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 "messages.h"
17 #include "compression.h"
18 #include "ctree.h"
19 #include "super.h"
20
21 #define LZO_LEN 4
22
23 /*
24 * Btrfs LZO compression format
25 *
26 * Regular and inlined LZO compressed data extents consist of:
27 *
28 * 1. Header
29 * Fixed size. LZO_LEN (4) bytes long, LE32.
30 * Records the total size (including the header) of compressed data.
31 *
32 * 2. Segment(s)
33 * Variable size. Each segment includes one segment header, followed by data
34 * payload.
35 * One regular LZO compressed extent can have one or more segments.
36 * For inlined LZO compressed extent, only one segment is allowed.
37 * One segment represents at most one sector of uncompressed data.
38 *
39 * 2.1 Segment header
40 * Fixed size. LZO_LEN (4) bytes long, LE32.
41 * Records the total size of the segment (not including the header).
42 * Segment header never crosses sector boundary, thus it's possible to
43 * have at most 3 padding zeros at the end of the sector.
44 *
45 * 2.2 Data Payload
46 * Variable size. Size up limit should be lzo1x_worst_compress(sectorsize)
47 * which is 4419 for a 4KiB sectorsize.
48 *
49 * Example with 4K sectorsize:
50 * Page 1:
51 * 0 0x2 0x4 0x6 0x8 0xa 0xc 0xe 0x10
52 * 0x0000 | Header | SegHdr 01 | Data payload 01 ... |
53 * ...
54 * 0x0ff0 | SegHdr N | Data payload N ... |00|
55 * ^^ padding zeros
56 * Page 2:
57 * 0x1000 | SegHdr N+1| Data payload N+1 ... |
58 */
59
60 #define WORKSPACE_BUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE))
61 #define WORKSPACE_CBUF_LENGTH (lzo1x_worst_compress(PAGE_SIZE))
62
63 struct workspace {
64 void *mem;
65 void *buf; /* where decompressed data goes */
66 void *cbuf; /* where compressed data goes */
67 struct list_head list;
68 };
69
70 static struct workspace_manager wsm;
71
lzo_free_workspace(struct list_head * ws)72 void lzo_free_workspace(struct list_head *ws)
73 {
74 struct workspace *workspace = list_entry(ws, struct workspace, list);
75
76 kvfree(workspace->buf);
77 kvfree(workspace->cbuf);
78 kvfree(workspace->mem);
79 kfree(workspace);
80 }
81
lzo_alloc_workspace(unsigned int level)82 struct list_head *lzo_alloc_workspace(unsigned int level)
83 {
84 struct workspace *workspace;
85
86 workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
87 if (!workspace)
88 return ERR_PTR(-ENOMEM);
89
90 workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
91 workspace->buf = kvmalloc(WORKSPACE_BUF_LENGTH, GFP_KERNEL);
92 workspace->cbuf = kvmalloc(WORKSPACE_CBUF_LENGTH, GFP_KERNEL);
93 if (!workspace->mem || !workspace->buf || !workspace->cbuf)
94 goto fail;
95
96 INIT_LIST_HEAD(&workspace->list);
97
98 return &workspace->list;
99 fail:
100 lzo_free_workspace(&workspace->list);
101 return ERR_PTR(-ENOMEM);
102 }
103
write_compress_length(char * buf,size_t len)104 static inline void write_compress_length(char *buf, size_t len)
105 {
106 __le32 dlen;
107
108 dlen = cpu_to_le32(len);
109 memcpy(buf, &dlen, LZO_LEN);
110 }
111
read_compress_length(const char * buf)112 static inline size_t read_compress_length(const char *buf)
113 {
114 __le32 dlen;
115
116 memcpy(&dlen, buf, LZO_LEN);
117 return le32_to_cpu(dlen);
118 }
119
120 /*
121 * Will do:
122 *
123 * - Write a segment header into the destination
124 * - Copy the compressed buffer into the destination
125 * - Make sure we have enough space in the last sector to fit a segment header
126 * If not, we will pad at most (LZO_LEN (4)) - 1 bytes of zeros.
127 *
128 * Will allocate new pages when needed.
