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 #include "ctree.h"
18
19 #define LZO_LEN 4
20
21 /*
22 * Btrfs LZO compression format
23 *
24 * Regular and inlined LZO compressed data extents consist of:
25 *
26 * 1. Header
27 * Fixed size. LZO_LEN (4) bytes long, LE32.
28 * Records the total size (including the header) of compressed data.
29 *
30 * 2. Segment(s)
31 * Variable size. Each segment includes one segment header, followed by data
32 * payload.
33 * One regular LZO compressed extent can have one or more segments.
34 * For inlined LZO compressed extent, only one segment is allowed.
35 * One segment represents at most one sector of uncompressed data.
36 *
37 * 2.1 Segment header
38 * Fixed size. LZO_LEN (4) bytes long, LE32.
39 * Records the total size of the segment (not including the header).
40 * Segment header never crosses sector boundary, thus it's possible to
41 * have at most 3 padding zeros at the end of the sector.
42 *
43 * 2.2 Data Payload
44 * Variable size. Size up limit should be lzo1x_worst_compress(sectorsize)
45 * which is 4419 for a 4KiB sectorsize.
46 *
47 * Example with 4K sectorsize:
48 * Page 1:
49 * 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10
50 * 0x0000 | Header | SegHdr 01 | Data payload 01 ... |
51 * ...
52 * 0x0ff0 | SegHdr N | Data payload N ... |00|
53 * ^^ padding zeros
54 * Page 2:
55 * 0x1000 | SegHdr N+1| Data payload N+1 ... |
56 */
57
58 #define WORKSPACE_BUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE))
59 #define WORKSPACE_CBUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE))
60
61 struct workspace {
62 void *mem;
63 void *buf; /* where decompressed data goes */
64 void *cbuf; /* where compressed data goes */
65 struct list_head list;
66 };
67
68 static struct workspace_manager wsm;
69
lzo_free_workspace(struct list_head * ws)70 void lzo_free_workspace(struct list_head *ws)
71 {
72 struct workspace *workspace = list_entry(ws, struct workspace, list);
73
74 kvfree(workspace->buf);
75 kvfree(workspace->cbuf);
76 kvfree(workspace->mem);
77 kfree(workspace);
78 }
79
lzo_alloc_workspace(unsigned int level)80 struct list_head *lzo_alloc_workspace(unsigned int level)
81 {
82 struct workspace *workspace;
83
84 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
85 if (!workspace)
86 return ERR_PTR(-ENOMEM);
87
88 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
89 workspace->buf = kvmalloc(WORKSPACE_BUF_LENGTH, GFP_KERNEL);
90 workspace->cbuf = kvmalloc(WORKSPACE_CBUF_LENGTH, GFP_KERNEL);
91 if (!workspace->mem || !workspace->buf || !workspace->cbuf)
92 goto fail;
93
94 INIT_LIST_HEAD(&workspace->list);
95
96 return &workspace->list;
97 fail:
98 lzo_free_workspace(&workspace->list);
99 return ERR_PTR(-ENOMEM);
100 }
101
write_compress_length(char * buf,size_t len)102 static inline void write_compress_length(char *buf, size_t len)
103 {
104 __le32 dlen;
105
106 dlen = cpu_to_le32(len);
107 memcpy(buf, &dlen, LZO_LEN);
108 }
109
read_compress_length(const char * buf)110 static inline size_t read_compress_length(const char *buf)
111 {
112 __le32 dlen;
113
114 memcpy(&dlen, buf, LZO_LEN);
115 return le32_to_cpu(dlen);
116 }
117
118 /*
119 * Will do:
120 *
121 * - Write a segment header into the destination
122 * - Copy the compressed buffer into the destination
123 * - Make sure we have enough space in the last sector to fit a segment header
124 * If not, we will pad at most (LZO_LEN (4)) - 1 bytes of zeros.
125 *
126 * Will allocate new pages when needed.
