf(f, "%lu", knp->value.ul);
+			break;
+		case KSTAT_DATA_STRING:
+			KSTAT_NAMED_STR_PTR(knp)
+				[KSTAT_NAMED_STR_BUFLEN(knp)-1] = '\0';
+			seq_printf(f, "%s", KSTAT_NAMED_STR_PTR(knp));
+			break;
+		default:
+			PANIC("Undefined kstat data type %d\n", knp->data_type);
+	}
+
+	seq_printf(f, "\n");
+
+	return (0);
+}
+
+static int
+kstat_seq_show_intr(struct seq_file *f, kstat_intr_t *kip)
+{
+	seq_printf(f, "%-8u %-8u %-8u %-8u %-8u\n",
+	    kip->intrs[KSTAT_INTR_HARD],
+	    kip->intrs[KSTAT_INTR_SOFT],
+	    kip->intrs[KSTAT_INTR_WATCHDOG],
+	    kip->intrs[KSTAT_INTR_SPURIOUS],
+	    kip->intrs[KSTAT_INTR_MULTSVC]);
+
+	return (0);
+}
+
+static int
+kstat_seq_show_io(struct seq_file *f, kstat_io_t *kip)
+{
+	/* though wlentime & friends are signed, they will never be negative */
+	seq_printf(f,
+	    "%-8llu %-8llu %-8u %-8u %-8llu %-8llu "
+	    "%-8llu %-8llu %-8llu %-8llu %-8u %-8u\n",
+	    kip->nread, kip->nwritten,
+	    kip->reads, kip->writes,
+	    kip->wtime, kip->wlentime, kip->wlastupdate,
+	    kip->rtime, kip->rlentime, kip->rlastupdate,
+	    kip->wcnt,  kip->rcnt);
+
+	return (0);
+}
+
+static int
+kstat_seq_show_timer(struct seq_file *f, kstat_timer_t *ktp)
+{
+	seq_printf(f,
+	    "%-31s %-8llu %-8llu %-8llu %-8llu %-8llu %-8llu\n",
+	    ktp->name, ktp->num_events, ktp->elapsed_time,
+	    ktp->min_time, ktp->max_time,
+	    ktp->start_time, ktp->stop_time);
+
+	return (0);
+}
+
+static int
+kstat_seq_show(struct seq_file *f, void *p)
+{
+	kstat_t *ksp = (kstat_t *)f->private;
+	int rc = 0;
+
+	ASSERT(ksp->ks_magic == KS_MAGIC);
+
+	switch (ksp->ks_type) {
+		case KSTAT_TYPE_RAW:
+restart:
+			if (ksp->ks_raw_ops.data) {
+				rc = ksp->ks_raw_ops.data(
+				    ksp->ks_raw_buf, ksp->ks_raw_bufsize, p);
+				if (rc == ENOMEM && !kstat_resize_raw(ksp))
+					goto restart;
+				if (!rc)
+					seq_puts(f, ksp->ks_raw_buf);
+			} else {
+				ASSERT(ksp->ks_ndata == 1);
+				rc = kstat_seq_show_raw(f, ksp->ks_data,
+				    ksp->ks_data_size);
+			}
+			break;
+		case KSTAT_TYPE_NAMED:
+			rc = kstat_seq_show_named(f, (kstat_named_t *)p);
+			break;
+		case KSTAT_TYPE_INTR:
+			rc = kstat_seq_show_intr(f, (kstat_intr_t *)p);
+			break;
+		case KSTAT_TYPE_IO:
+			rc = kstat_seq_show_io(f, (kstat_io_t *)p);
+			break;
+		case KSTAT_TYPE_TIMER:
+			rc = kstat_seq_show_timer(f, (kstat_timer_t *)p);
+			break;
+		default:
+			PANIC("Undefined kstat type %d\n", ksp->ks_type);
+	}
+
+	return (-rc);
+}
+
+static int
+kstat_default_update(kstat_t *ksp, int rw)
+{
+	ASSERT(ksp != NULL);
+
+	if (rw == KSTAT_WRITE)
+		return (EACCES);
+
+	return (0);
+}
+
+static void *
+kstat_seq_data_addr(kstat_t *ksp, loff_t n)
+{
+	void *rc = NULL;
+
+	switch (ksp->ks_type) {
+		case KSTAT_TYPE_RAW:
+			if (ksp->ks_raw_ops.addr)
+				rc = ksp->ks_raw_ops.addr(ksp, n);
+			else
+				rc = ksp->ks_data;
+			break;
+		case KSTAT_TYPE_NAMED:
+			rc = ksp->ks_data + n * sizeof (kstat_named_t);
+			break;
+		case KSTAT_TYPE_INTR:
+			rc = ksp->ks_data + n * sizeof (kstat_intr_t);
+			break;
+		case KSTAT_TYPE_IO:
+			rc = ksp->ks_data + n * sizeof (kstat_io_t);
+			break;
+		case KSTAT_TYPE_TIMER:
+			rc = ksp->ks_data + n * sizeof (kstat_timer_t);
+			break;
+		default:
+			PANIC("Undefined kstat type %d\n", ksp->ks_type);
+	}
+
+	return (rc);
+}
+
+static void *
+kstat_seq_start(struct seq_file *f, loff_t *pos)
+{
+	loff_t n = *pos;
+	kstat_t *ksp = (kstat_t *)f->private;
+	ASSERT(ksp->ks_magic == KS_MAGIC);
+
+	mutex_enter(ksp->ks_lock);
+
+	if (ksp->ks_type == KSTAT_TYPE_RAW) {
+		ksp->ks_raw_bufsize = PAGE_SIZE;
+		ksp->ks_raw_buf = vmem_alloc(ksp->ks_raw_bufsize, KM_SLEEP);
+	}
+
+	/* Dynamically update kstat, on error existing kstats are used */
+	(void) ksp->ks_update(ksp, KSTAT_READ);
+
+	ksp->ks_snaptime = gethrtime();
+
+	if (!(ksp->ks_flags & KSTAT_FLAG_NO_HEADERS) && !n &&
+	    kstat_seq_show_headers(f))
+		return (NULL);
+
+	if (n >= ksp->ks_ndata)
+		return (NULL);
+
+	return (kstat_seq_data_addr(ksp, n));
+}
+
+static void *
+kstat_seq_next(struct seq_file *f, void *p, loff_t *pos)
+{
+	kstat_t *ksp = (kstat_t *)f->private;
+	ASSERT(ksp->ks_magic == KS_MAGIC);
+
+	++*pos;
+	if (*pos >= ksp->ks_ndata)
+		return (NULL);
+
+	return (kstat_seq_data_addr(ksp, *pos));
+}
+
+static void
+kstat_seq_stop(struct seq_file *f, void *v)
+{
+	kstat_t *ksp = (kstat_t *)f->private;
+	ASSERT(ksp->ks_magic == KS_MAGIC);
+
+	if (ksp->ks_type == KSTAT_TYPE_RAW)
+		vmem_free(ksp->ks_raw_buf, ksp->ks_raw_bufsize);
+
+	mutex_exit(ksp->ks_lock);
+}
+
+static struct seq_operations kstat_seq_ops = {
+	.show  = kstat_seq_show,
+	.start = kstat_seq_start,
+	.next  = kstat_seq_next,
+	.stop  = kstat_seq_stop,
+};
+
+static kstat_module_t *
+kstat_find_module(char *name)
+{
+	kstat_module_t *module;
+
+	list_for_each_entry(module, &kstat_module_list, ksm_module_list) {
+		if (strncmp(name, module->ksm_name, KSTAT_STRLEN) == 0)
+			return (module);
+	}
+
+	return (NULL);
+}
+
+static kstat_module_t *
+kstat_create_module(char *name)
+{
+	kstat_module_t *module;
+	struct proc_dir_entry *pde;
+
+	pde = proc_mkdir(name, proc_spl_kstat);
+	if (pde == NULL)
+		return (NULL);
+
+	module = kmem_alloc(sizeof (kstat_module_t), KM_SLEEP);
+	module->ksm_proc = pde;
+	strlcpy(module->ksm_name, name, KSTAT_STRLEN+1);
+	INIT_LIST_HEAD(&module->ksm_kstat_list);
+	list_add_tail(&module->ksm_module_list, &kstat_module_list);
+
+	return (module);
+
+}
+
+static void
+kstat_delete_module(kstat_module_t *module)
+{
+	ASSERT(list_empty(&module->ksm_kstat_list));
+	remove_proc_entry(module->ksm_name, proc_spl_kstat);
+	list_del(&module->ksm_module_list);
+	kmem_free(module, sizeof (kstat_module_t));
+}
+
+static int
+proc_kstat_open(struct inode *inode, struct file *filp)
+{
+	struct seq_file *f;
+	int rc;
+
+	rc = seq_open(filp, &kstat_seq_ops);
+	if (rc)
+		return (rc);
+
+	f = filp->private_data;
+	f->private = PDE_DATA(inode);
+
+	return (rc);
+}
+
+static ssize_t
+proc_kstat_write(struct file *filp, const char __user *buf, size_t len,
+    loff_t *ppos)
+{
+	struct seq_file *f = filp->private_data;
+	kstat_t *ksp = f->private;
+	int rc;
+
+	ASSERT(ksp->ks_magic == KS_MAGIC);
+
+	mutex_enter(ksp->ks_lock);
+	rc = ksp->ks_update(ksp, KSTAT_WRITE);
+	mutex_exit(ksp->ks_lock);
+
+	if (rc)
+		return (-rc);
+
+	*ppos += len;
+	return (len);
+}
+
+static struct file_operations proc_kstat_operations = {
+	.open		= proc_kstat_open,
+	.write		= proc_kstat_write,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+void
+__kstat_set_raw_ops(kstat_t *ksp,
+    int (*headers)(char *buf, size_t size),
+    int (*data)(char *buf, size_t size, void *data),
+    void *(*addr)(kstat_t *ksp, loff_t index))
+{
+	ksp->ks_raw_ops.headers = headers;
+	ksp->ks_raw_ops.data    = data;
+	ksp->ks_raw_ops.addr    = addr;
+}
+EXPORT_SYMBOL(__kstat_set_raw_ops);
+
+void
+kstat_proc_entry_init(kstat_proc_entry_t *kpep, const char *module,
+    const char *name)
+{
+	kpep->kpe_owner = NULL;
+	kpep->kpe_proc = NULL;
+	INIT_LIST_HEAD(&kpep->kpe_list);
+	strncpy(kpep->kpe_module, module, KSTAT_STRLEN);
+	strncpy(kpep->kpe_name, name, KSTAT_STRLEN);
+}
+EXPORT_SYMBOL(kstat_proc_entry_init);
+
+kstat_t *
+__kstat_create(const char *ks_module, int ks_instance, const char *ks_name,
+    const char *ks_class, uchar_t ks_type, uint_t ks_ndata,
+    uchar_t ks_flags)
+{
+	kstat_t *ksp;
+
+	ASSERT(ks_module);
+	ASSERT(ks_instance == 0);
+	ASSERT(ks_name);
+
+	if ((ks_type == KSTAT_TYPE_INTR) || (ks_type == KSTAT_TYPE_IO))
+		ASSERT(ks_ndata == 1);
+
+	ksp = kmem_zalloc(sizeof (*ksp), KM_SLEEP);
+	if (ksp == NULL)
+		return (ksp);
+
+	mutex_enter(&kstat_module_lock);
+	ksp->ks_kid = kstat_id;
+	kstat_id++;
+	mutex_exit(&kstat_module_lock);
+
+	ksp->ks_magic = KS_MAGIC;
+	mutex_init(&ksp->ks_private_lock, NULL, MUTEX_DEFAULT, NULL);
+	ksp->ks_lock = &ksp->ks_private_lock;
+
+	ksp->ks_crtime = gethrtime();
+	ksp->ks_snaptime = ksp->ks_crtime;
+	ksp->ks_instance = ks_instance;
+	strncpy(ksp->ks_class, ks_class, KSTAT_STRLEN);
+	ksp->ks_type = ks_type;
+	ksp->ks_flags = ks_flags;
+	ksp->ks_update = kstat_default_update;
+	ksp->ks_private = NULL;
+	ksp->ks_raw_ops.headers = NULL;
+	ksp->ks_raw_ops.data = NULL;
+	ksp->ks_raw_ops.addr = NULL;
+	ksp->ks_raw_buf = NULL;
+	ksp->ks_raw_bufsize = 0;
+	kstat_proc_entry_init(&ksp->ks_proc, ks_module, ks_name);
+
+	switch (ksp->ks_type) {
+		case KSTAT_TYPE_RAW:
+			ksp->ks_ndata = 1;
+			ksp->ks_data_size = ks_ndata;
+			break;
+		case KSTAT_TYPE_NAMED:
+			ksp->ks_ndata = ks_ndata;
+			ksp->ks_data_size = ks_ndata * sizeof (kstat_named_t);
+			break;
+		case KSTAT_TYPE_INTR:
+			ksp->ks_ndata = ks_ndata;
+			ksp->ks_data_size = ks_ndata * sizeof (kstat_intr_t);
+			break;
+		case KSTAT_TYPE_IO:
+			ksp->ks_ndata = ks_ndata;
+			ksp->ks_data_size = ks_ndata * sizeof (kstat_io_t);
+			break;
+		case KSTAT_TYPE_TIMER:
+			ksp->ks_ndata = ks_ndata;
+			ksp->ks_data_size = ks_ndata * sizeof (kstat_timer_t);
+			break;
+		default:
+			PANIC("Undefined kstat type %d\n", ksp->ks_type);
+	}
+
+	if (ksp->ks_flags & KSTAT_FLAG_VIRTUAL) {
+		ksp->ks_data = NULL;
+	} else {
+		ksp->ks_data = kmem_zalloc(ksp->ks_data_size, KM_SLEEP);
+		if (ksp->ks_data == NULL) {
+			kmem_free(ksp, sizeof (*ksp));
+			ksp = NULL;
+		}
+	}
+
+	return (ksp);
+}
+EXPORT_SYMBOL(__kstat_create);
+
+static int
+kstat_detect_collision(kstat_proc_entry_t *kpep)
+{
+	kstat_module_t *module;
+	kstat_proc_entry_t *tmp;
+	char *parent;
+	char *cp;
+
+	parent = kmem_asprintf("%s", kpep->kpe_module);
+
+	if ((cp = strrchr(parent, '/')) == NULL) {
+		strfree(parent);
+		return (0);
+	}
+
+	cp[0] = '\0';
+	if ((module = kstat_find_module(parent)) != NULL) {
+		list_for_each_entry(tmp, &module->ksm_kstat_list, kpe_list) {
+			if (strncmp(tmp->kpe_name, cp+1, KSTAT_STRLEN) == 0) {
+				strfree(parent);
+				return (EEXIST);
+			}
+		}
+	}
+
+	strfree(parent);
+	return (0);
+}
+
+/*
+ * Add a file to the proc filesystem under the kstat namespace (i.e.
+ * /proc/spl/kstat/). The file need not necessarily be implemented as a
+ * kstat.
+ */
+void
+kstat_proc_entry_install(kstat_proc_entry_t *kpep, mode_t mode,
+    const struct file_operations *file_ops, void *data)
+{
+	kstat_module_t *module;
+	kstat_proc_entry_t *tmp;
+
+	ASSERT(kpep);
+
+	mutex_enter(&kstat_module_lock);
+
+	module = kstat_find_module(kpep->kpe_module);
+	if (module == NULL) {
+		if (kstat_detect_collision(kpep) != 0) {
+			cmn_err(CE_WARN, "kstat_create('%s', '%s'): namespace" \
+			    " collision", kpep->kpe_module, kpep->kpe_name);
+			goto out;
+		}
+		module = kstat_create_module(kpep->kpe_module);
+		if (module == NULL)
+			goto out;
+	}
+
+	/*
+	 * Only one entry by this name per-module, on failure the module
+	 * shouldn't be deleted because we know it has at least one entry.
+	 */
+	list_for_each_entry(tmp, &module->ksm_kstat_list, kpe_list) {
+		if (strncmp(tmp->kpe_name, kpep->kpe_name, KSTAT_STRLEN) == 0)
+			goto out;
+	}
+
+	list_add_tail(&kpep->kpe_list, &module->ksm_kstat_list);
+
+	kpep->kpe_owner = module;
+	kpep->kpe_proc = proc_create_data(kpep->kpe_name, mode,
+	    module->ksm_proc, file_ops, data);
+	if (kpep->kpe_proc == NULL) {
+		list_del_init(&kpep->kpe_list);
+		if (list_empty(&module->ksm_kstat_list))
+			kstat_delete_module(module);
+	}
+out:
+	mutex_exit(&kstat_module_lock);
+
+}
+EXPORT_SYMBOL(kstat_proc_entry_install);
+
+void
+__kstat_install(kstat_t *ksp)
+{
+	ASSERT(ksp);
+	mode_t mode;
+	/* Specify permission modes for different kstats */
+	if (strncmp(ksp->ks_proc.kpe_name, "dbufs", KSTAT_STRLEN) == 0) {
+		mode = 0600;
+	} else {
+		mode = 0644;
+	}
+	kstat_proc_entry_install(
+	    &ksp->ks_proc, mode, &proc_kstat_operations, ksp);
+}
+EXPORT_SYMBOL(__kstat_install);
+
+void
+kstat_proc_entry_delete(kstat_proc_entry_t *kpep)
+{
+	kstat_module_t *module = kpep->kpe_owner;
+	if (kpep->kpe_proc)
+		remove_proc_entry(kpep->kpe_name, module->ksm_proc);
+
+	mutex_enter(&kstat_module_lock);
+	list_del_init(&kpep->kpe_list);
+
+	/*
+	 * Remove top level module directory if it wasn't empty before, but now
+	 * is.
+	 */
+	if (kpep->kpe_proc && list_empty(&module->ksm_kstat_list))
+		kstat_delete_module(module);
+	mutex_exit(&kstat_module_lock);
+
+}
+EXPORT_SYMBOL(kstat_proc_entry_delete);
+
+void
+__kstat_delete(kstat_t *ksp)
+{
+	kstat_proc_entry_delete(&ksp->ks_proc);
+
+	if (!(ksp->ks_flags & KSTAT_FLAG_VIRTUAL))
+		kmem_free(ksp->ks_data, ksp->ks_data_size);
+
+	ksp->ks_lock = NULL;
+	mutex_destroy(&ksp->ks_private_lock);
+	kmem_free(ksp, sizeof (*ksp));
+}
+EXPORT_SYMBOL(__kstat_delete);
+
+int
+spl_kstat_init(void)
+{
+	mutex_init(&kstat_module_lock, NULL, MUTEX_DEFAULT, NULL);
+	INIT_LIST_HEAD(&kstat_module_list);
+	kstat_id = 0;
+	return (0);
+}
+
+void
+spl_kstat_fini(void)
+{
+	ASSERT(list_empty(&kstat_module_list));
+	mutex_destroy(&kstat_module_lock);
+}
diff --git a/module/os/linux/spl/spl-proc.c b/module/os/linux/spl/spl-proc.c
new file mode 100644
index 000000000..a75bcc214
--- /dev/null
+++ b/module/os/linux/spl/spl-proc.c
@@ -0,0 +1,782 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Proc Implementation.
+ */
+
+#include <sys/systeminfo.h>
+#include <sys/kstat.h>
+#include <sys/kmem.h>
+#include <sys/kmem_cache.h>
+#include <sys/vmem.h>
+#include <sys/taskq.h>
+#include <sys/proc.h>
+#include <linux/ctype.h>
+#include <linux/kmod.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include <linux/version.h>
+
+#if defined(CONSTIFY_PLUGIN) && LINUX_VERSION_CODE >= KERNEL_VERSION(3, 8, 0)
+typedef struct ctl_table __no_const spl_ctl_table;
+#else
+typedef struct ctl_table spl_ctl_table;
+#endif
+
+static unsigned long table_min = 0;
+static unsigned long table_max = ~0;
+
+static struct ctl_table_header *spl_header = NULL;
+static struct proc_dir_entry *proc_spl = NULL;
+static struct proc_dir_entry *proc_spl_kmem = NULL;
+static struct proc_dir_entry *proc_spl_kmem_slab = NULL;
+static struct proc_dir_entry *proc_spl_taskq_all = NULL;
+static struct proc_dir_entry *proc_spl_taskq = NULL;
+struct proc_dir_entry *proc_spl_kstat = NULL;
+
+static int
+proc_copyin_string(char *kbuffer, int kbuffer_size, const char *ubuffer,
+    int ubuffer_size)
+{
+	int size;
+
+	if (ubuffer_size > kbuffer_size)
+		return (-EOVERFLOW);
+
+	if (copy_from_user((void *)kbuffer, (void *)ubuffer, ubuffer_size))
+		return (-EFAULT);
+
+	/* strip trailing whitespace */
+	size = strnlen(kbuffer, ubuffer_size);
+	while (size-- >= 0)
+		if (!isspace(kbuffer[size]))
+			break;
+
+	/* empty string */
+	if (size < 0)
+		return (-EINVAL);
+
+	/* no space to terminate */
+	if (size == kbuffer_size)
+		return (-EOVERFLOW);
+
+	kbuffer[size + 1] = 0;
+	return (0);
+}
+
+static int
+proc_copyout_string(char *ubuffer, int ubuffer_size, const char *kbuffer,
+    char *append)
+{
+	/*
+	 * NB if 'append' != NULL, it's a single character to append to the
+	 * copied out string - usually "\n", for /proc entries and
+	 * (i.e. a terminating zero byte) for sysctl entries
+	 */
+	int size = MIN(strlen(kbuffer), ubuffer_size);
+
+	if (copy_to_user(ubuffer, kbuffer, size))
+		return (-EFAULT);
+
+	if (append != NULL && size < ubuffer_size) {
+		if (copy_to_user(ubuffer + size, append, 1))
+			return (-EFAULT);
+
+		size++;
+	}
+
+	return (size);
+}
+
+#ifdef DEBUG_KMEM
+static int
+proc_domemused(struct ctl_table *table, int write,
+    void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	int rc = 0;
+	unsigned long min = 0, max = ~0, val;
+	spl_ctl_table dummy = *table;
+
+	dummy.data = &val;
+	dummy.proc_handler = &proc_dointvec;
+	dummy.extra1 = &min;
+	dummy.extra2 = &max;
+
+	if (write) {
+		*ppos += *lenp;
+	} else {
+#ifdef HAVE_ATOMIC64_T
+		val = atomic64_read((atomic64_t *)table->data);
+#else
+		val = atomic_read((atomic_t *)table->data);
+#endif /* HAVE_ATOMIC64_T */
+		rc = proc_doulongvec_minmax(&dummy, write, buffer, lenp, ppos);
+	}
+
+	return (rc);
+}
+#endif /* DEBUG_KMEM */
+
+static int
+proc_doslab(struct ctl_table *table, int write,
+    void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	int rc = 0;
+	unsigned long min = 0, max = ~0, val = 0, mask;
+	spl_ctl_table dummy = *table;
+	spl_kmem_cache_t *skc;
+
+	dummy.data = &val;
+	dummy.proc_handler = &proc_dointvec;
+	dummy.extra1 = &min;
+	dummy.extra2 = &max;
+
+	if (write) {
+		*ppos += *lenp;
+	} else {
+		down_read(&spl_kmem_cache_sem);
+		mask = (unsigned long)table->data;
+
+		list_for_each_entry(skc, &spl_kmem_cache_list, skc_list) {
+
+			/* Only use slabs of the correct kmem/vmem type */
+			if (!(skc->skc_flags & mask))
+				continue;
+
+			/* Sum the specified field for selected slabs */
+			switch (mask & (KMC_TOTAL | KMC_ALLOC | KMC_MAX)) {
+			case KMC_TOTAL:
+				val += skc->skc_slab_size * skc->skc_slab_total;
+				break;
+			case KMC_ALLOC:
+				val += skc->skc_obj_size * skc->skc_obj_alloc;
+				break;
+			case KMC_MAX:
+				val += skc->skc_obj_size * skc->skc_obj_max;
+				break;
+			}
+		}
+
+		up_read(&spl_kmem_cache_sem);
+		rc = proc_doulongvec_minmax(&dummy, write, buffer, lenp, ppos);
+	}
+
+	return (rc);
+}
+
+static int
+proc_dohostid(struct ctl_table *table, int write,
+    void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	int len, rc = 0;
+	char *end, str[32];
+
+	if (write) {
+		/*
+		 * We can't use proc_doulongvec_minmax() in the write
+		 * case here because hostid while a hex value has no
+		 * leading 0x which confuses the helper function.
