[mirror_ubuntu-artful-kernel.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/mm.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 <linux/refcount.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);

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

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

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

	workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
	workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
	workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
	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(const 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,
			      struct page **pages,
			      unsigned long *out_pages,
			      unsigned long *total_in,
			      unsigned long *total_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;
	unsigned long len = *total_out;
	unsigned long nr_dest_pages = *out_pages;
	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
	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) {
			pr_debug("BTRFS: lzo 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) {
		ret = -E2BIG;
		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_bio(struct list_head *ws, struct compressed_bio *cb)
{
	struct workspace *workspace = list_entry(ws, struct workspace, list);
	int ret = 0, ret2;
	char *data_in;
	unsigned long page_in_index = 0;
	size_t srclen = cb->compressed_len;
	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;
	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;
	struct page **pages_in = cb->compressed_pages;
	u64 disk_start = cb->start;
	struct bio *orig_bio = cb->orig_bio;

	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;

	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) {
			pr_warn("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, orig_bio);
		if (ret2 == 0)
			break;
	}
done:
	kunmap(pages_in[page_in_index]);
	if (!ret)
		zero_fill_bio(orig_bio);
	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) {
		pr_warn("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_bio		= lzo_decompress_bio,
	.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>
6acafd1e	21	#include <linux/mm.h>
a6fa6fae LZ	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>
e1ddce71	28	#include <linux/refcount.h>
a6fa6fae LZ	29	#include "compression.h"
	30
	31	#define LZO_LEN 4
	32
	33	struct workspace {
	34	void *mem;
3fb40375 JL	35	void buf; / where decompressed data goes */
3fb40375 JL	36	void cbuf; / where compressed data goes */
a6fa6fae LZ	37	struct list_head list;
	38	};
	39
	40	static void lzo_free_workspace(struct list_head *ws)
	41	{
	42	struct workspace *workspace = list_entry(ws, struct workspace, list);
	43
6acafd1e DS	44	kvfree(workspace->buf);
	45	kvfree(workspace->cbuf);
	46	kvfree(workspace->mem);
a6fa6fae LZ	47	kfree(workspace);
	48	}
	49
	50	static struct list_head *lzo_alloc_workspace(void)
	51	{
	52	struct workspace *workspace;
	53
389a6cfc	54	workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
a6fa6fae LZ	55	if (!workspace)
	56	return ERR_PTR(-ENOMEM);
	57
6acafd1e DS	58	workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
	59	workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
	60	workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
a6fa6fae LZ	61	if (!workspace->mem \|\| !workspace->buf \|\| !workspace->cbuf)
	62	goto fail;
	63
	64	INIT_LIST_HEAD(&workspace->list);
	65
	66	return &workspace->list;
	67	fail:
	68	lzo_free_workspace(&workspace->list);
	69	return ERR_PTR(-ENOMEM);