129 */
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)130 static int copy_compressed_data_to_page(char *compressed_data,
131 size_t compressed_size,
132 struct page **out_pages,
133 unsigned long max_nr_page,
134 u32 *cur_out,
135 const u32 sectorsize)
136 {
137 u32 sector_bytes_left;
138 u32 orig_out;
139 struct page *cur_page;
140 char *kaddr;
141
142 if ((*cur_out / PAGE_SIZE) >= max_nr_page)
143 return -E2BIG;
144
145 /*
146 * We never allow a segment header crossing sector boundary, previous
147 * run should ensure we have enough space left inside the sector.
148 */
149 ASSERT((*cur_out / sectorsize) == (*cur_out + LZO_LEN - 1) / sectorsize);
150
151 cur_page = out_pages[*cur_out / PAGE_SIZE];
152 /* Allocate a new page */
153 if (!cur_page) {
154 cur_page = alloc_page(GFP_NOFS);
155 if (!cur_page)
156 return -ENOMEM;
157 out_pages[*cur_out / PAGE_SIZE] = cur_page;
158 }
159
160 kaddr = kmap_local_page(cur_page);
161 write_compress_length(kaddr + offset_in_page(*cur_out),
162 compressed_size);
163 *cur_out += LZO_LEN;
164
165 orig_out = *cur_out;
166
167 /* Copy compressed data */
168 while (*cur_out - orig_out < compressed_size) {
169 u32 copy_len = min_t(u32, sectorsize - *cur_out % sectorsize,
170 orig_out + compressed_size - *cur_out);
171
172 kunmap_local(kaddr);
173
174 if ((*cur_out / PAGE_SIZE) >= max_nr_page)
175 return -E2BIG;
176
177 cur_page = out_pages[*cur_out / PAGE_SIZE];
178 /* Allocate a new page */
179 if (!cur_page) {
180 cur_page = alloc_page(GFP_NOFS);
181 if (!cur_page)
182 return -ENOMEM;
183 out_pages[*cur_out / PAGE_SIZE] = cur_page;
184 }
185 kaddr = kmap_local_page(cur_page);
186
187 memcpy(kaddr + offset_in_page(*cur_out),
188 compressed_data + *cur_out - orig_out, copy_len);
189
190 *cur_out += copy_len;
191 }
192
193 /*
194 * Check if we can fit the next segment header into the remaining space
195 * of the sector.
196 */
197 sector_bytes_left = round_up(*cur_out, sectorsize) - *cur_out;
198 if (sector_bytes_left >= LZO_LEN || sector_bytes_left == 0)
199 goto out;
200
201 /* The remaining size is not enough, pad it with zeros */
202 memset(kaddr + offset_in_page(*cur_out), 0,
203 sector_bytes_left);
204 *cur_out += sector_bytes_left;
205
206 out:
207 kunmap_local(kaddr);
208 return 0;
209 }
210
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)211 int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
212 u64 start, struct page **pages, unsigned long *out_pages,
213 unsigned long *total_in, unsigned long *total_out)
214 {
215 struct workspace *workspace = list_entry(ws, struct workspace, list);
216 const u32 sectorsize = btrfs_sb(mapping->host->i_sb)->sectorsize;
217 struct page *page_in = NULL;
218 char *sizes_ptr;
219 const unsigned long max_nr_page = *out_pages;
220 int ret = 0;
221 /* Points to the file offset of input data */
222 u64 cur_in = start;
223 /* Points to the current output byte */
224 u32 cur_out = 0;
225 u32 len = *total_out;
226
227 ASSERT(max_nr_page > 0);
228 *out_pages = 0;
229 *total_out = 0;
230 *total_in = 0;
231
232 /*
233 * Skip the header for now, we will later come back and write the total
234 * compressed size
235 */
236 cur_out += LZO_LEN;
237 while (cur_in < start + len) {
238 char *data_in;
239 const u32 sectorsize_mask = sectorsize - 1;
240 u32 sector_off = (cur_in - start) & sectorsize_mask;
241 u32 in_len;
242 size_t out_len;
243
244 /* Get the input page first */
245 if (!page_in) {
246 page_in = find_get_page(mapping, cur_in >> PAGE_SHIFT);
247 ASSERT(page_in);
248 }
249
250 /* Compress at most one sector of data each time */
251 in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off);
252 ASSERT(in_len);
253 data_in = kmap_local_page(page_in);
254 ret = lzo1x_1_compress(data_in +
255 offset_in_page(cur_in), in_len,
256 workspace->cbuf, &out_len,
257 workspace->mem);
258 kunmap_local(data_in);
259 if (ret < 0) {
260 pr_debug("BTRFS: lzo in loop returned %d\n", ret);
261 ret = -EIO;
262 goto out;
263 }
264
265 ret = copy_compressed_data_to_page(workspace->cbuf, out_len,
266 pages, max_nr_page,
267 &cur_out, sectorsize);
268 if (ret < 0)
269 goto out;
270
271 cur_in += in_len;
272
273 /*
274 * Check if we're making it bigger after two sectors. And if
275 * it is so, give up.
