[linux.git] / fs / btrfs / lzo.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.
 */

#include <linux/kernel.h>
#include <linux/slab.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 <linux/lzo.h>
#include "compression.h"

#define LZO_LEN	4

struct workspace {
	void *mem;
	void *buf;	/* where decompressed data goes */
	void *cbuf;	/* where compressed data goes */
	struct list_head list;
};

static void lzo_free_workspace(struct list_head *ws)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);

	vfree(workspace->buf);
	vfree(workspace->cbuf);
	vfree(workspace->mem);
	kfree(workspace);
}

static struct list_head *lzo_alloc_workspace(void)
{
	struct workspace *workspace;

	workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
	if (!workspace)
		return ERR_PTR(-ENOMEM);

	workspace->mem = vmalloc(LZO1X_MEM_COMPRESS);
	workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
	workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
	if (!workspace->mem || !workspace->buf || !workspace->cbuf)
		goto fail;

	INIT_LIST_HEAD(&workspace->list);

	return &workspace->list;
fail:
	lzo_free_workspace(&workspace->list);
	return ERR_PTR(-ENOMEM);
}

static inline void write_compress_length(char *buf, size_t len)
{
	__le32 dlen;

	dlen = cpu_to_le32(len);
	memcpy(buf, &dlen, LZO_LEN);
}

static inline size_t read_compress_length(char *buf)
{
	__le32 dlen;

	memcpy(&dlen, buf, LZO_LEN);
	return le32_to_cpu(dlen);
}

static int lzo_compress_pages(struct list_head *ws,
			      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)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	int ret = 0;
	char *data_in;
	char *cpage_out;
	int nr_pages = 0;
	struct page *in_page = NULL;
	struct page *out_page = NULL;
	unsigned long bytes_left;

	size_t in_len;
	size_t out_len;
	char *buf;
	unsigned long tot_in = 0;
	unsigned long tot_out = 0;
	unsigned long pg_bytes_left;
	unsigned long out_offset;
	unsigned long bytes;

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

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

	/*
	 * store the size of all chunks of compressed data in
	 * the first 4 bytes
	 */
	out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
	if (out_page == NULL) {
		ret = -ENOMEM;
		goto out;
	}
	cpage_out = kmap(out_page);
	out_offset = LZO_LEN;
	tot_out = LZO_LEN;
	pages[0] = out_page;
	nr_pages = 1;
	pg_bytes_left = PAGE_SIZE - LZO_LEN;

	/* compress at most one page of data each time */
	in_len = min(len, PAGE_SIZE);
	while (tot_in < len) {
		ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
				       &out_len, workspace->mem);
		if (ret != LZO_E_OK) {
			printk(KERN_DEBUG "BTRFS: deflate in loop returned %d\n",
			       ret);
			ret = -EIO;
			goto out;
		}

		/* store the size of this chunk of compressed data */
		write_compress_length(cpage_out + out_offset, out_len);
		tot_out += LZO_LEN;
		out_offset += LZO_LEN;
		pg_bytes_left -= LZO_LEN;

		tot_in += in_len;
		tot_out += out_len;

		/* copy bytes from the working buffer into the pages */
		buf = workspace->cbuf;
		while (out_len) {
			bytes = min_t(unsigned long, pg_bytes_left, out_len);

			memcpy(cpage_out + out_offset, buf, bytes);

			out_len -= bytes;
			pg_bytes_left -= bytes;
			buf += bytes;
			out_offset += bytes;

			/*
			 * we need another page for writing out.
			 *
			 * Note if there's less than 4 bytes left, we just
			 * skip to a new page.
			 */
			if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
			    pg_bytes_left == 0) {
				if (pg_bytes_left) {
					memset(cpage_out + out_offset, 0,
					       pg_bytes_left);
					tot_out += pg_bytes_left;
				}

				/* we're done, don't allocate new page */
				if (out_len == 0 && tot_in >= len)
					break;

				kunmap(out_page);
				if (nr_pages == nr_dest_pages) {
					out_page = NULL;
					ret = -E2BIG;
					goto out;
				}

				out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
				if (out_page == NULL) {
					ret = -ENOMEM;
					goto out;
				}
				cpage_out = kmap(out_page);
				pages[nr_pages++] = out_page;

				pg_bytes_left = PAGE_SIZE;
				out_offset = 0;
			}
		}

		/* we're making it bigger, give up */
		if (tot_in > 8192 && tot_in < tot_out) {
			ret = -E2BIG;
			goto out;
		}

