[mirror_ubuntu-bionic-kernel.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;

	}
	if (atomic_read(&alloc_workspace) > cpus) {
		DEFINE_WAIT(wait);

		spin_unlock(&workspace_lock);
		prepare_to_wait(&workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
		if (atomic_read(&alloc_workspace) > cpus && !num_workspace)
			schedule();
		finish_wait(&workspace_wait, &wait);
		goto again;
	}
	atomic_inc(&alloc_workspace);
	spin_unlock(&workspace_lock);

	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	}
c8b97818 CM	78	if (atomic_read(&alloc_workspace) > cpus) {
c8b97818 CM	79	DEFINE_WAIT(wait);
8844355d LZ	80
8844355d LZ	81	spin_unlock(&workspace_lock);
c8b97818	82	prepare_to_wait(&workspace_wait, &wait, TASK_UNINTERRUPTIBLE);
8844355d	83	if (atomic_read(&alloc_workspace) > cpus && !num_workspace)
c8b97818 CM	84	schedule();
	85	finish_wait(&workspace_wait, &wait);
	86	goto again;
	87	}
	88	atomic_inc(&alloc_workspace);
8844355d LZ	89	spin_unlock(&workspace_lock);
8844355d LZ	90
c8b97818 CM	91	workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
	92	if (!workspace) {
	93	ret = -ENOMEM;
	94	goto fail;
	95	}
	96
	97	workspace->def_strm.workspace = vmalloc(zlib_deflate_workspacesize());
	98	if (!workspace->def_strm.workspace) {
	99	ret = -ENOMEM;
	100	goto fail;
	101	}
	102	workspace->inf_strm.workspace = vmalloc(zlib_inflate_workspacesize());
	103	if (!workspace->inf_strm.workspace) {
	104	ret = -ENOMEM;
	105	goto fail_inflate;
	106	}
	107	workspace->buf = kmalloc(PAGE_CACHE_SIZE, GFP_NOFS);
	108	if (!workspace->buf) {
	109	ret = -ENOMEM;
	110	goto fail_kmalloc;
	111	}
	112	return workspace;
	113
	114	fail_kmalloc:
	115	vfree(workspace->inf_strm.workspace);
	116	fail_inflate:
	117	vfree(workspace->def_strm.workspace);
	118	fail:
	119	kfree(workspace);
	120	atomic_dec(&alloc_workspace);
	121	wake_up(&workspace_wait);
	122	return ERR_PTR(ret);
	123	}
	124
	125	/*
	126	* put a workspace struct back on the list or free it if we have enough
	127	* idle ones sitting around
	128	*/
	129	static int free_workspace(struct workspace *workspace)
	130	{
	131	spin_lock(&workspace_lock);
	132	if (num_workspace < num_online_cpus()) {
	133	list_add_tail(&workspace->list, &idle_workspace);
	134	num_workspace++;
	135	spin_unlock(&workspace_lock);
	136	if (waitqueue_active(&workspace_wait))
	137	wake_up(&workspace_wait);
	138	return 0;
	139	}
	140	spin_unlock(&workspace_lock);
	141	vfree(workspace->def_strm.workspace);
	142	vfree(workspace->inf_strm.workspace);
	143	kfree(workspace->buf);
	144	kfree(workspace);
	145
	146	atomic_dec(&alloc_workspace);
	147	if (waitqueue_active(&workspace_wait))
	148	wake_up(&workspace_wait);
	149	return 0;
	150	}
	151
	152	/*
	153	* cleanup function for module exit
	154	*/
155	static void free_workspaces(void)
156	{
157	struct workspace *workspace;
d397712b	158	while (!list_empty(&idle_workspace)) {
c8b97818 CM	159	workspace = list_entry(idle_workspace.next, struct workspace,
	160	list);
	161	list_del(&workspace->list);
	162	vfree(workspace->def_strm.workspace);
	163	vfree(workspace->inf_strm.workspace);
	164	kfree(workspace->buf);
	165	kfree(workspace);
	166	atomic_dec(&alloc_workspace);
	167	}
	168	}
	169
	170	/*
	171	* given an address space and start/len, compress the bytes.