+		 */
+		rc = proc_copyin_string(str, sizeof (str), buffer, *lenp);
+		if (rc < 0)
+			return (rc);
+
+		spl_hostid = simple_strtoul(str, &end, 16);
+		if (str == end)
+			return (-EINVAL);
+
+	} else {
+		len = snprintf(str, sizeof (str), "%lx",
+		    (unsigned long) zone_get_hostid(NULL));
+		if (*ppos >= len)
+			rc = 0;
+		else
+			rc = proc_copyout_string(buffer,
+			    *lenp, str + *ppos, "\n");
+
+		if (rc >= 0) {
+			*lenp = rc;
+			*ppos += rc;
+		}
+	}
+
+	return (rc);
+}
+
+static void
+taskq_seq_show_headers(struct seq_file *f)
+{
+	seq_printf(f, "%-25s %5s %5s %5s %5s %5s %5s %12s %5s %10s\n",
+	    "taskq", "act", "nthr", "spwn", "maxt", "pri",
+	    "mina", "maxa", "cura", "flags");
+}
+
+/* indices into the lheads array below */
+#define	LHEAD_PEND	0
+#define	LHEAD_PRIO	1
+#define	LHEAD_DELAY	2
+#define	LHEAD_WAIT	3
+#define	LHEAD_ACTIVE	4
+#define	LHEAD_SIZE	5
+
+/* BEGIN CSTYLED */
+static unsigned int spl_max_show_tasks = 512;
+module_param(spl_max_show_tasks, uint, 0644);
+MODULE_PARM_DESC(spl_max_show_tasks, "Max number of tasks shown in taskq proc");
+/* END CSTYLED */
+
+static int
+taskq_seq_show_impl(struct seq_file *f, void *p, boolean_t allflag)
+{
+	taskq_t *tq = p;
+	taskq_thread_t *tqt;
+	spl_wait_queue_entry_t *wq;
+	struct task_struct *tsk;
+	taskq_ent_t *tqe;
+	char name[100];
+	struct list_head *lheads[LHEAD_SIZE], *lh;
+	static char *list_names[LHEAD_SIZE] =
+	    {"pend", "prio", "delay", "wait", "active" };
+	int i, j, have_lheads = 0;
+	unsigned long wflags, flags;
+
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+	spin_lock_irqsave(&tq->tq_wait_waitq.lock, wflags);
+
+	/* get the various lists and check whether they're empty */
+	lheads[LHEAD_PEND] = &tq->tq_pend_list;
+	lheads[LHEAD_PRIO] = &tq->tq_prio_list;
+	lheads[LHEAD_DELAY] = &tq->tq_delay_list;
+#ifdef HAVE_WAIT_QUEUE_HEAD_ENTRY
+	lheads[LHEAD_WAIT] = &tq->tq_wait_waitq.head;
+#else
+	lheads[LHEAD_WAIT] = &tq->tq_wait_waitq.task_list;
+#endif
+	lheads[LHEAD_ACTIVE] = &tq->tq_active_list;
+
+	for (i = 0; i < LHEAD_SIZE; ++i) {
+		if (list_empty(lheads[i]))
+			lheads[i] = NULL;
+		else
+			++have_lheads;
+	}
+
+	/* early return in non-"all" mode if lists are all empty */
+	if (!allflag && !have_lheads) {
+		spin_unlock_irqrestore(&tq->tq_wait_waitq.lock, wflags);
+		spin_unlock_irqrestore(&tq->tq_lock, flags);
+		return (0);
+	}
+
+	/* unlock the waitq quickly */
+	if (!lheads[LHEAD_WAIT])
+		spin_unlock_irqrestore(&tq->tq_wait_waitq.lock, wflags);
+
+	/* show the base taskq contents */
+	snprintf(name, sizeof (name), "%s/%d", tq->tq_name, tq->tq_instance);
+	seq_printf(f, "%-25s ", name);
+	seq_printf(f, "%5d %5d %5d %5d %5d %5d %12d %5d %10x\n",
+	    tq->tq_nactive, tq->tq_nthreads, tq->tq_nspawn,
+	    tq->tq_maxthreads, tq->tq_pri, tq->tq_minalloc, tq->tq_maxalloc,
+	    tq->tq_nalloc, tq->tq_flags);
+
+	/* show the active list */
+	if (lheads[LHEAD_ACTIVE]) {
+		j = 0;
+		list_for_each_entry(tqt, &tq->tq_active_list, tqt_active_list) {
+			if (j == 0)
+				seq_printf(f, "\t%s:",
+				    list_names[LHEAD_ACTIVE]);
+			else if (j == 2) {
+				seq_printf(f, "\n\t       ");
+				j = 0;
+			}
+			seq_printf(f, " [%d]%pf(%ps)",
+			    tqt->tqt_thread->pid,
+			    tqt->tqt_task->tqent_func,
+			    tqt->tqt_task->tqent_arg);
+			++j;
+		}
+		seq_printf(f, "\n");
+	}
+
+	for (i = LHEAD_PEND; i <= LHEAD_WAIT; ++i)
+		if (lheads[i]) {
+			j = 0;
+			list_for_each(lh, lheads[i]) {
+				if (spl_max_show_tasks != 0 &&
+				    j >= spl_max_show_tasks) {
+					seq_printf(f, "\n\t(truncated)");
+					break;
+				}
+				/* show the wait waitq list */
+				if (i == LHEAD_WAIT) {
+#ifdef HAVE_WAIT_QUEUE_HEAD_ENTRY
+					wq = list_entry(lh,
+					    spl_wait_queue_entry_t, entry);
+#else
+					wq = list_entry(lh,
+					    spl_wait_queue_entry_t, task_list);
+#endif
+					if (j == 0)
+						seq_printf(f, "\t%s:",
+						    list_names[i]);
+					else if (j % 8 == 0)
+						seq_printf(f, "\n\t     ");
+
+					tsk = wq->private;
+					seq_printf(f, " %d", tsk->pid);
+				/* pend, prio and delay lists */
+				} else {
+					tqe = list_entry(lh, taskq_ent_t,
+					    tqent_list);
+					if (j == 0)
+						seq_printf(f, "\t%s:",
+						    list_names[i]);
+					else if (j % 2 == 0)
+						seq_printf(f, "\n\t     ");
+
+					seq_printf(f, " %pf(%ps)",
+					    tqe->tqent_func,
+					    tqe->tqent_arg);
+				}
+				++j;
+			}
+			seq_printf(f, "\n");
+		}
+	if (lheads[LHEAD_WAIT])
+		spin_unlock_irqrestore(&tq->tq_wait_waitq.lock, wflags);
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	return (0);
+}
+
+static int
+taskq_all_seq_show(struct seq_file *f, void *p)
+{
+	return (taskq_seq_show_impl(f, p, B_TRUE));
+}
+
+static int
+taskq_seq_show(struct seq_file *f, void *p)
+{
+	return (taskq_seq_show_impl(f, p, B_FALSE));
+}
+
+static void *
+taskq_seq_start(struct seq_file *f, loff_t *pos)
+{
+	struct list_head *p;
+	loff_t n = *pos;
+
+	down_read(&tq_list_sem);
+	if (!n)
+		taskq_seq_show_headers(f);
+
+	p = tq_list.next;
+	while (n--) {
+		p = p->next;
+		if (p == &tq_list)
+		return (NULL);
+	}
+
+	return (list_entry(p, taskq_t, tq_taskqs));
+}
+
+static void *
+taskq_seq_next(struct seq_file *f, void *p, loff_t *pos)
+{
+	taskq_t *tq = p;
+
+	++*pos;
+	return ((tq->tq_taskqs.next == &tq_list) ?
+	    NULL : list_entry(tq->tq_taskqs.next, taskq_t, tq_taskqs));
+}
+
+static void
+slab_seq_show_headers(struct seq_file *f)
+{
+	seq_printf(f,
+	    "--------------------- cache ----------"
+	    "---------------------------------------------  "
+	    "----- slab ------  "
+	    "---- object -----  "
+	    "--- emergency ---\n");
+	seq_printf(f,
+	    "name                                  "
+	    "  flags      size     alloc slabsize  objsize  "
+	    "total alloc   max  "
+	    "total alloc   max  "
+	    "dlock alloc   max\n");
+}
+
+static int
+slab_seq_show(struct seq_file *f, void *p)
+{
+	spl_kmem_cache_t *skc = p;
+
+	ASSERT(skc->skc_magic == SKC_MAGIC);
+
+	/*
+	 * Backed by Linux slab see /proc/slabinfo.
+	 */
+	if (skc->skc_flags & KMC_SLAB)
+		return (0);
+
+	spin_lock(&skc->skc_lock);
+	seq_printf(f, "%-36s  ", skc->skc_name);
+	seq_printf(f, "0x%05lx %9lu %9lu %8u %8u  "
+	    "%5lu %5lu %5lu  %5lu %5lu %5lu  %5lu %5lu %5lu\n",
+	    (long unsigned)skc->skc_flags,
+	    (long unsigned)(skc->skc_slab_size * skc->skc_slab_total),
+	    (long unsigned)(skc->skc_obj_size * skc->skc_obj_alloc),
+	    (unsigned)skc->skc_slab_size,
+	    (unsigned)skc->skc_obj_size,
+	    (long unsigned)skc->skc_slab_total,
+	    (long unsigned)skc->skc_slab_alloc,
+	    (long unsigned)skc->skc_slab_max,
+	    (long unsigned)skc->skc_obj_total,
+	    (long unsigned)skc->skc_obj_alloc,
+	    (long unsigned)skc->skc_obj_max,
+	    (long unsigned)skc->skc_obj_deadlock,
+	    (long unsigned)skc->skc_obj_emergency,
+	    (long unsigned)skc->skc_obj_emergency_max);
+
+	spin_unlock(&skc->skc_lock);
+
+	return (0);
+}
+
+static void *
+slab_seq_start(struct seq_file *f, loff_t *pos)
+{
+	struct list_head *p;
+	loff_t n = *pos;
+
+	down_read(&spl_kmem_cache_sem);
+	if (!n)
+		slab_seq_show_headers(f);
+
+	p = spl_kmem_cache_list.next;
+	while (n--) {
+		p = p->next;
+		if (p == &spl_kmem_cache_list)
+			return (NULL);
+	}
+
+	return (list_entry(p, spl_kmem_cache_t, skc_list));
+}
+
+static void *
+slab_seq_next(struct seq_file *f, void *p, loff_t *pos)
+{
+	spl_kmem_cache_t *skc = p;
+
+	++*pos;
+	return ((skc->skc_list.next == &spl_kmem_cache_list) ?
+	    NULL : list_entry(skc->skc_list.next, spl_kmem_cache_t, skc_list));
+}
+
+static void
+slab_seq_stop(struct seq_file *f, void *v)
+{
+	up_read(&spl_kmem_cache_sem);
+}
+
+static struct seq_operations slab_seq_ops = {
+	.show  = slab_seq_show,
+	.start = slab_seq_start,
+	.next  = slab_seq_next,
+	.stop  = slab_seq_stop,
+};
+
+static int
+proc_slab_open(struct inode *inode, struct file *filp)
+{
+	return (seq_open(filp, &slab_seq_ops));
+}
+
+static struct file_operations proc_slab_operations = {
+	.open	   = proc_slab_open,
+	.read	   = seq_read,
+	.llseek	 = seq_lseek,
+	.release	= seq_release,
+};
+
+static void
+taskq_seq_stop(struct seq_file *f, void *v)
+{
+	up_read(&tq_list_sem);
+}
+
+static struct seq_operations taskq_all_seq_ops = {
+	.show	= taskq_all_seq_show,
+	.start	= taskq_seq_start,
+	.next	= taskq_seq_next,
+	.stop	= taskq_seq_stop,
+};
+
+static struct seq_operations taskq_seq_ops = {
+	.show	= taskq_seq_show,
+	.start	= taskq_seq_start,
+	.next	= taskq_seq_next,
+	.stop	= taskq_seq_stop,
+};
+
+static int
+proc_taskq_all_open(struct inode *inode, struct file *filp)
+{
+	return (seq_open(filp, &taskq_all_seq_ops));
+}
+
+static int
+proc_taskq_open(struct inode *inode, struct file *filp)
+{
+	return (seq_open(filp, &taskq_seq_ops));
+}
+
+static struct file_operations proc_taskq_all_operations = {
+	.open		= proc_taskq_all_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static struct file_operations proc_taskq_operations = {
+	.open		= proc_taskq_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static struct ctl_table spl_kmem_table[] = {
+#ifdef DEBUG_KMEM
+	{
+		.procname	= "kmem_used",
+		.data		= &kmem_alloc_used,
+#ifdef HAVE_ATOMIC64_T
+		.maxlen		= sizeof (atomic64_t),
+#else
+		.maxlen		= sizeof (atomic_t),
+#endif /* HAVE_ATOMIC64_T */
+		.mode		= 0444,
+		.proc_handler	= &proc_domemused,
+	},
+	{
+		.procname	= "kmem_max",
+		.data		= &kmem_alloc_max,
+		.maxlen		= sizeof (unsigned long),
+		.extra1		= &table_min,
+		.extra2		= &table_max,
+		.mode		= 0444,
+		.proc_handler	= &proc_doulongvec_minmax,
+	},
+#endif /* DEBUG_KMEM */
+	{
+		.procname	= "slab_kmem_total",
+		.data		= (void *)(KMC_KMEM | KMC_TOTAL),
+		.maxlen		= sizeof (unsigned long),
+		.extra1		= &table_min,
+		.extra2		= &table_max,
+		.mode		= 0444,
+		.proc_handler = &proc_doslab,
+	},
+	{
+		.procname	= "slab_kmem_alloc",
+		.data		= (void *)(KMC_KMEM | KMC_ALLOC),
+		.maxlen		= sizeof (unsigned long),
+		.extra1		= &table_min,
+		.extra2		= &table_max,
+		.mode		= 0444,
+		.proc_handler	= &proc_doslab,
+	},
+	{
+		.procname	= "slab_kmem_max",
+		.data		= (void *)(KMC_KMEM | KMC_MAX),
+		.maxlen		= sizeof (unsigned long),
+		.extra1		= &table_min,
+		.extra2		= &table_max,
+		.mode		= 0444,
+		.proc_handler	= &proc_doslab,
+	},
+	{
+		.procname	= "slab_vmem_total",
+		.data		= (void *)(KMC_VMEM | KMC_TOTAL),
+		.maxlen		= sizeof (unsigned long),
+		.extra1		= &table_min,
+		.extra2		= &table_max,
+		.mode		= 0444,
+		.proc_handler	= &proc_doslab,
+	},
+	{
+		.procname	= "slab_vmem_alloc",
+		.data		= (void *)(KMC_VMEM | KMC_ALLOC),
+		.maxlen		= sizeof (unsigned long),
+		.extra1		= &table_min,
+		.extra2		= &table_max,
+		.mode		= 0444,
+		.proc_handler	= &proc_doslab,
+	},
+	{
+		.procname	= "slab_vmem_max",
+		.data		= (void *)(KMC_VMEM | KMC_MAX),
+		.maxlen		= sizeof (unsigned long),
+		.extra1		= &table_min,
+		.extra2		= &table_max,
+		.mode		= 0444,
+		.proc_handler	= &proc_doslab,
+	},
+	{},
+};
+
+static struct ctl_table spl_kstat_table[] = {
+	{},
+};
+
+static struct ctl_table spl_table[] = {
+	/*
+	 * NB No .strategy entries have been provided since
+	 * sysctl(8) prefers to go via /proc for portability.
+	 */
+	{
+		.procname	= "gitrev",
+		.data		= spl_gitrev,
+		.maxlen		= sizeof (spl_gitrev),
+		.mode		= 0444,
+		.proc_handler	= &proc_dostring,
+	},
+	{
+		.procname	= "hostid",
+		.data		= &spl_hostid,
+		.maxlen		= sizeof (unsigned long),
+		.mode		= 0644,
+		.proc_handler	= &proc_dohostid,
+	},
+	{
+		.procname	= "kmem",
+		.mode		= 0555,
+		.child		= spl_kmem_table,
+	},
+	{
+		.procname	= "kstat",
+		.mode		= 0555,
+		.child		= spl_kstat_table,
+	},
+	{},
+};
+
+static struct ctl_table spl_dir[] = {
+	{
+		.procname	= "spl",
+		.mode		= 0555,
+		.child		= spl_table,
+	},
+	{}
+};
+
+static struct ctl_table spl_root[] = {
+	{
+#ifdef HAVE_CTL_NAME
+	.ctl_name = CTL_KERN,
+#endif
+	.procname = "kernel",
+	.mode = 0555,
+	.child = spl_dir,
+	},
+	{}
+};
+
+int
+spl_proc_init(void)
+{
+	int rc = 0;
+
+	spl_header = register_sysctl_table(spl_root);
+	if (spl_header == NULL)
+		return (-EUNATCH);
+
+	proc_spl = proc_mkdir("spl", NULL);
+	if (proc_spl == NULL) {
+		rc = -EUNATCH;
+		goto out;
+	}
+
+	proc_spl_taskq_all = proc_create_data("taskq-all", 0444, proc_spl,
+	    &proc_taskq_all_operations, NULL);
+	if (proc_spl_taskq_all == NULL) {
+		rc = -EUNATCH;
+		goto out;
+	}
+
+	proc_spl_taskq = proc_create_data("taskq", 0444, proc_spl,
+	    &proc_taskq_operations, NULL);
+	if (proc_spl_taskq == NULL) {
+		rc = -EUNATCH;
+		goto out;
+	}
+
+	proc_spl_kmem = proc_mkdir("kmem", proc_spl);
+	if (proc_spl_kmem == NULL) {
+		rc = -EUNATCH;
+		goto out;
+	}
+
+	proc_spl_kmem_slab = proc_create_data("slab", 0444, proc_spl_kmem,
+	    &proc_slab_operations, NULL);
+	if (proc_spl_kmem_slab == NULL) {
+		rc = -EUNATCH;
+		goto out;
+	}
+
+	proc_spl_kstat = proc_mkdir("kstat", proc_spl);
+	if (proc_spl_kstat == NULL) {
+		rc = -EUNATCH;
+		goto out;
+	}
+out:
+	if (rc) {
+		remove_proc_entry("kstat", proc_spl);
+		remove_proc_entry("slab", proc_spl_kmem);
+		remove_proc_entry("kmem", proc_spl);
+		remove_proc_entry("taskq-all", proc_spl);
+		remove_proc_entry("taskq", proc_spl);
+		remove_proc_entry("spl", NULL);
+		unregister_sysctl_table(spl_header);
+	}
+
+	return (rc);
+}
+
+void
+spl_proc_fini(void)
+{
+	remove_proc_entry("kstat", proc_spl);
+	remove_proc_entry("slab", proc_spl_kmem);
+	remove_proc_entry("kmem", proc_spl);
+	remove_proc_entry("taskq-all", proc_spl);
+	remove_proc_entry("taskq", proc_spl);
+	remove_proc_entry("spl", NULL);
+
+	ASSERT(spl_header != NULL);
+	unregister_sysctl_table(spl_header);
+}
diff --git a/module/os/linux/spl/spl-procfs-list.c b/module/os/linux/spl/spl-procfs-list.c
new file mode 100644
index 000000000..f6a00da5c
--- /dev/null
+++ b/module/os/linux/spl/spl-procfs-list.c
@@ -0,0 +1,257 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2018 by Delphix. All rights reserved.
+ */
+
+#include <sys/list.h>
+#include <sys/mutex.h>
+#include <sys/procfs_list.h>
+#include <linux/proc_fs.h>
+
+/*
+ * A procfs_list is a wrapper around a linked list which implements the seq_file
+ * interface, allowing the contents of the list to be exposed through procfs.
+ * The kernel already has some utilities to help implement the seq_file
+ * interface for linked lists (seq_list_*), but they aren't appropriate for use
+ * with lists that have many entries, because seq_list_start walks the list at
+ * the start of each read syscall to find where it left off, so reading a file
+ * ends up being quadratic in the number of entries in the list.