	70	}
	71
	72	static inline void write_compress_length(char *buf, size_t len)
	73	{
	74	__le32 dlen;
	75
	76	dlen = cpu_to_le32(len);
	77	memcpy(buf, &dlen, LZO_LEN);
	78	}
	79
14a3357b	80	static inline size_t read_compress_length(const char *buf)
a6fa6fae LZ	81	{
	82	__le32 dlen;
	83
	84	memcpy(&dlen, buf, LZO_LEN);
	85	return le32_to_cpu(dlen);
	86	}
	87
	88	static int lzo_compress_pages(struct list_head *ws,
	89	struct address_space *mapping,
38c31464	90	u64 start,
a6fa6fae	91	struct page **pages,
a6fa6fae LZ	92	unsigned long *out_pages,
a6fa6fae LZ	93	unsigned long *total_in,
e5d74902	94	unsigned long *total_out)
a6fa6fae LZ	95	{
	96	struct workspace *workspace = list_entry(ws, struct workspace, list);
	97	int ret = 0;
	98	char *data_in;
	99	char *cpage_out;
	100	int nr_pages = 0;
	101	struct page *in_page = NULL;
	102	struct page *out_page = NULL;
	103	unsigned long bytes_left;
38c31464	104	unsigned long len = *total_out;
4d3a800e	105	unsigned long nr_dest_pages = *out_pages;
e5d74902	106	const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
a6fa6fae LZ	107	size_t in_len;
	108	size_t out_len;
	109	char *buf;
	110	unsigned long tot_in = 0;
	111	unsigned long tot_out = 0;
	112	unsigned long pg_bytes_left;
	113	unsigned long out_offset;
	114	unsigned long bytes;
	115
	116	*out_pages = 0;
	117	*total_out = 0;
	118	*total_in = 0;
	119
09cbfeaf	120	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
a6fa6fae LZ	121	data_in = kmap(in_page);
	122
	123	/*
	124	* store the size of all chunks of compressed data in
	125	* the first 4 bytes
	126	*/
	127	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	128	if (out_page == NULL) {
	129	ret = -ENOMEM;
	130	goto out;
	131	}
	132	cpage_out = kmap(out_page);
	133	out_offset = LZO_LEN;
	134	tot_out = LZO_LEN;
	135	pages[0] = out_page;
	136	nr_pages = 1;
09cbfeaf	137	pg_bytes_left = PAGE_SIZE - LZO_LEN;
a6fa6fae LZ	138
a6fa6fae LZ	139	/* compress at most one page of data each time */
09cbfeaf	140	in_len = min(len, PAGE_SIZE);
a6fa6fae LZ	141	while (tot_in < len) {
	142	ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
	143	&out_len, workspace->mem);
	144	if (ret != LZO_E_OK) {
036b0217	145	pr_debug("BTRFS: lzo in loop returned %d\n",
a6fa6fae	146	ret);
60e1975a	147	ret = -EIO;
a6fa6fae LZ	148	goto out;
	149	}
	150
	151	/* store the size of this chunk of compressed data */
	152	write_compress_length(cpage_out + out_offset, out_len);
	153	tot_out += LZO_LEN;
	154	out_offset += LZO_LEN;
	155	pg_bytes_left -= LZO_LEN;
	156
	157	tot_in += in_len;
	158	tot_out += out_len;
	159
	160	/* copy bytes from the working buffer into the pages */
	161	buf = workspace->cbuf;
	162	while (out_len) {
	163	bytes = min_t(unsigned long, pg_bytes_left, out_len);
	164
	165	memcpy(cpage_out + out_offset, buf, bytes);
	166
	167	out_len -= bytes;
	168	pg_bytes_left -= bytes;
	169	buf += bytes;
	170	out_offset += bytes;
	171
	172	/*
	173	* we need another page for writing out.
	174	*
	175	* Note if there's less than 4 bytes left, we just
	176	* skip to a new page.
	177	*/
	178	if ((out_len == 0 && pg_bytes_left < LZO_LEN) \|\|
	179	pg_bytes_left == 0) {
	180	if (pg_bytes_left) {
	181	memset(cpage_out + out_offset, 0,
	182	pg_bytes_left);
	183	tot_out += pg_bytes_left;
	184	}
	185
	186	/* we're done, don't allocate new page */
	187	if (out_len == 0 && tot_in >= len)
	188	break;
	189
	190	kunmap(out_page);
	191	if (nr_pages == nr_dest_pages) {
	192	out_page = NULL;
60e1975a	193	ret = -E2BIG;
a6fa6fae LZ	194	goto out;
	195	}
	196
	197	out_page = alloc_page(GFP_NOFS \| __GFP_HIGHMEM);