	172	*
	173	* pages are allocated to hold the compressed result and stored
	174	* in 'pages'
	175	*
	176	* out_pages is used to return the number of pages allocated. There
	177	* may be pages allocated even if we return an error
	178	*
	179	* total_in is used to return the number of bytes actually read. It
	180	* may be smaller then len if we had to exit early because we
	181	* ran out of room in the pages array or because we cross the
	182	* max_out threshold.
	183	*
	184	* total_out is used to return the total number of compressed bytes
	185	*
	186	* max_out tells us the max number of bytes that we're allowed to
	187	* stuff into pages
	188	*/
	189	int btrfs_zlib_compress_pages(struct address_space *mapping,
	190	u64 start, unsigned long len,
	191	struct page **pages,
	192	unsigned long nr_dest_pages,
	193	unsigned long *out_pages,
	194	unsigned long *total_in,
	195	unsigned long *total_out,
	196	unsigned long max_out)
	197	{
	198	int ret;
	199	struct workspace *workspace;
	200	char *data_in;
	201	char *cpage_out;
	202	int nr_pages = 0;
	203	struct page *in_page = NULL;
	204	struct page *out_page = NULL;
c8b97818 CM	205	unsigned long bytes_left;
	206
	207	*out_pages = 0;
	208	*total_out = 0;
	209	*total_in = 0;
	210
	211	workspace = find_zlib_workspace();
60f2e8f8	212	if (IS_ERR(workspace))
c8b97818 CM	213	return -1;
	214
	215	if (Z_OK != zlib_deflateInit(&workspace->def_strm, 3)) {
	216	printk(KERN_WARNING "deflateInit failed\n");
	217	ret = -1;
	218	goto out;
	219	}
	220
	221	workspace->def_strm.total_in = 0;
	222	workspace->def_strm.total_out = 0;
	223
	224	in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
	225	data_in = kmap(in_page);
	226
	227	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	228	cpage_out = kmap(out_page);
	229	pages[0] = out_page;
	230	nr_pages = 1;
	231
	232	workspace->def_strm.next_in = data_in;
	233	workspace->def_strm.next_out = cpage_out;
	234	workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
	235	workspace->def_strm.avail_in = min(len, PAGE_CACHE_SIZE);
	236
c8b97818 CM	237	while (workspace->def_strm.total_in < len) {
	238	ret = zlib_deflate(&workspace->def_strm, Z_SYNC_FLUSH);
	239	if (ret != Z_OK) {
	240	printk(KERN_DEBUG "btrfs deflate in loop returned %d\n",
	241	ret);
	242	zlib_deflateEnd(&workspace->def_strm);
	243	ret = -1;
	244	goto out;
	245	}
	246
	247	/* we're making it bigger, give up */
	248	if (workspace->def_strm.total_in > 8192 &&
	249	workspace->def_strm.total_in <
	250	workspace->def_strm.total_out) {
	251	ret = -1;
	252	goto out;
	253	}
	254	/* we need another page for writing out. Test this
	255	* before the total_in so we will pull in a new page for
	256	* the stream end if required
	257	*/
	258	if (workspace->def_strm.avail_out == 0) {
	259	kunmap(out_page);
	260	if (nr_pages == nr_dest_pages) {
	261	out_page = NULL;
	262	ret = -1;
	263	goto out;
	264	}
	265	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	266	cpage_out = kmap(out_page);
	267	pages[nr_pages] = out_page;
	268	nr_pages++;
	269	workspace->def_strm.avail_out = PAGE_CACHE_SIZE;
	270	workspace->def_strm.next_out = cpage_out;
	271	}
	272	/* we're all done */
	273	if (workspace->def_strm.total_in >= len)
	274	break;
	275
	276	/* we've read in a full page, get a new one */
	277	if (workspace->def_strm.avail_in == 0) {
	278	if (workspace->def_strm.total_out > max_out)
	279	break;
	280
	281	bytes_left = len - workspace->def_strm.total_in;
	282	kunmap(in_page);
	283	page_cache_release(in_page);
	284
	285	start += PAGE_CACHE_SIZE;
	286	in_page = find_get_page(mapping,
	287	start >> PAGE_CACHE_SHIFT);
	288	data_in = kmap(in_page);
	289	workspace->def_strm.avail_in = min(bytes_left,
	290	PAGE_CACHE_SIZE);
	291	workspace->def_strm.next_in = data_in;
	292	}
	293	}
	294	workspace->def_strm.avail_in = 0;
	295	ret = zlib_deflate(&workspace->def_strm, Z_FINISH);
	296	zlib_deflateEnd(&workspace->def_strm);
	297
	298	if (ret != Z_STREAM_END) {
	299	ret = -1;
	300	goto out;
301	}
302
303	if (workspace->def_strm.total_out >= workspace->def_strm.total_in) {
304	ret = -1;
305	goto out;
306	}
307
308	ret = 0;
309	*total_out = workspace->def_strm.total_out;
310	*total_in = workspace->def_strm.total_in;
311	out:
312	*out_pages = nr_pages;
313	if (out_page)
314	kunmap(out_page);
315
316	if (in_page) {
317	kunmap(in_page);
318	page_cache_release(in_page);
319	}
320	free_workspace(workspace);
321	return ret;
322	}
323
324	/*
325	* pages_in is an array of pages with compressed data.
