[net-next-2.6.git] / fs / btrfs / zlib.c

/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program 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 this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 *
 * Based on jffs2 zlib code:
 * Copyright © 2001-2007 Red Hat, Inc.
 * Created by David Woodhouse <dwmw2@infradead.org>
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/zlib.h>
#include <linux/zutil.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/bio.h>
#include "compression.h"

/* Plan: call deflate() with avail_in == *sourcelen,
	avail_out = *dstlen - 12 and flush == Z_FINISH.
	If it doesn't manage to finish,	call it again with
	avail_in == 0 and avail_out set to the remaining 12
	bytes for it to clean up.
   Q: Is 12 bytes sufficient?
*/
#define STREAM_END_SPACE 12

struct workspace {
	z_stream inf_strm;
	z_stream def_strm;
	char *buf;
	struct list_head list;
};

static LIST_HEAD(idle_workspace);
static DEFINE_SPINLOCK(workspace_lock);
static unsigned long num_workspace;
static atomic_t alloc_workspace = ATOMIC_INIT(0);
static DECLARE_WAIT_QUEUE_HEAD(workspace_wait);

/*
 * this finds an available zlib workspace or allocates a new one
 * NULL or an ERR_PTR is returned if things go bad.
 */
static struct workspace *find_zlib_workspace(void)
{
	struct workspace *workspace;
	int ret;
	int cpus = num_online_cpus();

again:
	spin_lock(&workspace_lock);
	if (!list_empty(&idle_workspace)) {
		workspace = list_entry(idle_workspace.next, struct workspace,
				       list);
		list_del(&workspace->list);
		num_workspace--;
		spin_unlock(&workspace_lock);
		return workspace;

	}
	spin_unlock(&workspace_lock);
	if (atomic_read(&alloc_workspace) > cpus) {
		DEFINE_WAIT(wait);
		prepare_to_wait(&workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
		if (atomic_read(&alloc_workspace) > cpus)
			schedule();
		finish_wait(&workspace_wait, &wait);
		goto again;
	}
	atomic_inc(&alloc_workspace);
	workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
	if (!workspace) {
		ret = -ENOMEM;
		goto fail;
	}

	workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize());
	if (!workspace->def_strm.workspace) {
		ret = -ENOMEM;
		goto fail;
	}
	workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
	if (!workspace->inf_strm.workspace) {
		ret = -ENOMEM;
		goto fail_inflate;
	}
	workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS);
	if (!workspace->buf) {
		ret = -ENOMEM;
		goto fail_kmalloc;
	}
	return workspace;

fail_kmalloc:
	vfree(workspace->inf_strm.workspace);
fail_inflate:
	vfree(workspace->def_strm.workspace);
fail:
	kfree(workspace);
	atomic_dec(&alloc_workspace);
	wake_up(&workspace_wait);
	return ERR_PTR(ret);
}

/*
 * put a workspace struct back on the list or free it if we have enough
 * idle ones sitting around
 */
static int free_workspace(struct workspace *workspace)
{
	spin_lock(&workspace_lock);
	if (num_workspace < num_online_cpus()) {
		list_add_tail(&workspace->list, &idle_workspace);
		num_workspace++;
		spin_unlock(&workspace_lock);
		if (waitqueue_active(&workspace_wait))
			wake_up(&workspace_wait);
		return 0;
	}
	spin_unlock(&workspace_lock);
	vfree(workspace->def_strm.workspace);
	vfree(workspace->inf_strm.workspace);
	kfree(workspace->buf);
	kfree(workspace);

	atomic_dec(&alloc_workspace);
	if (waitqueue_active(&workspace_wait))
		wake_up(&workspace_wait);
	return 0;
}

/*
 * cleanup function for module exit
 */
static void free_workspaces(void)
{
	struct workspace *workspace;
	while (!list_empty(&idle_workspace)) {
		workspace = list_entry(idle_workspace.next, struct workspace,
				       list);
		list_del(&workspace->list);
		vfree(workspace->def_strm.workspace);
		vfree(workspace->inf_strm.workspace);
		kfree(workspace->buf);
		kfree(workspace);
		atomic_dec(&alloc_workspace);
	}
}

/*
 * given an address space and start/len, compress the bytes.
 *
 * pages are allocated to hold the compressed result and stored
 * in 'pages'
 *
 * out_pages is used to return the number of pages allocated.  There
 * may be pages allocated even if we return an error
 *
 * total_in is used to return the number of bytes actually read.  It
 * may be smaller then len if we had to exit early because we
 * ran out of room in the pages array or because we cross the
 * max_out threshold.
 *
 * total_out is used to return the total number of compressed bytes
 *
 * max_out tells us the max number of bytes that we're allowed to
 * stuff into pages
 */
int btrfs_zlib_compress_pages(struct address_space *mapping,
			      u64 start, unsigned long len,
			      struct page **pages,
			      unsigned long nr_dest_pages,
			      unsigned long *out_pages,
			      unsigned long *total_in,
			      unsigned long *total_out,
			      unsigned long max_out)
{
	int ret;
	struct workspace *workspace;
	char *data_in;
	char *cpage_out;
	int nr_pages = 0;
	struct page *in_page = NULL;
	struct page *out_page = NULL;
	unsigned long bytes_left;

