Commit | Line | Data |
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68252eb5 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
e2780ab1 PL |
2 | /* |
3 | * Squashfs - a compressed read only filesystem for Linux | |
4 | * | |
5 | * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 | |
d7f2ff67 | 6 | * Phillip Lougher <phillip@squashfs.org.uk> |
e2780ab1 | 7 | * |
e2780ab1 PL |
8 | * block.c |
9 | */ | |
10 | ||
11 | /* | |
12 | * This file implements the low-level routines to read and decompress | |
13 | * datablocks and metadata blocks. | |
14 | */ | |
15 | ||
93e72b3c | 16 | #include <linux/blkdev.h> |
e2780ab1 PL |
17 | #include <linux/fs.h> |
18 | #include <linux/vfs.h> | |
19 | #include <linux/slab.h> | |
e994f5b6 | 20 | #include <linux/pagemap.h> |
e2780ab1 | 21 | #include <linux/string.h> |
2f8b5444 | 22 | #include <linux/bio.h> |
e2780ab1 PL |
23 | |
24 | #include "squashfs_fs.h" | |
25 | #include "squashfs_fs_sb.h" | |
e2780ab1 | 26 | #include "squashfs.h" |
4c0f0bb2 | 27 | #include "decompressor.h" |
846b730e | 28 | #include "page_actor.h" |
e2780ab1 PL |
29 | |
30 | /* | |
93e72b3c | 31 | * Returns the amount of bytes copied to the page actor. |
e2780ab1 | 32 | */ |
93e72b3c PL |
33 | static int copy_bio_to_actor(struct bio *bio, |
34 | struct squashfs_page_actor *actor, | |
35 | int offset, int req_length) | |
36 | { | |
f268eedd | 37 | void *actor_addr; |
93e72b3c PL |
38 | struct bvec_iter_all iter_all = {}; |
39 | struct bio_vec *bvec = bvec_init_iter_all(&iter_all); | |
40 | int copied_bytes = 0; | |
41 | int actor_offset = 0; | |
42 | ||
f268eedd PL |
43 | squashfs_actor_nobuff(actor); |
44 | actor_addr = squashfs_first_page(actor); | |
45 | ||
93e72b3c PL |
46 | if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) |
47 | return 0; | |
48 | ||
49 | while (copied_bytes < req_length) { | |
50 | int bytes_to_copy = min_t(int, bvec->bv_len - offset, | |
51 | PAGE_SIZE - actor_offset); | |
52 | ||
53 | bytes_to_copy = min_t(int, bytes_to_copy, | |
54 | req_length - copied_bytes); | |
f268eedd PL |
55 | if (!IS_ERR(actor_addr)) |
56 | memcpy(actor_addr + actor_offset, bvec_virt(bvec) + | |
57 | offset, bytes_to_copy); | |
93e72b3c PL |
58 | |
59 | actor_offset += bytes_to_copy; | |
60 | copied_bytes += bytes_to_copy; | |
61 | offset += bytes_to_copy; | |
62 | ||
63 | if (actor_offset >= PAGE_SIZE) { | |
64 | actor_addr = squashfs_next_page(actor); | |
65 | if (!actor_addr) | |
66 | break; | |
67 | actor_offset = 0; | |
68 | } | |
69 | if (offset >= bvec->bv_len) { | |
70 | if (!bio_next_segment(bio, &iter_all)) | |
71 | break; | |
72 | offset = 0; | |
73 | } | |
74 | } | |
75 | squashfs_finish_page(actor); | |
76 | return copied_bytes; | |
77 | } | |
78 | ||
e994f5b6 VW |
79 | static int squashfs_bio_read_cached(struct bio *fullbio, |
80 | struct address_space *cache_mapping, u64 index, int length, | |
81 | u64 read_start, u64 read_end, int page_count) | |
82 | { | |
83 | struct page *head_to_cache = NULL, *tail_to_cache = NULL; | |
84 | struct block_device *bdev = fullbio->bi_bdev; | |
85 | int start_idx = 0, end_idx = 0; | |
86 | struct bvec_iter_all iter_all; | |
87 | struct bio *bio = NULL; | |