		/* we're all done */
		if (tot_in >= len)
			break;

		if (tot_out > max_out)
			break;

		bytes_left = len - tot_in;
		kunmap(in_page);
		put_page(in_page);

		start += PAGE_SIZE;
		in_page = find_get_page(mapping, start >> PAGE_SHIFT);
		data_in = kmap(in_page);
		in_len = min(bytes_left, PAGE_SIZE);
	}

	if (tot_out > tot_in)
		goto out;

	/* store the size of all chunks of compressed data */
	cpage_out = kmap(pages[0]);
	write_compress_length(cpage_out, tot_out);

	kunmap(pages[0]);

	ret = 0;
	*total_out = tot_out;
	*total_in = tot_in;
out:
	*out_pages = nr_pages;
	if (out_page)
		kunmap(out_page);

	if (in_page) {
		kunmap(in_page);
		put_page(in_page);
	}

	return ret;
}

static int lzo_decompress_biovec(struct list_head *ws,
				 struct page **pages_in,
				 u64 disk_start,
				 struct bio_vec *bvec,
				 int vcnt,
				 size_t srclen)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	int ret = 0, ret2;
	char *data_in;
	unsigned long page_in_index = 0;
	unsigned long page_out_index = 0;
	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
	unsigned long buf_start;
	unsigned long buf_offset = 0;
	unsigned long bytes;
	unsigned long working_bytes;
	unsigned long pg_offset;

	size_t in_len;
	size_t out_len;
	unsigned long in_offset;
	unsigned long in_page_bytes_left;
	unsigned long tot_in;
	unsigned long tot_out;
	unsigned long tot_len;
	char *buf;
	bool may_late_unmap, need_unmap;

	data_in = kmap(pages_in[0]);
	tot_len = read_compress_length(data_in);

	tot_in = LZO_LEN;
	in_offset = LZO_LEN;
	tot_len = min_t(size_t, srclen, tot_len);
	in_page_bytes_left = PAGE_SIZE - LZO_LEN;

	tot_out = 0;
	pg_offset = 0;

	while (tot_in < tot_len) {
		in_len = read_compress_length(data_in + in_offset);
		in_page_bytes_left -= LZO_LEN;
		in_offset += LZO_LEN;
		tot_in += LZO_LEN;

		tot_in += in_len;
		working_bytes = in_len;
		may_late_unmap = need_unmap = false;

		/* fast path: avoid using the working buffer */
		if (in_page_bytes_left >= in_len) {
			buf = data_in + in_offset;
			bytes = in_len;
			may_late_unmap = true;
			goto cont;
		}

		/* copy bytes from the pages into the working buffer */
		buf = workspace->cbuf;
		buf_offset = 0;
		while (working_bytes) {
			bytes = min(working_bytes, in_page_bytes_left);

			memcpy(buf + buf_offset, data_in + in_offset, bytes);
			buf_offset += bytes;
cont:
			working_bytes -= bytes;
			in_page_bytes_left -= bytes;
			in_offset += bytes;

			/* check if we need to pick another page */
			if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
			    || in_page_bytes_left == 0) {
				tot_in += in_page_bytes_left;

				if (working_bytes == 0 && tot_in >= tot_len)
					break;

				if (page_in_index + 1 >= total_pages_in) {
					ret = -EIO;
					goto done;
				}

				if (may_late_unmap)
					need_unmap = true;
				else
					kunmap(pages_in[page_in_index]);

				data_in = kmap(pages_in[++page_in_index]);

				in_page_bytes_left = PAGE_SIZE;
				in_offset = 0;
			}
		}

		out_len = lzo1x_worst_compress(PAGE_SIZE);
		ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
					    &out_len);
		if (need_unmap)
			kunmap(pages_in[page_in_index - 1]);
		if (ret != LZO_E_OK) {
			printk(KERN_WARNING "BTRFS: decompress failed\n");
			ret = -EIO;
			break;
		}

		buf_start = tot_out;
		tot_out += out_len;

		ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
						 tot_out, disk_start,
						 bvec, vcnt,
						 &page_out_index, &pg_offset);
		if (ret2 == 0)
			break;
	}
done:
	kunmap(pages_in[page_in_index]);
	if (!ret)
		btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset);
	return ret;
}

static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
			  struct page *dest_page,
			  unsigned long start_byte,
			  size_t srclen, size_t destlen)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	size_t in_len;
	size_t out_len;
	size_t tot_len;
	int ret = 0;
	char *kaddr;
	unsigned long bytes;