326	*
327	* disk_start is the starting logical offset of this array in the file
328	*
329	* bvec is a bio_vec of pages from the file that we want to decompress into
330	*
331	* vcnt is the count of pages in the biovec
332	*
333	* srclen is the number of bytes in pages_in
334	*
335	* The basic idea is that we have a bio that was created by readpages.
336	* The pages in the bio are for the uncompressed data, and they may not
337	* be contiguous. They all correspond to the range of bytes covered by
338	* the compressed extent.
339	*/
340	int btrfs_zlib_decompress_biovec(struct page **pages_in,
341	u64 disk_start,
342	struct bio_vec *bvec,
343	int vcnt,
344	size_t srclen)
345	{
346	int ret = 0;
347	int wbits = MAX_WBITS;
348	struct workspace *workspace;
349	char *data_in;
350	size_t total_out = 0;
351	unsigned long page_bytes_left;
352	unsigned long page_in_index = 0;
353	unsigned long page_out_index = 0;
354	struct page *page_out;
355	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
356	PAGE_CACHE_SIZE;
357	unsigned long buf_start;
358	unsigned long buf_offset;
359	unsigned long bytes;
360	unsigned long working_bytes;
361	unsigned long pg_offset;
362	unsigned long start_byte;
363	unsigned long current_buf_start;
364	char *kaddr;
365
366	workspace = find_zlib_workspace();
60f2e8f8	367	if (IS_ERR(workspace))
c8b97818 CM	368	return -ENOMEM;
	369
	370	data_in = kmap(pages_in[page_in_index]);
	371	workspace->inf_strm.next_in = data_in;
5b050f04	372	workspace->inf_strm.avail_in = min_t(size_t, srclen, PAGE_CACHE_SIZE);
c8b97818 CM	373	workspace->inf_strm.total_in = 0;
	374
	375	workspace->inf_strm.total_out = 0;
	376	workspace->inf_strm.next_out = workspace->buf;
	377	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	378	page_out = bvec[page_out_index].bv_page;
	379	page_bytes_left = PAGE_CACHE_SIZE;
	380	pg_offset = 0;
	381
	382	/* If it's deflate, and it's got no preset dictionary, then
	383	we can tell zlib to skip the adler32 check. */
	384	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	385	((data_in[0] & 0x0f) == Z_DEFLATED) &&
	386	!(((data_in[0]<<8) + data_in[1]) % 31)) {
	387
	388	wbits = -((data_in[0] >> 4) + 8);
	389	workspace->inf_strm.next_in += 2;
	390	workspace->inf_strm.avail_in -= 2;
	391	}
	392
	393	if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
	394	printk(KERN_WARNING "inflateInit failed\n");
	395	ret = -1;
	396	goto out;
	397	}
d397712b	398	while (workspace->inf_strm.total_in < srclen) {
c8b97818	399	ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
d397712b	400	if (ret != Z_OK && ret != Z_STREAM_END)
c8b97818	401	break;
c8b97818 CM	402	/*
	403	* buf start is the byte offset we're of the start of
	404	* our workspace buffer
	405	*/
	406	buf_start = total_out;
	407
	408	/* total_out is the last byte of the workspace buffer */
	409	total_out = workspace->inf_strm.total_out;
	410
	411	working_bytes = total_out - buf_start;
	412
	413	/*
	414	* start byte is the first byte of the page we're currently
	415	* copying into relative to the start of the compressed data.
