1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2008 Oracle. All rights reserved.
4 */
5
6 #include <linux/kernel.h>
7 #include <linux/slab.h>
8 #include <linux/mm.h>
9 #include <linux/init.h>
10 #include <linux/err.h>
11 #include <linux/sched.h>
12 #include <linux/pagemap.h>
13 #include <linux/bio.h>
14 #include <linux/lzo.h>
15 #include <linux/refcount.h>
16 #include "compression.h"
17
18 #define LZO_LEN 4
19
20 /*
21 * Btrfs LZO compression format
22 *
23 * Regular and inlined LZO compressed data extents consist of:
24 *
25 * 1. Header
26 * Fixed size. LZO_LEN (4) bytes long, LE32.
27 * Records the total size (including the header) of compressed data.
28 *
29 * 2. Segment(s)
30 * Variable size. Each segment includes one segment header, followed by data
31 * payload.
32 * One regular LZO compressed extent can have one or more segments.
33 * For inlined LZO compressed extent, only one segment is allowed.
34 * One segment represents at most one page of uncompressed data.
35 *
36 * 2.1 Segment header
37 * Fixed size. LZO_LEN (4) bytes long, LE32.
38 * Records the total size of the segment (not including the header).
39 * Segment header never crosses page boundary, thus it's possible to
40 * have at most 3 padding zeros at the end of the page.
41 *
42 * 2.2 Data Payload
43 * Variable size. Size up limit should be lzo1x_worst_compress(PAGE_SIZE)
44 * which is 4419 for a 4KiB page.
45 *
46 * Example:
47 * Page 1:
48 * 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10
49 * 0x0000 | Header | SegHdr 01 | Data payload 01 ... |
50 * ...
51 * 0x0ff0 | SegHdr N | Data payload N ... |00|
52 * ^^ padding zeros
53 * Page 2:
54 * 0x1000 | SegHdr N+1| Data payload N+1 ... |
55 */
56
57 struct workspace {
58 void *mem;
59 void *buf; /* where decompressed data goes */
60 void *cbuf; /* where compressed data goes */
61 struct list_head list;
62 };
63
64 static struct workspace_manager wsm;
65
lzo_init_workspace_manager(void)66 static void lzo_init_workspace_manager(void)
67 {
68 btrfs_init_workspace_manager(&wsm, &btrfs_lzo_compress);
69 }
70
lzo_cleanup_workspace_manager(void)71 static void lzo_cleanup_workspace_manager(void)
72 {
73 btrfs_cleanup_workspace_manager(&wsm);
74 }
75
lzo_get_workspace(unsigned int level)76 static struct list_head *lzo_get_workspace(unsigned int level)
77 {
78 return btrfs_get_workspace(&wsm, level);
79 }
80
lzo_put_workspace(struct list_head * ws)81 static void lzo_put_workspace(struct list_head *ws)
82 {
83 btrfs_put_workspace(&wsm, ws);
84 }
85
lzo_free_workspace(struct list_head * ws)86 static void lzo_free_workspace(struct list_head *ws)
87 {
88 struct workspace *workspace = list_entry(ws, struct workspace, list);
89
90 kvfree(workspace->buf);
91 kvfree(workspace->cbuf);
92 kvfree(workspace->mem);
93 kfree(workspace);
94 }
95
lzo_alloc_workspace(unsigned int level)96 static struct list_head *lzo_alloc_workspace(unsigned int level)
97 {
98 struct workspace *workspace;
99
100 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
101 if (!workspace)
102 return ERR_PTR(-ENOMEM);
103
104 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
105 workspace->buf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