88 | struct bio_vec *bv; | |
89 | int idx = 0; | |
90 | int err = 0; | |
91 | ||
92 | bio_for_each_segment_all(bv, fullbio, iter_all) { | |
93 | struct page *page = bv->bv_page; | |
94 | ||
95 | if (page->mapping == cache_mapping) { | |
96 | idx++; | |
97 | continue; | |
98 | } | |
99 | ||
100 | /* | |
101 | * We only use this when the device block size is the same as | |
102 | * the page size, so read_start and read_end cover full pages. | |
103 | * | |
104 | * Compare these to the original required index and length to | |
105 | * only cache pages which were requested partially, since these | |
106 | * are the ones which are likely to be needed when reading | |
107 | * adjacent blocks. | |
108 | */ | |
109 | if (idx == 0 && index != read_start) | |
110 | head_to_cache = page; | |
111 | else if (idx == page_count - 1 && index + length != read_end) | |
112 | tail_to_cache = page; | |
113 | ||
114 | if (!bio || idx != end_idx) { | |
115 | struct bio *new = bio_alloc_clone(bdev, fullbio, | |
116 | GFP_NOIO, &fs_bio_set); | |
117 | ||
118 | if (bio) { | |
119 | bio_trim(bio, start_idx * PAGE_SECTORS, | |
120 | (end_idx - start_idx) * PAGE_SECTORS); | |
121 | bio_chain(bio, new); | |
122 | submit_bio(bio); | |
123 | } | |
124 | ||
125 | bio = new; | |
126 | start_idx = idx; | |
127 | } | |
128 | ||
129 | idx++; | |
130 | end_idx = idx; | |
131 | } | |
132 | ||
133 | if (bio) { | |
134 | bio_trim(bio, start_idx * PAGE_SECTORS, | |
135 | (end_idx - start_idx) * PAGE_SECTORS); | |
136 | err = submit_bio_wait(bio); | |
137 | bio_put(bio); | |
138 | } | |
139 | ||
140 | if (err) | |
141 | return err; | |
142 | ||
143 | if (head_to_cache) { | |
144 | int ret = add_to_page_cache_lru(head_to_cache, cache_mapping, | |
145 | read_start >> PAGE_SHIFT, | |
146 | GFP_NOIO); | |
147 | ||
148 | if (!ret) { | |
149 | SetPageUptodate(head_to_cache); | |
150 | unlock_page(head_to_cache); | |
151 | } | |
152 | ||
153 | } | |
154 | ||
155 | if (tail_to_cache) { | |
156 | int ret = add_to_page_cache_lru(tail_to_cache, cache_mapping, | |
157 | (read_end >> PAGE_SHIFT) - 1, | |
158 | GFP_NOIO); | |
159 | ||
160 | if (!ret) { | |
161 | SetPageUptodate(tail_to_cache); | |
162 | unlock_page(tail_to_cache); | |
163 | } | |
164 | } | |
165 | ||
166 | return 0; | |
167 | } | |
168 | ||
08bab74a VW |
169 | static struct page *squashfs_get_cache_page(struct address_space *mapping, |
170 | pgoff_t index) | |
171 | { | |
172 | struct page *page; | |
173 | ||
174 | if (!mapping) | |
175 | return NULL; | |
176 | ||
177 | page = find_get_page(mapping, index); | |
178 | if (!page) | |
179 | return NULL; | |
180 | ||
181 | if (!PageUptodate(page)) { | |
182 | put_page(page); | |
183 | return NULL; | |
184 | } | |
185 | ||
186 | return page; | |
187 | } | |
188 | ||
93e72b3c PL |
189 | static int squashfs_bio_read(struct super_block *sb, u64 index, int length, |
190 | struct bio **biop, int *block_offset) | |
e2780ab1 PL |
191 | { |
192 | struct squashfs_sb_info *msblk = sb->s_fs_info; | |
e994f5b6 | 193 | struct address_space *cache_mapping = msblk->cache_mapping; |
93e72b3c PL |
194 | const u64 read_start = round_down(index, msblk->devblksize); |
