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 decompressed data goes */
35 void *cbuf; /* where compressed data goes */
36 struct list_head list;
37 };
38
lzo_free_workspace(struct list_head * ws)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
lzo_alloc_workspace(void)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_SIZE));
59 workspace->cbuf = vmalloc(lzo1x_worst_compress(PAGE_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
write_compress_length(char * buf,size_t len)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
read_compress_length(char * buf)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
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)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_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_SIZE - LZO_LEN;
137
138 /* compress at most one page of data each time */
139 in_len = min(len, PAGE_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 pr_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_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 put_page(in_page);
225
226 start += PAGE_SIZE;
227 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
228 data_in = kmap(in_page);
229 in_len = min(bytes_left, PAGE_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;
244 out:
245 *out_pages = nr_pages;
246 if (out_page)
247 kunmap(out_page);
248
249 if (in_page) {
250 kunmap(in_page);
251 put_page(in_page);
252 }
253
254 return ret;
255 }
256
lzo_decompress_biovec(struct list_head * ws,struct page ** pages_in,u64 disk_start,struct bio_vec * bvec,int vcnt,size_t srclen)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);
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_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_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;
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
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_SIZE;
349 in_offset = 0;
350 }
351 }
352
353 out_len = lzo1x_worst_compress(PAGE_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 pr_warn("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 }
374 done:
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
lzo_decompress(struct list_head * ws,unsigned char * data_in,struct page * dest_page,unsigned long start_byte,size_t srclen,size_t destlen)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
402 out_len = PAGE_SIZE;
403 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
404 if (ret != LZO_E_OK) {
405 pr_warn("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);
433 out:
434 return ret;
435 }
436
437 const 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