+ *
+ * This implementation avoids this penalty by maintaining a separate cursor into
+ * the list per instance of the file that is open. It also maintains some extra
+ * information in each node of the list to prevent reads of entries that have
+ * been dropped from the list.
+ *
+ * Callers should only add elements to the list using procfs_list_add, which
+ * adds an element to the tail of the list. Other operations can be performed
+ * directly on the wrapped list using the normal list manipulation functions,
+ * but elements should only be removed from the head of the list.
+ */
+
+#define	NODE_ID(procfs_list, obj) \
+		(((procfs_list_node_t *)(((char *)obj) + \
+		(procfs_list)->pl_node_offset))->pln_id)
+
+typedef struct procfs_list_cursor {
+	procfs_list_t	*procfs_list;	/* List into which this cursor points */
+	void		*cached_node;	/* Most recently accessed node */
+	loff_t		cached_pos;	/* Position of cached_node */
+} procfs_list_cursor_t;
+
+static int
+procfs_list_seq_show(struct seq_file *f, void *p)
+{
+	procfs_list_cursor_t *cursor = f->private;
+	procfs_list_t *procfs_list = cursor->procfs_list;
+
+	ASSERT(MUTEX_HELD(&procfs_list->pl_lock));
+	if (p == SEQ_START_TOKEN) {
+		if (procfs_list->pl_show_header != NULL)
+			return (procfs_list->pl_show_header(f));
+		else
+			return (0);
+	}
+	return (procfs_list->pl_show(f, p));
+}
+
+static void *
+procfs_list_next_node(procfs_list_cursor_t *cursor, loff_t *pos)
+{
+	void *next_node;
+	procfs_list_t *procfs_list = cursor->procfs_list;
+
+	if (cursor->cached_node == SEQ_START_TOKEN)
+		next_node = list_head(&procfs_list->pl_list);
+	else
+		next_node = list_next(&procfs_list->pl_list,
+		    cursor->cached_node);
+
+	if (next_node != NULL) {
+		cursor->cached_node = next_node;
+		cursor->cached_pos = NODE_ID(procfs_list, cursor->cached_node);
+		*pos = cursor->cached_pos;
+	}
+	return (next_node);
+}
+
+static void *
+procfs_list_seq_start(struct seq_file *f, loff_t *pos)
+{
+	procfs_list_cursor_t *cursor = f->private;
+	procfs_list_t *procfs_list = cursor->procfs_list;
+
+	mutex_enter(&procfs_list->pl_lock);
+
+	if (*pos == 0) {
+		cursor->cached_node = SEQ_START_TOKEN;
+		cursor->cached_pos = 0;
+		return (SEQ_START_TOKEN);
+	}
+
+	/*
+	 * Check if our cached pointer has become stale, which happens if the
+	 * the message where we left off has been dropped from the list since
+	 * the last read syscall completed.
+	 */
+	void *oldest_node = list_head(&procfs_list->pl_list);
+	if (cursor->cached_node != SEQ_START_TOKEN && (oldest_node == NULL ||
+	    NODE_ID(procfs_list, oldest_node) > cursor->cached_pos))
+		return (ERR_PTR(-EIO));
+
+	/*
+	 * If it isn't starting from the beginning of the file, the seq_file
+	 * code will either pick up at the same position it visited last or the
+	 * following one.
+	 */
+	if (*pos == cursor->cached_pos) {
+		return (cursor->cached_node);
+	} else {
+		ASSERT3U(*pos, ==, cursor->cached_pos + 1);
+		return (procfs_list_next_node(cursor, pos));
+	}
+}
+
+static void *
+procfs_list_seq_next(struct seq_file *f, void *p, loff_t *pos)
+{
+	procfs_list_cursor_t *cursor = f->private;
+	ASSERT(MUTEX_HELD(&cursor->procfs_list->pl_lock));
+	return (procfs_list_next_node(cursor, pos));
+}
+
+static void
+procfs_list_seq_stop(struct seq_file *f, void *p)
+{
+	procfs_list_cursor_t *cursor = f->private;
+	procfs_list_t *procfs_list = cursor->procfs_list;
+	mutex_exit(&procfs_list->pl_lock);
+}
+
+static struct seq_operations procfs_list_seq_ops = {
+	.show  = procfs_list_seq_show,
+	.start = procfs_list_seq_start,
+	.next  = procfs_list_seq_next,
+	.stop  = procfs_list_seq_stop,
+};
+
+static int
+procfs_list_open(struct inode *inode, struct file *filp)
+{
+	int rc = seq_open_private(filp, &procfs_list_seq_ops,
+	    sizeof (procfs_list_cursor_t));
+	if (rc != 0)
+		return (rc);
+
+	struct seq_file *f = filp->private_data;
+	procfs_list_cursor_t *cursor = f->private;
+	cursor->procfs_list = PDE_DATA(inode);
+	cursor->cached_node = NULL;
+	cursor->cached_pos = 0;
+
+	return (0);
+}
+
+static ssize_t
+procfs_list_write(struct file *filp, const char __user *buf, size_t len,
+    loff_t *ppos)
+{
+	struct seq_file *f = filp->private_data;
+	procfs_list_cursor_t *cursor = f->private;
+	procfs_list_t *procfs_list = cursor->procfs_list;
+	int rc;
+
+	if (procfs_list->pl_clear != NULL &&
+	    (rc = procfs_list->pl_clear(procfs_list)) != 0)
+		return (-rc);
+	return (len);
+}
+
+static struct file_operations procfs_list_operations = {
+	.owner		= THIS_MODULE,
+	.open		= procfs_list_open,
+	.write		= procfs_list_write,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release_private,
+};
+
+/*
+ * Initialize a procfs_list and create a file for it in the proc filesystem
+ * under the kstat namespace.
+ */
+void
+procfs_list_install(const char *module,
+    const char *name,
+    mode_t mode,
+    procfs_list_t *procfs_list,
+    int (*show)(struct seq_file *f, void *p),
+    int (*show_header)(struct seq_file *f),
+    int (*clear)(procfs_list_t *procfs_list),
+    size_t procfs_list_node_off)
+{
+	mutex_init(&procfs_list->pl_lock, NULL, MUTEX_DEFAULT, NULL);
+	list_create(&procfs_list->pl_list,
+	    procfs_list_node_off + sizeof (procfs_list_node_t),
+	    procfs_list_node_off + offsetof(procfs_list_node_t, pln_link));
+	procfs_list->pl_next_id = 1; /* Save id 0 for SEQ_START_TOKEN */
+	procfs_list->pl_show = show;
+	procfs_list->pl_show_header = show_header;
+	procfs_list->pl_clear = clear;
+	procfs_list->pl_node_offset = procfs_list_node_off;
+
+	kstat_proc_entry_init(&procfs_list->pl_kstat_entry, module, name);
+	kstat_proc_entry_install(&procfs_list->pl_kstat_entry, mode,
+	    &procfs_list_operations, procfs_list);
+}
+EXPORT_SYMBOL(procfs_list_install);
+
+/* Remove the proc filesystem file corresponding to the given list */
+void
+procfs_list_uninstall(procfs_list_t *procfs_list)
+{
+	kstat_proc_entry_delete(&procfs_list->pl_kstat_entry);
+}
+EXPORT_SYMBOL(procfs_list_uninstall);
+
+void
+procfs_list_destroy(procfs_list_t *procfs_list)
+{
+	ASSERT(list_is_empty(&procfs_list->pl_list));
+	list_destroy(&procfs_list->pl_list);
+	mutex_destroy(&procfs_list->pl_lock);
+}
+EXPORT_SYMBOL(procfs_list_destroy);
+
+/*
+ * Add a new node to the tail of the list. While the standard list manipulation
+ * functions can be use for all other operation, adding elements to the list
+ * should only be done using this helper so that the id of the new node is set
+ * correctly.
+ */
+void
+procfs_list_add(procfs_list_t *procfs_list, void *p)
+{
+	ASSERT(MUTEX_HELD(&procfs_list->pl_lock));
+	NODE_ID(procfs_list, p) = procfs_list->pl_next_id++;
+	list_insert_tail(&procfs_list->pl_list, p);
+}
+EXPORT_SYMBOL(procfs_list_add);
diff --git a/module/os/linux/spl/spl-taskq.c b/module/os/linux/spl/spl-taskq.c
new file mode 100644
index 000000000..90e1d0a4d
--- /dev/null
+++ b/module/os/linux/spl/spl-taskq.c
@@ -0,0 +1,1292 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Task Queue Implementation.
+ */
+
+#include <sys/timer.h>
+#include <sys/taskq.h>
+#include <sys/kmem.h>
+#include <sys/tsd.h>
+#include <sys/simd.h>
+
+int spl_taskq_thread_bind = 0;
+module_param(spl_taskq_thread_bind, int, 0644);
+MODULE_PARM_DESC(spl_taskq_thread_bind, "Bind taskq thread to CPU by default");
+
+
+int spl_taskq_thread_dynamic = 1;
+module_param(spl_taskq_thread_dynamic, int, 0644);
+MODULE_PARM_DESC(spl_taskq_thread_dynamic, "Allow dynamic taskq threads");
+
+int spl_taskq_thread_priority = 1;
+module_param(spl_taskq_thread_priority, int, 0644);
+MODULE_PARM_DESC(spl_taskq_thread_priority,
+	"Allow non-default priority for taskq threads");
+
+int spl_taskq_thread_sequential = 4;
+module_param(spl_taskq_thread_sequential, int, 0644);
+MODULE_PARM_DESC(spl_taskq_thread_sequential,
+	"Create new taskq threads after N sequential tasks");
+
+/* Global system-wide dynamic task queue available for all consumers */
+taskq_t *system_taskq;
+EXPORT_SYMBOL(system_taskq);
+/* Global dynamic task queue for long delay */
+taskq_t *system_delay_taskq;
+EXPORT_SYMBOL(system_delay_taskq);
+
+/* Private dedicated taskq for creating new taskq threads on demand. */
+static taskq_t *dynamic_taskq;
+static taskq_thread_t *taskq_thread_create(taskq_t *);
+
+/* List of all taskqs */
+LIST_HEAD(tq_list);
+struct rw_semaphore tq_list_sem;
+static uint_t taskq_tsd;
+
+static int
+task_km_flags(uint_t flags)
+{
+	if (flags & TQ_NOSLEEP)
+		return (KM_NOSLEEP);
+
+	if (flags & TQ_PUSHPAGE)
+		return (KM_PUSHPAGE);
+
+	return (KM_SLEEP);
+}
+
+/*
+ * taskq_find_by_name - Find the largest instance number of a named taskq.
+ */
+static int
+taskq_find_by_name(const char *name)
+{
+	struct list_head *tql;
+	taskq_t *tq;
+
+	list_for_each_prev(tql, &tq_list) {
+		tq = list_entry(tql, taskq_t, tq_taskqs);
+		if (strcmp(name, tq->tq_name) == 0)
+			return (tq->tq_instance);
+	}
+	return (-1);
+}
+
+/*
+ * NOTE: Must be called with tq->tq_lock held, returns a list_t which
+ * is not attached to the free, work, or pending taskq lists.
+ */
+static taskq_ent_t *
+task_alloc(taskq_t *tq, uint_t flags, unsigned long *irqflags)
+{
+	taskq_ent_t *t;
+	int count = 0;
+
+	ASSERT(tq);
+retry:
+	/* Acquire taskq_ent_t's from free list if available */
+	if (!list_empty(&tq->tq_free_list) && !(flags & TQ_NEW)) {
+		t = list_entry(tq->tq_free_list.next, taskq_ent_t, tqent_list);
+
+		ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
+		ASSERT(!(t->tqent_flags & TQENT_FLAG_CANCEL));
+		ASSERT(!timer_pending(&t->tqent_timer));
+
+		list_del_init(&t->tqent_list);
+		return (t);
+	}
+
+	/* Free list is empty and memory allocations are prohibited */
+	if (flags & TQ_NOALLOC)
+		return (NULL);
+
+	/* Hit maximum taskq_ent_t pool size */
+	if (tq->tq_nalloc >= tq->tq_maxalloc) {
+		if (flags & TQ_NOSLEEP)
+			return (NULL);
+
+		/*
+		 * Sleep periodically polling the free list for an available
+		 * taskq_ent_t. Dispatching with TQ_SLEEP should always succeed
+		 * but we cannot block forever waiting for an taskq_ent_t to
+		 * show up in the free list, otherwise a deadlock can happen.
+		 *
+		 * Therefore, we need to allocate a new task even if the number
+		 * of allocated tasks is above tq->tq_maxalloc, but we still
+		 * end up delaying the task allocation by one second, thereby
+		 * throttling the task dispatch rate.
+		 */
+		spin_unlock_irqrestore(&tq->tq_lock, *irqflags);
+		schedule_timeout(HZ / 100);
+		spin_lock_irqsave_nested(&tq->tq_lock, *irqflags,
+		    tq->tq_lock_class);
+		if (count < 100) {
+			count++;
+			goto retry;
+		}
+	}
+
+	spin_unlock_irqrestore(&tq->tq_lock, *irqflags);
+	t = kmem_alloc(sizeof (taskq_ent_t), task_km_flags(flags));
+	spin_lock_irqsave_nested(&tq->tq_lock, *irqflags, tq->tq_lock_class);
+
+	if (t) {
+		taskq_init_ent(t);
+		tq->tq_nalloc++;
+	}
+
+	return (t);
+}
+
+/*
+ * NOTE: Must be called with tq->tq_lock held, expects the taskq_ent_t
+ * to already be removed from the free, work, or pending taskq lists.
+ */
+static void
+task_free(taskq_t *tq, taskq_ent_t *t)
+{
+	ASSERT(tq);
+	ASSERT(t);
+	ASSERT(list_empty(&t->tqent_list));
+	ASSERT(!timer_pending(&t->tqent_timer));
+
+	kmem_free(t, sizeof (taskq_ent_t));
+	tq->tq_nalloc--;
+}
+
+/*
+ * NOTE: Must be called with tq->tq_lock held, either destroys the
+ * taskq_ent_t if too many exist or moves it to the free list for later use.
+ */
+static void
+task_done(taskq_t *tq, taskq_ent_t *t)
+{
+	ASSERT(tq);
+	ASSERT(t);
+
+	/* Wake tasks blocked in taskq_wait_id() */
+	wake_up_all(&t->tqent_waitq);
+
+	list_del_init(&t->tqent_list);
+
+	if (tq->tq_nalloc <= tq->tq_minalloc) {
+		t->tqent_id = TASKQID_INVALID;
+		t->tqent_func = NULL;
+		t->tqent_arg = NULL;
+		t->tqent_flags = 0;
+
+		list_add_tail(&t->tqent_list, &tq->tq_free_list);
+	} else {
+		task_free(tq, t);
+	}
+}
+
+/*
+ * When a delayed task timer expires remove it from the delay list and
+ * add it to the priority list in order for immediate processing.
+ */
+static void
+task_expire_impl(taskq_ent_t *t)
+{
+	taskq_ent_t *w;
+	taskq_t *tq = t->tqent_taskq;
+	struct list_head *l;
+	unsigned long flags;
+
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+
+	if (t->tqent_flags & TQENT_FLAG_CANCEL) {
+		ASSERT(list_empty(&t->tqent_list));
+		spin_unlock_irqrestore(&tq->tq_lock, flags);
+		return;
+	}
+
+	t->tqent_birth = jiffies;
+	/*
+	 * The priority list must be maintained in strict task id order
+	 * from lowest to highest for lowest_id to be easily calculable.
+	 */
+	list_del(&t->tqent_list);
+	list_for_each_prev(l, &tq->tq_prio_list) {
+		w = list_entry(l, taskq_ent_t, tqent_list);
+		if (w->tqent_id < t->tqent_id) {
+			list_add(&t->tqent_list, l);
+			break;
+		}
+	}
+	if (l == &tq->tq_prio_list)
+		list_add(&t->tqent_list, &tq->tq_prio_list);
+
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	wake_up(&tq->tq_work_waitq);
+}
+
+static void
+task_expire(spl_timer_list_t tl)
+{
+	struct timer_list *tmr = (struct timer_list *)tl;
+	taskq_ent_t *t = from_timer(t, tmr, tqent_timer);
+	task_expire_impl(t);
+}
+
+/*
+ * Returns the lowest incomplete taskqid_t.  The taskqid_t may
+ * be queued on the pending list, on the priority list, on the
+ * delay list, or on the work list currently being handled, but
+ * it is not 100% complete yet.
+ */
+static taskqid_t
+taskq_lowest_id(taskq_t *tq)
+{
+	taskqid_t lowest_id = tq->tq_next_id;
+	taskq_ent_t *t;
+	taskq_thread_t *tqt;
+
+	ASSERT(tq);
+
+	if (!list_empty(&tq->tq_pend_list)) {
+		t = list_entry(tq->tq_pend_list.next, taskq_ent_t, tqent_list);
+		lowest_id = MIN(lowest_id, t->tqent_id);
+	}
+
+	if (!list_empty(&tq->tq_prio_list)) {
+		t = list_entry(tq->tq_prio_list.next, taskq_ent_t, tqent_list);
+		lowest_id = MIN(lowest_id, t->tqent_id);
+	}
+
+	if (!list_empty(&tq->tq_delay_list)) {
+		t = list_entry(tq->tq_delay_list.next, taskq_ent_t, tqent_list);
+		lowest_id = MIN(lowest_id, t->tqent_id);
+	}
+
+	if (!list_empty(&tq->tq_active_list)) {
+		tqt = list_entry(tq->tq_active_list.next, taskq_thread_t,
+		    tqt_active_list);
+		ASSERT(tqt->tqt_id != TASKQID_INVALID);
+		lowest_id = MIN(lowest_id, tqt->tqt_id);
+	}
+
+	return (lowest_id);
+}
+
+/*
+ * Insert a task into a list keeping the list sorted by increasing taskqid.
+ */
+static void
+taskq_insert_in_order(taskq_t *tq, taskq_thread_t *tqt)
+{
+	taskq_thread_t *w;
+	struct list_head *l;
+
+	ASSERT(tq);
+	ASSERT(tqt);
+
+	list_for_each_prev(l, &tq->tq_active_list) {
+		w = list_entry(l, taskq_thread_t, tqt_active_list);
+		if (w->tqt_id < tqt->tqt_id) {
+			list_add(&tqt->tqt_active_list, l);
+			break;
+		}
+	}
+	if (l == &tq->tq_active_list)
+		list_add(&tqt->tqt_active_list, &tq->tq_active_list);
+}
+
+/*
+ * Find and return a task from the given list if it exists.  The list
+ * must be in lowest to highest task id order.
+ */
+static taskq_ent_t *
+taskq_find_list(taskq_t *tq, struct list_head *lh, taskqid_t id)
+{
+	struct list_head *l;
+	taskq_ent_t *t;
+
+	list_for_each(l, lh) {
+		t = list_entry(l, taskq_ent_t, tqent_list);
+
+		if (t->tqent_id == id)
+			return (t);
+
+		if (t->tqent_id > id)
+			break;
+	}
+
+	return (NULL);
+}
+
+/*
+ * Find an already dispatched task given the task id regardless of what
+ * state it is in.  If a task is still pending it will be returned.
+ * If a task is executing, then -EBUSY will be returned instead.
+ * If the task has already been run then NULL is returned.
+ */
+static taskq_ent_t *
+taskq_find(taskq_t *tq, taskqid_t id)
+{
+	taskq_thread_t *tqt;
+	struct list_head *l;
+	taskq_ent_t *t;
+
+	t = taskq_find_list(tq, &tq->tq_delay_list, id);
+	if (t)
+		return (t);
+
+	t = taskq_find_list(tq, &tq->tq_prio_list, id);
+	if (t)
+		return (t);
+
+	t = taskq_find_list(tq, &tq->tq_pend_list, id);
+	if (t)
+		return (t);
+
+	list_for_each(l, &tq->tq_active_list) {
+		tqt = list_entry(l, taskq_thread_t, tqt_active_list);
+		if (tqt->tqt_id == id) {
+			/*
+			 * Instead of returning tqt_task, we just return a non
+			 * NULL value to prevent misuse, since tqt_task only
+			 * has two valid fields.
+			 */
+			return (ERR_PTR(-EBUSY));
+		}
+	}
+
+	return (NULL);
+}
+
+/*
+ * Theory for the taskq_wait_id(), taskq_wait_outstanding(), and
+ * taskq_wait() functions below.
+ *
+ * Taskq waiting is accomplished by tracking the lowest outstanding task
+ * id and the next available task id.  As tasks are dispatched they are
+ * added to the tail of the pending, priority, or delay lists.  As worker
+ * threads become available the tasks are removed from the heads of these
+ * lists and linked to the worker threads.  This ensures the lists are
+ * kept sorted by lowest to highest task id.
+ *
+ * Therefore the lowest outstanding task id can be quickly determined by
+ * checking the head item from all of these lists.  This value is stored
+ * with the taskq as the lowest id.  It only needs to be recalculated when
+ * either the task with the current lowest id completes or is canceled.
+ *
+ * By blocking until the lowest task id exceeds the passed task id the
+ * taskq_wait_outstanding() function can be easily implemented.  Similarly,
+ * by blocking until the lowest task id matches the next task id taskq_wait()
+ * can be implemented.
+ *
+ * Callers should be aware that when there are multiple worked threads it
+ * is possible for larger task ids to complete before smaller ones.  Also
+ * when the taskq contains delay tasks with small task ids callers may
+ * block for a considerable length of time waiting for them to expire and
+ * execute.
+ */
+static int
+taskq_wait_id_check(taskq_t *tq, taskqid_t id)
+{
+	int rc;
+	unsigned long flags;
+
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+	rc = (taskq_find(tq, id) == NULL);
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	return (rc);
+}
+
+/*
+ * The taskq_wait_id() function blocks until the passed task id completes.
+ * This does not guarantee that all lower task ids have completed.
