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 

1 files changed, 1034 insertions, 0 deletions

diff --git a/module/os/linux/zfs/spa_stats.c b/module/os/linux/zfs/spa_stats.c
new file mode 100644
index 000000000..6895428f4
--- /dev/null
+++ b/module/os/linux/zfs/spa_stats.c
@@ -0,0 +1,1034 @@
+/*
+ * 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
+ */
+
+#include <sys/zfs_context.h>
+#include <sys/spa_impl.h>
+#include <sys/vdev_impl.h>
+#include <sys/spa.h>
+#include <zfs_comutil.h>
+
+/*
+ * Keeps stats on last N reads per spa_t, disabled by default.
+ */
+int zfs_read_history = 0;
+
+/*
+ * Include cache hits in history, disabled by default.
+ */
+int zfs_read_history_hits = 0;
+
+/*
+ * Keeps stats on the last 100 txgs by default.
+ */
+int zfs_txg_history = 100;
+
+/*
+ * Keeps stats on the last N MMP updates, disabled by default.
+ */
+int zfs_multihost_history = 0;
+
+/*
+ * ==========================================================================
+ * SPA Read History Routines
+ * ==========================================================================
+ */
+
+/*
+ * Read statistics - Information exported regarding each arc_read call
+ */
+typedef struct spa_read_history {
+	hrtime_t	start;		/* time read completed */
+	uint64_t	objset;		/* read from this objset */
+	uint64_t	object;		/* read of this object number */
+	uint64_t	level;		/* block's indirection level */
+	uint64_t	blkid;		/* read of this block id */
+	char		origin[24];	/* read originated from here */
+	uint32_t	aflags;		/* ARC flags (cached, prefetch, etc.) */
+	pid_t		pid;		/* PID of task doing read */
+	char		comm[16];	/* process name of task doing read */
+	procfs_list_node_t	srh_node;
+} spa_read_history_t;
+
+static int
+spa_read_history_show_header(struct seq_file *f)
+{
+	seq_printf(f, "%-8s %-16s %-8s %-8s %-8s %-8s %-8s "
+	    "%-24s %-8s %-16s\n", "UID", "start", "objset", "object",
+	    "level", "blkid", "aflags", "origin", "pid", "process");
+
+	return (0);
+}
+
+static int
+spa_read_history_show(struct seq_file *f, void *data)
+{
+	spa_read_history_t *srh = (spa_read_history_t *)data;
+
+	seq_printf(f, "%-8llu %-16llu 0x%-6llx "
+	    "%-8lli %-8lli %-8lli 0x%-6x %-24s %-8i %-16s\n",
+	    (u_longlong_t)srh->srh_node.pln_id, srh->start,
+	    (longlong_t)srh->objset, (longlong_t)srh->object,
+	    (longlong_t)srh->level, (longlong_t)srh->blkid,
+	    srh->aflags, srh->origin, srh->pid, srh->comm);
+
+	return (0);
+}
+
+/* Remove oldest elements from list until there are no more than 'size' left */
+static void
+spa_read_history_truncate(spa_history_list_t *shl, unsigned int size)
+{
+	spa_read_history_t *srh;
+	while (shl->size > size) {
+		srh = list_remove_head(&shl->procfs_list.pl_list);
+		ASSERT3P(srh, !=, NULL);
+		kmem_free(srh, sizeof (spa_read_history_t));
+		shl->size--;
+	}
+
+	if (size == 0)
+		ASSERT(list_is_empty(&shl->procfs_list.pl_list));
+}
+
+static int
+spa_read_history_clear(procfs_list_t *procfs_list)
+{
+	spa_history_list_t *shl = procfs_list->pl_private;
+	mutex_enter(&procfs_list->pl_lock);
+	spa_read_history_truncate(shl, 0);
+	mutex_exit(&procfs_list->pl_lock);
+	return (0);
+}
+
+static void
+spa_read_history_init(spa_t *spa)
+{
+	spa_history_list_t *shl = &spa->spa_stats.read_history;
+	char *module;
+
+	shl->size = 0;
+
+	module = kmem_asprintf("zfs/%s", spa_name(spa));
