1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
// SPDX-License-Identifier: GPL-2.0
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/ceph/pagelist.h>
struct ceph_pagelist *ceph_pagelist_alloc(gfp_t gfp_flags)
{
struct ceph_pagelist *pl;
pl = kmalloc(sizeof(*pl), gfp_flags);
if (!pl)
return NULL;
INIT_LIST_HEAD(&pl->head);
pl->mapped_tail = NULL;
pl->length = 0;
pl->room = 0;
INIT_LIST_HEAD(&pl->free_list);
pl->num_pages_free = 0;
refcount_set(&pl->refcnt, 1);
return pl;
}
EXPORT_SYMBOL(ceph_pagelist_alloc);
static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
{
if (pl->mapped_tail) {
struct page *page = list_entry(pl->head.prev, struct page, lru);
kunmap(page);
pl->mapped_tail = NULL;
}
}
void ceph_pagelist_release(struct ceph_pagelist *pl)
{
if (!refcount_dec_and_test(&pl->refcnt))
return;
ceph_pagelist_unmap_tail(pl);
while (!list_empty(&pl->head)) {
struct page *page = list_first_entry(&pl->head, struct page,
lru);
list_del(&page->lru);
__free_page(page);
}
ceph_pagelist_free_reserve(pl);
kfree(pl);
}
EXPORT_SYMBOL(ceph_pagelist_release);
static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
{
struct page *page;
if (!pl->num_pages_free) {
page = __page_cache_alloc(GFP_NOFS);
} else {
page = list_first_entry(&pl->free_list, struct page, lru);
list_del(&page->lru);
--pl->num_pages_free;
}
if (!page)
return -ENOMEM;
pl->room += PAGE_SIZE;
ceph_pagelist_unmap_tail(pl);
list_add_tail(&page->lru, &pl->head);
pl->mapped_tail = kmap(page);
return 0;
}
int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len)
{
while (pl->room < len) {
size_t bit = pl->room;
int ret;
memcpy(pl->mapped_tail + (pl->length & ~PAGE_MASK),
buf, bit);
pl->length += bit;
pl->room -= bit;
buf += bit;
len -= bit;
ret = ceph_pagelist_addpage(pl);
if (ret)
return ret;
}
memcpy(pl->mapped_tail + (pl->length & ~PAGE_MASK), buf, len);
pl->length += len;
pl->room -= len;
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_append);
/* Allocate enough pages for a pagelist to append the given amount
* of data without without allocating.
* Returns: 0 on success, -ENOMEM on error.
*/
int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
{
if (space <= pl->room)
return 0;
space -= pl->room;
space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT; /* conv to num pages */
while (space > pl->num_pages_free) {
struct page *page = __page_cache_alloc(GFP_NOFS);
if (!page)
return -ENOMEM;
list_add_tail(&page->lru, &pl->free_list);
++pl->num_pages_free;
}
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_reserve);
/* Free any pages that have been preallocated. */
int ceph_pagelist_free_reserve(struct ceph_pagelist *pl)
{
while (!list_empty(&pl->free_list)) {
struct page *page = list_first_entry(&pl->free_list,
struct page, lru);
list_del(&page->lru);
__free_page(page);
--pl->num_pages_free;
}
BUG_ON(pl->num_pages_free);
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_free_reserve);
/* Create a truncation point. */
void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
struct ceph_pagelist_cursor *c)
{
c->pl = pl;
c->page_lru = pl->head.prev;
c->room = pl->room;
}
EXPORT_SYMBOL(ceph_pagelist_set_cursor);
/* Truncate a pagelist to the given point. Move extra pages to reserve.
* This won't sleep.
* Returns: 0 on success,
* -EINVAL if the pagelist doesn't match the trunc point pagelist
*/
int ceph_pagelist_truncate(struct ceph_pagelist *pl,
struct ceph_pagelist_cursor *c)
{
struct page *page;
if (pl != c->pl)
return -EINVAL;
ceph_pagelist_unmap_tail(pl);
while (pl->head.prev != c->page_lru) {
page = list_entry(pl->head.prev, struct page, lru);
/* move from pagelist to reserve */
list_move_tail(&page->lru, &pl->free_list);
++pl->num_pages_free;
}
pl->room = c->room;
if (!list_empty(&pl->head)) {
page = list_entry(pl->head.prev, struct page, lru);
pl->mapped_tail = kmap(page);
}
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_truncate);
|