+ */
+void
+taskq_wait_id(taskq_t *tq, taskqid_t id)
+{
+	wait_event(tq->tq_wait_waitq, taskq_wait_id_check(tq, id));
+}
+EXPORT_SYMBOL(taskq_wait_id);
+
+static int
+taskq_wait_outstanding_check(taskq_t *tq, taskqid_t id)
+{
+	int rc;
+	unsigned long flags;
+
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+	rc = (id < tq->tq_lowest_id);
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	return (rc);
+}
+
+/*
+ * The taskq_wait_outstanding() function will block until all tasks with a
+ * lower taskqid than the passed 'id' have been completed.  Note that all
+ * task id's are assigned monotonically at dispatch time.  Zero may be
+ * passed for the id to indicate all tasks dispatch up to this point,
+ * but not after, should be waited for.
+ */
+void
+taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
+{
+	id = id ? id : tq->tq_next_id - 1;
+	wait_event(tq->tq_wait_waitq, taskq_wait_outstanding_check(tq, id));
+}
+EXPORT_SYMBOL(taskq_wait_outstanding);
+
+static int
+taskq_wait_check(taskq_t *tq)
+{
+	int rc;
+	unsigned long flags;
+
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+	rc = (tq->tq_lowest_id == tq->tq_next_id);
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	return (rc);
+}
+
+/*
+ * The taskq_wait() function will block until the taskq is empty.
+ * This means that if a taskq re-dispatches work to itself taskq_wait()
+ * callers will block indefinitely.
+ */
+void
+taskq_wait(taskq_t *tq)
+{
+	wait_event(tq->tq_wait_waitq, taskq_wait_check(tq));
+}
+EXPORT_SYMBOL(taskq_wait);
+
+int
+taskq_member(taskq_t *tq, kthread_t *t)
+{
+	return (tq == (taskq_t *)tsd_get_by_thread(taskq_tsd, t));
+}
+EXPORT_SYMBOL(taskq_member);
+
+/*
+ * Cancel an already dispatched task given the task id.  Still pending tasks
+ * will be immediately canceled, and if the task is active the function will
+ * block until it completes.  Preallocated tasks which are canceled must be
+ * freed by the caller.
+ */
+int
+taskq_cancel_id(taskq_t *tq, taskqid_t id)
+{
+	taskq_ent_t *t;
+	int rc = ENOENT;
+	unsigned long flags;
+
+	ASSERT(tq);
+
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+	t = taskq_find(tq, id);
+	if (t && t != ERR_PTR(-EBUSY)) {
+		list_del_init(&t->tqent_list);
+		t->tqent_flags |= TQENT_FLAG_CANCEL;
+
+		/*
+		 * When canceling the lowest outstanding task id we
+		 * must recalculate the new lowest outstanding id.
+		 */
+		if (tq->tq_lowest_id == t->tqent_id) {
+			tq->tq_lowest_id = taskq_lowest_id(tq);
+			ASSERT3S(tq->tq_lowest_id, >, t->tqent_id);
+		}
+
+		/*
+		 * The task_expire() function takes the tq->tq_lock so drop
+		 * drop the lock before synchronously cancelling the timer.
+		 */
+		if (timer_pending(&t->tqent_timer)) {
+			spin_unlock_irqrestore(&tq->tq_lock, flags);
+			del_timer_sync(&t->tqent_timer);
+			spin_lock_irqsave_nested(&tq->tq_lock, flags,
+			    tq->tq_lock_class);
+		}
+
+		if (!(t->tqent_flags & TQENT_FLAG_PREALLOC))
+			task_done(tq, t);
+
+		rc = 0;
+	}
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	if (t == ERR_PTR(-EBUSY)) {
+		taskq_wait_id(tq, id);
+		rc = EBUSY;
+	}
+
+	return (rc);
+}
+EXPORT_SYMBOL(taskq_cancel_id);
+
+static int taskq_thread_spawn(taskq_t *tq);
+
+taskqid_t
+taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
+{
+	taskq_ent_t *t;
+	taskqid_t rc = TASKQID_INVALID;
+	unsigned long irqflags;
+
+	ASSERT(tq);
+	ASSERT(func);
+
+	spin_lock_irqsave_nested(&tq->tq_lock, irqflags, tq->tq_lock_class);
+
+	/* Taskq being destroyed and all tasks drained */
+	if (!(tq->tq_flags & TASKQ_ACTIVE))
+		goto out;
+
+	/* Do not queue the task unless there is idle thread for it */
+	ASSERT(tq->tq_nactive <= tq->tq_nthreads);
+	if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads)) {
+		/* Dynamic taskq may be able to spawn another thread */
+		if (!(tq->tq_flags & TASKQ_DYNAMIC) ||
+		    taskq_thread_spawn(tq) == 0)
+			goto out;
+	}
+
+	if ((t = task_alloc(tq, flags, &irqflags)) == NULL)
+		goto out;
+
+	spin_lock(&t->tqent_lock);
+
+	/* Queue to the front of the list to enforce TQ_NOQUEUE semantics */
+	if (flags & TQ_NOQUEUE)
+		list_add(&t->tqent_list, &tq->tq_prio_list);
+	/* Queue to the priority list instead of the pending list */
+	else if (flags & TQ_FRONT)
+		list_add_tail(&t->tqent_list, &tq->tq_prio_list);
+	else
+		list_add_tail(&t->tqent_list, &tq->tq_pend_list);
+
+	t->tqent_id = rc = tq->tq_next_id;
+	tq->tq_next_id++;
+	t->tqent_func = func;
+	t->tqent_arg = arg;
+	t->tqent_taskq = tq;
+	t->tqent_timer.function = NULL;
+	t->tqent_timer.expires = 0;
+	t->tqent_birth = jiffies;
+
+	ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
+
+	spin_unlock(&t->tqent_lock);
+
+	wake_up(&tq->tq_work_waitq);
+out:
+	/* Spawn additional taskq threads if required. */
+	if (!(flags & TQ_NOQUEUE) && tq->tq_nactive == tq->tq_nthreads)
+		(void) taskq_thread_spawn(tq);
+
+	spin_unlock_irqrestore(&tq->tq_lock, irqflags);
+	return (rc);
+}
+EXPORT_SYMBOL(taskq_dispatch);
+
+taskqid_t
+taskq_dispatch_delay(taskq_t *tq, task_func_t func, void *arg,
+    uint_t flags, clock_t expire_time)
+{
+	taskqid_t rc = TASKQID_INVALID;
+	taskq_ent_t *t;
+	unsigned long irqflags;
+
+	ASSERT(tq);
+	ASSERT(func);
+
+	spin_lock_irqsave_nested(&tq->tq_lock, irqflags, tq->tq_lock_class);
+
+	/* Taskq being destroyed and all tasks drained */
+	if (!(tq->tq_flags & TASKQ_ACTIVE))
+		goto out;
+
+	if ((t = task_alloc(tq, flags, &irqflags)) == NULL)
+		goto out;
+
+	spin_lock(&t->tqent_lock);
+
+	/* Queue to the delay list for subsequent execution */
+	list_add_tail(&t->tqent_list, &tq->tq_delay_list);
+
+	t->tqent_id = rc = tq->tq_next_id;
+	tq->tq_next_id++;
+	t->tqent_func = func;
+	t->tqent_arg = arg;
+	t->tqent_taskq = tq;
+	t->tqent_timer.function = task_expire;
+	t->tqent_timer.expires = (unsigned long)expire_time;
+	add_timer(&t->tqent_timer);
+
+	ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
+
+	spin_unlock(&t->tqent_lock);
+out:
+	/* Spawn additional taskq threads if required. */
+	if (tq->tq_nactive == tq->tq_nthreads)
+		(void) taskq_thread_spawn(tq);
+	spin_unlock_irqrestore(&tq->tq_lock, irqflags);
+	return (rc);
+}
+EXPORT_SYMBOL(taskq_dispatch_delay);
+
+void
+taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
+    taskq_ent_t *t)
+{
+	unsigned long irqflags;
+	ASSERT(tq);
+	ASSERT(func);
+
+	spin_lock_irqsave_nested(&tq->tq_lock, irqflags,
+	    tq->tq_lock_class);
+
+	/* Taskq being destroyed and all tasks drained */
+	if (!(tq->tq_flags & TASKQ_ACTIVE)) {
+		t->tqent_id = TASKQID_INVALID;
+		goto out;
+	}
+
+	if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads)) {
+		/* Dynamic taskq may be able to spawn another thread */
+		if (!(tq->tq_flags & TASKQ_DYNAMIC) ||
+		    taskq_thread_spawn(tq) == 0)
+			goto out2;
+		flags |= TQ_FRONT;
+	}
+
+	spin_lock(&t->tqent_lock);
+
+	/*
+	 * Make sure the entry is not on some other taskq; it is important to
+	 * ASSERT() under lock
+	 */
+	ASSERT(taskq_empty_ent(t));
+
+	/*
+	 * Mark it as a prealloc'd task.  This is important
+	 * to ensure that we don't free it later.
+	 */
+	t->tqent_flags |= TQENT_FLAG_PREALLOC;
+
+	/* Queue to the priority list instead of the pending list */
+	if (flags & TQ_FRONT)
+		list_add_tail(&t->tqent_list, &tq->tq_prio_list);
+	else
+		list_add_tail(&t->tqent_list, &tq->tq_pend_list);
+
+	t->tqent_id = tq->tq_next_id;
+	tq->tq_next_id++;
+	t->tqent_func = func;
+	t->tqent_arg = arg;
+	t->tqent_taskq = tq;
+	t->tqent_birth = jiffies;
+
+	spin_unlock(&t->tqent_lock);
+
+	wake_up(&tq->tq_work_waitq);
+out:
+	/* Spawn additional taskq threads if required. */
+	if (tq->tq_nactive == tq->tq_nthreads)
+		(void) taskq_thread_spawn(tq);
+out2:
+	spin_unlock_irqrestore(&tq->tq_lock, irqflags);
+}
+EXPORT_SYMBOL(taskq_dispatch_ent);
+
+int
+taskq_empty_ent(taskq_ent_t *t)
+{
+	return (list_empty(&t->tqent_list));
+}
+EXPORT_SYMBOL(taskq_empty_ent);
+
+void
+taskq_init_ent(taskq_ent_t *t)
+{
+	spin_lock_init(&t->tqent_lock);
+	init_waitqueue_head(&t->tqent_waitq);
+	timer_setup(&t->tqent_timer, NULL, 0);
+	INIT_LIST_HEAD(&t->tqent_list);
+	t->tqent_id = 0;
+	t->tqent_func = NULL;
+	t->tqent_arg = NULL;
+	t->tqent_flags = 0;
+	t->tqent_taskq = NULL;
+}
+EXPORT_SYMBOL(taskq_init_ent);
+
+/*
+ * Return the next pending task, preference is given to tasks on the
+ * priority list which were dispatched with TQ_FRONT.
+ */
+static taskq_ent_t *
+taskq_next_ent(taskq_t *tq)
+{
+	struct list_head *list;
+
+	if (!list_empty(&tq->tq_prio_list))
+		list = &tq->tq_prio_list;
+	else if (!list_empty(&tq->tq_pend_list))
+		list = &tq->tq_pend_list;
+	else
+		return (NULL);
+
+	return (list_entry(list->next, taskq_ent_t, tqent_list));
+}
+
+/*
+ * Spawns a new thread for the specified taskq.
+ */
+static void
+taskq_thread_spawn_task(void *arg)
+{
+	taskq_t *tq = (taskq_t *)arg;
+	unsigned long flags;
+
+	if (taskq_thread_create(tq) == NULL) {
+		/* restore spawning count if failed */
+		spin_lock_irqsave_nested(&tq->tq_lock, flags,
+		    tq->tq_lock_class);
+		tq->tq_nspawn--;
+		spin_unlock_irqrestore(&tq->tq_lock, flags);
+	}
+}
+
+/*
+ * Spawn addition threads for dynamic taskqs (TASKQ_DYNAMIC) the current
+ * number of threads is insufficient to handle the pending tasks.  These
+ * new threads must be created by the dedicated dynamic_taskq to avoid
+ * deadlocks between thread creation and memory reclaim.  The system_taskq
+ * which is also a dynamic taskq cannot be safely used for this.
+ */
+static int
+taskq_thread_spawn(taskq_t *tq)
+{
+	int spawning = 0;
+
+	if (!(tq->tq_flags & TASKQ_DYNAMIC))
+		return (0);
+
+	if ((tq->tq_nthreads + tq->tq_nspawn < tq->tq_maxthreads) &&
+	    (tq->tq_flags & TASKQ_ACTIVE)) {
+		spawning = (++tq->tq_nspawn);
+		taskq_dispatch(dynamic_taskq, taskq_thread_spawn_task,
+		    tq, TQ_NOSLEEP);
+	}
+
+	return (spawning);
+}
+
+/*
+ * Threads in a dynamic taskq should only exit once it has been completely
+ * drained and no other threads are actively servicing tasks.  This prevents
+ * threads from being created and destroyed more than is required.
+ *
+ * The first thread is the thread list is treated as the primary thread.
+ * There is nothing special about the primary thread but in order to avoid
+ * all the taskq pids from changing we opt to make it long running.
+ */
+static int
+taskq_thread_should_stop(taskq_t *tq, taskq_thread_t *tqt)
+{
+	if (!(tq->tq_flags & TASKQ_DYNAMIC))
+		return (0);
+
+	if (list_first_entry(&(tq->tq_thread_list), taskq_thread_t,
+	    tqt_thread_list) == tqt)
+		return (0);
+
+	return
+	    ((tq->tq_nspawn == 0) &&	/* No threads are being spawned */
+	    (tq->tq_nactive == 0) &&	/* No threads are handling tasks */
+	    (tq->tq_nthreads > 1) &&	/* More than 1 thread is running */
+	    (!taskq_next_ent(tq)) &&	/* There are no pending tasks */
+	    (spl_taskq_thread_dynamic)); /* Dynamic taskqs are allowed */
+}
+
+static int
+taskq_thread(void *args)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	sigset_t blocked;
+	taskq_thread_t *tqt = args;
+	taskq_t *tq;
+	taskq_ent_t *t;
+	int seq_tasks = 0;
+	unsigned long flags;
+	taskq_ent_t dup_task = {};
+
+	ASSERT(tqt);
+	ASSERT(tqt->tqt_tq);
+	tq = tqt->tqt_tq;
+	current->flags |= PF_NOFREEZE;
+
+	(void) spl_fstrans_mark();
+
+	sigfillset(&blocked);
+	sigprocmask(SIG_BLOCK, &blocked, NULL);
+	flush_signals(current);
+	kfpu_initialize();
+
+	tsd_set(taskq_tsd, tq);
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+	/*
+	 * If we are dynamically spawned, decrease spawning count. Note that
+	 * we could be created during taskq_create, in which case we shouldn't
+	 * do the decrement. But it's fine because taskq_create will reset
+	 * tq_nspawn later.
+	 */
+	if (tq->tq_flags & TASKQ_DYNAMIC)
+		tq->tq_nspawn--;
+
+	/* Immediately exit if more threads than allowed were created. */
+	if (tq->tq_nthreads >= tq->tq_maxthreads)
+		goto error;
+
+	tq->tq_nthreads++;
+	list_add_tail(&tqt->tqt_thread_list, &tq->tq_thread_list);
+	wake_up(&tq->tq_wait_waitq);
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	while (!kthread_should_stop()) {
+
+		if (list_empty(&tq->tq_pend_list) &&
+		    list_empty(&tq->tq_prio_list)) {
+
+			if (taskq_thread_should_stop(tq, tqt)) {
+				wake_up_all(&tq->tq_wait_waitq);
+				break;
+			}
+
+			add_wait_queue_exclusive(&tq->tq_work_waitq, &wait);
+			spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+			schedule();
+			seq_tasks = 0;
+
+			spin_lock_irqsave_nested(&tq->tq_lock, flags,
+			    tq->tq_lock_class);
+			remove_wait_queue(&tq->tq_work_waitq, &wait);
+		} else {
+			__set_current_state(TASK_RUNNING);
+		}
+
+		if ((t = taskq_next_ent(tq)) != NULL) {
+			list_del_init(&t->tqent_list);
+
+			/*
+			 * A TQENT_FLAG_PREALLOC task may be reused or freed
+			 * during the task function call. Store tqent_id and
+			 * tqent_flags here.
+			 *
+			 * Also use an on stack taskq_ent_t for tqt_task
+			 * assignment in this case. We only populate the two
+			 * fields used by the only user in taskq proc file.
+			 */
+			tqt->tqt_id = t->tqent_id;
+			tqt->tqt_flags = t->tqent_flags;
+
+			if (t->tqent_flags & TQENT_FLAG_PREALLOC) {
+				dup_task.tqent_func = t->tqent_func;
+				dup_task.tqent_arg = t->tqent_arg;
+				t = &dup_task;
+			}
+			tqt->tqt_task = t;
+
+			taskq_insert_in_order(tq, tqt);
+			tq->tq_nactive++;
+			spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+			/* Perform the requested task */
+			t->tqent_func(t->tqent_arg);
+
+			spin_lock_irqsave_nested(&tq->tq_lock, flags,
+			    tq->tq_lock_class);
+			tq->tq_nactive--;
+			list_del_init(&tqt->tqt_active_list);
+			tqt->tqt_task = NULL;
+
+			/* For prealloc'd tasks, we don't free anything. */
+			if (!(tqt->tqt_flags & TQENT_FLAG_PREALLOC))
+				task_done(tq, t);
+
+			/*
+			 * When the current lowest outstanding taskqid is
+			 * done calculate the new lowest outstanding id
+			 */
+			if (tq->tq_lowest_id == tqt->tqt_id) {
+				tq->tq_lowest_id = taskq_lowest_id(tq);
+				ASSERT3S(tq->tq_lowest_id, >, tqt->tqt_id);
+			}
+
+			/* Spawn additional taskq threads if required. */
+			if ((++seq_tasks) > spl_taskq_thread_sequential &&
+			    taskq_thread_spawn(tq))
+				seq_tasks = 0;
+
+			tqt->tqt_id = TASKQID_INVALID;
+			tqt->tqt_flags = 0;
+			wake_up_all(&tq->tq_wait_waitq);
+		} else {
+			if (taskq_thread_should_stop(tq, tqt))
+				break;
+		}
+
+		set_current_state(TASK_INTERRUPTIBLE);
+
+	}
+
+	__set_current_state(TASK_RUNNING);
+	tq->tq_nthreads--;
+	list_del_init(&tqt->tqt_thread_list);
+error:
+	kmem_free(tqt, sizeof (taskq_thread_t));
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	tsd_set(taskq_tsd, NULL);
+
+	return (0);
+}
+
+static taskq_thread_t *
+taskq_thread_create(taskq_t *tq)
+{
+	static int last_used_cpu = 0;
+	taskq_thread_t *tqt;
+
+	tqt = kmem_alloc(sizeof (*tqt), KM_PUSHPAGE);
+	INIT_LIST_HEAD(&tqt->tqt_thread_list);
+	INIT_LIST_HEAD(&tqt->tqt_active_list);
+	tqt->tqt_tq = tq;
+	tqt->tqt_id = TASKQID_INVALID;
+
+	tqt->tqt_thread = spl_kthread_create(taskq_thread, tqt,
+	    "%s", tq->tq_name);
+	if (tqt->tqt_thread == NULL) {
+		kmem_free(tqt, sizeof (taskq_thread_t));
+		return (NULL);
+	}
+
+	if (spl_taskq_thread_bind) {
+		last_used_cpu = (last_used_cpu + 1) % num_online_cpus();
+		kthread_bind(tqt->tqt_thread, last_used_cpu);
+	}
+
+	if (spl_taskq_thread_priority)
+		set_user_nice(tqt->tqt_thread, PRIO_TO_NICE(tq->tq_pri));
+
+	wake_up_process(tqt->tqt_thread);
+
+	return (tqt);
+}
+
+taskq_t *
+taskq_create(const char *name, int nthreads, pri_t pri,
+    int minalloc, int maxalloc, uint_t flags)
+{
+	taskq_t *tq;
+	taskq_thread_t *tqt;
+	int count = 0, rc = 0, i;
+	unsigned long irqflags;
+
+	ASSERT(name != NULL);
+	ASSERT(minalloc >= 0);
+	ASSERT(maxalloc <= INT_MAX);
+	ASSERT(!(flags & (TASKQ_CPR_SAFE))); /* Unsupported */
+
+	/* Scale the number of threads using nthreads as a percentage */
+	if (flags & TASKQ_THREADS_CPU_PCT) {
+		ASSERT(nthreads <= 100);
+		ASSERT(nthreads >= 0);
+		nthreads = MIN(nthreads, 100);
+		nthreads = MAX(nthreads, 0);
+		nthreads = MAX((num_online_cpus() * nthreads) / 100, 1);
+	}
+
+	tq = kmem_alloc(sizeof (*tq), KM_PUSHPAGE);
+	if (tq == NULL)
+		return (NULL);
+
+	spin_lock_init(&tq->tq_lock);
+	INIT_LIST_HEAD(&tq->tq_thread_list);
+	INIT_LIST_HEAD(&tq->tq_active_list);
+	tq->tq_name = strdup(name);
+	tq->tq_nactive = 0;
+	tq->tq_nthreads = 0;
+	tq->tq_nspawn = 0;
+	tq->tq_maxthreads = nthreads;
+	tq->tq_pri = pri;
+	tq->tq_minalloc = minalloc;
+	tq->tq_maxalloc = maxalloc;
+	tq->tq_nalloc = 0;
+	tq->tq_flags = (flags | TASKQ_ACTIVE);
+	tq->tq_next_id = TASKQID_INITIAL;
+	tq->tq_lowest_id = TASKQID_INITIAL;
+	INIT_LIST_HEAD(&tq->tq_free_list);
+	INIT_LIST_HEAD(&tq->tq_pend_list);
+	INIT_LIST_HEAD(&tq->tq_prio_list);
+	INIT_LIST_HEAD(&tq->tq_delay_list);
+	init_waitqueue_head(&tq->tq_work_waitq);
+	init_waitqueue_head(&tq->tq_wait_waitq);
+	tq->tq_lock_class = TQ_LOCK_GENERAL;
+	INIT_LIST_HEAD(&tq->tq_taskqs);
+
+	if (flags & TASKQ_PREPOPULATE) {
+		spin_lock_irqsave_nested(&tq->tq_lock, irqflags,
+		    tq->tq_lock_class);
+
+		for (i = 0; i < minalloc; i++)
+			task_done(tq, task_alloc(tq, TQ_PUSHPAGE | TQ_NEW,
+			    &irqflags));
+
+		spin_unlock_irqrestore(&tq->tq_lock, irqflags);
+	}
+
+	if ((flags & TASKQ_DYNAMIC) && spl_taskq_thread_dynamic)
+		nthreads = 1;
+
+	for (i = 0; i < nthreads; i++) {
+		tqt = taskq_thread_create(tq);
+		if (tqt == NULL)
+			rc = 1;
+		else
+			count++;
+	}
+
+	/* Wait for all threads to be started before potential destroy */
+	wait_event(tq->tq_wait_waitq, tq->tq_nthreads == count);
+	/*
+	 * taskq_thread might have touched nspawn, but we don't want them to
+	 * because they're not dynamically spawned. So we reset it to 0
+	 */
+	tq->tq_nspawn = 0;
+
+	if (rc) {
+		taskq_destroy(tq);
+		tq = NULL;
+	} else {
+		down_write(&tq_list_sem);
+		tq->tq_instance = taskq_find_by_name(name) + 1;
+		list_add_tail(&tq->tq_taskqs, &tq_list);
+		up_write(&tq_list_sem);
+	}
+
+	return (tq);
+}
+EXPORT_SYMBOL(taskq_create);
+
+void
+taskq_destroy(taskq_t *tq)
+{
+	struct task_struct *thread;
+	taskq_thread_t *tqt;
+	taskq_ent_t *t;
+	unsigned long flags;
+
+	ASSERT(tq);
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+	tq->tq_flags &= ~TASKQ_ACTIVE;
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	/*
+	 * When TASKQ_ACTIVE is clear new tasks may not be added nor may
+	 * new worker threads be spawned for dynamic taskq.