	*out_pages = 0;
	*total_out = 0;
	*total_in = 0;

	workspace = find_zlib_workspace();
	if (IS_ERR(workspace))
		return -1;

	if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
		printk(KERN_WARNING "deflateInit failed\n");
		ret = -1;
		goto out;
	}

	workspace->def_strm.total_in = 0;
	workspace->def_strm.total_out = 0;

	in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
	data_in = kmap(in_page);

	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
	cpage_out = kmap(out_page);
	pages[0] = out_page;
	nr_pages = 1;

	workspace->def_strm.next_in = data_in;
	workspace->def_strm.next_out = cpage_out;
	workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
	workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE);

	while (workspace->def_strm.total_in < len) {
		ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH);
		if (ret != Z_OK) {
			printk(KERN_DEBUG "btrfs deflate in loop returned %d\n",
			       ret);
			zlib_deflateEnd(&workspace->def_strm);
			ret = -1;
			goto out;
		}

		/* we're making it bigger, give up */
		if (workspace->def_strm.total_in > 8192 &&
		    workspace->def_strm.total_in <
		    workspace->def_strm.total_out) {
			ret = -1;
			goto out;
		}
		/* we need another page for writing out.  Test this
		 * before the total_in so we will pull in a new page for
		 * the stream end if required
		 */
		if (workspace->def_strm.avail_out == 0) {
			kunmap(out_page);
			if (nr_pages == nr_dest_pages) {
				out_page = NULL;
				ret = -1;
				goto out;
			}
			out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
			cpage_out = kmap(out_page);
			pages[nr_pages] = out_page;
			nr_pages++;
			workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
			workspace->def_strm.next_out = cpage_out;
		}
		/* we're all done */
		if (workspace->def_strm.total_in >= len)
			break;

		/* we've read in a full page, get a new one */
		if (workspace->def_strm.avail_in == 0) {
			if (workspace->def_strm.total_out > max_out)
				break;

			bytes_left = len - workspace->def_strm.total_in;
			kunmap(in_page);
			page_cache_release(in_page);

			start += PAGE_CACHE_SIZE;
			in_page = find_get_page(mapping,
						start >> PAGE_CACHE_SHIFT);
			data_in = kmap(in_page);
			workspace->def_strm.avail_in = min(bytes_left,
							   PAGE_CACHE_SIZE);
			workspace->def_strm.next_in = data_in;
		}
	}
	workspace->def_strm.avail_in = 0;
	ret = zlib_deflate(&workspace->def_strm, Z_FINISH);
	zlib_deflateEnd(&workspace->def_strm);

	if (ret != Z_STREAM_END) {
		ret = -1;
		goto out;
	}

	if (workspace->def_strm.total_out >= workspace->def_strm.total_in) {
		ret = -1;
		goto out;
	}

	ret = 0;
	*total_out = workspace->def_strm.total_out;
	*total_in = workspace->def_strm.total_in;
out:
	*out_pages = nr_pages;
	if (out_page)
		kunmap(out_page);

	if (in_page) {
		kunmap(in_page);
		page_cache_release(in_page);
	}
	free_workspace(workspace);
	return ret;
}

/*
 * pages_in is an array of pages with compressed data.
 *
 * disk_start is the starting logical offset of this array in the file
 *
 * bvec is a bio_vec of pages from the file that we want to decompress into
 *
 * vcnt is the count of pages in the biovec
 *
 * srclen is the number of bytes in pages_in
 *
 * The basic idea is that we have a bio that was created by readpages.
 * The pages in the bio are for the uncompressed data, and they may not
 * be contiguous.  They all correspond to the range of bytes covered by
 * the compressed extent.
 */
int btrfs_zlib_decompress_biovec(struct page **pages_in,
			      u64 disk_start,
			      struct bio_vec *bvec,
			      int vcnt,
			      size_t srclen)
{
	int ret = 0;
	int wbits = MAX_WBITS;
	struct workspace *workspace;
	char *data_in;
	size_t total_out = 0;
	unsigned long page_bytes_left;
	unsigned long page_in_index = 0;
	unsigned long page_out_index = 0;
	struct page *page_out;
	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
					PAGE_CACHE_SIZE;
	unsigned long buf_start;
	unsigned long buf_offset;
	unsigned long bytes;
	unsigned long working_bytes;
	unsigned long pg_offset;
	unsigned long start_byte;
	unsigned long current_buf_start;
	char *kaddr;

	workspace = find_zlib_workspace();
	if (IS_ERR(workspace))
		return -ENOMEM;

	data_in = kmap(pages_in[page_in_index]);
	workspace->inf_strm.next_in = data_in;
	workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
	workspace->inf_strm.total_in = 0;

	workspace->inf_strm.total_out = 0;
	workspace->inf_strm.next_out = workspace->buf;
	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	page_out = bvec[page_out_index].bv_page;
	page_bytes_left = PAGE_CACHE_SIZE;
	pg_offset = 0;