276 */
277 if (cur_in - start > sectorsize * 2 && cur_in - start < cur_out) {
278 ret = -E2BIG;
279 goto out;
280 }
281
282 /* Check if we have reached page boundary */
283 if (PAGE_ALIGNED(cur_in)) {
284 put_page(page_in);
285 page_in = NULL;
286 }
287 }
288
289 /* Store the size of all chunks of compressed data */
290 sizes_ptr = kmap_local_page(pages[0]);
291 write_compress_length(sizes_ptr, cur_out);
292 kunmap_local(sizes_ptr);
293
294 ret = 0;
295 *total_out = cur_out;
296 *total_in = cur_in - start;
297 out:
298 if (page_in)
299 put_page(page_in);
300 *out_pages = DIV_ROUND_UP(cur_out, PAGE_SIZE);
301 return ret;
302 }
303
304 /*
305 * Copy the compressed segment payload into @dest.
306 *
307 * For the payload there will be no padding, just need to do page switching.
308 */
copy_compressed_segment(struct compressed_bio * cb,char * dest,u32 len,u32 * cur_in)309 static void copy_compressed_segment(struct compressed_bio *cb,
310 char *dest, u32 len, u32 *cur_in)
311 {
312 u32 orig_in = *cur_in;
313
314 while (*cur_in < orig_in + len) {
315 struct page *cur_page;
316 u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),
317 orig_in + len - *cur_in);
318
319 ASSERT(copy_len);
320 cur_page = cb->compressed_pages[*cur_in / PAGE_SIZE];
321
322 memcpy_from_page(dest + *cur_in - orig_in, cur_page,
323 offset_in_page(*cur_in), copy_len);
324
325 *cur_in += copy_len;
326 }
327 }
328
lzo_decompress_bio(struct list_head * ws,struct compressed_bio * cb)329 int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
330 {
331 struct workspace *workspace = list_entry(ws, struct workspace, list);
332 const struct btrfs_fs_info *fs_info = btrfs_sb(cb->inode->i_sb);
333 const u32 sectorsize = fs_info->sectorsize;
334 char *kaddr;
335 int ret;
336 /* Compressed data length, can be unaligned */
337 u32 len_in;
338 /* Offset inside the compressed data */
339 u32 cur_in = 0;
340 /* Bytes decompressed so far */
341 u32 cur_out = 0;
342
343 kaddr = kmap_local_page(cb->compressed_pages[0]);
344 len_in = read_compress_length(kaddr);
345 kunmap_local(kaddr);
346 cur_in += LZO_LEN;
347
348 /*
349 * LZO header length check
350 *
351 * The total length should not exceed the maximum extent length,
352 * and all sectors should be used.
353 * If this happens, it means the compressed extent is corrupted.
354 */
355 if (len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
356 round_up(len_in, sectorsize) < cb->compressed_len) {
357 btrfs_err(fs_info,
358 "invalid lzo header, lzo len %u compressed len %u",
359 len_in, cb->compressed_len);
360 return -EUCLEAN;
361 }
362
363 /* Go through each lzo segment */
364 while (cur_in < len_in) {
365 struct page *cur_page;
366 /* Length of the compressed segment */
367 u32 seg_len;
368 u32 sector_bytes_left;
369 size_t out_len = lzo1x_worst_compress(sectorsize);
370
371 /*
372 * We should always have enough space for one segment header
373 * inside current sector.