+	 */
+	if (dynamic_taskq != NULL)
+		taskq_wait_outstanding(dynamic_taskq, 0);
+
+	taskq_wait(tq);
+
+	/* remove taskq from global list used by the kstats */
+	down_write(&tq_list_sem);
+	list_del(&tq->tq_taskqs);
+	up_write(&tq_list_sem);
+
+	spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
+	/* wait for spawning threads to insert themselves to the list */
+	while (tq->tq_nspawn) {
+		spin_unlock_irqrestore(&tq->tq_lock, flags);
+		schedule_timeout_interruptible(1);
+		spin_lock_irqsave_nested(&tq->tq_lock, flags,
+		    tq->tq_lock_class);
+	}
+
+	/*
+	 * Signal each thread to exit and block until it does.  Each thread
+	 * is responsible for removing itself from the list and freeing its
+	 * taskq_thread_t.  This allows for idle threads to opt to remove
+	 * themselves from the taskq.  They can be recreated as needed.
+	 */
+	while (!list_empty(&tq->tq_thread_list)) {
+		tqt = list_entry(tq->tq_thread_list.next,
+		    taskq_thread_t, tqt_thread_list);
+		thread = tqt->tqt_thread;
+		spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+		kthread_stop(thread);
+
+		spin_lock_irqsave_nested(&tq->tq_lock, flags,
+		    tq->tq_lock_class);
+	}
+
+	while (!list_empty(&tq->tq_free_list)) {
+		t = list_entry(tq->tq_free_list.next, taskq_ent_t, tqent_list);
+
+		ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
+
+		list_del_init(&t->tqent_list);
+		task_free(tq, t);
+	}
+
+	ASSERT0(tq->tq_nthreads);
+	ASSERT0(tq->tq_nalloc);
+	ASSERT0(tq->tq_nspawn);
+	ASSERT(list_empty(&tq->tq_thread_list));
+	ASSERT(list_empty(&tq->tq_active_list));
+	ASSERT(list_empty(&tq->tq_free_list));
+	ASSERT(list_empty(&tq->tq_pend_list));
+	ASSERT(list_empty(&tq->tq_prio_list));
+	ASSERT(list_empty(&tq->tq_delay_list));
+
+	spin_unlock_irqrestore(&tq->tq_lock, flags);
+
+	strfree(tq->tq_name);
+	kmem_free(tq, sizeof (taskq_t));
+}
+EXPORT_SYMBOL(taskq_destroy);
+
+
+static unsigned int spl_taskq_kick = 0;
+
+/*
+ * 2.6.36 API Change
+ * module_param_cb is introduced to take kernel_param_ops and
+ * module_param_call is marked as obsolete. Also set and get operations
+ * were changed to take a 'const struct kernel_param *'.
+ */
+static int
+#ifdef module_param_cb
+param_set_taskq_kick(const char *val, const struct kernel_param *kp)
+#else
+param_set_taskq_kick(const char *val, struct kernel_param *kp)
+#endif
+{
+	int ret;
+	taskq_t *tq;
+	taskq_ent_t *t;
+	unsigned long flags;
+
+	ret = param_set_uint(val, kp);
+	if (ret < 0 || !spl_taskq_kick)
+		return (ret);
+	/* reset value */
+	spl_taskq_kick = 0;
+
+	down_read(&tq_list_sem);
+	list_for_each_entry(tq, &tq_list, tq_taskqs) {
+		spin_lock_irqsave_nested(&tq->tq_lock, flags,
+		    tq->tq_lock_class);
+		/* Check if the first pending is older than 5 seconds */
+		t = taskq_next_ent(tq);
+		if (t && time_after(jiffies, t->tqent_birth + 5*HZ)) {
+			(void) taskq_thread_spawn(tq);
+			printk(KERN_INFO "spl: Kicked taskq %s/%d\n",
+			    tq->tq_name, tq->tq_instance);
+		}
+		spin_unlock_irqrestore(&tq->tq_lock, flags);
+	}
+	up_read(&tq_list_sem);
+	return (ret);
+}
+
+#ifdef module_param_cb
+static const struct kernel_param_ops param_ops_taskq_kick = {
+	.set = param_set_taskq_kick,
+	.get = param_get_uint,
+};
+module_param_cb(spl_taskq_kick, &param_ops_taskq_kick, &spl_taskq_kick, 0644);
+#else
+module_param_call(spl_taskq_kick, param_set_taskq_kick, param_get_uint,
+	&spl_taskq_kick, 0644);
+#endif
+MODULE_PARM_DESC(spl_taskq_kick,
+	"Write nonzero to kick stuck taskqs to spawn more threads");
+
+int
+spl_taskq_init(void)
+{
+	init_rwsem(&tq_list_sem);
+	tsd_create(&taskq_tsd, NULL);
+
+	system_taskq = taskq_create("spl_system_taskq", MAX(boot_ncpus, 64),
+	    maxclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE|TASKQ_DYNAMIC);
+	if (system_taskq == NULL)
+		return (1);
+
+	system_delay_taskq = taskq_create("spl_delay_taskq", MAX(boot_ncpus, 4),
+	    maxclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE|TASKQ_DYNAMIC);
+	if (system_delay_taskq == NULL) {
+		taskq_destroy(system_taskq);
+		return (1);
+	}
+
+	dynamic_taskq = taskq_create("spl_dynamic_taskq", 1,
+	    maxclsyspri, boot_ncpus, INT_MAX, TASKQ_PREPOPULATE);
+	if (dynamic_taskq == NULL) {
+		taskq_destroy(system_taskq);
+		taskq_destroy(system_delay_taskq);
+		return (1);
+	}
+
+	/*
+	 * This is used to annotate tq_lock, so
+	 *   taskq_dispatch -> taskq_thread_spawn -> taskq_dispatch
+	 * does not trigger a lockdep warning re: possible recursive locking
+	 */
+	dynamic_taskq->tq_lock_class = TQ_LOCK_DYNAMIC;
+
+	return (0);
+}
+
+void
+spl_taskq_fini(void)
+{
+	taskq_destroy(dynamic_taskq);
+	dynamic_taskq = NULL;
+
+	taskq_destroy(system_delay_taskq);
+	system_delay_taskq = NULL;
+
+	taskq_destroy(system_taskq);
+	system_taskq = NULL;
+
+	tsd_destroy(&taskq_tsd);
+}
diff --git a/module/os/linux/spl/spl-thread.c b/module/os/linux/spl/spl-thread.c
new file mode 100644
index 000000000..29de9252a
--- /dev/null
+++ b/module/os/linux/spl/spl-thread.c
@@ -0,0 +1,163 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Thread Implementation.
+ */
+
+#include <sys/thread.h>
+#include <sys/kmem.h>
+#include <sys/tsd.h>
+#include <sys/simd.h>
+
+/*
+ * Thread interfaces
+ */
+typedef struct thread_priv_s {
+	unsigned long tp_magic;		/* Magic */
+	int tp_name_size;		/* Name size */
+	char *tp_name;			/* Name (without _thread suffix) */
+	void (*tp_func)(void *);	/* Registered function */
+	void *tp_args;			/* Args to be passed to function */
+	size_t tp_len;			/* Len to be passed to function */
+	int tp_state;			/* State to start thread at */
+	pri_t tp_pri;			/* Priority to start threat at */
+} thread_priv_t;
+
+static int
+thread_generic_wrapper(void *arg)
+{
+	thread_priv_t *tp = (thread_priv_t *)arg;
+	void (*func)(void *);
+	void *args;
+
+	ASSERT(tp->tp_magic == TP_MAGIC);
+	func = tp->tp_func;
+	args = tp->tp_args;
+	set_current_state(tp->tp_state);
+	set_user_nice((kthread_t *)current, PRIO_TO_NICE(tp->tp_pri));
+	kfpu_initialize();
+	kmem_free(tp->tp_name, tp->tp_name_size);
+	kmem_free(tp, sizeof (thread_priv_t));
+
+	if (func)
+		func(args);
+
+	return (0);
+}
+
+void
+__thread_exit(void)
+{
+	tsd_exit();
+	complete_and_exit(NULL, 0);
+	/* Unreachable */
+}
+EXPORT_SYMBOL(__thread_exit);
+
+/*
+ * thread_create() may block forever if it cannot create a thread or
+ * allocate memory.  This is preferable to returning a NULL which Solaris
+ * style callers likely never check for... since it can't fail.
+ */
+kthread_t *
+__thread_create(caddr_t stk, size_t  stksize, thread_func_t func,
+    const char *name, void *args, size_t len, proc_t *pp, int state, pri_t pri)
+{
+	thread_priv_t *tp;
+	struct task_struct *tsk;
+	char *p;
+
+	/* Option pp is simply ignored */
+	/* Variable stack size unsupported */
+	ASSERT(stk == NULL);
+
+	tp = kmem_alloc(sizeof (thread_priv_t), KM_PUSHPAGE);
+	if (tp == NULL)
+		return (NULL);
+
+	tp->tp_magic = TP_MAGIC;
+	tp->tp_name_size = strlen(name) + 1;
+
+	tp->tp_name = kmem_alloc(tp->tp_name_size, KM_PUSHPAGE);
+	if (tp->tp_name == NULL) {
+		kmem_free(tp, sizeof (thread_priv_t));
+		return (NULL);
+	}
+
+	strncpy(tp->tp_name, name, tp->tp_name_size);
+
+	/*
+	 * Strip trailing "_thread" from passed name which will be the func
+	 * name since the exposed API has no parameter for passing a name.
+	 */
+	p = strstr(tp->tp_name, "_thread");
+	if (p)
+		p[0] = '\0';
+
+	tp->tp_func  = func;
+	tp->tp_args  = args;
+	tp->tp_len   = len;
+	tp->tp_state = state;
+	tp->tp_pri   = pri;
+
+	tsk = spl_kthread_create(thread_generic_wrapper, (void *)tp,
+	    "%s", tp->tp_name);
+	if (IS_ERR(tsk))
+		return (NULL);
+
+	wake_up_process(tsk);
+	return ((kthread_t *)tsk);
+}
+EXPORT_SYMBOL(__thread_create);
+
+/*
+ * spl_kthread_create - Wrapper providing pre-3.13 semantics for
+ * kthread_create() in which it is not killable and less likely
+ * to return -ENOMEM.
+ */
+struct task_struct *
+spl_kthread_create(int (*func)(void *), void *data, const char namefmt[], ...)
+{
+	struct task_struct *tsk;
+	va_list args;
+	char name[TASK_COMM_LEN];
+
+	va_start(args, namefmt);
+	vsnprintf(name, sizeof (name), namefmt, args);
+	va_end(args);
+	do {
+		tsk = kthread_create(func, data, "%s", name);
+		if (IS_ERR(tsk)) {
+			if (signal_pending(current)) {
+				clear_thread_flag(TIF_SIGPENDING);
+				continue;
+			}
+			if (PTR_ERR(tsk) == -ENOMEM)
+				continue;
+			return (NULL);
+		} else {
+			return (tsk);
+		}
+	} while (1);
+}
+EXPORT_SYMBOL(spl_kthread_create);
diff --git a/module/os/linux/spl/spl-tsd.c b/module/os/linux/spl/spl-tsd.c
new file mode 100644
index 000000000..14342d5a6
--- /dev/null
+++ b/module/os/linux/spl/spl-tsd.c
@@ -0,0 +1,720 @@
+/*
+ *  Copyright (C) 2010 Lawrence Livermore National Security, LLC.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ *  Solaris Porting Layer (SPL) Thread Specific Data Implementation.
+ *
+ *  Thread specific data has implemented using a hash table, this avoids
+ *  the need to add a member to the task structure and allows maximum
+ *  portability between kernels.  This implementation has been optimized
+ *  to keep the tsd_set() and tsd_get() times as small as possible.
+ *
+ *  The majority of the entries in the hash table are for specific tsd
+ *  entries.  These entries are hashed by the product of their key and
+ *  pid because by design the key and pid are guaranteed to be unique.
+ *  Their product also has the desirable properly that it will be uniformly
+ *  distributed over the hash bins providing neither the pid nor key is zero.
+ *  Under linux the zero pid is always the init process and thus won't be
+ *  used, and this implementation is careful to never to assign a zero key.
+ *  By default the hash table is sized to 512 bins which is expected to
+ *  be sufficient for light to moderate usage of thread specific data.
+ *
+ *  The hash table contains two additional type of entries.  They first
+ *  type is entry is called a 'key' entry and it is added to the hash during
+ *  tsd_create().  It is used to store the address of the destructor function
+ *  and it is used as an anchor point.  All tsd entries which use the same
+ *  key will be linked to this entry.  This is used during tsd_destroy() to
+ *  quickly call the destructor function for all tsd associated with the key.
+ *  The 'key' entry may be looked up with tsd_hash_search() by passing the
+ *  key you wish to lookup and DTOR_PID constant as the pid.
+ *
+ *  The second type of entry is called a 'pid' entry and it is added to the
+ *  hash the first time a process set a key.  The 'pid' entry is also used
+ *  as an anchor and all tsd for the process will be linked to it.  This
+ *  list is using during tsd_exit() to ensure all registered destructors
+ *  are run for the process.  The 'pid' entry may be looked up with
+ *  tsd_hash_search() by passing the PID_KEY constant as the key, and
+ *  the process pid.  Note that tsd_exit() is called by thread_exit()
+ *  so if your using the Solaris thread API you should not need to call
+ *  tsd_exit() directly.
+ *
+ */
+
+#include <sys/kmem.h>
+#include <sys/thread.h>
+#include <sys/tsd.h>
+#include <linux/hash.h>
+
+typedef struct tsd_hash_bin {
+	spinlock_t		hb_lock;
+	struct hlist_head	hb_head;
+} tsd_hash_bin_t;
+
+typedef struct tsd_hash_table {
+	spinlock_t		ht_lock;
+	uint_t			ht_bits;
+	uint_t			ht_key;
+	tsd_hash_bin_t		*ht_bins;
+} tsd_hash_table_t;
+
+typedef struct tsd_hash_entry {
+	uint_t			he_key;
+	pid_t			he_pid;
+	dtor_func_t		he_dtor;
+	void			*he_value;
+	struct hlist_node	he_list;
+	struct list_head	he_key_list;
+	struct list_head	he_pid_list;
+} tsd_hash_entry_t;
+
+static tsd_hash_table_t *tsd_hash_table = NULL;
+
+
+/*
+ * tsd_hash_search - searches hash table for tsd_hash_entry
+ * @table: hash table
+ * @key: search key
+ * @pid: search pid
+ */
+static tsd_hash_entry_t *
+tsd_hash_search(tsd_hash_table_t *table, uint_t key, pid_t pid)
+{
+	struct hlist_node *node;
+	tsd_hash_entry_t *entry;
+	tsd_hash_bin_t *bin;
+	ulong_t hash;
+
+	hash = hash_long((ulong_t)key * (ulong_t)pid, table->ht_bits);
+	bin = &table->ht_bins[hash];
+	spin_lock(&bin->hb_lock);
+	hlist_for_each(node, &bin->hb_head) {
+		entry = list_entry(node, tsd_hash_entry_t, he_list);
+		if ((entry->he_key == key) && (entry->he_pid == pid)) {
+			spin_unlock(&bin->hb_lock);
+			return (entry);
+		}
+	}
+
+	spin_unlock(&bin->hb_lock);
+	return (NULL);
+}
+
+/*
+ * tsd_hash_dtor - call the destructor and free all entries on the list
+ * @work: list of hash entries
+ *
+ * For a list of entries which have all already been removed from the
+ * hash call their registered destructor then free the associated memory.
+ */
+static void
+tsd_hash_dtor(struct hlist_head *work)
+{
+	tsd_hash_entry_t *entry;
+
+	while (!hlist_empty(work)) {
+		entry = hlist_entry(work->first, tsd_hash_entry_t, he_list);
+		hlist_del(&entry->he_list);
+
+		if (entry->he_dtor && entry->he_pid != DTOR_PID)
+			entry->he_dtor(entry->he_value);
+
+		kmem_free(entry, sizeof (tsd_hash_entry_t));
+	}
+}
+
+/*
+ * tsd_hash_add - adds an entry to hash table
+ * @table: hash table
+ * @key: search key
+ * @pid: search pid
+ *
+ * The caller is responsible for ensuring the unique key/pid do not
+ * already exist in the hash table.  This possible because all entries
+ * are thread specific thus a concurrent thread will never attempt to
+ * add this key/pid.  Because multiple bins must be checked to add
+ * links to the dtor and pid entries the entire table is locked.
+ */
+static int
+tsd_hash_add(tsd_hash_table_t *table, uint_t key, pid_t pid, void *value)
+{
+	tsd_hash_entry_t *entry, *dtor_entry, *pid_entry;
+	tsd_hash_bin_t *bin;
+	ulong_t hash;
+	int rc = 0;
+
+	ASSERT3P(tsd_hash_search(table, key, pid), ==, NULL);
+
+	/* New entry allocate structure, set value, and add to hash */
+	entry = kmem_alloc(sizeof (tsd_hash_entry_t), KM_PUSHPAGE);
+	if (entry == NULL)
+		return (ENOMEM);
+
+	entry->he_key = key;
+	entry->he_pid = pid;
+	entry->he_value = value;
+	INIT_HLIST_NODE(&entry->he_list);
+	INIT_LIST_HEAD(&entry->he_key_list);
+	INIT_LIST_HEAD(&entry->he_pid_list);
+
+	spin_lock(&table->ht_lock);
+
+	/* Destructor entry must exist for all valid keys */
+	dtor_entry = tsd_hash_search(table, entry->he_key, DTOR_PID);
+	ASSERT3P(dtor_entry, !=, NULL);
+	entry->he_dtor = dtor_entry->he_dtor;
+
+	/* Process entry must exist for all valid processes */
+	pid_entry = tsd_hash_search(table, PID_KEY, entry->he_pid);
+	ASSERT3P(pid_entry, !=, NULL);
+
+	hash = hash_long((ulong_t)key * (ulong_t)pid, table->ht_bits);
+	bin = &table->ht_bins[hash];
+	spin_lock(&bin->hb_lock);
+
+	/* Add to the hash, key, and pid lists */
+	hlist_add_head(&entry->he_list, &bin->hb_head);
+	list_add(&entry->he_key_list, &dtor_entry->he_key_list);
+	list_add(&entry->he_pid_list, &pid_entry->he_pid_list);
+
+	spin_unlock(&bin->hb_lock);
+	spin_unlock(&table->ht_lock);
+
+	return (rc);
+}
+
+/*
+ * tsd_hash_add_key - adds a destructor entry to the hash table
+ * @table: hash table
+ * @keyp: search key
+ * @dtor: key destructor
+ *
+ * For every unique key there is a single entry in the hash which is used
+ * as anchor.  All other thread specific entries for this key are linked
+ * to this anchor via the 'he_key_list' list head.  On return they keyp
+ * will be set to the next available key for the hash table.
+ */
+static int
+tsd_hash_add_key(tsd_hash_table_t *table, uint_t *keyp, dtor_func_t dtor)
+{
+	tsd_hash_entry_t *tmp_entry, *entry;
+	tsd_hash_bin_t *bin;
+	ulong_t hash;
+	int keys_checked = 0;
+
+	ASSERT3P(table, !=, NULL);
+
+	/* Allocate entry to be used as a destructor for this key */
+	entry = kmem_alloc(sizeof (tsd_hash_entry_t), KM_PUSHPAGE);
+	if (entry == NULL)
+		return (ENOMEM);
+
+	/* Determine next available key value */
+	spin_lock(&table->ht_lock);
+	do {
+		/* Limited to TSD_KEYS_MAX concurrent unique keys */
+		if (table->ht_key++ > TSD_KEYS_MAX)
+			table->ht_key = 1;
+
+		/* Ensure failure when all TSD_KEYS_MAX keys are in use */
+		if (keys_checked++ >= TSD_KEYS_MAX) {
+			spin_unlock(&table->ht_lock);
+			return (ENOENT);
+		}
+
+		tmp_entry = tsd_hash_search(table, table->ht_key, DTOR_PID);
+	} while (tmp_entry);
+
+	/* Add destructor entry in to hash table */
+	entry->he_key = *keyp = table->ht_key;
+	entry->he_pid = DTOR_PID;
+	entry->he_dtor = dtor;
+	entry->he_value = NULL;
+	INIT_HLIST_NODE(&entry->he_list);
+	INIT_LIST_HEAD(&entry->he_key_list);
+	INIT_LIST_HEAD(&entry->he_pid_list);
+
+	hash = hash_long((ulong_t)*keyp * (ulong_t)DTOR_PID, table->ht_bits);
+	bin = &table->ht_bins[hash];
+	spin_lock(&bin->hb_lock);
+
+	hlist_add_head(&entry->he_list, &bin->hb_head);
+
+	spin_unlock(&bin->hb_lock);
+	spin_unlock(&table->ht_lock);
+
+	return (0);
+}
+
+/*
+ * tsd_hash_add_pid - adds a process entry to the hash table
+ * @table: hash table
+ * @pid: search pid
+ *
+ * For every process there is a single entry in the hash which is used
+ * as anchor.  All other thread specific entries for this process are
+ * linked to this anchor via the 'he_pid_list' list head.