	/* If it's deflate, and it's got no preset dictionary, then
	   we can tell zlib to skip the adler32 check. */
	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
	    !(((data_in[0]<<8) + data_in[1]) % 31)) {

		wbits = -((data_in[0] >> 4) + 8);
		workspace->inf_strm.next_in += 2;
		workspace->inf_strm.avail_in -= 2;
	}

	if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
		printk(KERN_WARNING "inflateInit failed\n");
		ret = -1;
		goto out;
	}
	while (workspace->inf_strm.total_in < srclen) {
		ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
		if (ret != Z_OK && ret != Z_STREAM_END)
			break;
		/*
		 * buf start is the byte offset we're of the start of
		 * our workspace buffer
		 */
		buf_start = total_out;

		/* total_out is the last byte of the workspace buffer */
		total_out = workspace->inf_strm.total_out;

		working_bytes = total_out - buf_start;

		/*
		 * start byte is the first byte of the page we're currently
		 * copying into relative to the start of the compressed data.
		 */
		start_byte = page_offset(page_out) - disk_start;

		if (working_bytes == 0) {
			/* we didn't make progress in this inflate
			 * call, we're done
			 */
			if (ret != Z_STREAM_END)
				ret = -1;
			break;
		}

		/* we haven't yet hit data corresponding to this page */
		if (total_out <= start_byte)
			goto next;

		/*
		 * the start of the data we care about is offset into
		 * the middle of our working buffer
		 */
		if (total_out > start_byte && buf_start < start_byte) {
			buf_offset = start_byte - buf_start;
			working_bytes -= buf_offset;
		} else {
			buf_offset = 0;
		}
		current_buf_start = buf_start;

		/* copy bytes from the working buffer into the pages */
		while (working_bytes > 0) {
			bytes = min(PAGE_CACHE_SIZE - pg_offset,
				    PAGE_CACHE_SIZE - buf_offset);
			bytes = min(bytes, working_bytes);
			kaddr = kmap_atomic(page_out, KM_USER0);
			memcpy(kaddr + pg_offset, workspace->buf + buf_offset,
			       bytes);
			kunmap_atomic(kaddr, KM_USER0);
			flush_dcache_page(page_out);

			pg_offset += bytes;
			page_bytes_left -= bytes;
			buf_offset += bytes;
			working_bytes -= bytes;
			current_buf_start += bytes;

			/* check if we need to pick another page */
			if (page_bytes_left == 0) {
				page_out_index++;
				if (page_out_index >= vcnt) {
					ret = 0;
					goto done;
				}

				page_out = bvec[page_out_index].bv_page;
				pg_offset = 0;
				page_bytes_left = PAGE_CACHE_SIZE;
				start_byte = page_offset(page_out) - disk_start;

				/*
				 * make sure our new page is covered by this
				 * working buffer
				 */
				if (total_out <= start_byte)
					goto next;

				/* the next page in the biovec might not
				 * be adjacent to the last page, but it
				 * might still be found inside this working
				 * buffer.  bump our offset pointer
				 */
				if (total_out > start_byte &&
				    current_buf_start < start_byte) {
					buf_offset = start_byte - buf_start;
					working_bytes = total_out - start_byte;
					current_buf_start = buf_start +
						buf_offset;
				}
			}
		}
next:
		workspace->inf_strm.next_out = workspace->buf;
		workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;

		if (workspace->inf_strm.avail_in == 0) {
			unsigned long tmp;
			kunmap(pages_in[page_in_index]);
			page_in_index++;
			if (page_in_index >= total_pages_in) {
				data_in = NULL;
				break;
			}
			data_in = kmap(pages_in[page_in_index]);
			workspace->inf_strm.next_in = data_in;
			tmp = srclen - workspace->inf_strm.total_in;
			workspace->inf_strm.avail_in = min(tmp,
							   PAGE_CACHE_SIZE);
		}
	}
	if (ret != Z_STREAM_END)
		ret = -1;
	else
		ret = 0;
done:
	zlib_inflateEnd(&workspace->inf_strm);
	if (data_in)
		kunmap(pages_in[page_in_index]);
out:
	free_workspace(workspace);
	return ret;
}

