[linux-block.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 compressed data goes */
	void *cbuf;	/* where decompressed 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_CACHE_SIZE));
	workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_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_CACHE_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_CACHE_SIZE - LZO_LEN;

	/* compress at most one page of data each time */
	in_len = min(len, PAGE_CACHE_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 = -1;
			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 = -1;
					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_CACHE_SIZE;
				out_offset = 0;
			}
		}

		/* we're making it bigger, give up */
		if (tot_in > 8192 && tot_in < tot_out)
			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);
		page_cache_release(in_page);

		start += PAGE_CACHE_SIZE;
		in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
		data_in = kmap(in_page);
		in_len = min(bytes_left, PAGE_CACHE_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);
		page_cache_release(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;
	char *data_in;
	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 = 0;
	unsigned long bytes;
	unsigned long working_bytes;
	unsigned long pg_offset;
	unsigned long start_byte;
	unsigned long current_buf_start;
	char *kaddr;

	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;

	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_CACHE_SIZE - LZO_LEN;

	tot_out = 0;
	page_out = bvec[0].bv_page;
	page_bytes_left = PAGE_CACHE_SIZE;
	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;

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

				kunmap(pages_in[page_in_index]);
				page_in_index++;
				if (page_in_index >= total_pages_in) {
					ret = -1;
					data_in = NULL;
					goto done;
				}
				data_in = kmap(pages_in[page_in_index]);

				in_page_bytes_left = PAGE_CACHE_SIZE;
				in_offset = 0;
			}
		}

		out_len = lzo1x_worst_compress(PAGE_CACHE_SIZE);
		ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
					    &out_len);
		if (ret != LZO_E_OK) {
			printk(KERN_WARNING "btrfs decompress failed\n");
			ret = -1;
			break;
		}

		/*
		 * buf start is the byte offset we're of the start of
		 * our workspace buffer
		 */
		buf_start = tot_out;

		/* tot_out is the last byte of the workspace buffer */
		tot_out += out_len;

		working_bytes = tot_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
			 */
			break;
		}

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

		/*
		 * the start of the data we care about is offset into
		 * the middle of our working buffer
		 */
		if (tot_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 (tot_out <= start_byte)
					break;

				/* 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 (tot_out > start_byte &&
				    current_buf_start < start_byte) {
					buf_offset = start_byte - buf_start;
					working_bytes = tot_out - start_byte;
					current_buf_start = buf_start +
						buf_offset;
				}
			}
		}
	}
done:
	if (data_in)
		kunmap(pages_in[page_in_index]);
	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_CACHE_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 = -1;
		goto out;
	}

	if (out_len < start_byte) {
		ret = -1;
		goto out;
	}

	bytes = min_t(unsigned long, destlen, out_len - start_byte);

	kaddr = kmap_atomic(dest_page, KM_USER0);
	memcpy(kaddr, workspace->buf + start_byte, bytes);
	kunmap_atomic(kaddr, KM_USER0);
out:
	return ret;
}