195 | const sector_t block = read_start >> msblk->devblksize_log2; | |
196 | const u64 read_end = round_up(index + length, msblk->devblksize); | |
197 | const sector_t block_end = read_end >> msblk->devblksize_log2; | |
198 | int offset = read_start - round_down(index, PAGE_SIZE); | |
199 | int total_len = (block_end - block) << msblk->devblksize_log2; | |
200 | const int page_count = DIV_ROUND_UP(total_len + offset, PAGE_SIZE); | |
201 | int error, i; | |
202 | struct bio *bio; | |
203 | ||
066ff571 | 204 | bio = bio_kmalloc(page_count, GFP_NOIO); |
93e72b3c PL |
205 | if (!bio) |
206 | return -ENOMEM; | |
066ff571 | 207 | bio_init(bio, sb->s_bdev, bio->bi_inline_vecs, page_count, REQ_OP_READ); |
93e72b3c PL |
208 | bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT); |
209 | ||
210 | for (i = 0; i < page_count; ++i) { | |
211 | unsigned int len = | |
212 | min_t(unsigned int, PAGE_SIZE - offset, total_len); | |
08bab74a VW |
213 | pgoff_t index = (read_start >> PAGE_SHIFT) + i; |
214 | struct page *page; | |
e994f5b6 | 215 | |
08bab74a | 216 | page = squashfs_get_cache_page(cache_mapping, index); |
e994f5b6 VW |
217 | if (!page) |
218 | page = alloc_page(GFP_NOIO); | |
93e72b3c PL |
219 | |
220 | if (!page) { | |
221 | error = -ENOMEM; | |
222 | goto out_free_bio; | |
223 | } | |
e994f5b6 VW |
224 | |
225 | /* | |
226 | * Use the __ version to avoid merging since we need each page | |
227 | * to be separate when we check for and avoid cached pages. | |
228 | */ | |
229 | __bio_add_page(bio, page, len, offset); | |
93e72b3c PL |
230 | offset = 0; |
231 | total_len -= len; | |
e2780ab1 PL |
232 | } |
233 | ||
e994f5b6 VW |
234 | if (cache_mapping) |
235 | error = squashfs_bio_read_cached(bio, cache_mapping, index, | |
236 | length, read_start, read_end, | |
237 | page_count); | |
238 | else | |
239 | error = submit_bio_wait(bio); | |
93e72b3c PL |
240 | if (error) |
241 | goto out_free_bio; | |
e2780ab1 | 242 | |
93e72b3c PL |
243 | *biop = bio; |
244 | *block_offset = index & ((1 << msblk->devblksize_log2) - 1); | |
245 | return 0; | |
246 | ||
247 | out_free_bio: | |
248 | bio_free_pages(bio); | |
066ff571 CH |
249 | bio_uninit(bio); |
250 | kfree(bio); | |
93e72b3c PL |
251 | return error; |
252 | } | |
e2780ab1 PL |
253 | |
254 | /* | |
255 | * Read and decompress a metadata block or datablock. Length is non-zero | |
256 | * if a datablock is being read (the size is stored elsewhere in the | |
257 | * filesystem), otherwise the length is obtained from the first two bytes of | |
258 | * the metadata block. A bit in the length field indicates if the block | |
259 | * is stored uncompressed in the filesystem (usually because compression | |
ec9267b6 PL |
260 | * generated a larger block - this does occasionally happen with compression |
261 | * algorithms). | |
e2780ab1 | 262 | */ |
846b730e | 263 | int squashfs_read_data(struct super_block *sb, u64 index, int length, |
93e72b3c | 264 | u64 *next_index, struct squashfs_page_actor *output) |
e2780ab1 PL |
265 | { |
266 | struct squashfs_sb_info *msblk = sb->s_fs_info; | |
93e72b3c PL |
267 | struct bio *bio = NULL; |
268 | int compressed; | |
269 | int res; | |