/*
 * a less complex decompression routine.  Our compressed data fits in a
 * single page, and we want to read a single page out of it.
 * start_byte tells us the offset into the compressed data we're interested in
 */
int btrfs_zlib_decompress(unsigned char *data_in,
			  struct page *dest_page,
			  unsigned long start_byte,
			  size_t srclen, size_t destlen)
{
	int ret = 0;
	int wbits = MAX_WBITS;
	struct workspace *workspace;
	unsigned long bytes_left = destlen;
	unsigned long total_out = 0;
	char *kaddr;

	if (destlen > PAGE_CACHE_SIZE)
		return -ENOMEM;

	workspace = find_zlib_workspace();
	if (IS_ERR(workspace))
		return -ENOMEM;

	workspace->inf_strm.next_in = data_in;
	workspace->inf_strm.avail_in = srclen;
	workspace->inf_strm.total_in = 0;

	workspace->inf_strm.next_out = workspace->buf;
	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	workspace->inf_strm.total_out = 0;
	/* If it's deflate, and it's got no preset dictionary, then
	   we can tell zlib to skip the adler32 check. */
	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
	    !(((data_in[0]<<8) + data_in[1]) % 31)) {

		wbits = -((data_in[0] >> 4) + 8);
		workspace->inf_strm.next_in += 2;
		workspace->inf_strm.avail_in -= 2;
	}

	if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
		printk(KERN_WARNING "inflateInit failed\n");
		ret = -1;
		goto out;
	}

	while (bytes_left > 0) {
		unsigned long buf_start;
		unsigned long buf_offset;
		unsigned long bytes;
		unsigned long pg_offset = 0;

		ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
		if (ret != Z_OK && ret != Z_STREAM_END)
			break;

		buf_start = total_out;
		total_out = workspace->inf_strm.total_out;

		if (total_out == buf_start) {
			ret = -1;
			break;
		}

		if (total_out <= start_byte)
			goto next;

		if (total_out > start_byte && buf_start < start_byte)
			buf_offset = start_byte - buf_start;
		else
			buf_offset = 0;

		bytes = min(PAGE_CACHE_SIZE - pg_offset,
			    PAGE_CACHE_SIZE - buf_offset);
		bytes = min(bytes, bytes_left);

		kaddr = kmap_atomic(dest_page, KM_USER0);
		memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
		kunmap_atomic(kaddr, KM_USER0);

		pg_offset += bytes;
		bytes_left -= bytes;
next:
		workspace->inf_strm.next_out = workspace->buf;
		workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	}

	if (ret != Z_STREAM_END && bytes_left != 0)
		ret = -1;
	else
		ret = 0;

	zlib_inflateEnd(&workspace->inf_strm);
out:
	free_workspace(workspace);
	return ret;
}