127 */
copy_compressed_data_to_page(char * compressed_data,size_t compressed_size,struct page ** out_pages,unsigned long max_nr_page,u32 * cur_out,const u32 sectorsize)128 static int copy_compressed_data_to_page(char *compressed_data,
129 size_t compressed_size,
130 struct page **out_pages,
131 unsigned long max_nr_page,
132 u32 *cur_out,
133 const u32 sectorsize)
134 {
135 u32 sector_bytes_left;
136 u32 orig_out;
137 struct page *cur_page;
138 char *kaddr;
139
140 if ((*cur_out / PAGE_SIZE) >= max_nr_page)
141 return -E2BIG;
142
143 /*
144 * We never allow a segment header crossing sector boundary, previous
145 * run should ensure we have enough space left inside the sector.
146 */
147 ASSERT((*cur_out / sectorsize) == (*cur_out + LZO_LEN - 1) / sectorsize);
148
149 cur_page = out_pages[*cur_out / PAGE_SIZE];
150 /* Allocate a new page */
151 if (!cur_page) {
152 cur_page = alloc_page(GFP_NOFS);
153 if (!cur_page)
154 return -ENOMEM;
155 out_pages[*cur_out / PAGE_SIZE] = cur_page;
156 }
157
158 kaddr = kmap_local_page(cur_page);
159 write_compress_length(kaddr + offset_in_page(*cur_out),
160 compressed_size);
161 *cur_out += LZO_LEN;
162
163 orig_out = *cur_out;
164
165 /* Copy compressed data */
166 while (*cur_out - orig_out < compressed_size) {
167 u32 copy_len = min_t(u32, sectorsize - *cur_out % sectorsize,
168 orig_out + compressed_size - *cur_out);
169
170 kunmap_local(kaddr);
171
172 if ((*cur_out / PAGE_SIZE) >= max_nr_page)
173 return -E2BIG;
174
175 cur_page = out_pages[*cur_out / PAGE_SIZE];
176 /* Allocate a new page */
177 if (!cur_page) {
178 cur_page = alloc_page(GFP_NOFS);
179 if (!cur_page)
180 return -ENOMEM;
181 out_pages[*cur_out / PAGE_SIZE] = cur_page;
182 }
183 kaddr = kmap_local_page(cur_page);
184
185 memcpy(kaddr + offset_in_page(*cur_out),
186 compressed_data + *cur_out - orig_out, copy_len);
187
188 *cur_out += copy_len;
189 }
190
191 /*
192 * Check if we can fit the next segment header into the remaining space
193 * of the sector.
194 */
195 sector_bytes_left = round_up(*cur_out, sectorsize) - *cur_out;
196 if (sector_bytes_left >= LZO_LEN || sector_bytes_left == 0)
197 goto out;
198
199 /* The remaining size is not enough, pad it with zeros */
200 memset(kaddr + offset_in_page(*cur_out), 0,
201 sector_bytes_left);
202 *cur_out += sector_bytes_left;
203
204 out:
205 kunmap_local(kaddr);
206 return 0;
207 }
208
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)209 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
210 u64 start, struct page **pages, unsigned long *out_pages,
211 unsigned long *total_in, unsigned long *total_out)
212 {
213 struct workspace *workspace = list_entry(ws, struct workspace, list);
214 const u32 sectorsize = btrfs_sb(mapping->host->i_sb)->sectorsize;
215 struct page *page_in = NULL;
216 char *sizes_ptr;
217 const unsigned long max_nr_page = *out_pages;
218 int ret = 0;
219 /* Points to the file offset of input data */
220 u64 cur_in = start;
221 /* Points to the current output byte */
222 u32 cur_out = 0;
223 u32 len = *total_out;
224
225 ASSERT(max_nr_page > 0);
226 *out_pages = 0;
227 *total_out = 0;
228 *total_in = 0;
229
230 /*
231 * Skip the header for now, we will later come back and write the total
232 * compressed size
233 */
234 cur_out += LZO_LEN;
235 while (cur_in < start + len) {
236 char *data_in;
237 const u32 sectorsize_mask = sectorsize - 1;
238 u32 sector_off = (cur_in - start) & sectorsize_mask;
239 u32 in_len;
240 size_t out_len;
241
242 /* Get the input page first */
243 if (!page_in) {
244 page_in = find_get_page(mapping, cur_in >> PAGE_SHIFT);
245 ASSERT(page_in);
246 }
247
248 /* Compress at most one sector of data each time */
249 in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off);
250 ASSERT(in_len);
251 data_in = kmap_local_page(page_in);
252 ret = lzo1x_1_compress(data_in +
253 offset_in_page(cur_in), in_len,
254 workspace->cbuf, &out_len,
255 workspace->mem);
256 kunmap_local(data_in);
257 if (ret < 0) {
258 pr_debug("BTRFS: lzo in loop returned %d\n", ret);
259 ret = -EIO;
260 goto out;
261 }
262
263 ret = copy_compressed_data_to_page(workspace->cbuf, out_len,
264 pages, max_nr_page,
265 &cur_out, sectorsize);
266 if (ret < 0)
267 goto out;
268
269 cur_in += in_len;
270
271 /*
272 * Check if we're making it bigger after two sectors. And if
273 * it is so, give up.