+
+	shl->procfs_list.pl_private = shl;
+	procfs_list_install(module,
+	    "reads",
+	    0600,
+	    &shl->procfs_list,
+	    spa_read_history_show,
+	    spa_read_history_show_header,
+	    spa_read_history_clear,
+	    offsetof(spa_read_history_t, srh_node));
+
+	strfree(module);
+}
+
+static void
+spa_read_history_destroy(spa_t *spa)
+{
+	spa_history_list_t *shl = &spa->spa_stats.read_history;
+	procfs_list_uninstall(&shl->procfs_list);
+	spa_read_history_truncate(shl, 0);
+	procfs_list_destroy(&shl->procfs_list);
+}
+
+void
+spa_read_history_add(spa_t *spa, const zbookmark_phys_t *zb, uint32_t aflags)
+{
+	spa_history_list_t *shl = &spa->spa_stats.read_history;
+	spa_read_history_t *srh;
+
+	ASSERT3P(spa, !=, NULL);
+	ASSERT3P(zb,  !=, NULL);
+
+	if (zfs_read_history == 0 && shl->size == 0)
+		return;
+
+	if (zfs_read_history_hits == 0 && (aflags & ARC_FLAG_CACHED))
+		return;
+
+	srh = kmem_zalloc(sizeof (spa_read_history_t), KM_SLEEP);
+	strlcpy(srh->comm, getcomm(), sizeof (srh->comm));
+	srh->start  = gethrtime();
+	srh->objset = zb->zb_objset;
+	srh->object = zb->zb_object;
+	srh->level  = zb->zb_level;
+	srh->blkid  = zb->zb_blkid;
+	srh->aflags = aflags;
+	srh->pid    = getpid();
+
+	mutex_enter(&shl->procfs_list.pl_lock);
+
+	procfs_list_add(&shl->procfs_list, srh);
+	shl->size++;
+
+	spa_read_history_truncate(shl, zfs_read_history);
+
+	mutex_exit(&shl->procfs_list.pl_lock);
+}
+
+/*
+ * ==========================================================================
+ * SPA TXG History Routines
+ * ==========================================================================
+ */
+
+/*
+ * Txg statistics - Information exported regarding each txg sync
+ */
+
+typedef struct spa_txg_history {
+	uint64_t	txg;		/* txg id */
+	txg_state_t	state;		/* active txg state */
+	uint64_t	nread;		/* number of bytes read */
+	uint64_t	nwritten;	/* number of bytes written */
+	uint64_t	reads;		/* number of read operations */
+	uint64_t	writes;		/* number of write operations */
+	uint64_t	ndirty;		/* number of dirty bytes */
+	hrtime_t	times[TXG_STATE_COMMITTED]; /* completion times */
+	procfs_list_node_t	sth_node;
+} spa_txg_history_t;
+
+static int
+spa_txg_history_show_header(struct seq_file *f)
+{
+	seq_printf(f, "%-8s %-16s %-5s %-12s %-12s %-12s "
+	    "%-8s %-8s %-12s %-12s %-12s %-12s\n", "txg", "birth", "state",
+	    "ndirty", "nread", "nwritten", "reads", "writes",
+	    "otime", "qtime", "wtime", "stime");
+	return (0);
+}
+
+static int
+spa_txg_history_show(struct seq_file *f, void *data)
+{
+	spa_txg_history_t *sth = (spa_txg_history_t *)data;
+	uint64_t open = 0, quiesce = 0, wait = 0, sync = 0;
+	char state;
+
+	switch (sth->state) {
+		case TXG_STATE_BIRTH:		state = 'B';	break;
+		case TXG_STATE_OPEN:		state = 'O';	break;
+		case TXG_STATE_QUIESCED:	state = 'Q';	break;
+		case TXG_STATE_WAIT_FOR_SYNC:	state = 'W';	break;
+		case TXG_STATE_SYNCED:		state = 'S';	break;
+		case TXG_STATE_COMMITTED:	state = 'C';	break;
+		default:			state = '?';	break;
+	}
+
+	if (sth->times[TXG_STATE_OPEN])
+		open = sth->times[TXG_STATE_OPEN] -
+		    sth->times[TXG_STATE_BIRTH];
+
+	if (sth->times[TXG_STATE_QUIESCED])
+		quiesce = sth->times[TXG_STATE_QUIESCED] -
+		    sth->times[TXG_STATE_OPEN];
+
+	if (sth->times[TXG_STATE_WAIT_FOR_SYNC])
+		wait = sth->times[TXG_STATE_WAIT_FOR_SYNC] -