void btrfs_zlib_exit(void)
{
    free_workspaces();
}
Commit	Line	Data
c8b97818 CM	1	/*
	2	* Copyright (C) 2008 Oracle. All rights reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public
	6	* License v2 as published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	11	* General Public License for more details.
	12	*
	13	* You should have received a copy of the GNU General Public
	14	* License along with this program; if not, write to the
	15	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	16	* Boston, MA 021110-1307, USA.
	17	*
	18	* Based on jffs2 zlib code:
	19	* Copyright © 2001-2007 Red Hat, Inc.
	20	* Created by David Woodhouse <dwmw2@infradead.org>
	21	*/
	22
	23	#include <linux/kernel.h>
	24	#include <linux/slab.h>
	25	#include <linux/zlib.h>
	26	#include <linux/zutil.h>
	27	#include <linux/vmalloc.h>
	28	#include <linux/init.h>
	29	#include <linux/err.h>
	30	#include <linux/sched.h>
	31	#include <linux/pagemap.h>
	32	#include <linux/bio.h>
b2950863	33	#include "compression.h"
c8b97818 CM	34
	35	/* Plan: call deflate() with avail_in == *sourcelen,
	36	avail_out = *dstlen - 12 and flush == Z_FINISH.
	37	If it doesn't manage to finish, call it again with
	38	avail_in == 0 and avail_out set to the remaining 12
	39	bytes for it to clean up.
	40	Q: Is 12 bytes sufficient?
	41	*/
	42	#define STREAM_END_SPACE 12
	43
	44	struct workspace {
	45	z_stream inf_strm;
	46	z_stream def_strm;
	47	char *buf;
	48	struct list_head list;
	49	};
	50
	51	static LIST_HEAD(idle_workspace);
	52	static DEFINE_SPINLOCK(workspace_lock);
	53	static unsigned long num_workspace;
	54	static atomic_t alloc_workspace = ATOMIC_INIT(0);
	55	static DECLARE_WAIT_QUEUE_HEAD(workspace_wait);
	56
	57	/*
	58	* this finds an available zlib workspace or allocates a new one
	59	* NULL or an ERR_PTR is returned if things go bad.
	60	*/
	61	static struct workspace *find_zlib_workspace(void)
	62	{
	63	struct workspace *workspace;
	64	int ret;
	65	int cpus = num_online_cpus();
	66
	67	again:
	68	spin_lock(&workspace_lock);
	69	if (!list_empty(&idle_workspace)) {
	70	workspace = list_entry(idle_workspace.next, struct workspace,
	71	list);
	72	list_del(&workspace->list);
	73	num_workspace--;
	74	spin_unlock(&workspace_lock);
	75	return workspace;
	76
	77	}
	78	spin_unlock(&workspace_lock);
	79	if (atomic_read(&alloc_workspace) > cpus) {
	80	DEFINE_WAIT(wait);
	81	prepare_to_wait(&workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
	82	if (atomic_read(&alloc_workspace) > cpus)
	83	schedule();
	84	finish_wait(&workspace_wait, &wait);
	85	goto again;
	86	}
	87	atomic_inc(&alloc_workspace);
	88	workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
	89	if (!workspace) {
	90	ret = -ENOMEM;
	91	goto fail;
	92	}
	93
	94	workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize());
	95	if (!workspace->def_strm.workspace) {
	96	ret = -ENOMEM;
	97	goto fail;
98	}
99	workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
100	if (!workspace->inf_strm.workspace) {
101	ret = -ENOMEM;
102	goto fail_inflate;
103	}
104	workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS);
105	if (!workspace->buf) {
106	ret = -ENOMEM;
107	goto fail_kmalloc;
108	}
109	return workspace;
110
111	fail_kmalloc:
112	vfree(workspace->inf_strm.workspace);
113	fail_inflate:
114	vfree(workspace->def_strm.workspace);
115	fail:
116	kfree(workspace);
117	atomic_dec(&alloc_workspace);
118	wake_up(&workspace_wait);
119	return ERR_PTR(ret);
120	}
121
122	/*
123	* put a workspace struct back on the list or free it if we have enough
124	* idle ones sitting around
125	*/
126	static int free_workspace(struct workspace *workspace)
127	{
128	spin_lock(&workspace_lock);
129	if (num_workspace < num_online_cpus()) {
130	list_add_tail(&workspace->list, &idle_workspace);
131	num_workspace++;
132	spin_unlock(&workspace_lock);
133	if (waitqueue_active(&workspace_wait))
134	wake_up(&workspace_wait);
135	return 0;
136	}
137	spin_unlock(&workspace_lock);
138	vfree(workspace->def_strm.workspace);
139	vfree(workspace->inf_strm.workspace);
140	kfree(workspace->buf);
141	kfree(workspace);
142
143	atomic_dec(&alloc_workspace);
144	if (waitqueue_active(&workspace_wait))
145	wake_up(&workspace_wait);
146	return 0;
147	}
148
149	/*
150	* cleanup function for module exit
151	*/
152	static void free_workspaces(void)
153	{
154	struct workspace *workspace;
d397712b	155	while (!list_empty(&idle_workspace)) {
c8b97818 CM	156	workspace = list_entry(idle_workspace.next, struct workspace,
	157	list);
	158	list_del(&workspace->list);
	159	vfree(workspace->def_strm.workspace);
	160	vfree(workspace->inf_strm.workspace);
	161	kfree(workspace->buf);