	198	if (out_page == NULL) {
	199	ret = -ENOMEM;
	200	goto out;
	201	}
	202	cpage_out = kmap(out_page);
	203	pages[nr_pages++] = out_page;
	204
09cbfeaf	205	pg_bytes_left = PAGE_SIZE;
a6fa6fae LZ	206	out_offset = 0;
	207	}
	208	}
	209
	210	/* we're making it bigger, give up */
59516f60	211	if (tot_in > 8192 && tot_in < tot_out) {
60e1975a	212	ret = -E2BIG;
a6fa6fae	213	goto out;
59516f60	214	}
a6fa6fae LZ	215
	216	/* we're all done */
	217	if (tot_in >= len)
	218	break;
	219
	220	if (tot_out > max_out)
	221	break;
	222
	223	bytes_left = len - tot_in;
	224	kunmap(in_page);
09cbfeaf	225	put_page(in_page);
a6fa6fae	226
09cbfeaf KS	227	start += PAGE_SIZE;
09cbfeaf KS	228	in_page = find_get_page(mapping, start >> PAGE_SHIFT);
a6fa6fae	229	data_in = kmap(in_page);
09cbfeaf	230	in_len = min(bytes_left, PAGE_SIZE);
a6fa6fae LZ	231	}
a6fa6fae LZ	232
1e9d7291 TT	233	if (tot_out >= tot_in) {
1e9d7291 TT	234	ret = -E2BIG;
a6fa6fae	235	goto out;
1e9d7291	236	}
a6fa6fae LZ	237
	238	/* store the size of all chunks of compressed data */
	239	cpage_out = kmap(pages[0]);
	240	write_compress_length(cpage_out, tot_out);
	241
	242	kunmap(pages[0]);
	243
	244	ret = 0;
	245	*total_out = tot_out;
	246	*total_in = tot_in;
	247	out:
	248	*out_pages = nr_pages;
	249	if (out_page)
	250	kunmap(out_page);
	251
	252	if (in_page) {
	253	kunmap(in_page);
09cbfeaf	254	put_page(in_page);
a6fa6fae LZ	255	}
	256
	257	return ret;
	258	}
	259
e1ddce71	260	static int lzo_decompress_bio(struct list_head ws, struct compressed_bio cb)
a6fa6fae LZ	261	{
a6fa6fae LZ	262	struct workspace *workspace = list_entry(ws, struct workspace, list);
3a39c18d	263	int ret = 0, ret2;
a6fa6fae	264	char *data_in;
a6fa6fae	265	unsigned long page_in_index = 0;
e1ddce71	266	size_t srclen = cb->compressed_len;
09cbfeaf	267	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
a6fa6fae LZ	268	unsigned long buf_start;
	269	unsigned long buf_offset = 0;
	270	unsigned long bytes;
	271	unsigned long working_bytes;
a6fa6fae LZ	272	size_t in_len;
	273	size_t out_len;
	274	unsigned long in_offset;
	275	unsigned long in_page_bytes_left;
	276	unsigned long tot_in;
	277	unsigned long tot_out;
	278	unsigned long tot_len;
	279	char *buf;
ca9b688c	280	bool may_late_unmap, need_unmap;
e1ddce71 AJ	281	struct page **pages_in = cb->compressed_pages;
	282	u64 disk_start = cb->start;
	283	struct bio *orig_bio = cb->orig_bio;
a6fa6fae LZ	284
	285	data_in = kmap(pages_in[0]);
	286	tot_len = read_compress_length(data_in);
	287
	288	tot_in = LZO_LEN;
	289	in_offset = LZO_LEN;
	290	tot_len = min_t(size_t, srclen, tot_len);
09cbfeaf	291	in_page_bytes_left = PAGE_SIZE - LZO_LEN;
a6fa6fae LZ	292
a6fa6fae LZ	293	tot_out = 0;
a6fa6fae LZ	294
	295	while (tot_in < tot_len) {
	296	in_len = read_compress_length(data_in + in_offset);
	297	in_page_bytes_left -= LZO_LEN;
	298	in_offset += LZO_LEN;
	299	tot_in += LZO_LEN;
	300
	301	tot_in += in_len;
	302	working_bytes = in_len;
ca9b688c	303	may_late_unmap = need_unmap = false;
a6fa6fae LZ	304
	305	/* fast path: avoid using the working buffer */
	306	if (in_page_bytes_left >= in_len) {
	307	buf = data_in + in_offset;
	308	bytes = in_len;
ca9b688c	309	may_late_unmap = true;
a6fa6fae LZ	310	goto cont;
	311	}
	312
	313	/* copy bytes from the pages into the working buffer */
	314	buf = workspace->cbuf;
	315	buf_offset = 0;
	316	while (working_bytes) {
	317	bytes = min(working_bytes, in_page_bytes_left);
	318
	319	memcpy(buf + buf_offset, data_in + in_offset, bytes);
	320	buf_offset += bytes;
	321	cont:
	322	working_bytes -= bytes;
	323	in_page_bytes_left -= bytes;
	324	in_offset += bytes;
	325
	326	/* check if we need to pick another page */
	327	if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
	328	\|\| in_page_bytes_left == 0) {
	329	tot_in += in_page_bytes_left;
	330
	331	if (working_bytes == 0 && tot_in >= tot_len)
	332	break;
	333
ca9b688c	334	if (page_in_index + 1 >= total_pages_in) {
60e1975a	335	ret = -EIO;
a6fa6fae LZ	336	goto done;
a6fa6fae LZ	337	}
ca9b688c LZ	338
	339	if (may_late_unmap)
	340	need_unmap = true;
	341	else
	342	kunmap(pages_in[page_in_index]);
	343
	344	data_in = kmap(pages_in[++page_in_index]);
a6fa6fae	345
09cbfeaf	346	in_page_bytes_left = PAGE_SIZE;
a6fa6fae LZ	347	in_offset = 0;
	348	}
	349	}
	350
09cbfeaf	351	out_len = lzo1x_worst_compress(PAGE_SIZE);
a6fa6fae LZ	352	ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
a6fa6fae LZ	353	&out_len);
ca9b688c LZ	354	if (need_unmap)
ca9b688c LZ	355	kunmap(pages_in[page_in_index - 1]);
a6fa6fae	356	if (ret != LZO_E_OK) {
62e85577	357	pr_warn("BTRFS: decompress failed\n");
60e1975a	358	ret = -EIO;
a6fa6fae LZ	359	break;
	360	}
	361
a6fa6fae	362	buf_start = tot_out;
a6fa6fae LZ	363	tot_out += out_len;
a6fa6fae LZ	364
3a39c18d	365	ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
974b1adc	366	tot_out, disk_start, orig_bio);
3a39c18d	367	if (ret2 == 0)
a6fa6fae	368	break;
a6fa6fae LZ	369	}
a6fa6fae LZ	370	done:
ca9b688c	371	kunmap(pages_in[page_in_index]);
2f19cad9	372	if (!ret)
974b1adc	373	zero_fill_bio(orig_bio);
a6fa6fae LZ	374	return ret;
	375	}
	376
	377	static int lzo_decompress(struct list_head ws, unsigned char data_in,
	378	struct page *dest_page,
	379	unsigned long start_byte,
	380	size_t srclen, size_t destlen)
	381	{
	382	struct workspace *workspace = list_entry(ws, struct workspace, list);
	383	size_t in_len;
	384	size_t out_len;
	385	size_t tot_len;
	386	int ret = 0;
	387	char *kaddr;
	388	unsigned long bytes;
	389
	390	BUG_ON(srclen < LZO_LEN);
	391
	392	tot_len = read_compress_length(data_in);
	393	data_in += LZO_LEN;
	394
	395	in_len = read_compress_length(data_in);
	396	data_in += LZO_LEN;
	397
09cbfeaf	398	out_len = PAGE_SIZE;
a6fa6fae LZ	399	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
a6fa6fae LZ	400	if (ret != LZO_E_OK) {
62e85577	401	pr_warn("BTRFS: decompress failed!\n");
60e1975a	402	ret = -EIO;
a6fa6fae LZ	403	goto out;
	404	}
	405
	406	if (out_len < start_byte) {
60e1975a	407	ret = -EIO;
a6fa6fae LZ	408	goto out;
	409	}
	410
2f19cad9 CM	411	/*
	412	* the caller is already checking against PAGE_SIZE, but lets
	413	* move this check closer to the memcpy/memset
	414	*/
	415	destlen = min_t(unsigned long, destlen, PAGE_SIZE);
a6fa6fae LZ	416	bytes = min_t(unsigned long, destlen, out_len - start_byte);
a6fa6fae LZ	417
7ac687d9	418	kaddr = kmap_atomic(dest_page);
a6fa6fae	419	memcpy(kaddr, workspace->buf + start_byte, bytes);
2f19cad9 CM	420
	421	/*
	422	* btrfs_getblock is doing a zero on the tail of the page too,
	423	* but this will cover anything missing from the decompressed
	424	* data.
	425	*/
	426	if (bytes < destlen)
	427	memset(kaddr+bytes, 0, destlen-bytes);
7ac687d9	428	kunmap_atomic(kaddr);
a6fa6fae LZ	429	out:
	430	return ret;
	431	}
	432
e8c9f186	433	const struct btrfs_compress_op btrfs_lzo_compress = {
a6fa6fae LZ	434	.alloc_workspace = lzo_alloc_workspace,
	435	.free_workspace = lzo_free_workspace,
	436	.compress_pages = lzo_compress_pages,
974b1adc	437	.decompress_bio = lzo_decompress_bio,
a6fa6fae LZ	438	.decompress = lzo_decompress,
a6fa6fae LZ	439	};