	416	*/
	417	start_byte = page_offset(page_out) - disk_start;
	418
	419	if (working_bytes == 0) {
	420	/* we didn't make progress in this inflate
	421	* call, we're done
	422	*/
d397712b	423	if (ret != Z_STREAM_END)
c8b97818 CM	424	ret = -1;
	425	break;
	426	}
	427
	428	/* we haven't yet hit data corresponding to this page */
d397712b	429	if (total_out <= start_byte)
c8b97818	430	goto next;
c8b97818 CM	431
	432	/*
	433	* the start of the data we care about is offset into
	434	* the middle of our working buffer
	435	*/
	436	if (total_out > start_byte && buf_start < start_byte) {
	437	buf_offset = start_byte - buf_start;
	438	working_bytes -= buf_offset;
	439	} else {
	440	buf_offset = 0;
	441	}
	442	current_buf_start = buf_start;
	443
	444	/* copy bytes from the working buffer into the pages */
d397712b	445	while (working_bytes > 0) {
c8b97818 CM	446	bytes = min(PAGE_CACHE_SIZE - pg_offset,
	447	PAGE_CACHE_SIZE - buf_offset);
	448	bytes = min(bytes, working_bytes);
	449	kaddr = kmap_atomic(page_out, KM_USER0);
	450	memcpy(kaddr + pg_offset, workspace->buf + buf_offset,
	451	bytes);
	452	kunmap_atomic(kaddr, KM_USER0);
	453	flush_dcache_page(page_out);
	454
	455	pg_offset += bytes;
	456	page_bytes_left -= bytes;
	457	buf_offset += bytes;
	458	working_bytes -= bytes;
	459	current_buf_start += bytes;
	460
	461	/* check if we need to pick another page */
	462	if (page_bytes_left == 0) {
	463	page_out_index++;
	464	if (page_out_index >= vcnt) {
	465	ret = 0;
	466	goto done;
	467	}
d397712b	468
c8b97818 CM	469	page_out = bvec[page_out_index].bv_page;
	470	pg_offset = 0;
	471	page_bytes_left = PAGE_CACHE_SIZE;
	472	start_byte = page_offset(page_out) - disk_start;
	473
	474	/*
	475	* make sure our new page is covered by this
	476	* working buffer
	477	*/
d397712b	478	if (total_out <= start_byte)
c8b97818	479	goto next;
c8b97818 CM	480
	481	/* the next page in the biovec might not
	482	* be adjacent to the last page, but it
	483	* might still be found inside this working
	484	* buffer. bump our offset pointer
	485	*/
	486	if (total_out > start_byte &&
	487	current_buf_start < start_byte) {
	488	buf_offset = start_byte - buf_start;
	489	working_bytes = total_out - start_byte;
	490	current_buf_start = buf_start +
	491	buf_offset;
	492	}
	493	}
	494	}
	495	next:
	496	workspace->inf_strm.next_out = workspace->buf;
	497	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	498
	499	if (workspace->inf_strm.avail_in == 0) {
	500	unsigned long tmp;
	501	kunmap(pages_in[page_in_index]);
	502	page_in_index++;
	503	if (page_in_index >= total_pages_in) {
	504	data_in = NULL;
	505	break;
	506	}
	507	data_in = kmap(pages_in[page_in_index]);
	508	workspace->inf_strm.next_in = data_in;
	509	tmp = srclen - workspace->inf_strm.total_in;
	510	workspace->inf_strm.avail_in = min(tmp,
	511	PAGE_CACHE_SIZE);
	512	}
	513	}
d397712b	514	if (ret != Z_STREAM_END)
c8b97818	515	ret = -1;
d397712b	516	else
c8b97818	517	ret = 0;
c8b97818 CM	518	done:
	519	zlib_inflateEnd(&workspace->inf_strm);
	520	if (data_in)
	521	kunmap(pages_in[page_in_index]);
	522	out:
	523	free_workspace(workspace);
	524	return ret;
	525	}
	526
	527	/*
	528	* a less complex decompression routine. Our compressed data fits in a
	529	* single page, and we want to read a single page out of it.