	162	kfree(workspace);
	163	atomic_dec(&alloc_workspace);
	164	}
	165	}
	166
	167	/*
	168	* given an address space and start/len, compress the bytes.
	169	*
	170	* pages are allocated to hold the compressed result and stored
	171	* in 'pages'
	172	*
	173	* out_pages is used to return the number of pages allocated. There
	174	* may be pages allocated even if we return an error
	175	*
	176	* total_in is used to return the number of bytes actually read. It
	177	* may be smaller then len if we had to exit early because we
	178	* ran out of room in the pages array or because we cross the
	179	* max_out threshold.
	180	*
	181	* total_out is used to return the total number of compressed bytes
	182	*
	183	* max_out tells us the max number of bytes that we're allowed to
	184	* stuff into pages
	185	*/
	186	int btrfs_zlib_compress_pages(struct address_space *mapping,
	187	u64 start, unsigned long len,
	188	struct page **pages,
	189	unsigned long nr_dest_pages,
	190	unsigned long *out_pages,
	191	unsigned long *total_in,
	192	unsigned long *total_out,
	193	unsigned long max_out)
	194	{
	195	int ret;
	196	struct workspace *workspace;
	197	char *data_in;
	198	char *cpage_out;
	199	int nr_pages = 0;
	200	struct page *in_page = NULL;
	201	struct page *out_page = NULL;
c8b97818 CM	202	unsigned long bytes_left;
	203
	204	*out_pages = 0;
	205	*total_out = 0;
	206	*total_in = 0;
	207
	208	workspace = find_zlib_workspace();
60f2e8f8	209	if (IS_ERR(workspace))
c8b97818 CM	210	return -1;
	211
	212	if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
	213	printk(KERN_WARNING "deflateInit failed\n");
	214	ret = -1;
	215	goto out;
	216	}
	217
	218	workspace->def_strm.total_in = 0;
	219	workspace->def_strm.total_out = 0;
	220
	221	in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
	222	data_in = kmap(in_page);
	223
	224	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	225	cpage_out = kmap(out_page);
	226	pages[0] = out_page;
	227	nr_pages = 1;
	228
	229	workspace->def_strm.next_in = data_in;
	230	workspace->def_strm.next_out = cpage_out;
	231	workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
	232	workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE);
	233
c8b97818 CM	234	while (workspace->def_strm.total_in < len) {
	235	ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH);
	236	if (ret != Z_OK) {
	237	printk(KERN_DEBUG "btrfs deflate in loop returned %d\n",
	238	ret);
	239	zlib_deflateEnd(&workspace->def_strm);
	240	ret = -1;
	241	goto out;
	242	}
	243
	244	/* we're making it bigger, give up */
	245	if (workspace->def_strm.total_in > 8192 &&
	246	workspace->def_strm.total_in <
	247	workspace->def_strm.total_out) {
	248	ret = -1;
	249	goto out;
	250	}
	251	/* we need another page for writing out. Test this
	252	* before the total_in so we will pull in a new page for
	253	* the stream end if required
	254	*/
	255	if (workspace->def_strm.avail_out == 0) {
	256	kunmap(out_page);
	257	if (nr_pages == nr_dest_pages) {
	258	out_page = NULL;
	259	ret = -1;
	260	goto out;
	261	}
	262	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	263	cpage_out = kmap(out_page);
	264	pages[nr_pages] = out_page;
	265	nr_pages++;
	266	workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
	267	workspace->def_strm.next_out = cpage_out;
	268	}
	269	/* we're all done */
	270	if (workspace->def_strm.total_in >= len)
	271	break;
	272
	273	/* we've read in a full page, get a new one */
	274	if (workspace->def_strm.avail_in == 0) {
	275	if (workspace->def_strm.total_out > max_out)
	276	break;
	277
	278	bytes_left = len - workspace->def_strm.total_in;
	279	kunmap(in_page);
	280	page_cache_release(in_page);
	281
	282	start += PAGE_CACHE_SIZE;
	283	in_page = find_get_page(mapping,
	284	start >> PAGE_CACHE_SHIFT);
	285	data_in = kmap(in_page);
	286	workspace->def_strm.avail_in = min(bytes_left,
	287	PAGE_CACHE_SIZE);
	288	workspace->def_strm.next_in = data_in;
	289	}
	290	}
	291	workspace->def_strm.avail_in = 0;
	292	ret = zlib_deflate(&workspace->def_strm, Z_FINISH);
	293	zlib_deflateEnd(&workspace->def_strm);
	294
	295	if (ret != Z_STREAM_END) {
	296	ret = -1;
	297	goto out;
298	}
299
300	if (workspace->def_strm.total_out >= workspace->def_strm.total_in) {
301	ret = -1;
302	goto out;
303	}
304
305	ret = 0;
306	*total_out = workspace->def_strm.total_out;
307	*total_in = workspace->def_strm.total_in;
308	out:
309	*out_pages = nr_pages;
310	if (out_page)
311	kunmap(out_page);
312
313	if (in_page) {
314	kunmap(in_page);
315	page_cache_release(in_page);
316	}
317	free_workspace(workspace);
318	return ret;
319	}
320
321	/*
322	* pages_in is an array of pages with compressed data.
323	*
