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/kernel.h> |
8 | #include <linux/slab.h> |
9 | #include <linux/pagemap.h> |
10 | #include "squashfs_fs_sb.h" |
11 | #include "decompressor.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(size: sizeof(*actor), GFP_KERNEL); |
47 | |
48 | if (actor == NULL) |
49 | return NULL; |
50 | |
51 | actor->length = length ? : pages * PAGE_SIZE; |
52 | actor->buffer = buffer; |
53 | actor->pages = pages; |
54 | actor->next_page = 0; |
55 | actor->tmp_buffer = NULL; |
56 | actor->squashfs_first_page = cache_first_page; |
57 | actor->squashfs_next_page = cache_next_page; |
58 | actor->squashfs_finish_page = cache_finish_page; |
59 | return actor; |
60 | } |
61 | |
62 | /* Implementation of page_actor for decompressing directly into page cache. */ |
63 | static void *handle_next_page(struct squashfs_page_actor *actor) |
64 | { |
65 | int max_pages = (actor->length + PAGE_SIZE - 1) >> PAGE_SHIFT; |
66 | |
67 | if (actor->returned_pages == max_pages) |
68 | return NULL; |
69 | |
70 | if ((actor->next_page == actor->pages) || |
71 | (actor->next_index != actor->page[actor->next_page]->index)) { |
72 | actor->next_index++; |
73 | actor->returned_pages++; |
74 | actor->last_page = NULL; |
75 | return actor->alloc_buffer ? actor->tmp_buffer : ERR_PTR(error: -ENOMEM); |
76 | } |
77 | |
78 | actor->next_index++; |
79 | actor->returned_pages++; |
80 | actor->last_page = actor->page[actor->next_page]; |
81 | return actor->pageaddr = kmap_local_page(page: actor->page[actor->next_page++]); |
82 | } |
83 | |
84 | static void *direct_first_page(struct squashfs_page_actor *actor) |
85 | { |
86 | return handle_next_page(actor); |
87 | } |
88 | |
89 | static void *direct_next_page(struct squashfs_page_actor *actor) |
90 | { |
91 | if (actor->pageaddr) { |
92 | kunmap_local(actor->pageaddr); |
93 | actor->pageaddr = NULL; |
94 | } |
95 | |
96 | return handle_next_page(actor); |
97 | } |
98 | |
99 | static void direct_finish_page(struct squashfs_page_actor *actor) |
100 | { |
101 | if (actor->pageaddr) |
102 | kunmap_local(actor->pageaddr); |
103 | } |
104 | |
105 | struct squashfs_page_actor *squashfs_page_actor_init_special(struct squashfs_sb_info *msblk, |
106 | struct page **page, int pages, int length) |
107 | { |
108 | struct squashfs_page_actor *actor = kmalloc(size: sizeof(*actor), GFP_KERNEL); |
109 | |
110 | if (actor == NULL) |
111 | return NULL; |
112 | |
113 | if (msblk->decompressor->alloc_buffer) { |
114 | actor->tmp_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL); |
115 | |
116 | if (actor->tmp_buffer == NULL) { |
117 | kfree(objp: actor); |
118 | return NULL; |
119 | } |
120 | } else |
121 | actor->tmp_buffer = NULL; |
122 | |
123 | actor->length = length ? : pages * PAGE_SIZE; |
124 | actor->page = page; |
125 | actor->pages = pages; |
126 | actor->next_page = 0; |
127 | actor->returned_pages = 0; |
128 | actor->next_index = page[0]->index & ~((1 << (msblk->block_log - PAGE_SHIFT)) - 1); |
129 | actor->pageaddr = NULL; |
130 | actor->last_page = NULL; |
131 | actor->alloc_buffer = msblk->decompressor->alloc_buffer; |
132 | actor->squashfs_first_page = direct_first_page; |
133 | actor->squashfs_next_page = direct_next_page; |
134 | actor->squashfs_finish_page = direct_finish_page; |
135 | return actor; |
136 | } |
137 |