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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 | { | |
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 | ||
79 | static int squashfs_bio_read(struct super_block *sb, u64 index, int length, | |
80 | struct bio **biop, int *block_offset) | |
e2780ab1 PL |
81 | { |
82 | struct squashfs_sb_info *msblk = sb->s_fs_info; | |
93e72b3c PL |
83 | const u64 read_start = round_down(index, msblk->devblksize); |
84 | const sector_t block = read_start >> msblk->devblksize_log2; | |
85 | const u64 read_end = round_up(index + length, msblk->devblksize); | |
86 | const sector_t block_end = read_end >> msblk->devblksize_log2; | |
87 | int offset = read_start - round_down(index, PAGE_SIZE); | |
88 | int total_len = (block_end - block) << msblk->devblksize_log2; | |
89 | const int page_count = DIV_ROUND_UP(total_len + offset, PAGE_SIZE); | |
90 | int error, i; | |
91 | struct bio *bio; | |
92 | ||
066ff571 | 93 | bio = bio_kmalloc(page_count, GFP_NOIO); |
93e72b3c PL |
94 | if (!bio) |
95 | return -ENOMEM; | |
066ff571 | 96 | bio_init(bio, sb->s_bdev, bio->bi_inline_vecs, page_count, REQ_OP_READ); |
93e72b3c PL |
97 | bio->bi_iter.bi_sector = block * (msblk->devblksize >> SECTOR_SHIFT); |
98 | ||
99 | for (i = 0; i < page_count; ++i) { | |
100 | unsigned int len = | |
101 | min_t(unsigned int, PAGE_SIZE - offset, total_len); | |
102 | struct page *page = alloc_page(GFP_NOIO); | |
103 | ||
104 | if (!page) { | |
105 | error = -ENOMEM; | |
106 | goto out_free_bio; | |
107 | } | |
108 | if (!bio_add_page(bio, page, len, offset)) { | |
109 | error = -EIO; | |
110 | goto out_free_bio; | |
3689456b | 111 | } |
93e72b3c PL |
112 | offset = 0; |
113 | total_len -= len; | |
e2780ab1 PL |
114 | } |
115 | ||
93e72b3c PL |
116 | error = submit_bio_wait(bio); |
117 | if (error) | |
118 | goto out_free_bio; | |
e2780ab1 | 119 | |
93e72b3c PL |
120 | *biop = bio; |
121 | *block_offset = index & ((1 << msblk->devblksize_log2) - 1); | |
122 | return 0; | |
123 | ||
124 | out_free_bio: | |
125 | bio_free_pages(bio); | |
066ff571 CH |
126 | bio_uninit(bio); |
127 | kfree(bio); | |
93e72b3c PL |
128 | return error; |
129 | } | |
e2780ab1 PL |
130 | |
131 | /* | |
132 | * Read and decompress a metadata block or datablock. Length is non-zero | |
133 | * if a datablock is being read (the size is stored elsewhere in the | |
134 | * filesystem), otherwise the length is obtained from the first two bytes of | |
135 | * the metadata block. A bit in the length field indicates if the block | |
136 | * is stored uncompressed in the filesystem (usually because compression | |
ec9267b6 PL |
137 | * generated a larger block - this does occasionally happen with compression |
138 | * algorithms). | |
e2780ab1 | 139 | */ |
846b730e | 140 | int squashfs_read_data(struct super_block *sb, u64 index, int length, |
93e72b3c | 141 | u64 *next_index, struct squashfs_page_actor *output) |
e2780ab1 PL |
142 | { |
143 | struct squashfs_sb_info *msblk = sb->s_fs_info; | |
93e72b3c PL |
144 | struct bio *bio = NULL; |
145 | int compressed; | |
146 | int res; | |
147 | int offset; | |
e2780ab1 PL |
148 | |
149 | if (length) { | |
150 | /* | |
151 | * Datablock. | |
152 | */ | |
e2780ab1 PL |
153 | compressed = SQUASHFS_COMPRESSED_BLOCK(length); |
154 | length = SQUASHFS_COMPRESSED_SIZE_BLOCK(length); | |
e2780ab1 | 155 | TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n", |
846b730e | 156 | index, compressed ? "" : "un", length, output->length); |
e2780ab1 PL |
157 | } else { |
158 | /* | |
159 | * Metadata block. | |
160 | */ | |
93e72b3c PL |
161 | const u8 *data; |
162 | struct bvec_iter_all iter_all = {}; | |
163 | struct bio_vec *bvec = bvec_init_iter_all(&iter_all); | |
e2780ab1 | 164 | |
93e72b3c PL |
165 | if (index + 2 > msblk->bytes_used) { |
166 | res = -EIO; | |
167 | goto out; | |
168 | } | |
169 | res = squashfs_bio_read(sb, index, 2, &bio, &offset); | |
170 | if (res) | |
171 | goto out; | |
172 | ||
173 | if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { | |
174 | res = -EIO; | |
175 | goto out_free_bio; | |
176 | } | |
177 | /* Extract the length of the metadata block */ | |
fbc27241 | 178 | data = bvec_virt(bvec); |
93e72b3c | 179 | length = data[offset]; |
2910c59f | 180 | if (offset < bvec->bv_len - 1) { |
93e72b3c PL |
181 | length |= data[offset + 1] << 8; |
182 | } else { | |
183 | if (WARN_ON_ONCE(!bio_next_segment(bio, &iter_all))) { | |
184 | res = -EIO; | |
185 | goto out_free_bio; | |
186 | } | |
fbc27241 | 187 | data = bvec_virt(bvec); |
93e72b3c PL |
188 | length |= data[0] << 8; |
189 | } | |
190 | bio_free_pages(bio); | |
066ff571 CH |
191 | bio_uninit(bio); |
192 | kfree(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); | |
066ff571 CH |
226 | bio_uninit(bio); |
227 | kfree(bio); | |
93e72b3c | 228 | out: |
10dde05b | 229 | if (res < 0) { |
93e72b3c | 230 | ERROR("Failed to read block 0x%llx: %d\n", index, res); |
10dde05b VW |
231 | if (msblk->panic_on_errors) |
232 | panic("squashfs read failed"); | |
233 | } | |
e2780ab1 | 234 | |
93e72b3c | 235 | return res; |
e2780ab1 | 236 | } |