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20c8ccb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
0d455c12 PL |
2 | /* |
3 | * Copyright (c) 2013 | |
4 | * Phillip Lougher <phillip@squashfs.org.uk> | |
0d455c12 PL |
5 | */ |
6 | ||
7 | #include <linux/kernel.h> | |
8 | #include <linux/slab.h> | |
9 | #include <linux/pagemap.h> | |
10 | #include "page_actor.h" | |
11 | ||
12 | /* | |
13 | * This file contains implementations of page_actor for decompressing into | |
14 | * an intermediate buffer, and for decompressing directly into the | |
15 | * page cache. | |
16 | * | |
17 | * Calling code should avoid sleeping between calls to squashfs_first_page() | |
18 | * and squashfs_finish_page(). | |
19 | */ | |
20 | ||
21 | /* Implementation of page_actor for decompressing into intermediate buffer */ | |
22 | static void *cache_first_page(struct squashfs_page_actor *actor) | |
23 | { | |
24 | actor->next_page = 1; | |
25 | return actor->buffer[0]; | |
26 | } | |
27 | ||
28 | static void *cache_next_page(struct squashfs_page_actor *actor) | |
29 | { | |
30 | if (actor->next_page == actor->pages) | |
31 | return NULL; | |
32 | ||
33 | return actor->buffer[actor->next_page++]; | |
34 | } | |
35 | ||
36 | static void cache_finish_page(struct squashfs_page_actor *actor) | |
37 | { | |
38 | /* empty */ | |
39 | } | |
40 | ||
41 | struct squashfs_page_actor *squashfs_page_actor_init(void **buffer, | |
42 | int pages, int length) | |
43 | { | |
44 | struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL); | |
45 | ||
46 | if (actor == NULL) | |
47 | return NULL; | |
48 | ||
09cbfeaf | 49 | actor->length = length ? : pages * PAGE_SIZE; |
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50 | actor->buffer = buffer; |
51 | actor->pages = pages; | |
52 | actor->next_page = 0; | |
53 | actor->squashfs_first_page = cache_first_page; | |
54 | actor->squashfs_next_page = cache_next_page; | |
55 | actor->squashfs_finish_page = cache_finish_page; | |
56 | return actor; | |
57 | } | |
58 | ||
59 | /* Implementation of page_actor for decompressing directly into page cache. */ | |
60 | static void *direct_first_page(struct squashfs_page_actor *actor) | |
61 | { | |
62 | actor->next_page = 1; | |
63 | return actor->pageaddr = kmap_atomic(actor->page[0]); | |
64 | } | |
65 | ||
66 | static void *direct_next_page(struct squashfs_page_actor *actor) | |
67 | { | |
68 | if (actor->pageaddr) | |
69 | kunmap_atomic(actor->pageaddr); | |
70 | ||
71 | return actor->pageaddr = actor->next_page == actor->pages ? NULL : | |
72 | kmap_atomic(actor->page[actor->next_page++]); | |
73 | } | |
74 | ||
75 | static void direct_finish_page(struct squashfs_page_actor *actor) | |
76 | { | |
77 | if (actor->pageaddr) | |
78 | kunmap_atomic(actor->pageaddr); | |
79 | } | |
80 | ||
81 | struct squashfs_page_actor *squashfs_page_actor_init_special(struct page **page, | |
82 | int pages, int length) | |
83 | { | |
84 | struct squashfs_page_actor *actor = kmalloc(sizeof(*actor), GFP_KERNEL); | |
85 | ||
86 | if (actor == NULL) | |
87 | return NULL; | |
88 | ||
09cbfeaf | 89 | actor->length = length ? : pages * PAGE_SIZE; |
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90 | actor->page = page; |
91 | actor->pages = pages; | |
92 | actor->next_page = 0; | |
93 | actor->pageaddr = NULL; | |
94 | actor->squashfs_first_page = direct_first_page; | |
95 | actor->squashfs_next_page = direct_next_page; | |
96 | actor->squashfs_finish_page = direct_finish_page; | |
97 | return actor; | |
98 | } |