	BUG_ON(srclen < LZO_LEN);

	tot_len = read_compress_length(data_in);
	data_in += LZO_LEN;

	in_len = read_compress_length(data_in);
	data_in += LZO_LEN;

	out_len = PAGE_SIZE;
	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
	if (ret != LZO_E_OK) {
		printk(KERN_WARNING "BTRFS: decompress failed!\n");
		ret = -EIO;
		goto out;
	}

	if (out_len < start_byte) {
		ret = -EIO;
		goto out;
	}

	/*
	 * the caller is already checking against PAGE_SIZE, but lets
	 * move this check closer to the memcpy/memset
	 */
	destlen = min_t(unsigned long, destlen, PAGE_SIZE);
	bytes = min_t(unsigned long, destlen, out_len - start_byte);

	kaddr = kmap_atomic(dest_page);
	memcpy(kaddr, workspace->buf + start_byte, bytes);

	/*
	 * btrfs_getblock is doing a zero on the tail of the page too,
	 * but this will cover anything missing from the decompressed
	 * data.
	 */
	if (bytes < destlen)
		memset(kaddr+bytes, 0, destlen-bytes);
	kunmap_atomic(kaddr);
out:
	return ret;
}

const struct btrfs_compress_op btrfs_lzo_compress = {
	.alloc_workspace	= lzo_alloc_workspace,
	.free_workspace		= lzo_free_workspace,
	.compress_pages		= lzo_compress_pages,
	.decompress_biovec	= lzo_decompress_biovec,
	.decompress		= lzo_decompress,
};
Commit	Line	Data
a6fa6fae LZ	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
	19	#include <linux/kernel.h>
	20	#include <linux/slab.h>
	21	#include <linux/vmalloc.h>
	22	#include <linux/init.h>
	23	#include <linux/err.h>
	24	#include <linux/sched.h>
	25	#include <linux/pagemap.h>
	26	#include <linux/bio.h>
	27	#include <linux/lzo.h>
	28	#include "compression.h"
	29
	30	#define LZO_LEN 4
	31
	32	struct workspace {
	33	void *mem;
3fb40375 JL	34	void buf; / where decompressed data goes */
3fb40375 JL	35	void cbuf; / where compressed data goes */
a6fa6fae LZ	36	struct list_head list;
	37	};
	38
	39	static void lzo_free_workspace(struct list_head *ws)
	40	{
	41	struct workspace *workspace = list_entry(ws, struct workspace, list);
	42
	43	vfree(workspace->buf);
	44	vfree(workspace->cbuf);
	45	vfree(workspace->mem);
	46	kfree(workspace);
	47	}
	48
	49	static struct list_head *lzo_alloc_workspace(void)
	50	{
	51	struct workspace *workspace;
	52
	53	workspace = kzalloc(sizeof(*workspace), GFP_NOFS);
	54	if (!workspace)
	55	return ERR_PTR(-ENOMEM);
	56
	57	workspace->mem = vmalloc(LZO1X_MEM_COMPRESS);
09cbfeaf KS	58	workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
09cbfeaf KS	59	workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_SIZE));
a6fa6fae LZ	60	if (!workspace->mem \|\| !workspace->buf \|\| !workspace->cbuf)
	61	goto fail;
	62
	63	INIT_LIST_HEAD(&workspace->list);
	64
	65	return &workspace->list;
	66	fail:
	67	lzo_free_workspace(&workspace->list);
	68	return ERR_PTR(-ENOMEM);
	69	}
	70
	71	static inline void write_compress_length(char *buf, size_t len)
	72	{
	73	__le32 dlen;
	74
	75	dlen = cpu_to_le32(len);
	76	memcpy(buf, &dlen, LZO_LEN);
	77	}
	78
	79	static inline size_t read_compress_length(char *buf)
	80	{
	81	__le32 dlen;
	82
	83	memcpy(&dlen, buf, LZO_LEN);
	84	return le32_to_cpu(dlen);
	85	}
	86
	87	static int lzo_compress_pages(struct list_head *ws,
	88	struct address_space *mapping,
	89	u64 start, unsigned long len,
	90	struct page **pages,
	91	unsigned long nr_dest_pages,
	92	unsigned long *out_pages,
