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