1
2 #include <linux/module.h>
3 #include <linux/gfp.h>
4 #include <linux/pagemap.h>
5 #include <linux/highmem.h>
6 #include <linux/ceph/pagelist.h>
7
ceph_pagelist_unmap_tail(struct ceph_pagelist * pl)8 static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
9 {
10 if (pl->mapped_tail) {
11 struct page *page = list_entry(pl->head.prev, struct page, lru);
12 kunmap(page);
13 pl->mapped_tail = NULL;
14 }
15 }
16
ceph_pagelist_release(struct ceph_pagelist * pl)17 int ceph_pagelist_release(struct ceph_pagelist *pl)
18 {
19 ceph_pagelist_unmap_tail(pl);
20 while (!list_empty(&pl->head)) {
21 struct page *page = list_first_entry(&pl->head, struct page,
22 lru);
23 list_del(&page->lru);
24 __free_page(page);
25 }
26 ceph_pagelist_free_reserve(pl);
27 return 0;
28 }
29 EXPORT_SYMBOL(ceph_pagelist_release);
30
ceph_pagelist_addpage(struct ceph_pagelist * pl)31 static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
32 {
33 struct page *page;
34
35 if (!pl->num_pages_free) {
36 page = __page_cache_alloc(GFP_NOFS);
37 } else {
38 page = list_first_entry(&pl->free_list, struct page, lru);
39 list_del(&page->lru);
40 --pl->num_pages_free;
41 }
42 if (!page)
43 return -ENOMEM;
44 pl->room += PAGE_SIZE;
45 ceph_pagelist_unmap_tail(pl);
46 list_add_tail(&page->lru, &pl->head);
47 pl->mapped_tail = kmap(page);
48 return 0;
49 }
50
ceph_pagelist_append(struct ceph_pagelist * pl,const void * buf,size_t len)51 int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len)
52 {
53 while (pl->room < len) {
54 size_t bit = pl->room;
55 int ret;
56
57 memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK),
58 buf, bit);
59 pl->length += bit;
60 pl->room -= bit;
61 buf += bit;
62 len -= bit;
63 ret = ceph_pagelist_addpage(pl);
64 if (ret)
65 return ret;
66 }
67
68 memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK), buf, len);
69 pl->length += len;
70 pl->room -= len;
71 return 0;
72 }
73 EXPORT_SYMBOL(ceph_pagelist_append);
74
75 /**
76 * Allocate enough pages for a pagelist to append the given amount
77 * of data without without allocating.
78 * Returns: 0 on success, -ENOMEM on error.
79 */
ceph_pagelist_reserve(struct ceph_pagelist * pl,size_t space)80 int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
81 {
82 if (space <= pl->room)
83 return 0;
84 space -= pl->room;
85 space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT; /* conv to num pages */
86
87 while (space > pl->num_pages_free) {
88 struct page *page = __page_cache_alloc(GFP_NOFS);
89 if (!page)
90 return -ENOMEM;
91 list_add_tail(&page->lru, &pl->free_list);
92 ++pl->num_pages_free;
93 }
94 return 0;
95 }
96 EXPORT_SYMBOL(ceph_pagelist_reserve);
97
98 /**
99 * Free any pages that have been preallocated.
100 */
ceph_pagelist_free_reserve(struct ceph_pagelist * pl)101 int ceph_pagelist_free_reserve(struct ceph_pagelist *pl)
102 {
103 while (!list_empty(&pl->free_list)) {
104 struct page *page = list_first_entry(&pl->free_list,
105 struct page, lru);
106 list_del(&page->lru);
107 __free_page(page);
108 --pl->num_pages_free;
109 }
110 BUG_ON(pl->num_pages_free);
111 return 0;
112 }
113 EXPORT_SYMBOL(ceph_pagelist_free_reserve);
114
115 /**
116 * Create a truncation point.
117 */
ceph_pagelist_set_cursor(struct ceph_pagelist * pl,struct ceph_pagelist_cursor * c)118 void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
119 struct ceph_pagelist_cursor *c)
120 {
121 c->pl = pl;
122 c->page_lru = pl->head.prev;
123 c->room = pl->room;
124 }
125 EXPORT_SYMBOL(ceph_pagelist_set_cursor);
126
127 /**
128 * Truncate a pagelist to the given point. Move extra pages to reserve.
129 * This won't sleep.
130 * Returns: 0 on success,
131 * -EINVAL if the pagelist doesn't match the trunc point pagelist
132 */
ceph_pagelist_truncate(struct ceph_pagelist * pl,struct ceph_pagelist_cursor * c)133 int ceph_pagelist_truncate(struct ceph_pagelist *pl,
134 struct ceph_pagelist_cursor *c)
135 {
136 struct page *page;
137
138 if (pl != c->pl)
139 return -EINVAL;
140 ceph_pagelist_unmap_tail(pl);
141 while (pl->head.prev != c->page_lru) {
142 page = list_entry(pl->head.prev, struct page, lru);
143 list_del(&page->lru); /* remove from pagelist */
144 list_add_tail(&page->lru, &pl->free_list); /* add to reserve */
145 ++pl->num_pages_free;
146 }
147 pl->room = c->room;
148 if (!list_empty(&pl->head)) {
149 page = list_entry(pl->head.prev, struct page, lru);
150 pl->mapped_tail = kmap(page);
151 }
152 return 0;
153 }
154 EXPORT_SYMBOL(ceph_pagelist_truncate);
155