324	* disk_start is the starting logical offset of this array in the file
325	*
326	* bvec is a bio_vec of pages from the file that we want to decompress into
327	*
328	* vcnt is the count of pages in the biovec
329	*
330	* srclen is the number of bytes in pages_in
331	*
332	* The basic idea is that we have a bio that was created by readpages.
333	* The pages in the bio are for the uncompressed data, and they may not
334	* be contiguous. They all correspond to the range of bytes covered by
335	* the compressed extent.
336	*/
337	int btrfs_zlib_decompress_biovec(struct page **pages_in,
338	u64 disk_start,
339	struct bio_vec *bvec,
340	int vcnt,
341	size_t srclen)
342	{
343	int ret = 0;
344	int wbits = MAX_WBITS;
345	struct workspace *workspace;
346	char *data_in;
347	size_t total_out = 0;
348	unsigned long page_bytes_left;
349	unsigned long page_in_index = 0;
350	unsigned long page_out_index = 0;
351	struct page *page_out;
352	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
353	PAGE_CACHE_SIZE;
354	unsigned long buf_start;
355	unsigned long buf_offset;
356	unsigned long bytes;
357	unsigned long working_bytes;
358	unsigned long pg_offset;
359	unsigned long start_byte;
360	unsigned long current_buf_start;
361	char *kaddr;
362
363	workspace = find_zlib_workspace();
60f2e8f8	364	if (IS_ERR(workspace))
c8b97818 CM	365	return -ENOMEM;
	366
	367	data_in = kmap(pages_in[page_in_index]);
	368	workspace->inf_strm.next_in = data_in;
5b050f04	369	workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
c8b97818 CM	370	workspace->inf_strm.total_in = 0;
	371
	372	workspace->inf_strm.total_out = 0;
	373	workspace->inf_strm.next_out = workspace->buf;
	374	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	375	page_out = bvec[page_out_index].bv_page;
	376	page_bytes_left = PAGE_CACHE_SIZE;
	377	pg_offset = 0;
	378
	379	/* If it's deflate, and it's got no preset dictionary, then
	380	we can tell zlib to skip the adler32 check. */
	381	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	382	((data_in[0] & 0x0f) == Z_DEFLATED) &&
	383	!(((data_in[0]<<8) + data_in[1]) % 31)) {
	384
	385	wbits = -((data_in[0] >> 4) + 8);
	386	workspace->inf_strm.next_in += 2;
	387	workspace->inf_strm.avail_in -= 2;
	388	}
	389
	390	if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
	391	printk(KERN_WARNING "inflateInit failed\n");
	392	ret = -1;
	393	goto out;
	394	}
d397712b	395	while (workspace->inf_strm.total_in < srclen) {
c8b97818	396	ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
d397712b	397	if (ret != Z_OK && ret != Z_STREAM_END)
c8b97818	398	break;
c8b97818 CM	399	/*
	400	* buf start is the byte offset we're of the start of
	401	* our workspace buffer
	402	*/
	403	buf_start = total_out;
	404
	405	/* total_out is the last byte of the workspace buffer */
	406	total_out = workspace->inf_strm.total_out;
	407
	408	working_bytes = total_out - buf_start;
	409
	410	/*
	411	* start byte is the first byte of the page we're currently
	412	* copying into relative to the start of the compressed data.
	413	*/
	414	start_byte = page_offset(page_out) - disk_start;
	415
	416	if (working_bytes == 0) {
	417	/* we didn't make progress in this inflate
	418	* call, we're done
	419	*/
d397712b	420	if (ret != Z_STREAM_END)
c8b97818 CM	421	ret = -1;
	422	break;
	423	}
	424
	425	/* we haven't yet hit data corresponding to this page */
d397712b	426	if (total_out <= start_byte)
c8b97818	427	goto next;
c8b97818 CM	428
	429	/*
	430	* the start of the data we care about is offset into
	431	* the middle of our working buffer
	432	*/
	433	if (total_out > start_byte && buf_start < start_byte) {
	434	buf_offset = start_byte - buf_start;
	435	working_bytes -= buf_offset;
	436	} else {
	437	buf_offset = 0;
	438	}
	439	current_buf_start = buf_start;
	440
	441	/* copy bytes from the working buffer into the pages */
d397712b	442	while (working_bytes > 0) {
c8b97818 CM	443	bytes = min(PAGE_CACHE_SIZE - pg_offset,
	444	PAGE_CACHE_SIZE - buf_offset);
	445	bytes = min(bytes, working_bytes);
	446	kaddr = kmap_atomic(page_out, KM_USER0);
	447	memcpy(kaddr + pg_offset, workspace->buf + buf_offset,
	448	bytes);
	449	kunmap_atomic(kaddr, KM_USER0);
	450	flush_dcache_page(page_out);
	451
	452	pg_offset += bytes;
	453	page_bytes_left -= bytes;
	454	buf_offset += bytes;
	455	working_bytes -= bytes;
	456	current_buf_start += bytes;
	457
	458	/* check if we need to pick another page */
	459	if (page_bytes_left == 0) {
	460	page_out_index++;
	461	if (page_out_index >= vcnt) {
	462	ret = 0;
	463	goto done;
	464	}
d397712b	465
c8b97818 CM	466	page_out = bvec[page_out_index].bv_page;
	467	pg_offset = 0;
	468	page_bytes_left = PAGE_CACHE_SIZE;