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;
	34	void buf; / where compressed data goes */
	35	void cbuf; / where decompressed data goes */
	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);
	58	workspace->buf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));
	59	workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_CACHE_SIZE));
	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
119	in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
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;
136	pg_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
137
138	/* compress at most one page of data each time */
139	in_len = min(len, PAGE_CACHE_SIZE);
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) {
144	printk(KERN_DEBUG "btrfs deflate in loop returned %d\n",
145	ret);
146	ret = -1;
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;
192	ret = -1;
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
204	pg_bytes_left = PAGE_CACHE_SIZE;
205	out_offset = 0;
206	}
207	}
208
209	/* we're making it bigger, give up */
210	if (tot_in > 8192 && tot_in < tot_out)
211	goto out;
212
213	/* we're all done */
214	if (tot_in >= len)
215	break;
216
217	if (tot_out > max_out)
218	break;
219
220	bytes_left = len - tot_in;
221	kunmap(in_page);
222	page_cache_release(in_page);
223
224	start += PAGE_CACHE_SIZE;
225	in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
226	data_in = kmap(in_page);
227	in_len = min(bytes_left, PAGE_CACHE_SIZE);
228	}
229
230	if (tot_out > tot_in)
231	goto out;
232
233	/* store the size of all chunks of compressed data */
234	cpage_out = kmap(pages[0]);
235	write_compress_length(cpage_out, tot_out);
236
237	kunmap(pages[0]);
238
239	ret = 0;
240	*total_out = tot_out;
241	*total_in = tot_in;
242	out:
243	*out_pages = nr_pages;
244	if (out_page)
245	kunmap(out_page);
246
247	if (in_page) {
248	kunmap(in_page);
249	page_cache_release(in_page);
250	}
251
252	return ret;
253	}
254
255	static int lzo_decompress_biovec(struct list_head *ws,
256	struct page **pages_in,
257	u64 disk_start,
258	struct bio_vec *bvec,
259	int vcnt,
260	size_t srclen)
261	{
262	struct workspace *workspace = list_entry(ws, struct workspace, list);
263	int ret = 0;
264	char *data_in;
265	unsigned long page_bytes_left;
266	unsigned long page_in_index = 0;
267	unsigned long page_out_index = 0;
268	struct page *page_out;
269	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
270	PAGE_CACHE_SIZE;
271	unsigned long buf_start;
272	unsigned long buf_offset = 0;
273	unsigned long bytes;
274	unsigned long working_bytes;
275	unsigned long pg_offset;
276	unsigned long start_byte;
277	unsigned long current_buf_start;
278	char *kaddr;
279
280	size_t in_len;
281	size_t out_len;
282	unsigned long in_offset;
283	unsigned long in_page_bytes_left;
284	unsigned long tot_in;
285	unsigned long tot_out;
286	unsigned long tot_len;
287	char *buf;
288
289	data_in = kmap(pages_in[0]);
290	tot_len = read_compress_length(data_in);
291
292	tot_in = LZO_LEN;
293	in_offset = LZO_LEN;
294	tot_len = min_t(size_t, srclen, tot_len);
295	in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
296
297	tot_out = 0;
298	page_out = bvec[0].bv_page;
299	page_bytes_left = PAGE_CACHE_SIZE;
300	pg_offset = 0;
301
302	while (tot_in < tot_len) {
303	in_len = read_compress_length(data_in + in_offset);
304	in_page_bytes_left -= LZO_LEN;
305	in_offset += LZO_LEN;
306	tot_in += LZO_LEN;
307
308	tot_in += in_len;
309	working_bytes = in_len;
310
311	/* fast path: avoid using the working buffer */
312	if (in_page_bytes_left >= in_len) {
313	buf = data_in + in_offset;
314	bytes = in_len;
315	goto cont;
316	}
317
318	/* copy bytes from the pages into the working buffer */
319	buf = workspace->cbuf;
320	buf_offset = 0;
321	while (working_bytes) {
322	bytes = min(working_bytes, in_page_bytes_left);
323
324	memcpy(buf + buf_offset, data_in + in_offset, bytes);
325	buf_offset += bytes;
326	cont:
327	working_bytes -= bytes;
328	in_page_bytes_left -= bytes;
329	in_offset += bytes;
330
331	/* check if we need to pick another page */
332	if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
333	\|\| in_page_bytes_left == 0) {
334	tot_in += in_page_bytes_left;
335
336	if (working_bytes == 0 && tot_in >= tot_len)
337	break;
338
339	kunmap(pages_in[page_in_index]);
340	page_in_index++;
