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
32struct workspace {
33	void *mem;
34	void *buf;	/* where decompressed data goes */
35	void *cbuf;	/* where compressed data goes */
36	struct list_head list;
37};
38
39static 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
49static 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;
66fail:
67	lzo_free_workspace(&workspace->list);
68	return ERR_PTR(-ENOMEM);
69}
70
71static 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
79static 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
87static 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 = -EIO;
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 = -E2BIG;
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			ret = -E2BIG;
212			goto out;
213		}
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);
224		page_cache_release(in_page);
225
226		start += PAGE_CACHE_SIZE;
227		in_page = find_get_page(mapping, start >> PAGE_CACHE_SHIFT);
228		data_in = kmap(in_page);
229		in_len = min(bytes_left, PAGE_CACHE_SIZE);
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;
244out:
245	*out_pages = nr_pages;
246	if (out_page)
247		kunmap(out_page);
248
249	if (in_page) {
250		kunmap(in_page);
251		page_cache_release(in_page);
252	}
253
254	return ret;
255}
256
257static 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);
265	int ret = 0, ret2;
266	char *data_in;
267	unsigned long page_in_index = 0;
268	unsigned long page_out_index = 0;
269	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_CACHE_SIZE);
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;
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;
284	bool may_late_unmap, need_unmap;
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);
292	in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;
293
294	tot_out = 0;
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;
305		may_late_unmap = need_unmap = false;
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;
311			may_late_unmap = true;
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;
323cont:
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
336				if (page_in_index + 1 >= total_pages_in) {
337					ret = -EIO;
338					goto done;
339				}
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]);
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 (need_unmap)
357			kunmap(pages_in[page_in_index - 1]);
358		if (ret != LZO_E_OK) {
359			printk(KERN_WARNING "BTRFS: decompress failed\n");
360			ret = -EIO;
361			break;
362		}
363
364		buf_start = tot_out;
365		tot_out += out_len;
366
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)
372			break;
373	}
374done:
375	kunmap(pages_in[page_in_index]);
376	if (!ret)
377		btrfs_clear_biovec_end(bvec, vcnt, page_out_index, pg_offset);
378	return ret;
379}
380
381static 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
402	out_len = PAGE_CACHE_SIZE;
403	ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
404	if (ret != LZO_E_OK) {
405		printk(KERN_WARNING "BTRFS: decompress failed!\n");
406		ret = -EIO;
407		goto out;
408	}
409
410	if (out_len < start_byte) {
411		ret = -EIO;
412		goto out;
413	}
414
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);
420	bytes = min_t(unsigned long, destlen, out_len - start_byte);
421
422	kaddr = kmap_atomic(dest_page);
423	memcpy(kaddr, workspace->buf + start_byte, bytes);
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);
432	kunmap_atomic(kaddr);
433out:
434	return ret;
435}
436
437const struct btrfs_compress_op btrfs_lzo_compress = {
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};
444