+		    sth->times[TXG_STATE_QUIESCED];
+
+	if (sth->times[TXG_STATE_SYNCED])
+		sync = sth->times[TXG_STATE_SYNCED] -
+		    sth->times[TXG_STATE_WAIT_FOR_SYNC];
+
+	seq_printf(f, "%-8llu %-16llu %-5c %-12llu "
+	    "%-12llu %-12llu %-8llu %-8llu %-12llu %-12llu %-12llu %-12llu\n",
+	    (longlong_t)sth->txg, sth->times[TXG_STATE_BIRTH], state,
+	    (u_longlong_t)sth->ndirty,
+	    (u_longlong_t)sth->nread, (u_longlong_t)sth->nwritten,
+	    (u_longlong_t)sth->reads, (u_longlong_t)sth->writes,
+	    (u_longlong_t)open, (u_longlong_t)quiesce, (u_longlong_t)wait,
+	    (u_longlong_t)sync);
+
+	return (0);
+}
+
+/* Remove oldest elements from list until there are no more than 'size' left */
+static void
+spa_txg_history_truncate(spa_history_list_t *shl, unsigned int size)
+{
+	spa_txg_history_t *sth;
+	while (shl->size > size) {
+		sth = list_remove_head(&shl->procfs_list.pl_list);
+		ASSERT3P(sth, !=, NULL);
+		kmem_free(sth, sizeof (spa_txg_history_t));
+		shl->size--;
+	}
+
+	if (size == 0)
+		ASSERT(list_is_empty(&shl->procfs_list.pl_list));
+
+}
+
+static int
+spa_txg_history_clear(procfs_list_t *procfs_list)
+{
+	spa_history_list_t *shl = procfs_list->pl_private;
+	mutex_enter(&procfs_list->pl_lock);
+	spa_txg_history_truncate(shl, 0);
+	mutex_exit(&procfs_list->pl_lock);
+	return (0);
+}
+
+static void
+spa_txg_history_init(spa_t *spa)
+{
+	spa_history_list_t *shl = &spa->spa_stats.txg_history;
+	char *module;
+
+	shl->size = 0;
+
+	module = kmem_asprintf("zfs/%s", spa_name(spa));
+
+	shl->procfs_list.pl_private = shl;
+	procfs_list_install(module,
+	    "txgs",
+	    0644,
+	    &shl->procfs_list,
+	    spa_txg_history_show,
+	    spa_txg_history_show_header,
+	    spa_txg_history_clear,
+	    offsetof(spa_txg_history_t, sth_node));
+
+	strfree(module);
+}
+
+static void
+spa_txg_history_destroy(spa_t *spa)
+{
+	spa_history_list_t *shl = &spa->spa_stats.txg_history;
+	procfs_list_uninstall(&shl->procfs_list);
+	spa_txg_history_truncate(shl, 0);
+	procfs_list_destroy(&shl->procfs_list);
+}
+
+/*
+ * Add a new txg to historical record.
+ */
+void
+spa_txg_history_add(spa_t *spa, uint64_t txg, hrtime_t birth_time)
+{
+	spa_history_list_t *shl = &spa->spa_stats.txg_history;
+	spa_txg_history_t *sth;
+
+	if (zfs_txg_history == 0 && shl->size == 0)
+		return;
+
+	sth = kmem_zalloc(sizeof (spa_txg_history_t), KM_SLEEP);
+	sth->txg = txg;
+	sth->state = TXG_STATE_OPEN;
+	sth->times[TXG_STATE_BIRTH] = birth_time;
+
+	mutex_enter(&shl->procfs_list.pl_lock);
+	procfs_list_add(&shl->procfs_list, sth);
+	shl->size++;
+	spa_txg_history_truncate(shl, zfs_txg_history);
+	mutex_exit(&shl->procfs_list.pl_lock);
+}
+
+/*
+ * Set txg state completion time and increment current state.
+ */
+int
+spa_txg_history_set(spa_t *spa, uint64_t txg, txg_state_t completed_state,
+    hrtime_t completed_time)
+{
+	spa_history_list_t *shl = &spa->spa_stats.txg_history;
+	spa_txg_history_t *sth;
+	int error = ENOENT;
+
+	if (zfs_txg_history == 0)
+		return (0);
+
+	mutex_enter(&shl->procfs_list.pl_lock);
+	for (sth = list_tail(&shl->procfs_list.pl_list); sth != NULL;
+	    sth = list_prev(&shl->procfs_list.pl_list, sth)) {
+		if (sth->txg == txg) {
+			sth->times[completed_state] = completed_time;
+			sth->state++;
+			error = 0;
+			break;
+		}
+	}
+	mutex_exit(&shl->procfs_list.pl_lock);
+
+	return (error);
+}
+
+/*
+ * Set txg IO stats.