	93	unsigned long *total_in,
	94	unsigned long *total_out,
	95	unsigned long max_out)
	96	{
	97	struct workspace *workspace = list_entry(ws, struct workspace, list);
	98	int ret = 0;
	99	char *data_in;
	100	char *cpage_out;
	101	int nr_pages = 0;
	102	struct page *in_page = NULL;
	103	struct page *out_page = NULL;
	104	unsigned long bytes_left;
	105
	106	size_t in_len;
	107	size_t out_len;
	108	char *buf;
	109	unsigned long tot_in = 0;
	110	unsigned long tot_out = 0;
	111	unsigned long pg_bytes_left;
	112	unsigned long out_offset;
	113	unsigned long bytes;
	114
	115	*out_pages = 0;
	116	*total_out = 0;
	117	*total_in = 0;
	118
09cbfeaf	119	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
a6fa6fae LZ	120	data_in = kmap(in_page);
	121
	122	/*
	123	* store the size of all chunks of compressed data in
	124	* the first 4 bytes
	125	*/
	126	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	127	if (out_page == NULL) {
	128	ret = -ENOMEM;
	129	goto out;
	130	}
	131	cpage_out = kmap(out_page);
	132	out_offset = LZO_LEN;
	133	tot_out = LZO_LEN;
	134	pages[0] = out_page;
	135	nr_pages = 1;
09cbfeaf	136	pg_bytes_left = PAGE_SIZE - LZO_LEN;
a6fa6fae LZ	137
a6fa6fae LZ	138	/* compress at most one page of data each time */
09cbfeaf	139	in_len = min(len, PAGE_SIZE);
a6fa6fae LZ	140	while (tot_in < len) {
	141	ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
	142	&out_len, workspace->mem);
	143	if (ret != LZO_E_OK) {
efe120a0	144	printk(KERN_DEBUG "BTRFS: deflate in loop returned %d\n",
a6fa6fae	145	ret);
60e1975a	146	ret = -EIO;
a6fa6fae LZ	147	goto out;
	148	}
	149
	150	/* store the size of this chunk of compressed data */
	151	write_compress_length(cpage_out + out_offset, out_len);
	152	tot_out += LZO_LEN;
	153	out_offset += LZO_LEN;
	154	pg_bytes_left -= LZO_LEN;
	155
	156	tot_in += in_len;
	157	tot_out += out_len;
	158
	159	/* copy bytes from the working buffer into the pages */
	160	buf = workspace->cbuf;
	161	while (out_len) {
	162	bytes = min_t(unsigned long, pg_bytes_left, out_len);
	163
	164	memcpy(cpage_out + out_offset, buf, bytes);
	165
	166	out_len -= bytes;
	167	pg_bytes_left -= bytes;
	168	buf += bytes;
	169	out_offset += bytes;
	170
	171	/*
	172	* we need another page for writing out.
	173	*
	174	* Note if there's less than 4 bytes left, we just
	175	* skip to a new page.
	176	*/
	177	if ((out_len == 0 && pg_bytes_left < LZO_LEN) \|\|
	178	pg_bytes_left == 0) {
	179	if (pg_bytes_left) {
	180	memset(cpage_out + out_offset, 0,
	181	pg_bytes_left);
	182	tot_out += pg_bytes_left;
	183	}
	184
	185	/* we're done, don't allocate new page */
	186	if (out_len == 0 && tot_in >= len)
	187	break;
	188
	189	kunmap(out_page);
	190	if (nr_pages == nr_dest_pages) {
	191	out_page = NULL;
60e1975a	192	ret = -E2BIG;
a6fa6fae LZ	193	goto out;
	194	}
	195
	196	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	197	if (out_page == NULL) {
	198	ret = -ENOMEM;
	199	goto out;
	200	}
	201	cpage_out = kmap(out_page);
	202	pages[nr_pages++] = out_page;
	203
09cbfeaf	204	pg_bytes_left = PAGE_SIZE;
a6fa6fae LZ	205	out_offset = 0;
	206	}
	207	}
	208
	209	/* we're making it bigger, give up */
59516f60	210	if (tot_in > 8192 && tot_in < tot_out) {
60e1975a	211	ret = -E2BIG;
a6fa6fae	212	goto out;
59516f60	213	}
a6fa6fae LZ	214
	215	/* we're all done */