106 workspace->cbuf = kvmalloc(lzo1x_worst_compress(PAGE_SIZE), GFP_KERNEL);
107 if (!workspace->mem || !workspace->buf || !workspace->cbuf)
108 goto fail;
109
110 INIT_LIST_HEAD(&workspace->list);
111
112 return &workspace->list;
113 fail:
114 lzo_free_workspace(&workspace->list);
115 return ERR_PTR(-ENOMEM);
116 }
117
write_compress_length(char * buf,size_t len)118 static inline void write_compress_length(char *buf, size_t len)
119 {
120 __le32 dlen;
121
122 dlen = cpu_to_le32(len);
123 memcpy(buf, &dlen, LZO_LEN);
124 }
125
read_compress_length(const char * buf)126 static inline size_t read_compress_length(const char *buf)
127 {
128 __le32 dlen;
129
130 memcpy(&dlen, buf, LZO_LEN);
131 return le32_to_cpu(dlen);
132 }
133
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)134 static int lzo_compress_pages(struct list_head *ws,
135 struct address_space *mapping,
136 u64 start,
137 struct page **pages,
138 unsigned long *out_pages,
139 unsigned long *total_in,
140 unsigned long *total_out)
141 {
142 struct workspace *workspace = list_entry(ws, struct workspace, list);
143 int ret = 0;
144 char *data_in;
145 char *cpage_out;
146 int nr_pages = 0;
147 struct page *in_page = NULL;
148 struct page *out_page = NULL;
149 unsigned long bytes_left;
150 unsigned long len = *total_out;
151 unsigned long nr_dest_pages = *out_pages;
152 const unsigned long max_out = nr_dest_pages * PAGE_SIZE;
153 size_t in_len;
154 size_t out_len;
155 char *buf;
156 unsigned long tot_in = 0;
157 unsigned long tot_out = 0;
158 unsigned long pg_bytes_left;
159 unsigned long out_offset;
160 unsigned long bytes;
161
162 *out_pages = 0;
163 *total_out = 0;
164 *total_in = 0;
165
166 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
167 data_in = kmap(in_page);
168
169 /*
170 * store the size of all chunks of compressed data in
171 * the first 4 bytes
172 */
173 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
174 if (out_page == NULL) {
175 ret = -ENOMEM;
176 goto out;
177 }
178 cpage_out = kmap(out_page);
179 out_offset = LZO_LEN;
180 tot_out = LZO_LEN;
181 pages[0] = out_page;
182 nr_pages = 1;
183 pg_bytes_left = PAGE_SIZE - LZO_LEN;
184
185 /* compress at most one page of data each time */
186 in_len = min(len, PAGE_SIZE);
187 while (tot_in < len) {
188 ret = lzo1x_1_compress(data_in, in_len, workspace->cbuf,
189 &out_len, workspace->mem);
190 if (ret != LZO_E_OK) {
191 pr_debug("BTRFS: lzo in loop returned %d\n",
192 ret);
193 ret = -EIO;
194 goto out;
195 }
196
197 /* store the size of this chunk of compressed data */
198 write_compress_length(cpage_out + out_offset, out_len);
199 tot_out += LZO_LEN;
200 out_offset += LZO_LEN;
201 pg_bytes_left -= LZO_LEN;
202
203 tot_in += in_len;
204 tot_out += out_len;
205
206 /* copy bytes from the working buffer into the pages */
207 buf = workspace->cbuf;
208 while (out_len) {
209 bytes = min_t(unsigned long, pg_bytes_left, out_len);
210
211 memcpy(cpage_out + out_offset, buf, bytes);
212
213 out_len -= bytes;
214 pg_bytes_left -= bytes;
215 buf += bytes;
216 out_offset += bytes;
217
218 /*
219 * we need another page for writing out.
220 *
221 * Note if there's less than 4 bytes left, we just
222 * skip to a new page.