	530	* start_byte tells us the offset into the compressed data we're interested in
	531	*/
	532	int btrfs_zlib_decompress(unsigned char *data_in,
	533	struct page *dest_page,
	534	unsigned long start_byte,
	535	size_t srclen, size_t destlen)
	536	{
	537	int ret = 0;
	538	int wbits = MAX_WBITS;
	539	struct workspace *workspace;
	540	unsigned long bytes_left = destlen;
	541	unsigned long total_out = 0;
	542	char *kaddr;
	543
	544	if (destlen > PAGE_CACHE_SIZE)
	545	return -ENOMEM;
	546
	547	workspace = find_zlib_workspace();
60f2e8f8	548	if (IS_ERR(workspace))
c8b97818 CM	549	return -ENOMEM;
	550
	551	workspace->inf_strm.next_in = data_in;
	552	workspace->inf_strm.avail_in = srclen;
	553	workspace->inf_strm.total_in = 0;
	554
	555	workspace->inf_strm.next_out = workspace->buf;
	556	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	557	workspace->inf_strm.total_out = 0;
	558	/* If it's deflate, and it's got no preset dictionary, then
	559	we can tell zlib to skip the adler32 check. */
	560	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	561	((data_in[0] & 0x0f) == Z_DEFLATED) &&
	562	!(((data_in[0]<<8) + data_in[1]) % 31)) {
	563
	564	wbits = -((data_in[0] >> 4) + 8);
	565	workspace->inf_strm.next_in += 2;
	566	workspace->inf_strm.avail_in -= 2;
	567	}
	568
	569	if (Z_OK != zlib_inflateInit2(&workspace->inf_strm, wbits)) {
	570	printk(KERN_WARNING "inflateInit failed\n");
	571	ret = -1;
	572	goto out;
	573	}
	574
d397712b	575	while (bytes_left > 0) {
c8b97818 CM	576	unsigned long buf_start;
	577	unsigned long buf_offset;
	578	unsigned long bytes;
	579	unsigned long pg_offset = 0;
	580
	581	ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);
d397712b	582	if (ret != Z_OK && ret != Z_STREAM_END)
c8b97818	583	break;
c8b97818 CM	584
	585	buf_start = total_out;
	586	total_out = workspace->inf_strm.total_out;
	587
	588	if (total_out == buf_start) {
	589	ret = -1;
	590	break;
	591	}
	592
d397712b	593	if (total_out <= start_byte)
c8b97818	594	goto next;
c8b97818	595
d397712b	596	if (total_out > start_byte && buf_start < start_byte)
c8b97818	597	buf_offset = start_byte - buf_start;
d397712b	598	else
c8b97818	599	buf_offset = 0;
c8b97818 CM	600
	601	bytes = min(PAGE_CACHE_SIZE - pg_offset,
	602	PAGE_CACHE_SIZE - buf_offset);
	603	bytes = min(bytes, bytes_left);
	604
	605	kaddr = kmap_atomic(dest_page, KM_USER0);
	606	memcpy(kaddr + pg_offset, workspace->buf + buf_offset, bytes);
	607	kunmap_atomic(kaddr, KM_USER0);
	608
	609	pg_offset += bytes;
	610	bytes_left -= bytes;
	611	next:
	612	workspace->inf_strm.next_out = workspace->buf;
	613	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;
	614	}
d397712b CM	615
d397712b CM	616	if (ret != Z_STREAM_END && bytes_left != 0)
c8b97818	617	ret = -1;
d397712b	618	else
c8b97818	619	ret = 0;
d397712b	620
c8b97818 CM	621	zlib_inflateEnd(&workspace->inf_strm);
	622	out:
	623	free_workspace(workspace);
	624	return ret;
	625	}
	626
	627	void btrfs_zlib_exit(void)
	628	{
	629	free_workspaces();
	630	}