+ */
+static int
+spa_txg_history_set_io(spa_t *spa, uint64_t txg, uint64_t nread,
+    uint64_t nwritten, uint64_t reads, uint64_t writes, uint64_t ndirty)
+{
+	spa_history_list_t *shl = &spa->spa_stats.txg_history;
+	spa_txg_history_t *sth;
+	int error = ENOENT;
+
+	if (zfs_txg_history == 0)
+		return (0);
+
+	mutex_enter(&shl->procfs_list.pl_lock);
+	for (sth = list_tail(&shl->procfs_list.pl_list); sth != NULL;
+	    sth = list_prev(&shl->procfs_list.pl_list, sth)) {
+		if (sth->txg == txg) {
+			sth->nread = nread;
+			sth->nwritten = nwritten;
+			sth->reads = reads;
+			sth->writes = writes;
+			sth->ndirty = ndirty;
+			error = 0;
+			break;
+		}
+	}
+	mutex_exit(&shl->procfs_list.pl_lock);
+
+	return (error);
+}
+
+txg_stat_t *
+spa_txg_history_init_io(spa_t *spa, uint64_t txg, dsl_pool_t *dp)
+{
+	txg_stat_t *ts;
+
+	if (zfs_txg_history == 0)
+		return (NULL);
+
+	ts = kmem_alloc(sizeof (txg_stat_t), KM_SLEEP);
+
+	spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
+	vdev_get_stats(spa->spa_root_vdev, &ts->vs1);
+	spa_config_exit(spa, SCL_CONFIG, FTAG);
+
+	ts->txg = txg;
+	ts->ndirty = dp->dp_dirty_pertxg[txg & TXG_MASK];
+
+	spa_txg_history_set(spa, txg, TXG_STATE_WAIT_FOR_SYNC, gethrtime());
+
+	return (ts);
+}
+
+void
+spa_txg_history_fini_io(spa_t *spa, txg_stat_t *ts)
+{
+	if (ts == NULL)
+		return;
+
+	if (zfs_txg_history == 0) {
+		kmem_free(ts, sizeof (txg_stat_t));
+		return;
+	}
+
+	spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
+	vdev_get_stats(spa->spa_root_vdev, &ts->vs2);
+	spa_config_exit(spa, SCL_CONFIG, FTAG);
+
+	spa_txg_history_set(spa, ts->txg, TXG_STATE_SYNCED, gethrtime());
+	spa_txg_history_set_io(spa, ts->txg,
+	    ts->vs2.vs_bytes[ZIO_TYPE_READ] - ts->vs1.vs_bytes[ZIO_TYPE_READ],
+	    ts->vs2.vs_bytes[ZIO_TYPE_WRITE] - ts->vs1.vs_bytes[ZIO_TYPE_WRITE],
+	    ts->vs2.vs_ops[ZIO_TYPE_READ] - ts->vs1.vs_ops[ZIO_TYPE_READ],
+	    ts->vs2.vs_ops[ZIO_TYPE_WRITE] - ts->vs1.vs_ops[ZIO_TYPE_WRITE],
+	    ts->ndirty);
+
+	kmem_free(ts, sizeof (txg_stat_t));
+}
+
+/*
+ * ==========================================================================
+ * SPA TX Assign Histogram Routines
+ * ==========================================================================
+ */
+
+/*
+ * Tx statistics - Information exported regarding dmu_tx_assign time.
+ */
+
+/*
+ * When the kstat is written zero all buckets.  When the kstat is read
+ * count the number of trailing buckets set to zero and update ks_ndata
+ * such that they are not output.
+ */
+static int
+spa_tx_assign_update(kstat_t *ksp, int rw)
+{
+	spa_t *spa = ksp->ks_private;
+	spa_history_kstat_t *shk = &spa->spa_stats.tx_assign_histogram;
+	int i;
+
+	if (rw == KSTAT_WRITE) {
+		for (i = 0; i < shk->count; i++)
+			((kstat_named_t *)shk->private)[i].value.ui64 = 0;
+	}
+
+	for (i = shk->count; i > 0; i--)
+		if (((kstat_named_t *)shk->private)[i-1].value.ui64 != 0)
+			break;
+
+	ksp->ks_ndata = i;
+	ksp->ks_data_size = i * sizeof (kstat_named_t);
+
+	return (0);
+}
+
+static void
+spa_tx_assign_init(spa_t *spa)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.tx_assign_histogram;
+	char *name;
+	kstat_named_t *ks;
+	kstat_t *ksp;
+	int i;
+
+	mutex_init(&shk->lock, NULL, MUTEX_DEFAULT, NULL);
+
+	shk->count = 42; /* power of two buckets for 1ns to 2,199s */
+	shk->size = shk->count * sizeof (kstat_named_t);
+	shk->private = kmem_alloc(shk->size, KM_SLEEP);
+
+	name = kmem_asprintf("zfs/%s", spa_name(spa));
+
+	for (i = 0; i < shk->count; i++) {
+		ks = &((kstat_named_t *)shk->private)[i];
+		ks->data_type = KSTAT_DATA_UINT64;
+		ks->value.ui64 = 0;
+		(void) snprintf(ks->name, KSTAT_STRLEN, "%llu ns",
+		    (u_longlong_t)1 << i);
+	}
+
+	ksp = kstat_create(name, 0, "dmu_tx_assign", "misc",