223 */
224 if ((out_len == 0 && pg_bytes_left < LZO_LEN) ||
225 pg_bytes_left == 0) {
226 if (pg_bytes_left) {
227 memset(cpage_out + out_offset, 0,
228 pg_bytes_left);
229 tot_out += pg_bytes_left;
230 }
231
232 /* we're done, don't allocate new page */
233 if (out_len == 0 && tot_in >= len)
234 break;
235
236 kunmap(out_page);
237 if (nr_pages == nr_dest_pages) {
238 out_page = NULL;
239 ret = -E2BIG;
240 goto out;
241 }
242
243 out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
244 if (out_page == NULL) {
245 ret = -ENOMEM;
246 goto out;
247 }
248 cpage_out = kmap(out_page);
249 pages[nr_pages++] = out_page;
250
251 pg_bytes_left = PAGE_SIZE;
252 out_offset = 0;
253 }
254 }
255
256 /* we're making it bigger, give up */
257 if (tot_in > 8192 && tot_in < tot_out) {
258 ret = -E2BIG;
259 goto out;
260 }
261
262 /* we're all done */
263 if (tot_in >= len)
264 break;
265
266 if (tot_out > max_out)
267 break;
268
269 bytes_left = len - tot_in;
270 kunmap(in_page);
271 put_page(in_page);
272
273 start += PAGE_SIZE;
274 in_page = find_get_page(mapping, start >> PAGE_SHIFT);
275 data_in = kmap(in_page);
276 in_len = min(bytes_left, PAGE_SIZE);
277 }
278
279 if (tot_out >= tot_in) {
280 ret = -E2BIG;
281 goto out;
282 }
283
284 /* store the size of all chunks of compressed data */
285 cpage_out = kmap(pages[0]);
286 write_compress_length(cpage_out, tot_out);
287
288 kunmap(pages[0]);
289
290 ret = 0;
291 *total_out = tot_out;
292 *total_in = tot_in;
293 out:
294 *out_pages = nr_pages;
295 if (out_page)
296 kunmap(out_page);
297
298 if (in_page) {
299 kunmap(in_page);
300 put_page(in_page);
301 }
302
303 return ret;
304 }
305
lzo_decompress_bio(struct list_head * ws,struct compressed_bio * cb)306 static int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
307 {
308 struct workspace *workspace = list_entry(ws, struct workspace, list);
309 int ret = 0, ret2;
310 char *data_in;
311 unsigned long page_in_index = 0;
312 size_t srclen = cb->compressed_len;
313 unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_SIZE);
314 unsigned long buf_start;
315 unsigned long buf_offset = 0;
316 unsigned long bytes;
317 unsigned long working_bytes;
318 size_t in_len;
319 size_t out_len;
320 const size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
321 unsigned long in_offset;
322 unsigned long in_page_bytes_left;
323 unsigned long tot_in;
324 unsigned long tot_out;
325 unsigned long tot_len;
326 char *buf;
327 bool may_late_unmap, need_unmap;
328 struct page **pages_in = cb->compressed_pages;
329 u64 disk_start = cb->start;
330 struct bio *orig_bio = cb->orig_bio;
331
332 data_in = kmap(pages_in[0]);
333 tot_len = read_compress_length(data_in);
334 /*
335 * Compressed data header check.
336 *
337 * The real compressed size can't exceed the maximum extent length, and
338 * all pages should be used (whole unused page with just the segment
339 * header is not possible). If this happens it means the compressed
340 * extent is corrupted.
341 */
342 if (tot_len > min_t(size_t, BTRFS_MAX_COMPRESSED, srclen) ||
343 tot_len < srclen - PAGE_SIZE) {
344 ret = -EUCLEAN;
345 goto done;
346 }
347
348 tot_in = LZO_LEN;
349 in_offset = LZO_LEN;
350 in_page_bytes_left = PAGE_SIZE - LZO_LEN;
351
352 tot_out = 0;
353
354 while (tot_in < tot_len) {
355 in_len = read_compress_length(data_in + in_offset);
356 in_page_bytes_left -= LZO_LEN;
357 in_offset += LZO_LEN;
358 tot_in += LZO_LEN;
359
360 /*
361 * Segment header check.
362 *
363 * The segment length must not exceed the maximum LZO
364 * compression size, nor the total compressed size.
