1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (c) 2013 |
4 | * Phillip Lougher <phillip@squashfs.org.uk> |
5 | */ |
6 | |
7 | #include <linux/fs.h> |
8 | #include <linux/vfs.h> |
9 | #include <linux/kernel.h> |
10 | #include <linux/slab.h> |
11 | #include <linux/string.h> |
12 | #include <linux/pagemap.h> |
13 | #include <linux/mutex.h> |
14 | |
15 | #include "squashfs_fs.h" |
16 | #include "squashfs_fs_sb.h" |
17 | #include "squashfs_fs_i.h" |
18 | #include "squashfs.h" |
19 | #include "page_actor.h" |
20 | |
21 | /* Read separately compressed datablock directly into page cache */ |
22 | int squashfs_readpage_block(struct page *target_page, u64 block, int bsize, |
23 | int expected) |
24 | |
25 | { |
26 | struct inode *inode = target_page->mapping->host; |
27 | struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; |
28 | |
29 | int file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT; |
30 | int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1; |
31 | int start_index = target_page->index & ~mask; |
32 | int end_index = start_index | mask; |
33 | int i, n, pages, bytes, res = -ENOMEM; |
34 | struct page **page; |
35 | struct squashfs_page_actor *actor; |
36 | void *pageaddr; |
37 | |
38 | if (end_index > file_end) |
39 | end_index = file_end; |
40 | |
41 | pages = end_index - start_index + 1; |
42 | |
43 | page = kmalloc_array(n: pages, size: sizeof(void *), GFP_KERNEL); |
44 | if (page == NULL) |
45 | return res; |
46 | |
47 | /* Try to grab all the pages covered by the Squashfs block */ |
48 | for (i = 0, n = start_index; n <= end_index; n++) { |
49 | page[i] = (n == target_page->index) ? target_page : |
50 | grab_cache_page_nowait(mapping: target_page->mapping, index: n); |
51 | |
52 | if (page[i] == NULL) |
53 | continue; |
54 | |
55 | if (PageUptodate(page: page[i])) { |
56 | unlock_page(page: page[i]); |
57 | put_page(page: page[i]); |
58 | continue; |
59 | } |
60 | |
61 | i++; |
62 | } |
63 | |
64 | pages = i; |
65 | |
66 | /* |
67 | * Create a "page actor" which will kmap and kunmap the |
68 | * page cache pages appropriately within the decompressor |
69 | */ |
70 | actor = squashfs_page_actor_init_special(msblk, page, pages, length: expected); |
71 | if (actor == NULL) |
72 | goto out; |
73 | |
74 | /* Decompress directly into the page cache buffers */ |
75 | res = squashfs_read_data(inode->i_sb, block, bsize, NULL, actor); |
76 | |
77 | squashfs_page_actor_free(actor); |
78 | |
79 | if (res < 0) |
80 | goto mark_errored; |
81 | |
82 | if (res != expected) { |
83 | res = -EIO; |
84 | goto mark_errored; |
85 | } |
86 | |
87 | /* Last page (if present) may have trailing bytes not filled */ |
88 | bytes = res % PAGE_SIZE; |
89 | if (page[pages - 1]->index == end_index && bytes) { |
90 | pageaddr = kmap_local_page(page: page[pages - 1]); |
91 | memset(pageaddr + bytes, 0, PAGE_SIZE - bytes); |
92 | kunmap_local(pageaddr); |
93 | } |
94 | |
95 | /* Mark pages as uptodate, unlock and release */ |
96 | for (i = 0; i < pages; i++) { |
97 | flush_dcache_page(page: page[i]); |
98 | SetPageUptodate(page[i]); |
99 | unlock_page(page: page[i]); |
100 | if (page[i] != target_page) |
101 | put_page(page: page[i]); |
102 | } |
103 | |
104 | kfree(objp: page); |
105 | |
106 | return 0; |
107 | |
108 | mark_errored: |
109 | /* Decompression failed, mark pages as errored. Target_page is |
110 | * dealt with by the caller |
111 | */ |
112 | for (i = 0; i < pages; i++) { |
113 | if (page[i] == NULL || page[i] == target_page) |
114 | continue; |
115 | flush_dcache_page(page: page[i]); |
116 | SetPageError(page[i]); |
117 | unlock_page(page: page[i]); |
118 | put_page(page: page[i]); |
119 | } |
120 | |
121 | out: |
122 | kfree(objp: page); |
123 | return res; |
124 | } |
125 | |