374 */
375 ASSERT(cur_in / sectorsize ==
376 (cur_in + LZO_LEN - 1) / sectorsize);
377 cur_page = cb->compressed_pages[cur_in / PAGE_SIZE];
378 ASSERT(cur_page);
379 kaddr = kmap_local_page(cur_page);
380 seg_len = read_compress_length(kaddr + offset_in_page(cur_in));
381 kunmap_local(kaddr);
382 cur_in += LZO_LEN;
383
384 if (seg_len > WORKSPACE_CBUF_LENGTH) {
385 /*
386 * seg_len shouldn't be larger than we have allocated
387 * for workspace->cbuf
388 */
389 btrfs_err(fs_info, "unexpectedly large lzo segment len %u",
390 seg_len);
391 ret = -EIO;
392 goto out;
393 }
394
395 /* Copy the compressed segment payload into workspace */
396 copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in);
397
398 /* Decompress the data */
399 ret = lzo1x_decompress_safe(workspace->cbuf, seg_len,
400 workspace->buf, &out_len);
401 if (ret != LZO_E_OK) {
402 btrfs_err(fs_info, "failed to decompress");
403 ret = -EIO;
404 goto out;
405 }
406
407 /* Copy the data into inode pages */
408 ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out);
409 cur_out += out_len;
410
411 /* All data read, exit */
412 if (ret == 0)
413 goto out;
414 ret = 0;
415
416 /* Check if the sector has enough space for a segment header */
417 sector_bytes_left = sectorsize - (cur_in % sectorsize);
418 if (sector_bytes_left >= LZO_LEN)
419 continue;
420
421 /* Skip the padding zeros */
422 cur_in += sector_bytes_left;
423 }
424 out:
425 if (!ret)
426 zero_fill_bio(cb->orig_bio);
427 return ret;
428 }
429
lzo_decompress(struct list_head * ws,const u8 * data_in,struct page * dest_page,unsigned long start_byte,size_t srclen,size_t destlen)430 int lzo_decompress(struct list_head *ws, const u8 *data_in,
431 struct page *dest_page, unsigned long start_byte, size_t srclen,
432 size_t destlen)
433 {
434 struct workspace *workspace = list_entry(ws, struct workspace, list);
435 size_t in_len;
436 size_t out_len;
437 size_t max_segment_len = WORKSPACE_BUF_LENGTH;
438 int ret = 0;
439 char *kaddr;
440 unsigned long bytes;
441
442 if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
443 return -EUCLEAN;
444
445 in_len = read_compress_length(data_in);
446 if (in_len != srclen)
447 return -EUCLEAN;
448 data_in += LZO_LEN;
449
450 in_len = read_compress_length(data_in);
451 if (in_len != srclen - LZO_LEN * 2) {
452 ret = -EUCLEAN;
453 goto out;
454 }
455 data_in += LZO_LEN;
456
457 out_len = PAGE_SIZE;
458 ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
459 if (ret != LZO_E_OK) {
460 pr_warn("BTRFS: decompress failed!\n");
461 ret = -EIO;
462 goto out;
463 }
464
465 if (out_len < start_byte) {
466 ret = -EIO;
467 goto out;
468 }
469
470 /*
471 * the caller is already checking against PAGE_SIZE, but lets
472 * move this check closer to the memcpy/memset
473 */
474 destlen = min_t(unsigned long, destlen, PAGE_SIZE);
475 bytes = min_t(unsigned long, destlen, out_len - start_byte);
476
477 kaddr = kmap_local_page(dest_page);
478 memcpy(kaddr, workspace->buf + start_byte, bytes);
479
480 /*
481 * btrfs_getblock is doing a zero on the tail of the page too,
482 * but this will cover anything missing from the decompressed
483 * data.
484 */
485 if (bytes < destlen)
486 memset(kaddr+bytes, 0, destlen-bytes);
487 kunmap_local(kaddr);
488 out:
489 return ret;
490 }
491
492 const struct btrfs_compress_op btrfs_lzo_compress = {
493 .workspace_manager = &wsm,
494 .max_level = 1,
495 .default_level = 1,
496 };
497