270 | int offset; | |
e2780ab1 PL |
271 | |
272 | if (length) { | |
273 | /* | |
274 | * Datablock. | |
275 | */ | |
e2780ab1 PL |
276 | compressed = SQUASHFS_COMPRESSED_BLOCK(length); |
277 | length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length); | |
e2780ab1 | 278 | TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n", |
846b730e | 279 | index, compressed ? "" : "un", length, output->length); |
e2780ab1 PL |
280 | } else { |
281 | /* | |
282 | * Metadata block. | |
283 | */ | |
93e72b3c PL |
284 | const u8 *data; |
285 | struct bvec_iter_all iter_all = {}; | |
286 | struct bio_vec *bvec = bvec_init_iter_all(&iter_all); | |
e2780ab1 | 287 | |
93e72b3c PL |
288 | if (index + 2 > msblk->bytes_used) { |
289 | res = -EIO; | |
290 | goto out; | |
291 | } | |
292 | res = squashfs_bio_read(sb, index, 2, &bio, &offset); | |
293 | if (res) | |
294 | goto out; | |
295 | ||
296 | if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { | |
297 | res = -EIO; | |
298 | goto out_free_bio; | |
299 | } | |
300 | /* Extract the length of the metadata block */ | |
fbc27241 | 301 | data = bvec_virt(bvec); |
93e72b3c | 302 | length = data[offset]; |
2910c59f | 303 | if (offset < bvec->bv_len - 1) { |
93e72b3c PL |
304 | length |= data[offset + 1] << 8; |
305 | } else { | |
306 | if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { | |
307 | res = -EIO; | |
308 | goto out_free_bio; | |
309 | } | |
fbc27241 | 310 | data = bvec_virt(bvec); |
93e72b3c PL |
311 | length |= data[0] << 8; |
312 | } | |
313 | bio_free_pages(bio); | |
066ff571 CH |
314 | bio_uninit(bio); |
315 | kfree(bio); | |
e2780ab1 | 316 | |
e2780ab1 PL |
317 | compressed = SQUASHFS_COMPRESSED(length); |
318 | length = SQUASHFS_COMPRESSED_SIZE(length); | |
93e72b3c | 319 | index += 2; |
e2780ab1 | 320 | |
e812cbbb | 321 | TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2, |
93e72b3c | 322 | compressed ? "" : "un", length); |
e2780ab1 | 323 | } |
eb66b8ab | 324 | if (length <= 0 || length > output->length || |
e812cbbb PL |
325 | (index + length) > msblk->bytes_used) { |
326 | res = -EIO; | |
327 | goto out; | |
328 | } | |
329 | ||
93e72b3c PL |
330 | if (next_index) |
331 | *next_index = index + length; | |
e2780ab1 | 332 | |
93e72b3c PL |
333 | res = squashfs_bio_read(sb, index, length, &bio, &offset); |
334 | if (res) | |
335 | goto out; | |
9508c6b9 | 336 | |
e2780ab1 | 337 | if (compressed) { |
93e72b3c PL |
338 | if (!msblk->stream) { |
339 | res = -EIO; | |
340 | goto out_free_bio; | |
e2780ab1 | 341 | } |
80f78409 | 342 | res = msblk->thread_ops->decompress(msblk, bio, offset, length, output); |
93e72b3c PL |
343 | } else { |
344 | res = copy_bio_to_actor(bio, output, offset, length); | |
e2780ab1 PL |
345 | } |
346 | ||
93e72b3c PL |
347 | out_free_bio: |
348 | bio_free_pages(bio); | |
066ff571 CH |
349 | bio_uninit(bio); |
350 | kfree(bio); | |
93e72b3c | 351 | out: |
10dde05b | 352 | if (res < 0) { |
93e72b3c | 353 | ERROR("Failed to read block 0x%llx: %d\n", index, res); |
10dde05b VW |
354 | if (msblk->panic_on_errors) |
355 | panic("squashfs read failed"); | |
356 | } | |
e2780ab1 | 357 | |
93e72b3c | 358 | return res; |
e2780ab1 | 359 | } |