	216	if (tot_in >= len)
	217	break;
	218
	219	if (tot_out > max_out)
	220	break;
	221
	222	bytes_left = len - tot_in;
	223	kunmap(in_page);
09cbfeaf	224	put_page(in_page);
a6fa6fae	225
09cbfeaf KS	226	start += PAGE_SIZE;
09cbfeaf KS	227	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
a6fa6fae	228	data_in = kmap(in_page);
09cbfeaf	229	in_len = min(bytes_left, PAGE_SIZE);
a6fa6fae LZ	230	}
	231
	232	if (tot_out > tot_in)
	233	goto out;
	234
	235	/* store the size of all chunks of compressed data */
	236	cpage_out = kmap(pages[0]);
	237	write_compress_length(cpage_out, tot_out);
	238
	239	kunmap(pages[0]);
	240
	241	ret = 0;
	242	*total_out = tot_out;
	243	*total_in = tot_in;
	244	out:
	245	*out_pages = nr_pages;
	246	if (out_page)
	247	kunmap(out_page);
	248
	249	if (in_page) {
	250	kunmap(in_page);
09cbfeaf	251	put_page(in_page);
a6fa6fae LZ	252	}
	253
	254	return ret;
	255	}
	256
	257	static int lzo_decompress_biovec(struct list_head *ws,
	258	struct page **pages_in,
	259	u64 disk_start,
	260	struct bio_vec *bvec,
	261	int vcnt,
	262	size_t srclen)
	263	{
	264	struct workspace *workspace = list_entry(ws, struct workspace, list);
3a39c18d	265	int ret = 0, ret2;
a6fa6fae	266	char *data_in;
a6fa6fae LZ	267	unsigned long page_in_index = 0;
a6fa6fae LZ	268	unsigned long page_out_index = 0;
09cbfeaf	269	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
a6fa6fae LZ	270	unsigned long buf_start;
	271	unsigned long buf_offset = 0;
	272	unsigned long bytes;
	273	unsigned long working_bytes;
	274	unsigned long pg_offset;
a6fa6fae LZ	275
	276	size_t in_len;
	277	size_t out_len;
	278	unsigned long in_offset;
	279	unsigned long in_page_bytes_left;
	280	unsigned long tot_in;
	281	unsigned long tot_out;
	282	unsigned long tot_len;
	283	char *buf;
ca9b688c	284	bool may_late_unmap, need_unmap;
a6fa6fae LZ	285
	286	data_in = kmap(pages_in[0]);
	287	tot_len = read_compress_length(data_in);
	288
	289	tot_in = LZO_LEN;
	290	in_offset = LZO_LEN;
	291	tot_len = min_t(size_t, srclen, tot_len);
09cbfeaf	292	in_page_bytes_left = PAGE_SIZE - LZO_LEN;
a6fa6fae LZ	293
a6fa6fae LZ	294	tot_out = 0;
a6fa6fae LZ	295	pg_offset = 0;
	296
	297	while (tot_in < tot_len) {
	298	in_len = read_compress_length(data_in + in_offset);
	299	in_page_bytes_left -= LZO_LEN;
	300	in_offset += LZO_LEN;
	301	tot_in += LZO_LEN;
	302
	303	tot_in += in_len;
	304	working_bytes = in_len;
ca9b688c	305	may_late_unmap = need_unmap = false;
a6fa6fae LZ	306
	307	/* fast path: avoid using the working buffer */
	308	if (in_page_bytes_left >= in_len) {
	309	buf = data_in + in_offset;
	310	bytes = in_len;
ca9b688c	311	may_late_unmap = true;
a6fa6fae LZ	312	goto cont;
	313	}
	314
	315	/* copy bytes from the pages into the working buffer */
	316	buf = workspace->cbuf;
	317	buf_offset = 0;
	318	while (working_bytes) {
	319	bytes = min(working_bytes, in_page_bytes_left);
	320
	321	memcpy(buf + buf_offset, data_in + in_offset, bytes);
	322	buf_offset += bytes;
	323	cont:
	324	working_bytes -= bytes;
	325	in_page_bytes_left -= bytes;
	326	in_offset += bytes;
	327
	328	/* check if we need to pick another page */
	329	if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
	330	\|\| in_page_bytes_left == 0) {
	331	tot_in += in_page_bytes_left;
	332
	333	if (working_bytes == 0 && tot_in >= tot_len)