+ */
+static int
+tsd_hash_add_pid(tsd_hash_table_t *table, pid_t pid)
+{
+	tsd_hash_entry_t *entry;
+	tsd_hash_bin_t *bin;
+	ulong_t hash;
+
+	/* Allocate entry to be used as the process reference */
+	entry = kmem_alloc(sizeof (tsd_hash_entry_t), KM_PUSHPAGE);
+	if (entry == NULL)
+		return (ENOMEM);
+
+	spin_lock(&table->ht_lock);
+	entry->he_key = PID_KEY;
+	entry->he_pid = pid;
+	entry->he_dtor = NULL;
+	entry->he_value = NULL;
+	INIT_HLIST_NODE(&entry->he_list);
+	INIT_LIST_HEAD(&entry->he_key_list);
+	INIT_LIST_HEAD(&entry->he_pid_list);
+
+	hash = hash_long((ulong_t)PID_KEY * (ulong_t)pid, table->ht_bits);
+	bin = &table->ht_bins[hash];
+	spin_lock(&bin->hb_lock);
+
+	hlist_add_head(&entry->he_list, &bin->hb_head);
+
+	spin_unlock(&bin->hb_lock);
+	spin_unlock(&table->ht_lock);
+
+	return (0);
+}
+
+/*
+ * tsd_hash_del - delete an entry from hash table, key, and pid lists
+ * @table: hash table
+ * @key: search key
+ * @pid: search pid
+ */
+static void
+tsd_hash_del(tsd_hash_table_t *table, tsd_hash_entry_t *entry)
+{
+	hlist_del(&entry->he_list);
+	list_del_init(&entry->he_key_list);
+	list_del_init(&entry->he_pid_list);
+}
+
+/*
+ * tsd_hash_table_init - allocate a hash table
+ * @bits: hash table size
+ *
+ * A hash table with 2^bits bins will be created, it may not be resized
+ * after the fact and must be free'd with tsd_hash_table_fini().
+ */
+static tsd_hash_table_t *
+tsd_hash_table_init(uint_t bits)
+{
+	tsd_hash_table_t *table;
+	int hash, size = (1 << bits);
+
+	table = kmem_zalloc(sizeof (tsd_hash_table_t), KM_SLEEP);
+	if (table == NULL)
+		return (NULL);
+
+	table->ht_bins = kmem_zalloc(sizeof (tsd_hash_bin_t) * size, KM_SLEEP);
+	if (table->ht_bins == NULL) {
+		kmem_free(table, sizeof (tsd_hash_table_t));
+		return (NULL);
+	}
+
+	for (hash = 0; hash < size; hash++) {
+		spin_lock_init(&table->ht_bins[hash].hb_lock);
+		INIT_HLIST_HEAD(&table->ht_bins[hash].hb_head);
+	}
+
+	spin_lock_init(&table->ht_lock);
+	table->ht_bits = bits;
+	table->ht_key = 1;
+
+	return (table);
+}
+
+/*
+ * tsd_hash_table_fini - free a hash table
+ * @table: hash table
+ *
+ * Free a hash table allocated by tsd_hash_table_init().  If the hash
+ * table is not empty this function will call the proper destructor for
+ * all remaining entries before freeing the memory used by those entries.
+ */
+static void
+tsd_hash_table_fini(tsd_hash_table_t *table)
+{
+	HLIST_HEAD(work);
+	tsd_hash_bin_t *bin;
+	tsd_hash_entry_t *entry;
+	int size, i;
+
+	ASSERT3P(table, !=, NULL);
+	spin_lock(&table->ht_lock);
+	for (i = 0, size = (1 << table->ht_bits); i < size; i++) {
+		bin = &table->ht_bins[i];
+		spin_lock(&bin->hb_lock);
+		while (!hlist_empty(&bin->hb_head)) {
+			entry = hlist_entry(bin->hb_head.first,
+			    tsd_hash_entry_t, he_list);
+			tsd_hash_del(table, entry);
+			hlist_add_head(&entry->he_list, &work);
+		}
+		spin_unlock(&bin->hb_lock);
+	}
+	spin_unlock(&table->ht_lock);
+
+	tsd_hash_dtor(&work);
+	kmem_free(table->ht_bins, sizeof (tsd_hash_bin_t)*(1<<table->ht_bits));
+	kmem_free(table, sizeof (tsd_hash_table_t));
+}
+
+/*
+ * tsd_remove_entry - remove a tsd entry for this thread
+ * @entry: entry to remove
+ *
+ * Remove the thread specific data @entry for this thread.
+ * If this is the last entry for this thread, also remove the PID entry.
+ */
+static void
+tsd_remove_entry(tsd_hash_entry_t *entry)
+{
+	HLIST_HEAD(work);
+	tsd_hash_table_t *table;
+	tsd_hash_entry_t *pid_entry;
+	tsd_hash_bin_t *pid_entry_bin, *entry_bin;
+	ulong_t hash;
+
+	table = tsd_hash_table;
+	ASSERT3P(table, !=, NULL);
+	ASSERT3P(entry, !=, NULL);
+
+	spin_lock(&table->ht_lock);
+
+	hash = hash_long((ulong_t)entry->he_key *
+	    (ulong_t)entry->he_pid, table->ht_bits);
+	entry_bin = &table->ht_bins[hash];
+
+	/* save the possible pid_entry */
+	pid_entry = list_entry(entry->he_pid_list.next, tsd_hash_entry_t,
+	    he_pid_list);
+
+	/* remove entry */
+	spin_lock(&entry_bin->hb_lock);
+	tsd_hash_del(table, entry);
+	hlist_add_head(&entry->he_list, &work);
+	spin_unlock(&entry_bin->hb_lock);
+
+	/* if pid_entry is indeed pid_entry, then remove it if it's empty */
+	if (pid_entry->he_key == PID_KEY &&
+	    list_empty(&pid_entry->he_pid_list)) {
+		hash = hash_long((ulong_t)pid_entry->he_key *
+		    (ulong_t)pid_entry->he_pid, table->ht_bits);
+		pid_entry_bin = &table->ht_bins[hash];
+
+		spin_lock(&pid_entry_bin->hb_lock);
+		tsd_hash_del(table, pid_entry);
+		hlist_add_head(&pid_entry->he_list, &work);
+		spin_unlock(&pid_entry_bin->hb_lock);
+	}
+
+	spin_unlock(&table->ht_lock);
+
+	tsd_hash_dtor(&work);
+}
+
+/*
+ * tsd_set - set thread specific data
+ * @key: lookup key
+ * @value: value to set
+ *
+ * Caller must prevent racing tsd_create() or tsd_destroy(), protected
+ * from racing tsd_get() or tsd_set() because it is thread specific.
+ * This function has been optimized to be fast for the update case.
+ * When setting the tsd initially it will be slower due to additional
+ * required locking and potential memory allocations.
+ */
+int
+tsd_set(uint_t key, void *value)
+{
+	tsd_hash_table_t *table;
+	tsd_hash_entry_t *entry;
+	pid_t pid;
+	int rc;
+	/* mark remove if value is NULL */
+	boolean_t remove = (value == NULL);
+
+	table = tsd_hash_table;
+	pid = curthread->pid;
+	ASSERT3P(table, !=, NULL);
+
+	if ((key == 0) || (key > TSD_KEYS_MAX))
+		return (EINVAL);
+
+	/* Entry already exists in hash table update value */
+	entry = tsd_hash_search(table, key, pid);
+	if (entry) {
+		entry->he_value = value;
+		/* remove the entry */
+		if (remove)
+			tsd_remove_entry(entry);
+		return (0);
+	}
+
+	/* don't create entry if value is NULL */
+	if (remove)
+		return (0);
+
+	/* Add a process entry to the hash if not yet exists */
+	entry = tsd_hash_search(table, PID_KEY, pid);
+	if (entry == NULL) {
+		rc = tsd_hash_add_pid(table, pid);
+		if (rc)
+			return (rc);
+	}
+
+	rc = tsd_hash_add(table, key, pid, value);
+	return (rc);
+}
+EXPORT_SYMBOL(tsd_set);
+
+/*
+ * tsd_get - get thread specific data
+ * @key: lookup key
+ *
+ * Caller must prevent racing tsd_create() or tsd_destroy().  This
+ * implementation is designed to be fast and scalable, it does not
+ * lock the entire table only a single hash bin.
+ */
+void *
+tsd_get(uint_t key)
+{
+	tsd_hash_entry_t *entry;
+
+	ASSERT3P(tsd_hash_table, !=, NULL);
+
+	if ((key == 0) || (key > TSD_KEYS_MAX))
+		return (NULL);
+
+	entry = tsd_hash_search(tsd_hash_table, key, curthread->pid);
+	if (entry == NULL)
+		return (NULL);
+
+	return (entry->he_value);
+}
+EXPORT_SYMBOL(tsd_get);
+
+/*
+ * tsd_get_by_thread - get thread specific data for specified thread
+ * @key: lookup key
+ * @thread: thread to lookup
+ *
+ * Caller must prevent racing tsd_create() or tsd_destroy().  This
+ * implementation is designed to be fast and scalable, it does not
+ * lock the entire table only a single hash bin.
+ */
+void *
+tsd_get_by_thread(uint_t key, kthread_t *thread)
+{
+	tsd_hash_entry_t *entry;
+
+	ASSERT3P(tsd_hash_table, !=, NULL);
+
+	if ((key == 0) || (key > TSD_KEYS_MAX))
+		return (NULL);
+
+	entry = tsd_hash_search(tsd_hash_table, key, thread->pid);
+	if (entry == NULL)
+		return (NULL);
+
+	return (entry->he_value);
+}
+EXPORT_SYMBOL(tsd_get_by_thread);
+
+/*
+ * tsd_create - create thread specific data key
+ * @keyp: lookup key address
+ * @dtor: destructor called during tsd_destroy() or tsd_exit()
+ *
+ * Provided key must be set to 0 or it assumed to be already in use.
+ * The dtor is allowed to be NULL in which case no additional cleanup
+ * for the data is performed during tsd_destroy() or tsd_exit().
+ *
+ * Caller must prevent racing tsd_set() or tsd_get(), this function is
+ * safe from racing tsd_create(), tsd_destroy(), and tsd_exit().
+ */
+void
+tsd_create(uint_t *keyp, dtor_func_t dtor)
+{
+	ASSERT3P(keyp, !=, NULL);
+	if (*keyp)
+		return;
+
+	(void) tsd_hash_add_key(tsd_hash_table, keyp, dtor);
+}
+EXPORT_SYMBOL(tsd_create);
+
+/*
+ * tsd_destroy - destroy thread specific data
+ * @keyp: lookup key address
+ *
+ * Destroys the thread specific data on all threads which use this key.
+ *
+ * Caller must prevent racing tsd_set() or tsd_get(), this function is
+ * safe from racing tsd_create(), tsd_destroy(), and tsd_exit().
+ */
+void
+tsd_destroy(uint_t *keyp)
+{
+	HLIST_HEAD(work);
+	tsd_hash_table_t *table;
+	tsd_hash_entry_t *dtor_entry, *entry;
+	tsd_hash_bin_t *dtor_entry_bin, *entry_bin;
+	ulong_t hash;
+
+	table = tsd_hash_table;
+	ASSERT3P(table, !=, NULL);
+
+	spin_lock(&table->ht_lock);
+	dtor_entry = tsd_hash_search(table, *keyp, DTOR_PID);
+	if (dtor_entry == NULL) {
+		spin_unlock(&table->ht_lock);
+		return;
+	}
+
+	/*
+	 * All threads which use this key must be linked off of the
+	 * DTOR_PID entry.  They are removed from the hash table and
+	 * linked in to a private working list to be destroyed.
+	 */
+	while (!list_empty(&dtor_entry->he_key_list)) {
+		entry = list_entry(dtor_entry->he_key_list.next,
+		    tsd_hash_entry_t, he_key_list);
+		ASSERT3U(dtor_entry->he_key, ==, entry->he_key);
+		ASSERT3P(dtor_entry->he_dtor, ==, entry->he_dtor);
+
+		hash = hash_long((ulong_t)entry->he_key *
+		    (ulong_t)entry->he_pid, table->ht_bits);
+		entry_bin = &table->ht_bins[hash];
+
+		spin_lock(&entry_bin->hb_lock);
+		tsd_hash_del(table, entry);
+		hlist_add_head(&entry->he_list, &work);
+		spin_unlock(&entry_bin->hb_lock);
+	}
+
+	hash = hash_long((ulong_t)dtor_entry->he_key *
+	    (ulong_t)dtor_entry->he_pid, table->ht_bits);
+	dtor_entry_bin = &table->ht_bins[hash];
+
+	spin_lock(&dtor_entry_bin->hb_lock);
+	tsd_hash_del(table, dtor_entry);
+	hlist_add_head(&dtor_entry->he_list, &work);
+	spin_unlock(&dtor_entry_bin->hb_lock);
+	spin_unlock(&table->ht_lock);
+
+	tsd_hash_dtor(&work);
+	*keyp = 0;
+}
+EXPORT_SYMBOL(tsd_destroy);
+
+/*
+ * tsd_exit - destroys all thread specific data for this thread
+ *
+ * Destroys all the thread specific data for this thread.
+ *
+ * Caller must prevent racing tsd_set() or tsd_get(), this function is
+ * safe from racing tsd_create(), tsd_destroy(), and tsd_exit().
+ */
+void
+tsd_exit(void)
+{
+	HLIST_HEAD(work);
+	tsd_hash_table_t *table;
+	tsd_hash_entry_t *pid_entry, *entry;
+	tsd_hash_bin_t *pid_entry_bin, *entry_bin;
+	ulong_t hash;
+
+	table = tsd_hash_table;
+	ASSERT3P(table, !=, NULL);
+
+	spin_lock(&table->ht_lock);
+	pid_entry = tsd_hash_search(table, PID_KEY, curthread->pid);
+	if (pid_entry == NULL) {
+		spin_unlock(&table->ht_lock);
+		return;
+	}
+
+	/*
+	 * All keys associated with this pid must be linked off of the
+	 * PID_KEY entry.  They are removed from the hash table and
+	 * linked in to a private working list to be destroyed.
+	 */
+
+	while (!list_empty(&pid_entry->he_pid_list)) {
+		entry = list_entry(pid_entry->he_pid_list.next,
+		    tsd_hash_entry_t, he_pid_list);
+		ASSERT3U(pid_entry->he_pid, ==, entry->he_pid);
+
+		hash = hash_long((ulong_t)entry->he_key *
+		    (ulong_t)entry->he_pid, table->ht_bits);
+		entry_bin = &table->ht_bins[hash];
+
+		spin_lock(&entry_bin->hb_lock);
+		tsd_hash_del(table, entry);
+		hlist_add_head(&entry->he_list, &work);
+		spin_unlock(&entry_bin->hb_lock);
+	}
+
+	hash = hash_long((ulong_t)pid_entry->he_key *
+	    (ulong_t)pid_entry->he_pid, table->ht_bits);
+	pid_entry_bin = &table->ht_bins[hash];
+
+	spin_lock(&pid_entry_bin->hb_lock);
+	tsd_hash_del(table, pid_entry);
+	hlist_add_head(&pid_entry->he_list, &work);
+	spin_unlock(&pid_entry_bin->hb_lock);
+	spin_unlock(&table->ht_lock);
+
+	tsd_hash_dtor(&work);
+}
+EXPORT_SYMBOL(tsd_exit);
+
+int
+spl_tsd_init(void)
+{
+	tsd_hash_table = tsd_hash_table_init(TSD_HASH_TABLE_BITS_DEFAULT);
+	if (tsd_hash_table == NULL)
+		return (1);
+
+	return (0);
+}
+
+void
+spl_tsd_fini(void)
+{
+	tsd_hash_table_fini(tsd_hash_table);
+	tsd_hash_table = NULL;
+}
diff --git a/module/os/linux/spl/spl-vmem.c b/module/os/linux/spl/spl-vmem.c
new file mode 100644
index 000000000..e1a84a911
--- /dev/null
+++ b/module/os/linux/spl/spl-vmem.c
@@ -0,0 +1,135 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <sys/debug.h>
+#include <sys/vmem.h>
+#include <sys/kmem_cache.h>
+#include <sys/shrinker.h>
+#include <linux/module.h>
+
+vmem_t *heap_arena = NULL;
+EXPORT_SYMBOL(heap_arena);
+
+vmem_t *zio_alloc_arena = NULL;
+EXPORT_SYMBOL(zio_alloc_arena);
+
+vmem_t *zio_arena = NULL;
+EXPORT_SYMBOL(zio_arena);
+
+#define	VMEM_FLOOR_SIZE		(4 * 1024 * 1024)	/* 4MB floor */
+
+/*
+ * Return approximate virtual memory usage based on these assumptions:
+ *
+ * 1) The major SPL consumer of virtual memory is the kmem cache.
+ * 2) Memory allocated with vmem_alloc() is short lived and can be ignored.
+ * 3) Allow a 4MB floor as a generous pad given normal consumption.
+ * 4) The spl_kmem_cache_sem only contends with cache create/destroy.
+ */
+size_t
+vmem_size(vmem_t *vmp, int typemask)
+{
+	spl_kmem_cache_t *skc;
+	size_t alloc = VMEM_FLOOR_SIZE;
+
+	if ((typemask & VMEM_ALLOC) && (typemask & VMEM_FREE))
+		return (VMALLOC_TOTAL);
+
+
+	down_read(&spl_kmem_cache_sem);
+	list_for_each_entry(skc, &spl_kmem_cache_list, skc_list) {
+		if (skc->skc_flags & KMC_VMEM)
+			alloc += skc->skc_slab_size * skc->skc_slab_total;
+	}
+	up_read(&spl_kmem_cache_sem);
+
+	if (typemask & VMEM_ALLOC)
+		return (MIN(alloc, VMALLOC_TOTAL));
+	else if (typemask & VMEM_FREE)
+		return (MAX(VMALLOC_TOTAL - alloc, 0));
+	else
+		return (0);
+}
+EXPORT_SYMBOL(vmem_size);
+
+/*
+ * Public vmem_alloc(), vmem_zalloc() and vmem_free() interfaces.
+ */
+void *
+spl_vmem_alloc(size_t size, int flags, const char *func, int line)
+{
+	ASSERT0(flags & ~KM_PUBLIC_MASK);
+
+	flags |= KM_VMEM;
+
+#if !defined(DEBUG_KMEM)
+	return (spl_kmem_alloc_impl(size, flags, NUMA_NO_NODE));
+#elif !defined(DEBUG_KMEM_TRACKING)
+	return (spl_kmem_alloc_debug(size, flags, NUMA_NO_NODE));
+#else
+	return (spl_kmem_alloc_track(size, flags, func, line, NUMA_NO_NODE));
+#endif
+}
+EXPORT_SYMBOL(spl_vmem_alloc);
+
+void *
+spl_vmem_zalloc(size_t size, int flags, const char *func, int line)
+{
+	ASSERT0(flags & ~KM_PUBLIC_MASK);
+
+	flags |= (KM_VMEM | KM_ZERO);
+
+#if !defined(DEBUG_KMEM)
+	return (spl_kmem_alloc_impl(size, flags, NUMA_NO_NODE));
+#elif !defined(DEBUG_KMEM_TRACKING)
+	return (spl_kmem_alloc_debug(size, flags, NUMA_NO_NODE));
+#else
+	return (spl_kmem_alloc_track(size, flags, func, line, NUMA_NO_NODE));
+#endif
+}
+EXPORT_SYMBOL(spl_vmem_zalloc);
+
+void
+spl_vmem_free(const void *buf, size_t size)
+{
+#if !defined(DEBUG_KMEM)
+	return (spl_kmem_free_impl(buf, size));
+#elif !defined(DEBUG_KMEM_TRACKING)
+	return (spl_kmem_free_debug(buf, size));
+#else
+	return (spl_kmem_free_track(buf, size));
+#endif
+}
+EXPORT_SYMBOL(spl_vmem_free);
+
+int
+spl_vmem_init(void)
+{
+	return (0);
+}
+
+void
+spl_vmem_fini(void)
+{
+}
diff --git a/module/os/linux/spl/spl-vnode.c b/module/os/linux/spl/spl-vnode.c
new file mode 100644
index 000000000..d9056c964
--- /dev/null
+++ b/module/os/linux/spl/spl-vnode.c
@@ -0,0 +1,719 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) Vnode Implementation.
