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1 | #include <linux/module.h> |
2 | #include <linux/gfp.h> |
3 | #include <linux/pagemap.h> |
4 | #include <linux/highmem.h> |
5 | #include <linux/ceph/pagelist.h> |
6 | |
7 | static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl) |
8 | { |
9 | if (pl->mapped_tail) { |
10 | struct page *page = list_entry(pl->head.prev, struct page, lru); |
11 | kunmap(page); |
12 | pl->mapped_tail = NULL; |
13 | } |
14 | } |
15 | |
16 | int ceph_pagelist_release(struct ceph_pagelist *pl) |
17 | { |
18 | ceph_pagelist_unmap_tail(pl); |
19 | while (!list_empty(&pl->head)) { |
20 | struct page *page = list_first_entry(&pl->head, struct page, |
21 | lru); |
22 | list_del(&page->lru); |
23 | __free_page(page); |
24 | } |
25 | ceph_pagelist_free_reserve(pl); |
26 | return 0; |
27 | } |
28 | EXPORT_SYMBOL(ceph_pagelist_release); |
29 | |
30 | static int ceph_pagelist_addpage(struct ceph_pagelist *pl) |
31 | { |
32 | struct page *page; |
33 | |
34 | if (!pl->num_pages_free) { |
35 | page = __page_cache_alloc(GFP_NOFS); |
36 | } else { |
37 | page = list_first_entry(&pl->free_list, struct page, lru); |
38 | list_del(&page->lru); |
39 | --pl->num_pages_free; |
40 | } |
41 | if (!page) |
42 | return -ENOMEM; |
43 | pl->room += PAGE_SIZE; |
44 | ceph_pagelist_unmap_tail(pl); |
45 | list_add_tail(&page->lru, &pl->head); |
46 | pl->mapped_tail = kmap(page); |
47 | return 0; |
48 | } |
49 | |
50 | int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len) |
51 | { |
52 | while (pl->room < len) { |
53 | size_t bit = pl->room; |
54 | int ret; |
55 | |
56 | memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK), |
57 | buf, bit); |
58 | pl->length += bit; |
59 | pl->room -= bit; |
60 | buf += bit; |
61 | len -= bit; |
62 | ret = ceph_pagelist_addpage(pl); |
63 | if (ret) |
64 | return ret; |
65 | } |
66 | |
67 | memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK), buf, len); |
68 | pl->length += len; |
69 | pl->room -= len; |
70 | return 0; |
71 | } |
72 | EXPORT_SYMBOL(ceph_pagelist_append); |
73 | |
74 | /* Allocate enough pages for a pagelist to append the given amount |
75 | * of data without without allocating. |
76 | * Returns: 0 on success, -ENOMEM on error. |
77 | */ |
78 | int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space) |
79 | { |
80 | if (space <= pl->room) |
81 | return 0; |
82 | space -= pl->room; |
83 | space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT; /* conv to num pages */ |
84 | |
85 | while (space > pl->num_pages_free) { |
86 | struct page *page = __page_cache_alloc(GFP_NOFS); |
87 | if (!page) |
88 | return -ENOMEM; |
89 | list_add_tail(&page->lru, &pl->free_list); |
90 | ++pl->num_pages_free; |
91 | } |
92 | return 0; |
93 | } |
94 | EXPORT_SYMBOL(ceph_pagelist_reserve); |
95 | |
96 | /* Free any pages that have been preallocated. */ |
97 | int ceph_pagelist_free_reserve(struct ceph_pagelist *pl) |
98 | { |
99 | while (!list_empty(&pl->free_list)) { |
100 | struct page *page = list_first_entry(&pl->free_list, |
101 | struct page, lru); |
102 | list_del(&page->lru); |
103 | __free_page(page); |
104 | --pl->num_pages_free; |
105 | } |
106 | BUG_ON(pl->num_pages_free); |
107 | return 0; |
108 | } |
109 | EXPORT_SYMBOL(ceph_pagelist_free_reserve); |
110 | |
111 | /* Create a truncation point. */ |
112 | void ceph_pagelist_set_cursor(struct ceph_pagelist *pl, |
113 | struct ceph_pagelist_cursor *c) |
114 | { |
115 | c->pl = pl; |
116 | c->page_lru = pl->head.prev; |
117 | c->room = pl->room; |
118 | } |
119 | EXPORT_SYMBOL(ceph_pagelist_set_cursor); |
120 | |
121 | /* Truncate a pagelist to the given point. Move extra pages to reserve. |
122 | * This won't sleep. |
123 | * Returns: 0 on success, |
124 | * -EINVAL if the pagelist doesn't match the trunc point pagelist |
125 | */ |
126 | int ceph_pagelist_truncate(struct ceph_pagelist *pl, |
127 | struct ceph_pagelist_cursor *c) |
128 | { |
129 | struct page *page; |
130 | |
131 | if (pl != c->pl) |
132 | return -EINVAL; |
133 | ceph_pagelist_unmap_tail(pl); |
134 | while (pl->head.prev != c->page_lru) { |
135 | page = list_entry(pl->head.prev, struct page, lru); |
136 | /* move from pagelist to reserve */ |
137 | list_move_tail(&page->lru, &pl->free_list); |
138 | ++pl->num_pages_free; |
139 | } |
140 | pl->room = c->room; |
141 | if (!list_empty(&pl->head)) { |
142 | page = list_entry(pl->head.prev, struct page, lru); |
143 | pl->mapped_tail = kmap(page); |
144 | } |
145 | return 0; |
146 | } |
147 | EXPORT_SYMBOL(ceph_pagelist_truncate); |
148 |
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od-2011-09-04
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v2.6.34-rc5
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