	334	break;
	335
ca9b688c	336	if (page_in_index + 1 >= total_pages_in) {
60e1975a	337	ret = -EIO;
a6fa6fae LZ	338	goto done;
a6fa6fae LZ	339	}
ca9b688c LZ	340
	341	if (may_late_unmap)
	342	need_unmap = true;
	343	else
	344	kunmap(pages_in[page_in_index]);
	345
	346	data_in = kmap(pages_in[++page_in_index]);
a6fa6fae	347
09cbfeaf	348	in_page_bytes_left = PAGE_SIZE;
a6fa6fae LZ	349	in_offset = 0;
	350	}
	351	}
	352
09cbfeaf	353	out_len = lzo1x_worst_compress(PAGE_SIZE);
a6fa6fae LZ	354	ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
a6fa6fae LZ	355	&out_len);
ca9b688c LZ	356	if (need_unmap)
ca9b688c LZ	357	kunmap(pages_in[page_in_index - 1]);
a6fa6fae	358	if (ret != LZO_E_OK) {
efe120a0	359	printk(KERN_WARNING "BTRFS: decompress failed\n");
60e1975a	360	ret = -EIO;
a6fa6fae LZ	361	break;
	362	}
	363
a6fa6fae	364	buf_start = tot_out;
a6fa6fae LZ	365	tot_out += out_len;
a6fa6fae LZ	366
3a39c18d LZ	367	ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
	368	tot_out, disk_start,
	369	bvec, vcnt,
	370	&page_out_index, &pg_offset);
	371	if (ret2 == 0)
a6fa6fae	372	break;
a6fa6fae LZ	373	}
a6fa6fae LZ	374	done:
ca9b688c	375	kunmap(pages_in[page_in_index]);
2f19cad9 CM	376	if (!ret)
2f19cad9 CM	377	btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset);
a6fa6fae LZ	378	return ret;
	379	}
	380
	381	static int lzo_decompress(struct list_head ws, unsigned char data_in,
	382	struct page *dest_page,
	383	unsigned long start_byte,
	384	size_t srclen, size_t destlen)
	385	{
	386	struct workspace *workspace = list_entry(ws, struct workspace, list);
	387	size_t in_len;
	388	size_t out_len;
	389	size_t tot_len;
	390	int ret = 0;
	391	char *kaddr;
	392	unsigned long bytes;
	393
	394	BUG_ON(srclen < LZO_LEN);
	395
	396	tot_len = read_compress_length(data_in);
	397	data_in += LZO_LEN;
	398
	399	in_len = read_compress_length(data_in);
	400	data_in += LZO_LEN;
	401
09cbfeaf	402	out_len = PAGE_SIZE;
a6fa6fae LZ	403	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
a6fa6fae LZ	404	if (ret != LZO_E_OK) {
efe120a0	405	printk(KERN_WARNING "BTRFS: decompress failed!\n");
60e1975a	406	ret = -EIO;
a6fa6fae LZ	407	goto out;
	408	}
	409
	410	if (out_len < start_byte) {
60e1975a	411	ret = -EIO;
a6fa6fae LZ	412	goto out;
	413	}
	414
2f19cad9 CM	415	/*
	416	* the caller is already checking against PAGE_SIZE, but lets
	417	* move this check closer to the memcpy/memset
	418	*/
	419	destlen = min_t(unsigned long, destlen, PAGE_SIZE);
a6fa6fae LZ	420	bytes = min_t(unsigned long, destlen, out_len - start_byte);
a6fa6fae LZ	421
7ac687d9	422	kaddr = kmap_atomic(dest_page);
a6fa6fae	423	memcpy(kaddr, workspace->buf + start_byte, bytes);
2f19cad9 CM	424
	425	/*
	426	* btrfs_getblock is doing a zero on the tail of the page too,
	427	* but this will cover anything missing from the decompressed
	428	* data.
	429	*/
	430	if (bytes < destlen)
	431	memset(kaddr+bytes, 0, destlen-bytes);
7ac687d9	432	kunmap_atomic(kaddr);
a6fa6fae LZ	433	out:
	434	return ret;
	435	}
	436
e8c9f186	437	const struct btrfs_compress_op btrfs_lzo_compress = {
a6fa6fae LZ	438	.alloc_workspace = lzo_alloc_workspace,
	439	.free_workspace = lzo_free_workspace,
	440	.compress_pages = lzo_compress_pages,
	441	.decompress_biovec = lzo_decompress_biovec,
	442	.decompress = lzo_decompress,
	443	};