+	    KSTAT_TYPE_NAMED, 0, KSTAT_FLAG_VIRTUAL);
+	shk->kstat = ksp;
+
+	if (ksp) {
+		ksp->ks_lock = &shk->lock;
+		ksp->ks_data = shk->private;
+		ksp->ks_ndata = shk->count;
+		ksp->ks_data_size = shk->size;
+		ksp->ks_private = spa;
+		ksp->ks_update = spa_tx_assign_update;
+		kstat_install(ksp);
+	}
+	strfree(name);
+}
+
+static void
+spa_tx_assign_destroy(spa_t *spa)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.tx_assign_histogram;
+	kstat_t *ksp;
+
+	ksp = shk->kstat;
+	if (ksp)
+		kstat_delete(ksp);
+
+	kmem_free(shk->private, shk->size);
+	mutex_destroy(&shk->lock);
+}
+
+void
+spa_tx_assign_add_nsecs(spa_t *spa, uint64_t nsecs)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.tx_assign_histogram;
+	uint64_t idx = 0;
+
+	while (((1ULL << idx) < nsecs) && (idx < shk->size - 1))
+		idx++;
+
+	atomic_inc_64(&((kstat_named_t *)shk->private)[idx].value.ui64);
+}
+
+/*
+ * ==========================================================================
+ * SPA IO History Routines
+ * ==========================================================================
+ */
+static int
+spa_io_history_update(kstat_t *ksp, int rw)
+{
+	if (rw == KSTAT_WRITE)
+		memset(ksp->ks_data, 0, ksp->ks_data_size);
+
+	return (0);
+}
+
+static void
+spa_io_history_init(spa_t *spa)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.io_history;
+	char *name;
+	kstat_t *ksp;
+
+	mutex_init(&shk->lock, NULL, MUTEX_DEFAULT, NULL);
+
+	name = kmem_asprintf("zfs/%s", spa_name(spa));
+
+	ksp = kstat_create(name, 0, "io", "disk", KSTAT_TYPE_IO, 1, 0);
+	shk->kstat = ksp;
+
+	if (ksp) {
+		ksp->ks_lock = &shk->lock;
+		ksp->ks_private = spa;
+		ksp->ks_update = spa_io_history_update;
+		kstat_install(ksp);
+	}
+	strfree(name);
+}
+
+static void
+spa_io_history_destroy(spa_t *spa)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.io_history;
+
+	if (shk->kstat)
+		kstat_delete(shk->kstat);
+
+	mutex_destroy(&shk->lock);
+}
+
+/*
+ * ==========================================================================
+ * SPA MMP History Routines
+ * ==========================================================================
+ */
+
+/*
+ * MMP statistics - Information exported regarding attempted MMP writes
+ *   For MMP writes issued, fields used as per comments below.
+ *   For MMP writes skipped, an entry represents a span of time when
+ *      writes were skipped for same reason (error from mmp_random_leaf).
+ *      Differences are:
+ *      timestamp	time first write skipped, if >1 skipped in a row
+ *      mmp_delay	delay value at timestamp
+ *      vdev_guid	number of writes skipped
+ *      io_error	one of enum mmp_error
+ *      duration	time span (ns) of skipped writes
+ */
+
+typedef struct spa_mmp_history {
+	uint64_t	mmp_node_id;	/* unique # for updates */
+	uint64_t	txg;		/* txg of last sync */
+	uint64_t	timestamp;	/* UTC time MMP write issued */
+	uint64_t	mmp_delay;	/* mmp_thread.mmp_delay at timestamp */
+	uint64_t	vdev_guid;	/* unique ID of leaf vdev */
+	char		*vdev_path;
+	int		vdev_label;	/* vdev label */
+	int		io_error;	/* error status of MMP write */
+	hrtime_t	error_start;	/* hrtime of start of error period */
+	hrtime_t	duration;	/* time from submission to completion */
+	procfs_list_node_t	smh_node;
+} spa_mmp_history_t;
+
+static int
+spa_mmp_history_show_header(struct seq_file *f)
+{
+	seq_printf(f, "%-10s %-10s %-10s %-6s %-10s %-12s %-24s "
+	    "%-10s %s\n", "id", "txg", "timestamp", "error", "duration",
+	    "mmp_delay", "vdev_guid", "vdev_label", "vdev_path");
+	return (0);
+}
+
+static int
+spa_mmp_history_show(struct seq_file *f, void *data)
+{
+	spa_mmp_history_t *smh = (spa_mmp_history_t *)data;
+	char skip_fmt[] = "%-10llu %-10llu %10llu %#6llx %10lld %12llu %-24llu "
