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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> | |
e2780ab1 PL |
20 | #include <linux/string.h> |
21 | #include <linux/buffer_head.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 | { | |
37 | void *actor_addr = squashfs_first_page(actor); | |
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 | ||
43 | if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) | |
44 | return 0; | |
45 | ||
46 | while (copied_bytes < req_length) { | |
47 | int bytes_to_copy = min_t(int, bvec->bv_len - offset, | |
48 | PAGE_SIZE - actor_offset); | |
49 | ||
50 | bytes_to_copy = min_t(int, bytes_to_copy, | |
51 | req_length - copied_bytes); | |
fbc27241 | 52 | memcpy(actor_addr + actor_offset, bvec_virt(bvec) + offset, |
93e72b3c PL |
53 | bytes_to_copy); |
54 | ||
55 | actor_offset += bytes_to_copy; | |
56 | copied_bytes += bytes_to_copy; | |
57 | offset += bytes_to_copy; | |
58 | ||
59 | if (actor_offset >= PAGE_SIZE) { | |
60 | actor_addr = squashfs_next_page(actor); | |
61 | if (!actor_addr) | |
62 | break; | |
63 | actor_offset = 0; | |
64 | } | |
65 | if (offset >= bvec->bv_len) { | |
66 | if (!bio_next_segment(bio, &iter_all)) | |
67 | break; | |
68 | offset = 0; | |
69 | } | |
70 | } | |
71 | squashfs_finish_page(actor); | |
72 | return copied_bytes; | |
73 | } | |
74 | ||
75 | static int squashfs_bio_read(struct super_block *sb, u64 index, int length, | |
76 | struct bio **biop, int *block_offset) | |
e2780ab1 PL |
77 | { |
78 | struct squashfs_sb_info *msblk = sb->s_fs_info; | |
93e72b3c PL |
79 | const u64 read_start = round_down(index, msblk->devblksize); |
80 | const sector_t block = read_start >> msblk->devblksize_log2; | |
81 | const u64 read_end = round_up(index + length, msblk->devblksize); | |
82 | const sector_t block_end = read_end >> msblk->devblksize_log2; | |
83 | int offset = read_start - round_down(index, PAGE_SIZE); | |
84 | int total_len = (block_end - block) << msblk->devblksize_log2; | |
85 | const int page_count = DIV_ROUND_UP(total_len + offset, PAGE_SIZE); | |
86 | int error, i; | |
87 | struct bio *bio; | |
88 | ||
a8affc03 | 89 | if (page_count <= BIO_MAX_VECS) |
f26044c8 PL |
90 | bio = bio_alloc(GFP_NOIO, page_count); |
91 | else | |
92 | bio = bio_kmalloc(GFP_NOIO, page_count); | |
93 | ||
93e72b3c PL |
94 | if (!bio) |
95 | return -ENOMEM; | |
96 | ||
97 | bio_set_dev(bio, sb->s_bdev); | |
98 | bio->bi_opf = READ; | |
99 | bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT); | |
100 | ||
101 | for (i = 0; i < page_count; ++i) { | |
102 | unsigned int len = | |
103 | min_t(unsigned int, PAGE_SIZE - offset, total_len); | |
104 | struct page *page = alloc_page(GFP_NOIO); | |
105 | ||
106 | if (!page) { | |
107 | error = -ENOMEM; | |
108 | goto out_free_bio; | |
109 | } | |
110 | if (!bio_add_page(bio, page, len, offset)) { | |
111 | error = -EIO; | |
112 | goto out_free_bio; | |
3689456b | 113 | } |
93e72b3c PL |
114 | offset = 0; |
115 | total_len -= len; | |
e2780ab1 PL |
116 | } |
117 | ||
93e72b3c PL |
118 | error = submit_bio_wait(bio); |
119 | if (error) | |
120 | goto out_free_bio; | |
e2780ab1 | 121 | |
93e72b3c PL |
122 | *biop = bio; |
123 | *block_offset = index & ((1 << msblk->devblksize_log2) - 1); | |
124 | return 0; | |
125 | ||
126 | out_free_bio: | |
127 | bio_free_pages(bio); | |
128 | bio_put(bio); | |
129 | return error; | |
130 | } | |
e2780ab1 PL |
131 | |
132 | /* | |
133 | * Read and decompress a metadata block or datablock. Length is non-zero | |
134 | * if a datablock is being read (the size is stored elsewhere in the | |
135 | * filesystem), otherwise the length is obtained from the first two bytes of | |
