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

source code of linux/fs/btrfs/lzo.c