+	    "%-10lld %s\n";
+	char write_fmt[] = "%-10llu %-10llu %10llu %6lld %10lld %12llu %-24llu "
+	    "%-10lld %s\n";
+
+	seq_printf(f, (smh->error_start ? skip_fmt : write_fmt),
+	    (u_longlong_t)smh->mmp_node_id, (u_longlong_t)smh->txg,
+	    (u_longlong_t)smh->timestamp, (longlong_t)smh->io_error,
+	    (longlong_t)smh->duration, (u_longlong_t)smh->mmp_delay,
+	    (u_longlong_t)smh->vdev_guid, (u_longlong_t)smh->vdev_label,
+	    (smh->vdev_path ? smh->vdev_path : "-"));
+
+	return (0);
+}
+
+/* Remove oldest elements from list until there are no more than 'size' left */
+static void
+spa_mmp_history_truncate(spa_history_list_t *shl, unsigned int size)
+{
+	spa_mmp_history_t *smh;
+	while (shl->size > size) {
+		smh = list_remove_head(&shl->procfs_list.pl_list);
+		if (smh->vdev_path)
+			strfree(smh->vdev_path);
+		kmem_free(smh, sizeof (spa_mmp_history_t));
+		shl->size--;
+	}
+
+	if (size == 0)
+		ASSERT(list_is_empty(&shl->procfs_list.pl_list));
+
+}
+
+static int
+spa_mmp_history_clear(procfs_list_t *procfs_list)
+{
+	spa_history_list_t *shl = procfs_list->pl_private;
+	mutex_enter(&procfs_list->pl_lock);
+	spa_mmp_history_truncate(shl, 0);
+	mutex_exit(&procfs_list->pl_lock);
+	return (0);
+}
+
+static void
+spa_mmp_history_init(spa_t *spa)
+{
+	spa_history_list_t *shl = &spa->spa_stats.mmp_history;
+	char *module;
+
+	shl->size = 0;
+
+	module = kmem_asprintf("zfs/%s", spa_name(spa));
+
+	shl->procfs_list.pl_private = shl;
+	procfs_list_install(module,
+	    "multihost",
+	    0644,
+	    &shl->procfs_list,
+	    spa_mmp_history_show,
+	    spa_mmp_history_show_header,
+	    spa_mmp_history_clear,
+	    offsetof(spa_mmp_history_t, smh_node));
+
+	strfree(module);
+}
+
+static void
+spa_mmp_history_destroy(spa_t *spa)
+{
+	spa_history_list_t *shl = &spa->spa_stats.mmp_history;
+	procfs_list_uninstall(&shl->procfs_list);
+	spa_mmp_history_truncate(shl, 0);
+	procfs_list_destroy(&shl->procfs_list);
+}
+
+/*
+ * Set duration in existing "skip" record to how long we have waited for a leaf
+ * vdev to become available.
+ *
+ * Important that we start search at the tail of the list where new
+ * records are inserted, so this is normally an O(1) operation.
+ */
+int
+spa_mmp_history_set_skip(spa_t *spa, uint64_t mmp_node_id)
+{
+	spa_history_list_t *shl = &spa->spa_stats.mmp_history;
+	spa_mmp_history_t *smh;
+	int error = ENOENT;
+
+	if (zfs_multihost_history == 0 && shl->size == 0)
+		return (0);
+
+	mutex_enter(&shl->procfs_list.pl_lock);
+	for (smh = list_tail(&shl->procfs_list.pl_list); smh != NULL;
+	    smh = list_prev(&shl->procfs_list.pl_list, smh)) {
+		if (smh->mmp_node_id == mmp_node_id) {
+			ASSERT3U(smh->io_error, !=, 0);
+			smh->duration = gethrtime() - smh->error_start;
+			smh->vdev_guid++;
+			error = 0;
+			break;
+		}
+	}
+	mutex_exit(&shl->procfs_list.pl_lock);
+
+	return (error);
+}
+
+/*
+ * Set MMP write duration and error status in existing record.
+ * See comment re: search order above spa_mmp_history_set_skip().
+ */
+int
+spa_mmp_history_set(spa_t *spa, uint64_t mmp_node_id, int io_error,
+    hrtime_t duration)
+{
+	spa_history_list_t *shl = &spa->spa_stats.mmp_history;
+	spa_mmp_history_t *smh;
+	int error = ENOENT;
+
+	if (zfs_multihost_history == 0 && shl->size == 0)
+		return (0);
+
+	mutex_enter(&shl->procfs_list.pl_lock);
+	for (smh = list_tail(&shl->procfs_list.pl_list); smh != NULL;
+	    smh = list_prev(&shl->procfs_list.pl_list, smh)) {
+		if (smh->mmp_node_id == mmp_node_id) {
+			ASSERT(smh->io_error == 0);
+			smh->io_error = io_error;
+			smh->duration = duration;
+			error = 0;
+			break;
+		}
+	}
+	mutex_exit(&shl->procfs_list.pl_lock);
+
+	return (error);
+}
+
+/*
+ * Add a new MMP historical record.