136 | * the metadata block. A bit in the length field indicates if the block | |
137 | * is stored uncompressed in the filesystem (usually because compression | |
ec9267b6 PL |
138 | * generated a larger block - this does occasionally happen with compression |
139 | * algorithms). | |
e2780ab1 | 140 | */ |
846b730e | 141 | int squashfs_read_data(struct super_block *sb, u64 index, int length, |
93e72b3c | 142 | u64 *next_index, struct squashfs_page_actor *output) |
e2780ab1 PL |
143 | { |
144 | struct squashfs_sb_info *msblk = sb->s_fs_info; | |
93e72b3c PL |
145 | struct bio *bio = NULL; |
146 | int compressed; | |
147 | int res; | |
148 | int offset; | |
e2780ab1 PL |
149 | |
150 | if (length) { | |
151 | /* | |
152 | * Datablock. | |
153 | */ | |
e2780ab1 PL |
154 | compressed = SQUASHFS_COMPRESSED_BLOCK(length); |
155 | length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length); | |
e2780ab1 | 156 | TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n", |
846b730e | 157 | index, compressed ? "" : "un", length, output->length); |
e2780ab1 PL |
158 | } else { |
159 | /* | |
160 | * Metadata block. | |
161 | */ | |
93e72b3c PL |
162 | const u8 *data; |
163 | struct bvec_iter_all iter_all = {}; | |
164 | struct bio_vec *bvec = bvec_init_iter_all(&iter_all); | |
e2780ab1 | 165 | |
93e72b3c PL |
166 | if (index + 2 > msblk->bytes_used) { |
167 | res = -EIO; | |
168 | goto out; | |
169 | } | |
170 | res = squashfs_bio_read(sb, index, 2, &bio, &offset); | |
171 | if (res) | |
172 | goto out; | |
173 | ||
174 | if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { | |
175 | res = -EIO; | |
176 | goto out_free_bio; | |
177 | } | |
178 | /* Extract the length of the metadata block */ | |
fbc27241 | 179 | data = bvec_virt(bvec); |
93e72b3c | 180 | length = data[offset]; |
2910c59f | 181 | if (offset < bvec->bv_len - 1) { |
93e72b3c PL |
182 | length |= data[offset + 1] << 8; |
183 | } else { | |
184 | if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { | |
185 | res = -EIO; | |
186 | goto out_free_bio; | |
187 | } | |
fbc27241 | 188 | data = bvec_virt(bvec); |
93e72b3c PL |
189 | length |= data[0] << 8; |
190 | } | |
191 | bio_free_pages(bio); | |
192 | bio_put(bio); | |
e2780ab1 | 193 | |
e2780ab1 PL |
194 | compressed = SQUASHFS_COMPRESSED(length); |
195 | length = SQUASHFS_COMPRESSED_SIZE(length); | |
93e72b3c | 196 | index += 2; |
e2780ab1 | 197 | |
e812cbbb | 198 | TRACE("Block @ 0x%llx, %scompressed size %d\n", index - 2, |
93e72b3c | 199 | compressed ? "" : "un", length); |
e2780ab1 | 200 | } |
e812cbbb PL |
201 | if (length < 0 || length > output->length || |
202 | (index + length) > msblk->bytes_used) { | |
203 | res = -EIO; | |
204 | goto out; | |
205 | } | |
206 | ||
93e72b3c PL |
207 | if (next_index) |
208 | *next_index = index + length; | |
e2780ab1 | 209 | |
93e72b3c PL |
210 | res = squashfs_bio_read(sb, index, length, &bio, &offset); |
211 | if (res) | |
212 | goto out; | |
9508c6b9 | 213 | |
e2780ab1 | 214 | if (compressed) { |
93e72b3c PL |
215 | if (!msblk->stream) { |
216 | res = -EIO; | |
217 | goto out_free_bio; | |
e2780ab1 | 218 | } |
93e72b3c PL |
219 | res = squashfs_decompress(msblk, bio, offset, length, output); |
220 | } else { | |
221 | res = copy_bio_to_actor(bio, output, offset, length); | |
e2780ab1 PL |
222 | } |
223 | ||
93e72b3c PL |
224 | out_free_bio: |
225 | bio_free_pages(bio); | |
226 | bio_put(bio); | |
227 | out: | |
10dde05b | 228 | if (res < 0) { |
93e72b3c | 229 | ERROR("Failed to read block 0x%llx: %d\n", index, res); |
10dde05b VW |
230 | if (msblk->panic_on_errors) |
231 | panic("squashfs read failed"); | |
232 | } | |
e2780ab1 | 233 | |
93e72b3c | 234 | return res; |
e2780ab1 | 235 | } |