274 */
275 if (cur_in - start > sectorsize * 2 && cur_in - start < cur_out) {
276 ret = -E2BIG;
277 goto out;
278 }
279
280 /* Check if we have reached page boundary */
281 if (IS_ALIGNED(cur_in, PAGE_SIZE)) {
282 put_page(page_in);
283 page_in = NULL;
284 }
285 }
286
287 /* Store the size of all chunks of compressed data */
288 sizes_ptr = kmap_local_page(pages[0]);
289 write_compress_length(sizes_ptr, cur_out);
290 kunmap_local(sizes_ptr);
291
292 ret = 0;
293 *total_out = cur_out;
294 *total_in = cur_in - start;
295 out:
296 if (page_in)
297 put_page(page_in);
298 *out_pages = DIV_ROUND_UP(cur_out, PAGE_SIZE);
299 return ret;
300 }
301
302 /*
303 * Copy the compressed segment payload into @dest.
304 *
305 * For the payload there will be no padding, just need to do page switching.
306 */
copy_compressed_segment(struct compressed_bio * cb,char * dest,u32 len,u32 * cur_in)307 static void copy_compressed_segment(struct compressed_bio *cb,
308 char *dest, u32 len, u32 *cur_in)
309 {
310 u32 orig_in = *cur_in;
311
312 while (*cur_in < orig_in + len) {
313 struct page *cur_page;
314 u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),
315 orig_in + len - *cur_in);
316
317 ASSERT(copy_len);
318 cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE];
319
320 memcpy_from_page(dest + *cur_in - orig_in, cur_page,
321 offset_in_page(*cur_in), copy_len);
322
323 *cur_in += copy_len;
324 }
325 }
326
lzo_decompress_bio(struct list_head * ws,struct compressed_bio * cb)327 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
328 {
329 struct workspace *workspace = list_entry(ws, struct workspace, list);
330 const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
331 const u32 sectorsize = fs_info->sectorsize;
332 char *kaddr;
333 int ret;
334 /* Compressed data length, can be unaligned */
335 u32 len_in;
336 /* Offset inside the compressed data */
337 u32 cur_in = 0;
338 /* Bytes decompressed so far */
339 u32 cur_out = 0;
340
341 kaddr = kmap_local_page(cb->compressed_pages[0]);
342 len_in = read_compress_length(kaddr);
343 kunmap_local(kaddr);
344 cur_in += LZO_LEN;
345
346 /*
347 * LZO header length check
348 *
349 * The total length should not exceed the maximum extent length,
350 * and all sectors should be used.
351 * If this happens, it means the compressed extent is corrupted.
352 */
353 if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
354 round_up(len_in, sectorsize) < cb->compressed_len) {
355 btrfs_err(fs_info,
356 "invalid lzo header, lzo len %u compressed len %u",
357 len_in, cb->compressed_len);
358 return -EUCLEAN;
359 }
360
361 /* Go through each lzo segment */
362 while (cur_in < len_in) {
363 struct page *cur_page;
364 /* Length of the compressed segment */
365 u32 seg_len;
366 u32 sector_bytes_left;
367 size_t out_len = lzo1x_worst_compress(sectorsize);
368
369 /*
370 * We should always have enough space for one segment header
371 * inside current sector.