+ */
+
+#include <sys/cred.h>
+#include <sys/vnode.h>
+#include <sys/kmem_cache.h>
+#include <linux/falloc.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#ifdef HAVE_FDTABLE_HEADER
+#include <linux/fdtable.h>
+#endif
+
+vnode_t *rootdir = (vnode_t *)0xabcd1234;
+EXPORT_SYMBOL(rootdir);
+
+static spl_kmem_cache_t *vn_cache;
+static spl_kmem_cache_t *vn_file_cache;
+
+static spinlock_t vn_file_lock;
+static LIST_HEAD(vn_file_list);
+
+static int
+spl_filp_fallocate(struct file *fp, int mode, loff_t offset, loff_t len)
+{
+	int error = -EOPNOTSUPP;
+
+#ifdef HAVE_FILE_FALLOCATE
+	if (fp->f_op->fallocate)
+		error = fp->f_op->fallocate(fp, mode, offset, len);
+#else
+#ifdef HAVE_INODE_FALLOCATE
+	if (fp->f_dentry && fp->f_dentry->d_inode &&
+	    fp->f_dentry->d_inode->i_op->fallocate)
+		error = fp->f_dentry->d_inode->i_op->fallocate(
+		    fp->f_dentry->d_inode, mode, offset, len);
+#endif /* HAVE_INODE_FALLOCATE */
+#endif /* HAVE_FILE_FALLOCATE */
+
+	return (error);
+}
+
+static int
+spl_filp_fsync(struct file *fp, int sync)
+{
+#ifdef HAVE_2ARGS_VFS_FSYNC
+	return (vfs_fsync(fp, sync));
+#else
+	return (vfs_fsync(fp, (fp)->f_dentry, sync));
+#endif /* HAVE_2ARGS_VFS_FSYNC */
+}
+
+static ssize_t
+spl_kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos)
+{
+#if defined(HAVE_KERNEL_WRITE_PPOS)
+	return (kernel_write(file, buf, count, pos));
+#else
+	mm_segment_t saved_fs;
+	ssize_t ret;
+
+	saved_fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	ret = vfs_write(file, (__force const char __user *)buf, count, pos);
+
+	set_fs(saved_fs);
+
+	return (ret);
+#endif
+}
+
+static ssize_t
+spl_kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
+{
+#if defined(HAVE_KERNEL_READ_PPOS)
+	return (kernel_read(file, buf, count, pos));
+#else
+	mm_segment_t saved_fs;
+	ssize_t ret;
+
+	saved_fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	ret = vfs_read(file, (void __user *)buf, count, pos);
+
+	set_fs(saved_fs);
+
+	return (ret);
+#endif
+}
+
+vtype_t
+vn_mode_to_vtype(mode_t mode)
+{
+	if (S_ISREG(mode))
+		return (VREG);
+
+	if (S_ISDIR(mode))
+		return (VDIR);
+
+	if (S_ISCHR(mode))
+		return (VCHR);
+
+	if (S_ISBLK(mode))
+		return (VBLK);
+
+	if (S_ISFIFO(mode))
+		return (VFIFO);
+
+	if (S_ISLNK(mode))
+		return (VLNK);
+
+	if (S_ISSOCK(mode))
+		return (VSOCK);
+
+	return (VNON);
+} /* vn_mode_to_vtype() */
+EXPORT_SYMBOL(vn_mode_to_vtype);
+
+mode_t
+vn_vtype_to_mode(vtype_t vtype)
+{
+	if (vtype == VREG)
+		return (S_IFREG);
+
+	if (vtype == VDIR)
+		return (S_IFDIR);
+
+	if (vtype == VCHR)
+		return (S_IFCHR);
+
+	if (vtype == VBLK)
+		return (S_IFBLK);
+
+	if (vtype == VFIFO)
+		return (S_IFIFO);
+
+	if (vtype == VLNK)
+		return (S_IFLNK);
+
+	if (vtype == VSOCK)
+		return (S_IFSOCK);
+
+	return (VNON);
+} /* vn_vtype_to_mode() */
+EXPORT_SYMBOL(vn_vtype_to_mode);
+
+vnode_t *
+vn_alloc(int flag)
+{
+	vnode_t *vp;
+
+	vp = kmem_cache_alloc(vn_cache, flag);
+	if (vp != NULL) {
+		vp->v_file = NULL;
+		vp->v_type = 0;
+	}
+
+	return (vp);
+} /* vn_alloc() */
+EXPORT_SYMBOL(vn_alloc);
+
+void
+vn_free(vnode_t *vp)
+{
+	kmem_cache_free(vn_cache, vp);
+} /* vn_free() */
+EXPORT_SYMBOL(vn_free);
+
+int
+vn_open(const char *path, uio_seg_t seg, int flags, int mode, vnode_t **vpp,
+    int x1, void *x2)
+{
+	struct file *fp;
+	struct kstat stat;
+	int rc, saved_umask = 0;
+	gfp_t saved_gfp;
+	vnode_t *vp;
+
+	ASSERT(flags & (FWRITE | FREAD));
+	ASSERT(seg == UIO_SYSSPACE);
+	ASSERT(vpp);
+	*vpp = NULL;
+
+	if (!(flags & FCREAT) && (flags & FWRITE))
+		flags |= FEXCL;
+
+	/*
+	 * Note for filp_open() the two low bits must be remapped to mean:
+	 * 01 - read-only  -> 00 read-only
+	 * 10 - write-only -> 01 write-only
+	 * 11 - read-write -> 10 read-write
+	 */
+	flags--;
+
+	if (flags & FCREAT)
+		saved_umask = xchg(&current->fs->umask, 0);
+
+	fp = filp_open(path, flags, mode);
+
+	if (flags & FCREAT)
+		(void) xchg(&current->fs->umask, saved_umask);
+
+	if (IS_ERR(fp))
+		return (-PTR_ERR(fp));
+
+#if defined(HAVE_4ARGS_VFS_GETATTR)
+	rc = vfs_getattr(&fp->f_path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
+#elif defined(HAVE_2ARGS_VFS_GETATTR)
+	rc = vfs_getattr(&fp->f_path, &stat);
+#else
+	rc = vfs_getattr(fp->f_path.mnt, fp->f_dentry, &stat);
+#endif
+	if (rc) {
+		filp_close(fp, 0);
+		return (-rc);
+	}
+
+	vp = vn_alloc(KM_SLEEP);
+	if (!vp) {
+		filp_close(fp, 0);
+		return (ENOMEM);
+	}
+
+	saved_gfp = mapping_gfp_mask(fp->f_mapping);
+	mapping_set_gfp_mask(fp->f_mapping, saved_gfp & ~(__GFP_IO|__GFP_FS));
+
+	mutex_enter(&vp->v_lock);
+	vp->v_type = vn_mode_to_vtype(stat.mode);
+	vp->v_file = fp;
+	vp->v_gfp_mask = saved_gfp;
+	*vpp = vp;
+	mutex_exit(&vp->v_lock);
+
+	return (0);
+} /* vn_open() */
+EXPORT_SYMBOL(vn_open);
+
+int
+vn_openat(const char *path, uio_seg_t seg, int flags, int mode,
+    vnode_t **vpp, int x1, void *x2, vnode_t *vp, int fd)
+{
+	char *realpath;
+	int len, rc;
+
+	ASSERT(vp == rootdir);
+
+	len = strlen(path) + 2;
+	realpath = kmalloc(len, kmem_flags_convert(KM_SLEEP));
+	if (!realpath)
+		return (ENOMEM);
+
+	(void) snprintf(realpath, len, "/%s", path);
+	rc = vn_open(realpath, seg, flags, mode, vpp, x1, x2);
+	kfree(realpath);
+
+	return (rc);
+} /* vn_openat() */
+EXPORT_SYMBOL(vn_openat);
+
+int
+vn_rdwr(uio_rw_t uio, vnode_t *vp, void *addr, ssize_t len, offset_t off,
+    uio_seg_t seg, int ioflag, rlim64_t x2, void *x3, ssize_t *residp)
+{
+	struct file *fp = vp->v_file;
+	loff_t offset = off;
+	int rc;
+
+	ASSERT(uio == UIO_WRITE || uio == UIO_READ);
+	ASSERT(seg == UIO_SYSSPACE);
+	ASSERT((ioflag & ~FAPPEND) == 0);
+
+	if (ioflag & FAPPEND)
+		offset = fp->f_pos;
+
+	if (uio & UIO_WRITE)
+		rc = spl_kernel_write(fp, addr, len, &offset);
+	else
+		rc = spl_kernel_read(fp, addr, len, &offset);
+
+	fp->f_pos = offset;
+
+	if (rc < 0)
+		return (-rc);
+
+	if (residp) {
+		*residp = len - rc;
+	} else {
+		if (rc != len)
+			return (EIO);
+	}
+
+	return (0);
+} /* vn_rdwr() */
+EXPORT_SYMBOL(vn_rdwr);
+
+int
+vn_close(vnode_t *vp, int flags, int x1, int x2, void *x3, void *x4)
+{
+	int rc;
+
+	ASSERT(vp);
+	ASSERT(vp->v_file);
+
+	mapping_set_gfp_mask(vp->v_file->f_mapping, vp->v_gfp_mask);
+	rc = filp_close(vp->v_file, 0);
+	vn_free(vp);
+
+	return (-rc);
+} /* vn_close() */
+EXPORT_SYMBOL(vn_close);
+
+/*
+ * vn_seek() does not actually seek it only performs bounds checking on the
+ * proposed seek.  We perform minimal checking and allow vn_rdwr() to catch
+ * anything more serious.
+ */
+int
+vn_seek(vnode_t *vp, offset_t ooff, offset_t *noffp, void *ct)
+{
+	return ((*noffp < 0 || *noffp > MAXOFFSET_T) ? EINVAL : 0);
+}
+EXPORT_SYMBOL(vn_seek);
+
+int
+vn_getattr(vnode_t *vp, vattr_t *vap, int flags, void *x3, void *x4)
+{
+	struct file *fp;
+	struct kstat stat;
+	int rc;
+
+	ASSERT(vp);
+	ASSERT(vp->v_file);
+	ASSERT(vap);
+
+	fp = vp->v_file;
+
+#if defined(HAVE_4ARGS_VFS_GETATTR)
+	rc = vfs_getattr(&fp->f_path, &stat, STATX_BASIC_STATS,
+	    AT_STATX_SYNC_AS_STAT);
+#elif defined(HAVE_2ARGS_VFS_GETATTR)
+	rc = vfs_getattr(&fp->f_path, &stat);
+#else
+	rc = vfs_getattr(fp->f_path.mnt, fp->f_dentry, &stat);
+#endif
+	if (rc)
+		return (-rc);
+
+	vap->va_type	= vn_mode_to_vtype(stat.mode);
+	vap->va_mode	= stat.mode;
+	vap->va_uid	= KUID_TO_SUID(stat.uid);
+	vap->va_gid	= KGID_TO_SGID(stat.gid);
+	vap->va_fsid	= 0;
+	vap->va_nodeid	= stat.ino;
+	vap->va_nlink	= stat.nlink;
+	vap->va_size	= stat.size;
+	vap->va_blksize	= stat.blksize;
+	vap->va_atime	= stat.atime;
+	vap->va_mtime	= stat.mtime;
+	vap->va_ctime	= stat.ctime;
+	vap->va_rdev	= stat.rdev;
+	vap->va_nblocks	= stat.blocks;
+
+	return (0);
+}
+EXPORT_SYMBOL(vn_getattr);
+
+int
+vn_fsync(vnode_t *vp, int flags, void *x3, void *x4)
+{
+	int datasync = 0;
+	int error;
+	int fstrans;
+
+	ASSERT(vp);
+	ASSERT(vp->v_file);
+
+	if (flags & FDSYNC)
+		datasync = 1;
+
+	/*
+	 * May enter XFS which generates a warning when PF_FSTRANS is set.
+	 * To avoid this the flag is cleared over vfs_sync() and then reset.
+	 */
+	fstrans = __spl_pf_fstrans_check();
+	if (fstrans)
+		current->flags &= ~(__SPL_PF_FSTRANS);
+
+	error = -spl_filp_fsync(vp->v_file, datasync);
+	if (fstrans)
+		current->flags |= __SPL_PF_FSTRANS;
+
+	return (error);
+} /* vn_fsync() */
+EXPORT_SYMBOL(vn_fsync);
+
+int vn_space(vnode_t *vp, int cmd, struct flock *bfp, int flag,
+    offset_t offset, void *x6, void *x7)
+{
+	int error = EOPNOTSUPP;
+#ifdef FALLOC_FL_PUNCH_HOLE
+	int fstrans;
+#endif
+
+	if (cmd != F_FREESP || bfp->l_whence != SEEK_SET)
+		return (EOPNOTSUPP);
+
+	ASSERT(vp);
+	ASSERT(vp->v_file);
+	ASSERT(bfp->l_start >= 0 && bfp->l_len > 0);
+
+#ifdef FALLOC_FL_PUNCH_HOLE
+	/*
+	 * May enter XFS which generates a warning when PF_FSTRANS is set.
+	 * To avoid this the flag is cleared over vfs_sync() and then reset.
+	 */
+	fstrans = __spl_pf_fstrans_check();
+	if (fstrans)
+		current->flags &= ~(__SPL_PF_FSTRANS);
+
+	/*
+	 * When supported by the underlying file system preferentially
+	 * use the fallocate() callback to preallocate the space.
+	 */
+	error = -spl_filp_fallocate(vp->v_file,
+	    FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
+	    bfp->l_start, bfp->l_len);
+
+	if (fstrans)
+		current->flags |= __SPL_PF_FSTRANS;
+
+	if (error == 0)
+		return (0);
+#endif
+
+#ifdef HAVE_INODE_TRUNCATE_RANGE
+	if (vp->v_file->f_dentry && vp->v_file->f_dentry->d_inode &&
+	    vp->v_file->f_dentry->d_inode->i_op &&
+	    vp->v_file->f_dentry->d_inode->i_op->truncate_range) {
+		off_t end = bfp->l_start + bfp->l_len;
+		/*
+		 * Judging from the code in shmem_truncate_range(),
+		 * it seems the kernel expects the end offset to be
+		 * inclusive and aligned to the end of a page.
+		 */
+		if (end % PAGE_SIZE != 0) {
+			end &= ~(off_t)(PAGE_SIZE - 1);
+			if (end <= bfp->l_start)
+				return (0);
+		}
+		--end;
+
+		vp->v_file->f_dentry->d_inode->i_op->truncate_range(
+		    vp->v_file->f_dentry->d_inode, bfp->l_start, end);
+
+		return (0);
+	}
+#endif
+
+	return (error);
+}
+EXPORT_SYMBOL(vn_space);
+
+/* Function must be called while holding the vn_file_lock */
+static file_t *
+file_find(int fd, struct task_struct *task)
+{
+	file_t *fp;
+
+	list_for_each_entry(fp, &vn_file_list,  f_list) {
+		if (fd == fp->f_fd && fp->f_task == task) {
+			ASSERT(atomic_read(&fp->f_ref) != 0);
+			return (fp);
+		}
+	}
+
+	return (NULL);
+} /* file_find() */
+
+file_t *
+vn_getf(int fd)
+{
+	struct kstat stat;
+	struct file *lfp;
+	file_t *fp;
+	vnode_t *vp;
+	int rc = 0;
+
+	if (fd < 0)
+		return (NULL);
+
+	/* Already open just take an extra reference */
+	spin_lock(&vn_file_lock);
+
+	fp = file_find(fd, current);
+	if (fp) {
+		lfp = fget(fd);
+		fput(fp->f_file);
+		/*
+		 * areleasef() can cause us to see a stale reference when
+		 * userspace has reused a file descriptor before areleasef()
+		 * has run. fput() the stale reference and replace it. We
+		 * retain the original reference count such that the concurrent
+		 * areleasef() will decrement its reference and terminate.
+		 */
+		if (lfp != fp->f_file) {
+			fp->f_file = lfp;
+			fp->f_vnode->v_file = lfp;
+		}
+		atomic_inc(&fp->f_ref);
+		spin_unlock(&vn_file_lock);
+		return (fp);
+	}
+
+	spin_unlock(&vn_file_lock);
+
+	/* File was not yet opened create the object and setup */
+	fp = kmem_cache_alloc(vn_file_cache, KM_SLEEP);
+	if (fp == NULL)
+		goto out;
+
+	mutex_enter(&fp->f_lock);
+
+	fp->f_fd = fd;
+	fp->f_task = current;
+	fp->f_offset = 0;
+	atomic_inc(&fp->f_ref);
+
+	lfp = fget(fd);
+	if (lfp == NULL)
+		goto out_mutex;
+
+	vp = vn_alloc(KM_SLEEP);
+	if (vp == NULL)
+		goto out_fget;
+
+#if defined(HAVE_4ARGS_VFS_GETATTR)
+	rc = vfs_getattr(&lfp->f_path, &stat, STATX_TYPE,
+	    AT_STATX_SYNC_AS_STAT);
+#elif defined(HAVE_2ARGS_VFS_GETATTR)
+	rc = vfs_getattr(&lfp->f_path, &stat);
+#else
+	rc = vfs_getattr(lfp->f_path.mnt, lfp->f_dentry, &stat);
+#endif
+	if (rc)
+		goto out_vnode;
+
+	mutex_enter(&vp->v_lock);
+	vp->v_type = vn_mode_to_vtype(stat.mode);
+	vp->v_file = lfp;
+	mutex_exit(&vp->v_lock);
+
+	fp->f_vnode = vp;
+	fp->f_file = lfp;
+
+	/* Put it on the tracking list */
+	spin_lock(&vn_file_lock);
+	list_add(&fp->f_list, &vn_file_list);
+	spin_unlock(&vn_file_lock);
+
+	mutex_exit(&fp->f_lock);
+	return (fp);
+
+out_vnode:
+	vn_free(vp);
+out_fget:
+	fput(lfp);
+out_mutex:
+	mutex_exit(&fp->f_lock);
+	kmem_cache_free(vn_file_cache, fp);
+out:
+	return (NULL);
+} /* getf() */
+EXPORT_SYMBOL(getf);
+
+static void releasef_locked(file_t *fp)
+{
+	ASSERT(fp->f_file);
+	ASSERT(fp->f_vnode);
+
+	/* Unlinked from list, no refs, safe to free outside mutex */
+	fput(fp->f_file);
+	vn_free(fp->f_vnode);
+
+	kmem_cache_free(vn_file_cache, fp);
+}
+
+void
+vn_releasef(int fd)
+{
+	areleasef(fd, P_FINFO(current));
+}
+EXPORT_SYMBOL(releasef);
+
+void
+vn_areleasef(int fd, uf_info_t *fip)
+{
+	file_t *fp;
+	struct task_struct *task = (struct task_struct *)fip;
+
+	if (fd < 0)
+		return;
+
+	spin_lock(&vn_file_lock);
+	fp = file_find(fd, task);
+	if (fp) {
+		atomic_dec(&fp->f_ref);
+		if (atomic_read(&fp->f_ref) > 0) {
+			spin_unlock(&vn_file_lock);
+			return;
+		}
+
+		list_del(&fp->f_list);
+		releasef_locked(fp);
+	}
+	spin_unlock(&vn_file_lock);
+} /* releasef() */
+EXPORT_SYMBOL(areleasef);
+
+static int
+vn_cache_constructor(void *buf, void *cdrarg, int kmflags)
+{
+	struct vnode *vp = buf;
+
+	mutex_init(&vp->v_lock, NULL, MUTEX_DEFAULT, NULL);
+
+	return (0);
+} /* vn_cache_constructor() */
+
+static void
+vn_cache_destructor(void *buf, void *cdrarg)
+{
+	struct vnode *vp = buf;
+
+	mutex_destroy(&vp->v_lock);
+} /* vn_cache_destructor() */
+
+static int
+vn_file_cache_constructor(void *buf, void *cdrarg, int kmflags)
+{
+	file_t *fp = buf;
+
+	atomic_set(&fp->f_ref, 0);
+	mutex_init(&fp->f_lock, NULL, MUTEX_DEFAULT, NULL);
+	INIT_LIST_HEAD(&fp->f_list);
+
+	return (0);
+} /* vn_file_cache_constructor() */
+
+static void
+vn_file_cache_destructor(void *buf, void *cdrarg)
+{
+	file_t *fp = buf;
+
+	mutex_destroy(&fp->f_lock);
+} /* vn_file_cache_destructor() */
+
+int
+spl_vn_init(void)
+{
+	spin_lock_init(&vn_file_lock);
+
+	vn_cache = kmem_cache_create("spl_vn_cache",
+	    sizeof (struct vnode), 64, vn_cache_constructor,
+	    vn_cache_destructor, NULL, NULL, NULL, 0);
+
+	vn_file_cache = kmem_cache_create("spl_vn_file_cache",
+	    sizeof (file_t), 64, vn_file_cache_constructor,
+	    vn_file_cache_destructor, NULL, NULL, NULL, 0);
+
+	return (0);
+} /* spl_vn_init() */
+
+void
+spl_vn_fini(void)
+{
+	file_t *fp, *next_fp;
+	int leaked = 0;
+
+	spin_lock(&vn_file_lock);
+
+	list_for_each_entry_safe(fp, next_fp, &vn_file_list,  f_list) {
+		list_del(&fp->f_list);
+		releasef_locked(fp);
+		leaked++;
+	}
+
+	spin_unlock(&vn_file_lock);
+
+	if (leaked > 0)
+		printk(KERN_WARNING "WARNING: %d vnode files leaked\n", leaked);
+
+	kmem_cache_destroy(vn_file_cache);
+	kmem_cache_destroy(vn_cache);
+} /* spl_vn_fini() */
diff --git a/module/os/linux/spl/spl-xdr.c b/module/os/linux/spl/spl-xdr.c
new file mode 100644
index 000000000..1dd31ffc1
--- /dev/null
+++ b/module/os/linux/spl/spl-xdr.c
@@ -0,0 +1,513 @@
+/*
+ *  Copyright (c) 2008-2010 Sun Microsystems, Inc.
+ *  Written by Ricardo Correia <[email protected]>
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  Solaris Porting Layer (SPL) XDR Implementation.
+ */
+
+#include <linux/string.h>
+#include <sys/kmem.h>
+#include <sys/debug.h>
+#include <sys/types.h>
+#include <sys/sysmacros.h>
+#include <rpc/xdr.h>
+
+/*
+ * SPL's XDR mem implementation.
+ *
+ * This is used by libnvpair to serialize/deserialize the name-value pair data
+ * structures into byte arrays in a well-defined and portable manner.
+ *
+ * These data structures are used by the DMU/ZFS to flexibly manipulate various
+ * information in memory and later serialize it/deserialize it to disk.
+ * Examples of usages include the pool configuration, lists of pool and dataset
+ * properties, etc.
+ *
+ * Reference documentation for the XDR representation and XDR operations can be
+ * found in RFC 1832 and xdr(3), respectively.
+ *
+ * ===  Implementation shortcomings ===
+ *
+ * It is assumed that the following C types have the following sizes:
+ *
+ * char/unsigned char:      1 byte
+ * short/unsigned short:    2 bytes
+ * int/unsigned int:        4 bytes
+ * longlong_t/u_longlong_t: 8 bytes
+ *
+ * The C standard allows these types to be larger (and in the case of ints,
+ * shorter), so if that is the case on some compiler/architecture, the build
+ * will fail (on purpose).