	469	start_byte = page_offset(page_out) - disk_start;
	470
	471	/*
	472	* make sure our new page is covered by this
	473	* working buffer
	474	*/
d397712b	475	if (total_out <= start_byte)
c8b97818	476	goto next;
c8b97818 CM	477
	478	/* the next page in the biovec might not
	479	* be adjacent to the last page, but it
	480	* might still be found inside this working
	481	* buffer. bump our offset pointer
	482	*/
	483	if (total_out > start_byte &&
	484	current_buf_start < start_byte) {
	485	buf_offset = start_byte - buf_start;
	486	working_bytes = total_out - start_byte;
	487	current_buf_start = buf_start +
	488	buf_offset;
	489	}
	490	}
	491	}
	492	next:
	493	workspace->inf_strm.next_out = workspace->buf;
	494	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	495
	496	if (workspace->inf_strm.avail_in == 0) {
	497	unsigned long tmp;
	498	kunmap(pages_in[page_in_index]);
	499	page_in_index++;
	500	if (page_in_index >= total_pages_in) {
	501	data_in = NULL;
	502	break;
	503	}
	504	data_in = kmap(pages_in[page_in_index]);
	505	workspace->inf_strm.next_in = data_in;
	506	tmp = srclen - workspace->inf_strm.total_in;
	507	workspace->inf_strm.avail_in = min(tmp,
	508	PAGE_CACHE_SIZE);
	509	}
	510	}
d397712b	511	if (ret != Z_STREAM_END)
c8b97818	512	ret = -1;
d397712b	513	else
c8b97818	514	ret = 0;
c8b97818 CM	515	done:
	516	zlib_inflateEnd(&workspace->inf_strm);
	517	if (data_in)
	518	kunmap(pages_in[page_in_index]);
	519	out:
	520	free_workspace(workspace);
	521	return ret;
	522	}
	523
	524	/*
	525	* a less complex decompression routine. Our compressed data fits in a
	526	* single page, and we want to read a single page out of it.
	527	* start_byte tells us the offset into the compressed data we're interested in
	528	*/
	529	int btrfs_zlib_decompress(unsigned char *data_in,
	530	struct page *dest_page,
	531	unsigned long start_byte,
	532	size_t srclen, size_t destlen)
	533	{
	534	int ret = 0;
	535	int wbits = MAX_WBITS;
	536	struct workspace *workspace;
	537	unsigned long bytes_left = destlen;
	538	unsigned long total_out = 0;
	539	char *kaddr;
	540
	541	if (destlen > PAGE_CACHE_SIZE)
	542	return -ENOMEM;
	543
	544	workspace = find_zlib_workspace();
60f2e8f8	545	if (IS_ERR(workspace))
c8b97818 CM	546	return -ENOMEM;
	547
	548	workspace->inf_strm.next_in = data_in;
	549	workspace->inf_strm.avail_in = srclen;
	550	workspace->inf_strm.total_in = 0;
	551
	552	workspace->inf_strm.next_out = workspace->buf;
	553	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	554	workspace->inf_strm.total_out = 0;
	555	/* If it's deflate, and it's got no preset dictionary, then
	556	we can tell zlib to skip the adler32 check. */
	557	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	558	((data_in[0] & 0x0f) == Z_DEFLATED) &&
	559	!(((data_in[0]<<8) + data_in[1]) % 31)) {
	560
	561	wbits = -((data_in[0] >> 4) + 8);
	562	workspace->inf_strm.next_in += 2;
	563	workspace->inf_strm.avail_in -= 2;
	564	}
	565
	566	if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
	567	printk(KERN_WARNING "inflateInit failed\n");
	568	ret = -1;
	569	goto out;
	570	}
	571
d397712b	572	while (bytes_left > 0) {
c8b97818 CM	573	unsigned long buf_start;
	574	unsigned long buf_offset;
	575	unsigned long bytes;
	576	unsigned long pg_offset = 0;
	577
	578	ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
d397712b	579	if (ret != Z_OK && ret != Z_STREAM_END)
c8b97818	580	break;
c8b97818 CM	581
	582	buf_start = total_out;
	583	total_out = workspace->inf_strm.total_out;
	584
	585	if (total_out == buf_start) {
	586	ret = -1;
	587	break;
	588	}
	589
d397712b	590	if (total_out <= start_byte)
c8b97818	591	goto next;
c8b97818	592
d397712b	593	if (total_out > start_byte && buf_start < start_byte)
c8b97818	594	buf_offset = start_byte - buf_start;
d397712b	595	else
c8b97818	596	buf_offset = 0;
c8b97818 CM	597
	598	bytes = min(PAGE_CACHE_SIZE - pg_offset,
	599	PAGE_CACHE_SIZE - buf_offset);
	600	bytes = min(bytes, bytes_left);
	601
	602	kaddr = kmap_atomic(dest_page, KM_USER0);
	603	memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
	604	kunmap_atomic(kaddr, KM_USER0);
	605
	606	pg_offset += bytes;
	607	bytes_left -= bytes;
	608	next:
	609	workspace->inf_strm.next_out = workspace->buf;
	610	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	611	}
d397712b CM	612
d397712b CM	613	if (ret != Z_STREAM_END && bytes_left != 0)
c8b97818	614	ret = -1;
d397712b	615	else
c8b97818	616	ret = 0;
d397712b	617
c8b97818 CM	618	zlib_inflateEnd(&workspace->inf_strm);
	619	out:
	620	free_workspace(workspace);
	621	return ret;
	622	}
	623
	624	void btrfs_zlib_exit(void)
	625	{
	626	free_workspaces();
	627	}