365 */
366 if (in_len > max_segment_len || tot_in + in_len > tot_len) {
367 ret = -EUCLEAN;
368 goto done;
369 }
370
371 tot_in += in_len;
372 working_bytes = in_len;
373 may_late_unmap = need_unmap = false;
374
375 /* fast path: avoid using the working buffer */
376 if (in_page_bytes_left >= in_len) {
377 buf = data_in + in_offset;
378 bytes = in_len;
379 may_late_unmap = true;
380 goto cont;
381 }
382
383 /* copy bytes from the pages into the working buffer */
384 buf = workspace->cbuf;
385 buf_offset = 0;
386 while (working_bytes) {
387 bytes = min(working_bytes, in_page_bytes_left);
388
389 memcpy(buf + buf_offset, data_in + in_offset, bytes);
390 buf_offset += bytes;
391 cont:
392 working_bytes -= bytes;
393 in_page_bytes_left -= bytes;
394 in_offset += bytes;
395
396 /* check if we need to pick another page */
397 if ((working_bytes == 0 && in_page_bytes_left < LZO_LEN)
398 || in_page_bytes_left == 0) {
399 tot_in += in_page_bytes_left;
400
401 if (working_bytes == 0 && tot_in >= tot_len)
402 break;
403
404 if (page_in_index + 1 >= total_pages_in) {
405 ret = -EIO;
406 goto done;
407 }
408
409 if (may_late_unmap)
410 need_unmap = true;
411 else
412 kunmap(pages_in[page_in_index]);
413
414 data_in = kmap(pages_in[++page_in_index]);
415
416 in_page_bytes_left = PAGE_SIZE;
417 in_offset = 0;
418 }
419 }
420
421 out_len = max_segment_len;
422 ret = lzo1x_decompress_safe(buf, in_len, workspace->buf,
423 &out_len);
424 if (need_unmap)
425 kunmap(pages_in[page_in_index - 1]);
426 if (ret != LZO_E_OK) {
427 pr_warn("BTRFS: decompress failed\n");
428 ret = -EIO;
429 break;
430 }
431
432 buf_start = tot_out;
433 tot_out += out_len;
434
435 ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,
436 tot_out, disk_start, orig_bio);
437 if (ret2 == 0)
438 break;
439 }
440 done:
441 kunmap(pages_in[page_in_index]);
442 if (!ret)
443 zero_fill_bio(orig_bio);
444 return ret;
445 }
446
lzo_decompress(struct list_head * ws,unsigned char * data_in,struct page * dest_page,unsigned long start_byte,size_t srclen,size_t destlen)447 static int lzo_decompress(struct list_head *ws, unsigned char *data_in,
448 struct page *dest_page,
449 unsigned long start_byte,
450 size_t srclen, size_t destlen)
451 {
452 struct workspace *workspace = list_entry(ws, struct workspace, list);
453 size_t in_len;
454 size_t out_len;
455 size_t max_segment_len = lzo1x_worst_compress(PAGE_SIZE);
456 int ret = 0;
457 char *kaddr;
458 unsigned long bytes;
459
460 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
461 return -EUCLEAN;
462
463 in_len = read_compress_length(data_in);
464 if (in_len != srclen)
465 return -EUCLEAN;
466 data_in += LZO_LEN;
467
468 in_len = read_compress_length(data_in);
469 if (in_len != srclen - LZO_LEN * 2) {
470 ret = -EUCLEAN;
471 goto out;
472 }
473 data_in += LZO_LEN;
474
475 out_len = PAGE_SIZE;
476 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
477 if (ret != LZO_E_OK) {
478 pr_warn("BTRFS: decompress failed!\n");
479 ret = -EIO;
480 goto out;
481 }
482
483 if (out_len < start_byte) {
484 ret = -EIO;
485 goto out;
486 }
487
488 /*
489 * the caller is already checking against PAGE_SIZE, but lets
490 * move this check closer to the memcpy/memset
491 */
492 destlen = min_t(unsigned long, destlen, PAGE_SIZE);
493 bytes = min_t(unsigned long, destlen, out_len - start_byte);
494
495 kaddr = kmap_atomic(dest_page);
496 memcpy(kaddr, workspace->buf + start_byte, bytes);
497
498 /*
499 * btrfs_getblock is doing a zero on the tail of the page too,
500 * but this will cover anything missing from the decompressed
501 * data.
502 */
503 if (bytes < destlen)
504 memset(kaddr+bytes, 0, destlen-bytes);
505 kunmap_atomic(kaddr);
506 out:
507 return ret;
508 }
509
510 const struct btrfs_compress_op btrfs_lzo_compress = {
511 .init_workspace_manager = lzo_init_workspace_manager,
512 .cleanup_workspace_manager = lzo_cleanup_workspace_manager,
513 .get_workspace = lzo_get_workspace,
514 .put_workspace = lzo_put_workspace,
515 .alloc_workspace = lzo_alloc_workspace,
516 .free_workspace = lzo_free_workspace,
517 .compress_pages = lzo_compress_pages,
518 .decompress_bio = lzo_decompress_bio,
519 .decompress = lzo_decompress,
520 .max_level = 1,
521 .default_level = 1,
522 };
523