+ * error == 0 : a write was issued.
+ * error != 0 : a write was not issued because no leaves were found.
+ */
+void
+spa_mmp_history_add(spa_t *spa, uint64_t txg, uint64_t timestamp,
+    uint64_t mmp_delay, vdev_t *vd, int label, uint64_t mmp_node_id,
+    int error)
+{
+	spa_history_list_t *shl = &spa->spa_stats.mmp_history;
+	spa_mmp_history_t *smh;
+
+	if (zfs_multihost_history == 0 && shl->size == 0)
+		return;
+
+	smh = kmem_zalloc(sizeof (spa_mmp_history_t), KM_SLEEP);
+	smh->txg = txg;
+	smh->timestamp = timestamp;
+	smh->mmp_delay = mmp_delay;
+	if (vd) {
+		smh->vdev_guid = vd->vdev_guid;
+		if (vd->vdev_path)
+			smh->vdev_path = strdup(vd->vdev_path);
+	}
+	smh->vdev_label = label;
+	smh->mmp_node_id = mmp_node_id;
+
+	if (error) {
+		smh->io_error = error;
+		smh->error_start = gethrtime();
+		smh->vdev_guid = 1;
+	}
+
+	mutex_enter(&shl->procfs_list.pl_lock);
+	procfs_list_add(&shl->procfs_list, smh);
+	shl->size++;
+	spa_mmp_history_truncate(shl, zfs_multihost_history);
+	mutex_exit(&shl->procfs_list.pl_lock);
+}
+
+static void *
+spa_state_addr(kstat_t *ksp, loff_t n)
+{
+	return (ksp->ks_private);	/* return the spa_t */
+}
+
+static int
+spa_state_data(char *buf, size_t size, void *data)
+{
+	spa_t *spa = (spa_t *)data;
+	(void) snprintf(buf, size, "%s\n", spa_state_to_name(spa));
+	return (0);
+}
+
+/*
+ * Return the state of the pool in /proc/spl/kstat/zfs/<pool>/state.
+ *
+ * This is a lock-less read of the pool's state (unlike using 'zpool', which
+ * can potentially block for seconds).  Because it doesn't block, it can useful
+ * as a pool heartbeat value.
+ */
+static void
+spa_state_init(spa_t *spa)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.state;
+	char *name;
+	kstat_t *ksp;
+
+	mutex_init(&shk->lock, NULL, MUTEX_DEFAULT, NULL);
+
+	name = kmem_asprintf("zfs/%s", spa_name(spa));
+	ksp = kstat_create(name, 0, "state", "misc",
+	    KSTAT_TYPE_RAW, 0, KSTAT_FLAG_VIRTUAL);
+
+	shk->kstat = ksp;
+	if (ksp) {
+		ksp->ks_lock = &shk->lock;
+		ksp->ks_data = NULL;
+		ksp->ks_private = spa;
+		ksp->ks_flags |= KSTAT_FLAG_NO_HEADERS;
+		kstat_set_raw_ops(ksp, NULL, spa_state_data, spa_state_addr);
+		kstat_install(ksp);
+	}
+
+	strfree(name);
+}
+
+static void
+spa_health_destroy(spa_t *spa)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.state;
+	kstat_t *ksp = shk->kstat;
+	if (ksp)
+		kstat_delete(ksp);
+
+	mutex_destroy(&shk->lock);
+}
+
+static spa_iostats_t spa_iostats_template = {
+	{ "trim_extents_written",		KSTAT_DATA_UINT64 },
+	{ "trim_bytes_written",			KSTAT_DATA_UINT64 },
+	{ "trim_extents_skipped",		KSTAT_DATA_UINT64 },
+	{ "trim_bytes_skipped",			KSTAT_DATA_UINT64 },
+	{ "trim_extents_failed",		KSTAT_DATA_UINT64 },
+	{ "trim_bytes_failed",			KSTAT_DATA_UINT64 },
+	{ "autotrim_extents_written",		KSTAT_DATA_UINT64 },
+	{ "autotrim_bytes_written",		KSTAT_DATA_UINT64 },
+	{ "autotrim_extents_skipped",		KSTAT_DATA_UINT64 },
+	{ "autotrim_bytes_skipped",		KSTAT_DATA_UINT64 },
+	{ "autotrim_extents_failed",		KSTAT_DATA_UINT64 },
+	{ "autotrim_bytes_failed",		KSTAT_DATA_UINT64 },
+};
+
+#define	SPA_IOSTATS_ADD(stat, val) \
+    atomic_add_64(&iostats->stat.value.ui64, (val));
+
+void
+spa_iostats_trim_add(spa_t *spa, trim_type_t type,
+    uint64_t extents_written, uint64_t bytes_written,