+ *
+ * If someone wants to fix the code to work properly on such environments, then:
+ *
+ * 1) Preconditions should be added to xdrmem_enc functions to make sure the
+ *    caller doesn't pass arguments which exceed the expected range.
+ * 2) Functions which take signed integers should be changed to properly do
+ *    sign extension.
+ * 3) For ints with less than 32 bits, well.. I suspect you'll have bigger
+ *    problems than this implementation.
+ *
+ * It is also assumed that:
+ *
+ * 1) Chars have 8 bits.
+ * 2) We can always do 32-bit-aligned int memory accesses and byte-aligned
+ *    memcpy, memset and memcmp.
+ * 3) Arrays passed to xdr_array() are packed and the compiler/architecture
+ *    supports element-sized-aligned memory accesses.
+ * 4) Negative integers are natively stored in two's complement binary
+ *    representation.
+ *
+ * No checks are done for the 4 assumptions above, though.
+ *
+ * === Caller expectations ===
+ *
+ * Existing documentation does not describe the semantics of XDR operations very
+ * well.  Therefore, some assumptions about failure semantics will be made and
+ * will be described below:
+ *
+ * 1) If any encoding operation fails (e.g., due to lack of buffer space), the
+ * the stream should be considered valid only up to the encoding operation
+ * previous to the one that first failed. However, the stream size as returned
+ * by xdr_control() cannot be considered to be strictly correct (it may be
+ * bigger).
+ *
+ * Putting it another way, if there is an encoding failure it's undefined
+ * whether anything is added to the stream in that operation and therefore
+ * neither xdr_control() nor future encoding operations on the same stream can
+ * be relied upon to produce correct results.
+ *
+ * 2) If a decoding operation fails, it's undefined whether anything will be
+ * decoded into passed buffers/pointers during that operation, or what the
+ * values on those buffers will look like.
+ *
+ * Future decoding operations on the same stream will also have similar
+ * undefined behavior.
+ *
+ * 3) When the first decoding operation fails it is OK to trust the results of
+ * previous decoding operations on the same stream, as long as the caller
+ * expects a failure to be possible (e.g. due to end-of-stream).
+ *
+ * However, this is highly discouraged because the caller should know the
+ * stream size and should be coded to expect any decoding failure to be data
+ * corruption due to hardware, accidental or even malicious causes, which should
+ * be handled gracefully in all cases.
+ *
+ * In very rare situations where there are strong reasons to believe the data
+ * can be trusted to be valid and non-tampered with, then the caller may assume
+ * a decoding failure to be a bug (e.g. due to mismatched data types) and may
+ * fail non-gracefully.
+ *
+ * 4) Non-zero padding bytes will cause the decoding operation to fail.
+ *
+ * 5) Zero bytes on string types will also cause the decoding operation to fail.
+ *
+ * 6) It is assumed that either the pointer to the stream buffer given by the
+ * caller is 32-bit aligned or the architecture supports non-32-bit-aligned int
+ * memory accesses.
+ *
+ * 7) The stream buffer and encoding/decoding buffers/ptrs should not overlap.
+ *
+ * 8) If a caller passes pointers to non-kernel memory (e.g., pointers to user
+ * space or MMIO space), the computer may explode.
+ */
+
+static struct xdr_ops xdrmem_encode_ops;
+static struct xdr_ops xdrmem_decode_ops;
+
+void
+xdrmem_create(XDR *xdrs, const caddr_t addr, const uint_t size,
+    const enum xdr_op op)
+{
+	switch (op) {
+		case XDR_ENCODE:
+			xdrs->x_ops = &xdrmem_encode_ops;
+			break;
+		case XDR_DECODE:
+			xdrs->x_ops = &xdrmem_decode_ops;
+			break;
+		default:
+			xdrs->x_ops = NULL; /* Let the caller know we failed */
+			return;
+	}
+
+	xdrs->x_op = op;
+	xdrs->x_addr = addr;
+	xdrs->x_addr_end = addr + size;
+
+	if (xdrs->x_addr_end < xdrs->x_addr) {
+		xdrs->x_ops = NULL;
+	}
+}
+EXPORT_SYMBOL(xdrmem_create);
+
+static bool_t
+xdrmem_control(XDR *xdrs, int req, void *info)
+{
+	struct xdr_bytesrec *rec = (struct xdr_bytesrec *)info;
+
+	if (req != XDR_GET_BYTES_AVAIL)
+		return (FALSE);
+
+	rec->xc_is_last_record = TRUE; /* always TRUE in xdrmem streams */
+	rec->xc_num_avail = xdrs->x_addr_end - xdrs->x_addr;
+
+	return (TRUE);
+}
+
+static bool_t
+xdrmem_enc_bytes(XDR *xdrs, caddr_t cp, const uint_t cnt)
+{
+	uint_t size = roundup(cnt, 4);
+	uint_t pad;
+
+	if (size < cnt)
+		return (FALSE); /* Integer overflow */
+
+	if (xdrs->x_addr > xdrs->x_addr_end)
+		return (FALSE);
+
+	if (xdrs->x_addr_end - xdrs->x_addr < size)
+		return (FALSE);
+
+	memcpy(xdrs->x_addr, cp, cnt);
+
+	xdrs->x_addr += cnt;
+
+	pad = size - cnt;
+	if (pad > 0) {
+		memset(xdrs->x_addr, 0, pad);
+		xdrs->x_addr += pad;
+	}
+
+	return (TRUE);
+}
+
+static bool_t
+xdrmem_dec_bytes(XDR *xdrs, caddr_t cp, const uint_t cnt)
+{
+	static uint32_t zero = 0;
+	uint_t size = roundup(cnt, 4);
+	uint_t pad;
+
+	if (size < cnt)
+		return (FALSE); /* Integer overflow */
+
+	if (xdrs->x_addr > xdrs->x_addr_end)
+		return (FALSE);
+
+	if (xdrs->x_addr_end - xdrs->x_addr < size)
+		return (FALSE);
+
+	memcpy(cp, xdrs->x_addr, cnt);
+	xdrs->x_addr += cnt;
+
+	pad = size - cnt;
+	if (pad > 0) {
+		/* An inverted memchr() would be useful here... */
+		if (memcmp(&zero, xdrs->x_addr, pad) != 0)
+			return (FALSE);
+
+		xdrs->x_addr += pad;
+	}
+
+	return (TRUE);
+}
+
+static bool_t
+xdrmem_enc_uint32(XDR *xdrs, uint32_t val)
+{
+	if (xdrs->x_addr + sizeof (uint32_t) > xdrs->x_addr_end)
+		return (FALSE);
+
+	*((uint32_t *)xdrs->x_addr) = cpu_to_be32(val);
+
+	xdrs->x_addr += sizeof (uint32_t);
+
+	return (TRUE);
+}
+
+static bool_t
+xdrmem_dec_uint32(XDR *xdrs, uint32_t *val)
+{
+	if (xdrs->x_addr + sizeof (uint32_t) > xdrs->x_addr_end)
+		return (FALSE);
+
+	*val = be32_to_cpu(*((uint32_t *)xdrs->x_addr));
+
+	xdrs->x_addr += sizeof (uint32_t);
+
+	return (TRUE);
+}
+
+static bool_t
+xdrmem_enc_char(XDR *xdrs, char *cp)
+{
+	uint32_t val;
+
+	BUILD_BUG_ON(sizeof (char) != 1);
+	val = *((unsigned char *) cp);
+
+	return (xdrmem_enc_uint32(xdrs, val));
+}
+
+static bool_t
+xdrmem_dec_char(XDR *xdrs, char *cp)
+{
+	uint32_t val;
+
+	BUILD_BUG_ON(sizeof (char) != 1);
+
+	if (!xdrmem_dec_uint32(xdrs, &val))
+		return (FALSE);
+
+	/*
+	 * If any of the 3 other bytes are non-zero then val will be greater
+	 * than 0xff and we fail because according to the RFC, this block does
+	 * not have a char encoded in it.
+	 */
+	if (val > 0xff)
+		return (FALSE);
+
+	*((unsigned char *) cp) = val;
+
+	return (TRUE);
+}
+
+static bool_t
+xdrmem_enc_ushort(XDR *xdrs, unsigned short *usp)
+{
+	BUILD_BUG_ON(sizeof (unsigned short) != 2);
+
+	return (xdrmem_enc_uint32(xdrs, *usp));
+}
+
+static bool_t
+xdrmem_dec_ushort(XDR *xdrs, unsigned short *usp)
+{
+	uint32_t val;
+
+	BUILD_BUG_ON(sizeof (unsigned short) != 2);
+
+	if (!xdrmem_dec_uint32(xdrs, &val))
+		return (FALSE);
+
+	/*
+	 * Short ints are not in the RFC, but we assume similar logic as in
+	 * xdrmem_dec_char().
+	 */
+	if (val > 0xffff)
+		return (FALSE);
+
+	*usp = val;
+
+	return (TRUE);
+}
+
+static bool_t
+xdrmem_enc_uint(XDR *xdrs, unsigned *up)
+{
+	BUILD_BUG_ON(sizeof (unsigned) != 4);
+
+	return (xdrmem_enc_uint32(xdrs, *up));
+}
+
+static bool_t
+xdrmem_dec_uint(XDR *xdrs, unsigned *up)
+{
+	BUILD_BUG_ON(sizeof (unsigned) != 4);
+
+	return (xdrmem_dec_uint32(xdrs, (uint32_t *)up));
+}
+
+static bool_t
+xdrmem_enc_ulonglong(XDR *xdrs, u_longlong_t *ullp)
+{
+	BUILD_BUG_ON(sizeof (u_longlong_t) != 8);
+
+	if (!xdrmem_enc_uint32(xdrs, *ullp >> 32))
+		return (FALSE);
+
+	return (xdrmem_enc_uint32(xdrs, *ullp & 0xffffffff));
+}
+
+static bool_t
+xdrmem_dec_ulonglong(XDR *xdrs, u_longlong_t *ullp)
+{
+	uint32_t low, high;
+
+	BUILD_BUG_ON(sizeof (u_longlong_t) != 8);
+
+	if (!xdrmem_dec_uint32(xdrs, &high))
+		return (FALSE);
+	if (!xdrmem_dec_uint32(xdrs, &low))
+		return (FALSE);
+
+	*ullp = ((u_longlong_t)high << 32) | low;
+
+	return (TRUE);
+}
+
+static bool_t
+xdr_enc_array(XDR *xdrs, caddr_t *arrp, uint_t *sizep, const uint_t maxsize,
+    const uint_t elsize, const xdrproc_t elproc)
+{
+	uint_t i;
+	caddr_t addr = *arrp;
+
+	if (*sizep > maxsize || *sizep > UINT_MAX / elsize)
+		return (FALSE);
+
+	if (!xdrmem_enc_uint(xdrs, sizep))
+		return (FALSE);
+
+	for (i = 0; i < *sizep; i++) {
+		if (!elproc(xdrs, addr))
+			return (FALSE);
+		addr += elsize;
+	}
+
+	return (TRUE);
+}
+
+static bool_t
+xdr_dec_array(XDR *xdrs, caddr_t *arrp, uint_t *sizep, const uint_t maxsize,
+    const uint_t elsize, const xdrproc_t elproc)
+{
+	uint_t i, size;
+	bool_t alloc = FALSE;
+	caddr_t addr;
+
+	if (!xdrmem_dec_uint(xdrs, sizep))
+		return (FALSE);
+
+	size = *sizep;
+
+	if (size > maxsize || size > UINT_MAX / elsize)
+		return (FALSE);
+
+	/*
+	 * The Solaris man page says: "If *arrp is NULL when decoding,
+	 * xdr_array() allocates memory and *arrp points to it".
+	 */
+	if (*arrp == NULL) {
+		BUILD_BUG_ON(sizeof (uint_t) > sizeof (size_t));
+
+		*arrp = kmem_alloc(size * elsize, KM_NOSLEEP);
+		if (*arrp == NULL)
+			return (FALSE);
+
+		alloc = TRUE;
+	}
+
+	addr = *arrp;
+
+	for (i = 0; i < size; i++) {
+		if (!elproc(xdrs, addr)) {
+			if (alloc)
+				kmem_free(*arrp, size * elsize);
+			return (FALSE);
+		}
+		addr += elsize;
+	}
+
+	return (TRUE);
+}
+
+static bool_t
+xdr_enc_string(XDR *xdrs, char **sp, const uint_t maxsize)
+{
+	size_t slen = strlen(*sp);
+	uint_t len;
+
+	if (slen > maxsize)
+		return (FALSE);
+
+	len = slen;
+
+	if (!xdrmem_enc_uint(xdrs, &len))
+		return (FALSE);
+
+	return (xdrmem_enc_bytes(xdrs, *sp, len));
+}
+
+static bool_t
+xdr_dec_string(XDR *xdrs, char **sp, const uint_t maxsize)
+{
+	uint_t size;
+	bool_t alloc = FALSE;
+
+	if (!xdrmem_dec_uint(xdrs, &size))
+		return (FALSE);
+
+	if (size > maxsize || size > UINT_MAX - 1)
+		return (FALSE);
+
+	/*
+	 * Solaris man page: "If *sp is NULL when decoding, xdr_string()
+	 * allocates memory and *sp points to it".
+	 */
+	if (*sp == NULL) {
+		BUILD_BUG_ON(sizeof (uint_t) > sizeof (size_t));
+
+		*sp = kmem_alloc(size + 1, KM_NOSLEEP);
+		if (*sp == NULL)
+			return (FALSE);
+
+		alloc = TRUE;
+	}
+
+	if (!xdrmem_dec_bytes(xdrs, *sp, size))
+		goto fail;
+
+	if (memchr(*sp, 0, size) != NULL)
+		goto fail;
+
+	(*sp)[size] = '\0';
+
+	return (TRUE);
+
+fail:
+	if (alloc)
+		kmem_free(*sp, size + 1);
+
+	return (FALSE);
+}
+
+static struct xdr_ops xdrmem_encode_ops = {
+	.xdr_control		= xdrmem_control,
+	.xdr_char		= xdrmem_enc_char,
+	.xdr_u_short		= xdrmem_enc_ushort,
+	.xdr_u_int		= xdrmem_enc_uint,
+	.xdr_u_longlong_t	= xdrmem_enc_ulonglong,
+	.xdr_opaque		= xdrmem_enc_bytes,
+	.xdr_string		= xdr_enc_string,
+	.xdr_array		= xdr_enc_array
+};
+
+static struct xdr_ops xdrmem_decode_ops = {
+	.xdr_control		= xdrmem_control,
+	.xdr_char		= xdrmem_dec_char,
+	.xdr_u_short		= xdrmem_dec_ushort,
+	.xdr_u_int		= xdrmem_dec_uint,
+	.xdr_u_longlong_t	= xdrmem_dec_ulonglong,
+	.xdr_opaque		= xdrmem_dec_bytes,
+	.xdr_string		= xdr_dec_string,
+	.xdr_array		= xdr_dec_array
+};
diff --git a/module/os/linux/spl/spl-zlib.c b/module/os/linux/spl/spl-zlib.c
new file mode 100644
index 000000000..62423343c
--- /dev/null
+++ b/module/os/linux/spl/spl-zlib.c
@@ -0,0 +1,217 @@
+/*
+ *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
+ *  Copyright (C) 2007 The Regents of the University of California.
+ *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ *  Written by Brian Behlendorf <[email protected]>.
+ *  UCRL-CODE-235197
+ *
+ *  This file is part of the SPL, Solaris Porting Layer.
+ *  For details, see <http://zfsonlinux.org/>.
+ *
+ *  The SPL is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License as published by the
+ *  Free Software Foundation; either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  The SPL is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ *  z_compress_level/z_uncompress are nearly identical copies of the
+ *  compress2/uncompress functions provided by the official zlib package
+ *  available at http://zlib.net/.  The only changes made we to slightly
+ *  adapt the functions called to match the linux kernel implementation
+ *  of zlib.  The full zlib license follows:
+ *
+ *  zlib.h -- interface of the 'zlib' general purpose compression library
+ *  version 1.2.5, April 19th, 2010
+ *
+ *  Copyright (C) 1995-2010 Jean-loup Gailly and Mark Adler
+ *
+ *  This software is provided 'as-is', without any express or implied
+ *  warranty.  In no event will the authors be held liable for any damages
+ *  arising from the use of this software.
+ *
+ *  Permission is granted to anyone to use this software for any purpose,
+ *  including commercial applications, and to alter it and redistribute it
+ *  freely, subject to the following restrictions:
+ *
+ *  1. The origin of this software must not be misrepresented; you must not
+ *     claim that you wrote the original software. If you use this software
+ *     in a product, an acknowledgment in the product documentation would be
+ *     appreciated but is not required.
+ *  2. Altered source versions must be plainly marked as such, and must not be
+ *     misrepresented as being the original software.
+ *  3. This notice may not be removed or altered from any source distribution.
+ *
+ *  Jean-loup Gailly
+ *  Mark Adler
+ */
+
+
+#include <sys/kmem.h>
+#include <sys/kmem_cache.h>
+#include <sys/zmod.h>
+
+static spl_kmem_cache_t *zlib_workspace_cache;
+
+/*
+ * A kmem_cache is used for the zlib workspaces to avoid having to vmalloc
+ * and vfree for every call.  Using a kmem_cache also has the advantage
+ * that improves the odds that the memory used will be local to this cpu.
+ * To further improve things it might be wise to create a dedicated per-cpu
+ * workspace for use.  This would take some additional care because we then
+ * must disable preemption around the critical section, and verify that
+ * zlib_deflate* and zlib_inflate* never internally call schedule().
+ */
+static void *
+zlib_workspace_alloc(int flags)
+{
+	return (kmem_cache_alloc(zlib_workspace_cache, flags & ~(__GFP_FS)));
+}
+
+static void
+zlib_workspace_free(void *workspace)
+{
+	kmem_cache_free(zlib_workspace_cache, workspace);
+}
+
+/*
+ * Compresses the source buffer into the destination buffer. The level
+ * parameter has the same meaning as in deflateInit.  sourceLen is the byte
+ * length of the source buffer. Upon entry, destLen is the total size of the
+ * destination buffer, which must be at least 0.1% larger than sourceLen plus
+ * 12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
+ *
+ * compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
+ * memory, Z_BUF_ERROR if there was not enough room in the output buffer,
+ * Z_STREAM_ERROR if the level parameter is invalid.
+ */
+int
+z_compress_level(void *dest, size_t *destLen, const void *source,
+    size_t sourceLen, int level)
+{
+	z_stream stream;
+	int err;
+
+	stream.next_in = (Byte *)source;
+	stream.avail_in = (uInt)sourceLen;
+	stream.next_out = dest;
+	stream.avail_out = (uInt)*destLen;
+
+	if ((size_t)stream.avail_out != *destLen)
+		return (Z_BUF_ERROR);
+
+	stream.workspace = zlib_workspace_alloc(KM_SLEEP);
+	if (!stream.workspace)
+		return (Z_MEM_ERROR);
+
+	err = zlib_deflateInit(&stream, level);
+	if (err != Z_OK) {
+		zlib_workspace_free(stream.workspace);
+		return (err);
+	}
+
+	err = zlib_deflate(&stream, Z_FINISH);
+	if (err != Z_STREAM_END) {
+		zlib_deflateEnd(&stream);
+		zlib_workspace_free(stream.workspace);
+		return (err == Z_OK ? Z_BUF_ERROR : err);
+	}
+	*destLen = stream.total_out;
+
+	err = zlib_deflateEnd(&stream);
+	zlib_workspace_free(stream.workspace);
+
+	return (err);
+}
+EXPORT_SYMBOL(z_compress_level);
+
+/*
+ * Decompresses the source buffer into the destination buffer.  sourceLen is
+ * the byte length of the source buffer. Upon entry, destLen is the total
+ * size of the destination buffer, which must be large enough to hold the
+ * entire uncompressed data. (The size of the uncompressed data must have
+ * been saved previously by the compressor and transmitted to the decompressor
+ * by some mechanism outside the scope of this compression library.)
+ * Upon exit, destLen is the actual size of the compressed buffer.
+ * This function can be used to decompress a whole file at once if the
+ * input file is mmap'ed.
+ *
+ * uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
+ * enough memory, Z_BUF_ERROR if there was not enough room in the output
+ * buffer, or Z_DATA_ERROR if the input data was corrupted.
+ */
+int
+z_uncompress(void *dest, size_t *destLen, const void *source, size_t sourceLen)
+{
+	z_stream stream;
+	int err;
+
+	stream.next_in = (Byte *)source;
+	stream.avail_in = (uInt)sourceLen;
+	stream.next_out = dest;
+	stream.avail_out = (uInt)*destLen;
+
+	if ((size_t)stream.avail_out != *destLen)
+		return (Z_BUF_ERROR);
+
+	stream.workspace = zlib_workspace_alloc(KM_SLEEP);
+	if (!stream.workspace)
+		return (Z_MEM_ERROR);
+
+	err = zlib_inflateInit(&stream);
+	if (err != Z_OK) {
+		zlib_workspace_free(stream.workspace);
+		return (err);
+	}
+
+	err = zlib_inflate(&stream, Z_FINISH);
+	if (err != Z_STREAM_END) {
+		zlib_inflateEnd(&stream);
+		zlib_workspace_free(stream.workspace);
+
+		if (err == Z_NEED_DICT ||
+		    (err == Z_BUF_ERROR && stream.avail_in == 0))
+			return (Z_DATA_ERROR);
+
+		return (err);
+	}
+	*destLen = stream.total_out;
+
+	err = zlib_inflateEnd(&stream);
+	zlib_workspace_free(stream.workspace);
+
+	return (err);
+}
+EXPORT_SYMBOL(z_uncompress);
+
+int
+spl_zlib_init(void)
+{
+	int size;
+
+	size = MAX(spl_zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
+	    zlib_inflate_workspacesize());
+
+	zlib_workspace_cache = kmem_cache_create(
+	    "spl_zlib_workspace_cache",
+	    size, 0, NULL, NULL, NULL, NULL, NULL,
+	    KMC_VMEM);
+	if (!zlib_workspace_cache)
+		return (1);
+
+	return (0);
+}
+
+void
+spl_zlib_fini(void)
+{
+	kmem_cache_destroy(zlib_workspace_cache);
+	zlib_workspace_cache = NULL;
+}