341	if (page_in_index >= total_pages_in) {
342	ret = -1;
343	data_in = NULL;
344	goto done;
345	}
346	data_in = kmap(pages_in[page_in_index]);
347
348	in_page_bytes_left = PAGE_CACHE_SIZE;
349	in_offset = 0;
350	}
351	}
352
353	out_len = lzo1x_worst_compress(PAGE_CACHE_SIZE);
354	ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
355	&out_len);
356	if (ret != LZO_E_OK) {
357	printk(KERN_WARNING "btrfs decompress failed\n");
358	ret = -1;
359	break;
360	}
361
362	/*
363	* buf start is the byte offset we're of the start of
364	* our workspace buffer
365	*/
366	buf_start = tot_out;
367
368	/* tot_out is the last byte of the workspace buffer */
369	tot_out += out_len;
370
371	working_bytes = tot_out - buf_start;
372
373	/*
374	* start_byte is the first byte of the page we're currently
375	* copying into relative to the start of the compressed data.
376	*/
377	start_byte = page_offset(page_out) - disk_start;
378
379	if (working_bytes == 0) {
380	/* we didn't make progress in this inflate
381	* call, we're done
382	*/
383	break;
384	}
385
386	/* we haven't yet hit data corresponding to this page */
387	if (tot_out <= start_byte)
388	continue;
389
390	/*
391	* the start of the data we care about is offset into
392	* the middle of our working buffer
393	*/
394	if (tot_out > start_byte && buf_start < start_byte) {
395	buf_offset = start_byte - buf_start;
396	working_bytes -= buf_offset;
397	} else {
398	buf_offset = 0;
399	}
400	current_buf_start = buf_start;
401
402	/* copy bytes from the working buffer into the pages */
403	while (working_bytes > 0) {
404	bytes = min(PAGE_CACHE_SIZE - pg_offset,
405	PAGE_CACHE_SIZE - buf_offset);
406	bytes = min(bytes, working_bytes);
407	kaddr = kmap_atomic(page_out, KM_USER0);
408	memcpy(kaddr + pg_offset, workspace->buf + buf_offset,
409	bytes);
410	kunmap_atomic(kaddr, KM_USER0);
411	flush_dcache_page(page_out);
412
413	pg_offset += bytes;
414	page_bytes_left -= bytes;
415	buf_offset += bytes;
416	working_bytes -= bytes;
417	current_buf_start += bytes;
418
419	/* check if we need to pick another page */
420	if (page_bytes_left == 0) {
421	page_out_index++;
422	if (page_out_index >= vcnt) {
423	ret = 0;
424	goto done;
425	}
426
427	page_out = bvec[page_out_index].bv_page;
428	pg_offset = 0;
429	page_bytes_left = PAGE_CACHE_SIZE;
430	start_byte = page_offset(page_out) - disk_start;
431
432	/*
433	* make sure our new page is covered by this
434	* working buffer
435	*/
436	if (tot_out <= start_byte)
437	break;
438
439	/* the next page in the biovec might not
440	* be adjacent to the last page, but it
441	* might still be found inside this working
442	* buffer. bump our offset pointer
443	*/
444	if (tot_out > start_byte &&
445	current_buf_start < start_byte) {
446	buf_offset = start_byte - buf_start;
447	working_bytes = tot_out - start_byte;
448	current_buf_start = buf_start +
449	buf_offset;
450	}
451	}
452	}
453	}
454	done:
455	if (data_in)
456	kunmap(pages_in[page_in_index]);
457	return ret;
458	}
459
460	static int lzo_decompress(struct list_head ws, unsigned char data_in,
461	struct page *dest_page,
462	unsigned long start_byte,
463	size_t srclen, size_t destlen)
464	{
465	struct workspace *workspace = list_entry(ws, struct workspace, list);
466	size_t in_len;
467	size_t out_len;
468	size_t tot_len;
469	int ret = 0;
470	char *kaddr;
471	unsigned long bytes;
472
473	BUG_ON(srclen < LZO_LEN);
474
475	tot_len = read_compress_length(data_in);
476	data_in += LZO_LEN;
477
478	in_len = read_compress_length(data_in);
479	data_in += LZO_LEN;
480
481	out_len = PAGE_CACHE_SIZE;
482	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
483	if (ret != LZO_E_OK) {
484	printk(KERN_WARNING "btrfs decompress failed!\n");
485	ret = -1;
486	goto out;
487	}
488
489	if (out_len < start_byte) {
490	ret = -1;
491	goto out;
492	}
493
494	bytes = min_t(unsigned long, destlen, out_len - start_byte);
495
496	kaddr = kmap_atomic(dest_page, KM_USER0);
497	memcpy(kaddr, workspace->buf + start_byte, bytes);
498	kunmap_atomic(kaddr, KM_USER0);
499	out:
500	return ret;
501	}
502
503	struct btrfs_compress_op btrfs_lzo_compress = {
504	.alloc_workspace = lzo_alloc_workspace,
505	.free_workspace = lzo_free_workspace,
506	.compress_pages = lzo_compress_pages,
507	.decompress_biovec = lzo_decompress_biovec,
508	.decompress = lzo_decompress,
509	};