Prepare SPL repo to merge with ZFS repo

This commit removes everything from the repository except the core
SPL implementation for Linux.  Those files which remain have been
moved to non-conflicting locations to facilitate the merge.
The README.md and associated files have been updated accordingly.

Signed-off-by: Brian Behlendorf <[email protected]>

1 files changed, 109 insertions, 0 deletions

diff --git a/include/spl/sys/vmem.h b/include/spl/sys/vmem.h
new file mode 100644
index 000000000..a9b12eeb9
--- /dev/null
+++ b/include/spl/sys/vmem.h
@@ -0,0 +1,109 @@
+/*
+ *  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/>.
+ */
+
+#ifndef _SPL_VMEM_H
+#define	_SPL_VMEM_H
+
+#include <sys/kmem.h>
+#include <linux/sched.h>
+#include <linux/vmalloc.h>
+
+typedef struct vmem { } vmem_t;
+
+extern vmem_t *heap_arena;
+extern vmem_t *zio_alloc_arena;
+extern vmem_t *zio_arena;
+
+extern size_t vmem_size(vmem_t *vmp, int typemask);
+
+/*
+ * Memory allocation interfaces
+ */
+#define	VMEM_ALLOC	0x01
+#define	VMEM_FREE	0x02
+
+#ifndef VMALLOC_TOTAL
+#define	VMALLOC_TOTAL	(VMALLOC_END - VMALLOC_START)
+#endif
+
+/*
+ * vmem_* is an interface to a low level arena-based memory allocator on
+ * Illumos that is used to allocate virtual address space. The kmem SLAB
+ * allocator allocates slabs from it. Then the generic allocation functions
+ * kmem_{alloc,zalloc,free}() are layered on top of SLAB allocators.
+ *
+ * On Linux, the primary means of doing allocations is via kmalloc(), which
+ * is similarly layered on top of something called the buddy allocator. The
+ * buddy allocator is not available to kernel modules, it uses physical
+ * memory addresses rather than virtual memory addresses and is prone to
+ * fragmentation.
+ *
+ * Linux sets aside a relatively small address space for in-kernel virtual
+ * memory from which allocations can be done using vmalloc().  It might seem
+ * like a good idea to use vmalloc() to implement something similar to
+ * Illumos' allocator. However, this has the following problems:
+ *
+ * 1. Page directory table allocations are hard coded to use GFP_KERNEL.
+ *    Consequently, any KM_PUSHPAGE or KM_NOSLEEP allocations done using
+ *    vmalloc() will not have proper semantics.
+ *
+ * 2. Address space exhaustion is a real issue on 32-bit platforms where
+ *    only a few 100MB are available. The kernel will handle it by spinning
+ *    when it runs out of address space.
+ *
+ * 3. All vmalloc() allocations and frees are protected by a single global
+ *    lock which serializes all allocations.
+ *
+ * 4. Accessing /proc/meminfo and /proc/vmallocinfo will iterate the entire
+ *    list. The former will sum the allocations while the latter will print
+ *    them to user space in a way that user space can keep the lock held
+ *    indefinitely.  When the total number of mapped allocations is large
+ *    (several 100,000) a large amount of time will be spent waiting on locks.
+ *
+ * 5. Linux has a wait_on_bit() locking primitive that assumes physical
+ *    memory is used, it simply does not work on virtual memory.  Certain
+ *    Linux structures (e.g. the superblock) use them and might be embedded
+ *    into a structure from Illumos.  This makes using Linux virtual memory
+ *    unsafe in certain situations.
+ *
+ * It follows that we cannot obtain identical semantics to those on Illumos.
+ * Consequently, we implement the kmem_{alloc,zalloc,free}() functions in
+ * such a way that they can be used as drop-in replacements for small vmem_*
+ * allocations (8MB in size or smaller) and map vmem_{alloc,zalloc,free}()
+ * to them.
+ */
+
+#define	vmem_alloc(sz, fl)	spl_vmem_alloc((sz), (fl), __func__, __LINE__)
+#define	vmem_zalloc(sz, fl)	spl_vmem_zalloc((sz), (fl), __func__, __LINE__)
+#define	vmem_free(ptr, sz)	spl_vmem_free((ptr), (sz))
+#define	vmem_qcache_reap(ptr)	((void)0)
+
+extern void *spl_vmem_alloc(size_t sz, int fl, const char *func, int line);
+extern void *spl_vmem_zalloc(size_t sz, int fl, const char *func, int line);
+extern void spl_vmem_free(const void *ptr, size_t sz);
+
+int spl_vmem_init(void);
+void spl_vmem_fini(void);
+
+#endif	/* _SPL_VMEM_H */