372 */
373 ASSERT(cur_in / sectorsize ==
374 (cur_in + LZO_LEN - 1) / sectorsize);
375 cur_page = cb->compressed_pages[cur_in / PAGE_SIZE];
376 ASSERT(cur_page);
377 kaddr = kmap_local_page(cur_page);
378 seg_len = read_compress_length(kaddr + offset_in_page(cur_in));
379 kunmap_local(kaddr);
380 cur_in += LZO_LEN;
381
382 if (seg_len > WORKSPACE_CBUF_LENGTH) {
383 /*
384 * seg_len shouldn't be larger than we have allocated
385 * for workspace->cbuf
386 */
387 btrfs_err(fs_info, "unexpectedly large lzo segment len %u",
388 seg_len);
389 ret = -EIO;
390 goto out;
391 }
392
393 /* Copy the compressed segment payload into workspace */
394 copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in);
395
396 /* Decompress the data */
397 ret = lzo1x_decompress_safe(workspace->cbuf, seg_len,
398 workspace->buf, &out_len);
399 if (ret != LZO_E_OK) {
400 btrfs_err(fs_info, "failed to decompress");
401 ret = -EIO;
402 goto out;
403 }
404
405 /* Copy the data into inode pages */
406 ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out);
407 cur_out += out_len;
408
409 /* All data read, exit */
410 if (ret == 0)
411 goto out;
412 ret = 0;
413
414 /* Check if the sector has enough space for a segment header */
415 sector_bytes_left = sectorsize - (cur_in % sectorsize);
416 if (sector_bytes_left >= LZO_LEN)
417 continue;
418
419 /* Skip the padding zeros */
420 cur_in += sector_bytes_left;
421 }
422 out:
423 if (!ret)
424 zero_fill_bio(cb->orig_bio);
425 return ret;
426 }
427
lzo_decompress(struct list_head * ws,unsigned char * data_in,struct page * dest_page,unsigned long start_byte,size_t srclen,size_t destlen)428 int lzo_decompress(struct list_head *ws, unsigned char *data_in,
429 struct page *dest_page, unsigned long start_byte, size_t srclen,
430 size_t destlen)
431 {
432 struct workspace *workspace = list_entry(ws, struct workspace, list);
433 size_t in_len;
434 size_t out_len;
435 size_t max_segment_len = WORKSPACE_BUF_LENGTH;
436 int ret = 0;
437 char *kaddr;
438 unsigned long bytes;
439
440 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
441 return -EUCLEAN;
442
443 in_len = read_compress_length(data_in);
444 if (in_len != srclen)
445 return -EUCLEAN;
446 data_in += LZO_LEN;
447
448 in_len = read_compress_length(data_in);
449 if (in_len != srclen - LZO_LEN * 2) {
450 ret = -EUCLEAN;
451 goto out;
452 }
453 data_in += LZO_LEN;
454
455 out_len = PAGE_SIZE;
456 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
457 if (ret != LZO_E_OK) {
458 pr_warn("BTRFS: decompress failed!\n");
459 ret = -EIO;
460 goto out;
461 }
462
463 if (out_len < start_byte) {
464 ret = -EIO;
465 goto out;
466 }
467
468 /*
469 * the caller is already checking against PAGE_SIZE, but lets
470 * move this check closer to the memcpy/memset
471 */
472 destlen = min_t(unsigned long, destlen, PAGE_SIZE);
473 bytes = min_t(unsigned long, destlen, out_len - start_byte);
474
475 kaddr = kmap_local_page(dest_page);
476 memcpy(kaddr, workspace->buf + start_byte, bytes);
477
478 /*
479 * btrfs_getblock is doing a zero on the tail of the page too,
480 * but this will cover anything missing from the decompressed
481 * data.
482 */
483 if (bytes < destlen)
484 memset(kaddr+bytes, 0, destlen-bytes);
485 kunmap_local(kaddr);
486 out:
487 return ret;
488 }
489
490 const struct btrfs_compress_op btrfs_lzo_compress = {
491 .workspace_manager = &wsm,
492 .max_level = 1,
493 .default_level = 1,
494 };
495