+    uint64_t extents_skipped, uint64_t bytes_skipped,
+    uint64_t extents_failed, uint64_t bytes_failed)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.iostats;
+	kstat_t *ksp = shk->kstat;
+	spa_iostats_t *iostats;
+
+	if (ksp == NULL)
+		return;
+
+	iostats = ksp->ks_data;
+	if (type == TRIM_TYPE_MANUAL) {
+		SPA_IOSTATS_ADD(trim_extents_written, extents_written);
+		SPA_IOSTATS_ADD(trim_bytes_written, bytes_written);
+		SPA_IOSTATS_ADD(trim_extents_skipped, extents_skipped);
+		SPA_IOSTATS_ADD(trim_bytes_skipped, bytes_skipped);
+		SPA_IOSTATS_ADD(trim_extents_failed, extents_failed);
+		SPA_IOSTATS_ADD(trim_bytes_failed, bytes_failed);
+	} else {
+		SPA_IOSTATS_ADD(autotrim_extents_written, extents_written);
+		SPA_IOSTATS_ADD(autotrim_bytes_written, bytes_written);
+		SPA_IOSTATS_ADD(autotrim_extents_skipped, extents_skipped);
+		SPA_IOSTATS_ADD(autotrim_bytes_skipped, bytes_skipped);
+		SPA_IOSTATS_ADD(autotrim_extents_failed, extents_failed);
+		SPA_IOSTATS_ADD(autotrim_bytes_failed, bytes_failed);
+	}
+}
+
+int
+spa_iostats_update(kstat_t *ksp, int rw)
+{
+	if (rw == KSTAT_WRITE) {
+		memcpy(ksp->ks_data, &spa_iostats_template,
+		    sizeof (spa_iostats_t));
+	}
+
+	return (0);
+}
+
+static void
+spa_iostats_init(spa_t *spa)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.iostats;
+
+	mutex_init(&shk->lock, NULL, MUTEX_DEFAULT, NULL);
+
+	char *name = kmem_asprintf("zfs/%s", spa_name(spa));
+	kstat_t *ksp = kstat_create(name, 0, "iostats", "misc",
+	    KSTAT_TYPE_NAMED, sizeof (spa_iostats_t) / sizeof (kstat_named_t),
+	    KSTAT_FLAG_VIRTUAL);
+
+	shk->kstat = ksp;
+	if (ksp) {
+		int size = sizeof (spa_iostats_t);
+		ksp->ks_lock = &shk->lock;
+		ksp->ks_private = spa;
+		ksp->ks_update = spa_iostats_update;
+		ksp->ks_data = kmem_alloc(size, KM_SLEEP);
+		memcpy(ksp->ks_data, &spa_iostats_template, size);
+		kstat_install(ksp);
+	}
+
+	strfree(name);
+}
+
+static void
+spa_iostats_destroy(spa_t *spa)
+{
+	spa_history_kstat_t *shk = &spa->spa_stats.iostats;
+	kstat_t *ksp = shk->kstat;
+	if (ksp) {
+		kmem_free(ksp->ks_data, sizeof (spa_iostats_t));
+		kstat_delete(ksp);
+	}
+
+	mutex_destroy(&shk->lock);
+}
+
+void
+spa_stats_init(spa_t *spa)
+{
+	spa_read_history_init(spa);
+	spa_txg_history_init(spa);
+	spa_tx_assign_init(spa);
+	spa_io_history_init(spa);
+	spa_mmp_history_init(spa);
+	spa_state_init(spa);
+	spa_iostats_init(spa);
+}
+
+void
+spa_stats_destroy(spa_t *spa)
+{
+	spa_iostats_destroy(spa);
+	spa_health_destroy(spa);
+	spa_tx_assign_destroy(spa);
+	spa_txg_history_destroy(spa);
+	spa_read_history_destroy(spa);
+	spa_io_history_destroy(spa);
+	spa_mmp_history_destroy(spa);
+}
+
+#if defined(_KERNEL)
+/* CSTYLED */
+module_param(zfs_read_history, int, 0644);
+MODULE_PARM_DESC(zfs_read_history,
+	"Historical statistics for the last N reads");
+
+module_param(zfs_read_history_hits, int, 0644);
+MODULE_PARM_DESC(zfs_read_history_hits,
+	"Include cache hits in read history");
+
+module_param(zfs_txg_history, int, 0644);
+MODULE_PARM_DESC(zfs_txg_history,
+	"Historical statistics for the last N txgs");
+
+module_param(zfs_multihost_history, int, 0644);
+MODULE_PARM_DESC(zfs_multihost_history,
+	"Historical statistics for last N multihost writes");
+/* END CSTYLED */
+#endif