diff options
Diffstat (limited to 'fs/squashfs/page_actor.c')
-rw-r--r-- | fs/squashfs/page_actor.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/fs/squashfs/page_actor.c b/fs/squashfs/page_actor.c new file mode 100644 index 000000000000..5a1c11f56441 --- /dev/null +++ b/fs/squashfs/page_actor.c | |||
@@ -0,0 +1,100 @@ | |||
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/kernel.h> | ||
10 | #include <linux/slab.h> | ||
11 | #include <linux/pagemap.h> | ||
12 | #include "page_actor.h" | ||
13 | |||
14 | /* | ||
15 | * This file contains implementations of page_actor for decompressing into | ||
16 | * an intermediate buffer, and for decompressing directly into the | ||
17 | * page cache. | ||
18 | * | ||
19 | * Calling code should avoid sleeping between calls to squashfs_first_page() | ||
20 | * and squashfs_finish_page(). | ||
21 | */ | ||
22 | |||
23 | /* Implementation of page_actor for decompressing into intermediate buffer */ | ||
24 | static void *cache_first_page(struct squashfs_page_actor *actor) | ||
25 | { | ||
26 | actor->next_page = 1; | ||
27 | return actor->buffer[0]; | ||
28 | } | ||
29 | |||
30 | static void *cache_next_page(struct squashfs_page_actor *actor) | ||
31 | { | ||
32 | if (actor->next_page == actor->pages) | ||
33 | return NULL; | ||
34 | |||
35 | return actor->buffer[actor->next_page++]; | ||
36 | } | ||
37 | |||
38 | static void cache_finish_page(struct squashfs_page_actor *actor) | ||
39 | { | ||
40 | /* empty */ | ||
41 | } | ||
42 | |||
43 | struct squashfs_page_actor *squashfs_page_actor_init(void **buffer, | ||
44 | int pages, int length) | ||
45 | { | ||
46 | struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL); | ||
47 | |||
48 | if (actor == NULL) | ||
49 | return NULL; | ||
50 | |||
51 | actor->length = length ? : pages * PAGE_CACHE_SIZE; | ||
52 | actor->buffer = buffer; | ||
53 | actor->pages = pages; | ||
54 | actor->next_page = 0; | ||
55 | actor->squashfs_first_page = cache_first_page; | ||
56 | actor->squashfs_next_page = cache_next_page; | ||
57 | actor->squashfs_finish_page = cache_finish_page; | ||
58 | return actor; | ||
59 | } | ||
60 | |||
61 | /* Implementation of page_actor for decompressing directly into page cache. */ | ||
62 | static void *direct_first_page(struct squashfs_page_actor *actor) | ||
63 | { | ||
64 | actor->next_page = 1; | ||
65 | return actor->pageaddr = kmap_atomic(actor->page[0]); | ||
66 | } | ||
67 | |||
68 | static void *direct_next_page(struct squashfs_page_actor *actor) | ||
69 | { | ||
70 | if (actor->pageaddr) | ||
71 | kunmap_atomic(actor->pageaddr); | ||
72 | |||
73 | return actor->pageaddr = actor->next_page == actor->pages ? NULL : | ||
74 | kmap_atomic(actor->page[actor->next_page++]); | ||
75 | } | ||
76 | |||
77 | static void direct_finish_page(struct squashfs_page_actor *actor) | ||
78 | { | ||
79 | if (actor->pageaddr) | ||
80 | kunmap_atomic(actor->pageaddr); | ||
81 | } | ||
82 | |||
83 | struct squashfs_page_actor *squashfs_page_actor_init_special(struct page **page, | ||
84 | int pages, int length) | ||
85 | { | ||
86 | struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL); | ||
87 | |||
88 | if (actor == NULL) | ||
89 | return NULL; | ||
90 | |||
91 | actor->length = length ? : pages * PAGE_CACHE_SIZE; | ||
92 | actor->page = page; | ||
93 | actor->pages = pages; | ||
94 | actor->next_page = 0; | ||
95 | actor->pageaddr = NULL; | ||
96 | actor->squashfs_first_page = direct_first_page; | ||
97 | actor->squashfs_next_page = direct_next_page; | ||
98 | actor->squashfs_finish_page = direct_finish_page; | ||
99 | return actor; | ||
100 | } | ||