Commit | Line | Data |
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0d455c12 PL |
1 | /* |
2 | * Copyright (c) 2013 | |
3 | * Phillip Lougher <phillip@squashfs.org.uk> | |
4 | * | |
5 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
6 | * the COPYING file in the top-level directory. | |
7 | */ | |
8 | ||
9 | #include <linux/fs.h> | |
10 | #include <linux/vfs.h> | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/string.h> | |
14 | #include <linux/pagemap.h> | |
15 | #include <linux/mutex.h> | |
16 | ||
17 | #include "squashfs_fs.h" | |
18 | #include "squashfs_fs_sb.h" | |
19 | #include "squashfs_fs_i.h" | |
20 | #include "squashfs.h" | |
21 | #include "page_actor.h" | |
22 | ||
23 | static int squashfs_read_cache(struct page *target_page, u64 block, int bsize, | |
a3f94cb9 | 24 | int pages, struct page **page, int bytes); |
0d455c12 PL |
25 | |
26 | /* Read separately compressed datablock directly into page cache */ | |
a3f94cb9 PL |
27 | int squashfs_readpage_block(struct page *target_page, u64 block, int bsize, |
28 | int expected) | |
0d455c12 PL |
29 | |
30 | { | |
31 | struct inode *inode = target_page->mapping->host; | |
32 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; | |
33 | ||
09cbfeaf KS |
34 | int file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT; |
35 | int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1; | |
0d455c12 PL |
36 | int start_index = target_page->index & ~mask; |
37 | int end_index = start_index | mask; | |
38 | int i, n, pages, missing_pages, bytes, res = -ENOMEM; | |
39 | struct page **page; | |
40 | struct squashfs_page_actor *actor; | |
41 | void *pageaddr; | |
42 | ||
43 | if (end_index > file_end) | |
44 | end_index = file_end; | |
45 | ||
46 | pages = end_index - start_index + 1; | |
47 | ||
14694888 | 48 | page = kmalloc_array(pages, sizeof(void *), GFP_KERNEL); |
0d455c12 PL |
49 | if (page == NULL) |
50 | return res; | |
51 | ||
52 | /* | |
53 | * Create a "page actor" which will kmap and kunmap the | |
54 | * page cache pages appropriately within the decompressor | |
55 | */ | |
56 | actor = squashfs_page_actor_init_special(page, pages, 0); | |
57 | if (actor == NULL) | |
58 | goto out; | |
59 | ||
60 | /* Try to grab all the pages covered by the Squashfs block */ | |
61 | for (missing_pages = 0, i = 0, n = start_index; i < pages; i++, n++) { | |
62 | page[i] = (n == target_page->index) ? target_page : | |
63 | grab_cache_page_nowait(target_page->mapping, n); | |
64 | ||
65 | if (page[i] == NULL) { | |
66 | missing_pages++; | |
67 | continue; | |
68 | } | |
69 | ||
70 | if (PageUptodate(page[i])) { | |
71 | unlock_page(page[i]); | |
09cbfeaf | 72 | put_page(page[i]); |
0d455c12 PL |
73 | page[i] = NULL; |
74 | missing_pages++; | |
75 | } | |
76 | } | |
77 | ||
78 | if (missing_pages) { | |
79 | /* | |
80 | * Couldn't get one or more pages, this page has either | |
81 | * been VM reclaimed, but others are still in the page cache | |
82 | * and uptodate, or we're racing with another thread in | |
83 | * squashfs_readpage also trying to grab them. Fall back to | |
84 | * using an intermediate buffer. | |
85 | */ | |
86 | res = squashfs_read_cache(target_page, block, bsize, pages, | |
a3f94cb9 | 87 | page, expected); |
6d565409 PL |
88 | if (res < 0) |
89 | goto mark_errored; | |
90 | ||
0d455c12 PL |
91 | goto out; |
92 | } | |
93 | ||
94 | /* Decompress directly into the page cache buffers */ | |
95 | res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor); | |
96 | if (res < 0) | |
97 | goto mark_errored; | |
98 | ||
a3f94cb9 PL |
99 | if (res != expected) { |
100 | res = -EIO; | |
101 | goto mark_errored; | |
102 | } | |
103 | ||
0d455c12 | 104 | /* Last page may have trailing bytes not filled */ |
09cbfeaf | 105 | bytes = res % PAGE_SIZE; |
0d455c12 PL |
106 | if (bytes) { |
107 | pageaddr = kmap_atomic(page[pages - 1]); | |
09cbfeaf | 108 | memset(pageaddr + bytes, 0, PAGE_SIZE - bytes); |
0d455c12 PL |
109 | kunmap_atomic(pageaddr); |
110 | } | |
111 | ||
112 | /* Mark pages as uptodate, unlock and release */ | |
113 | for (i = 0; i < pages; i++) { | |
114 | flush_dcache_page(page[i]); | |
115 | SetPageUptodate(page[i]); | |
116 | unlock_page(page[i]); | |
117 | if (page[i] != target_page) | |
09cbfeaf | 118 | put_page(page[i]); |
0d455c12 PL |
119 | } |
120 | ||
121 | kfree(actor); | |
122 | kfree(page); | |
123 | ||
124 | return 0; | |
125 | ||
126 | mark_errored: | |
127 | /* Decompression failed, mark pages as errored. Target_page is | |
128 | * dealt with by the caller | |
129 | */ | |
130 | for (i = 0; i < pages; i++) { | |
6d565409 | 131 | if (page[i] == NULL || page[i] == target_page) |
0d455c12 PL |
132 | continue; |
133 | flush_dcache_page(page[i]); | |
134 | SetPageError(page[i]); | |
135 | unlock_page(page[i]); | |
09cbfeaf | 136 | put_page(page[i]); |
0d455c12 PL |
137 | } |
138 | ||
139 | out: | |
140 | kfree(actor); | |
141 | kfree(page); | |
142 | return res; | |
143 | } | |
144 | ||
145 | ||
146 | static int squashfs_read_cache(struct page *target_page, u64 block, int bsize, | |
a3f94cb9 | 147 | int pages, struct page **page, int bytes) |
0d455c12 PL |
148 | { |
149 | struct inode *i = target_page->mapping->host; | |
150 | struct squashfs_cache_entry *buffer = squashfs_get_datablock(i->i_sb, | |
151 | block, bsize); | |
a3f94cb9 | 152 | int res = buffer->error, n, offset = 0; |
0d455c12 PL |
153 | |
154 | if (res) { | |
155 | ERROR("Unable to read page, block %llx, size %x\n", block, | |
156 | bsize); | |
157 | goto out; | |
158 | } | |
159 | ||
160 | for (n = 0; n < pages && bytes > 0; n++, | |
09cbfeaf KS |
161 | bytes -= PAGE_SIZE, offset += PAGE_SIZE) { |
162 | int avail = min_t(int, bytes, PAGE_SIZE); | |
0d455c12 PL |
163 | |
164 | if (page[n] == NULL) | |
165 | continue; | |
166 | ||
cdbb65c4 | 167 | squashfs_fill_page(page[n], buffer, offset, avail); |
0d455c12 PL |
168 | unlock_page(page[n]); |
169 | if (page[n] != target_page) | |
09cbfeaf | 170 | put_page(page[n]); |
0d455c12 PL |
171 | } |
172 | ||
173 | out: | |
174 | squashfs_cache_put(buffer); | |
175 | return res; | |
176 | } |