1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/module.h>
3 #include <linux/gfp.h>
4 #include <linux/slab.h>
5 #include <linux/pagemap.h>
6 #include <linux/highmem.h>
7 #include <linux/ceph/pagelist.h>
8
ceph_pagelist_alloc(gfp_t gfp_flags)9 struct ceph_pagelist *ceph_pagelist_alloc(gfp_t gfp_flags)
10 {
11 struct ceph_pagelist *pl;
12
13 pl = kmalloc(sizeof(*pl), gfp_flags);
14 if (!pl)
15 return NULL;
16
17 INIT_LIST_HEAD(&pl->head);
18 pl->mapped_tail = NULL;
19 pl->length = 0;
20 pl->room = 0;
21 INIT_LIST_HEAD(&pl->free_list);
22 pl->num_pages_free = 0;
23 refcount_set(&pl->refcnt, 1);
24
25 return pl;
26 }
27 EXPORT_SYMBOL(ceph_pagelist_alloc);
28
ceph_pagelist_unmap_tail(struct ceph_pagelist * pl)29 static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
30 {
31 if (pl->mapped_tail) {
32 struct page *page = list_entry(pl->head.prev, struct page, lru);
33 kunmap(page);
34 pl->mapped_tail = NULL;
35 }
36 }
37
ceph_pagelist_release(struct ceph_pagelist * pl)38 void ceph_pagelist_release(struct ceph_pagelist *pl)
39 {
40 if (!refcount_dec_and_test(&pl->refcnt))
41 return;
42 ceph_pagelist_unmap_tail(pl);
43 while (!list_empty(&pl->head)) {
44 struct page *page = list_first_entry(&pl->head, struct page,
45 lru);
46 list_del(&page->lru);
47 __free_page(page);
48 }
49 ceph_pagelist_free_reserve(pl);
50 kfree(pl);
51 }
52 EXPORT_SYMBOL(ceph_pagelist_release);
53
ceph_pagelist_addpage(struct ceph_pagelist * pl)54 static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
55 {
56 struct page *page;
57
58 if (!pl->num_pages_free) {
59 page = __page_cache_alloc(GFP_NOFS);
60 } else {
61 page = list_first_entry(&pl->free_list, struct page, lru);
62 list_del(&page->lru);
63 --pl->num_pages_free;
64 }
65 if (!page)
66 return -ENOMEM;
67 pl->room += PAGE_SIZE;
68 ceph_pagelist_unmap_tail(pl);
69 list_add_tail(&page->lru, &pl->head);
70 pl->mapped_tail = kmap(page);
71 return 0;
72 }
73
ceph_pagelist_append(struct ceph_pagelist * pl,const void * buf,size_t len)74 int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len)
75 {
76 while (pl->room < len) {
77 size_t bit = pl->room;
78 int ret;
79
80 memcpy(pl->mapped_tail + (pl->length & ~PAGE_MASK),
81 buf, bit);
82 pl->length += bit;
83 pl->room -= bit;
84 buf += bit;
85 len -= bit;
86 ret = ceph_pagelist_addpage(pl);
87 if (ret)
88 return ret;
89 }
90
91 memcpy(pl->mapped_tail + (pl->length & ~PAGE_MASK), buf, len);
92 pl->length += len;
93 pl->room -= len;
94 return 0;
95 }
96 EXPORT_SYMBOL(ceph_pagelist_append);
97
98 /* Allocate enough pages for a pagelist to append the given amount
99 * of data without without allocating.
100 * Returns: 0 on success, -ENOMEM on error.
101 */
ceph_pagelist_reserve(struct ceph_pagelist * pl,size_t space)102 int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
103 {
104 if (space <= pl->room)
105 return 0;
106 space -= pl->room;
107 space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT; /* conv to num pages */
108
109 while (space > pl->num_pages_free) {
110 struct page *page = __page_cache_alloc(GFP_NOFS);
111 if (!page)
112 return -ENOMEM;
113 list_add_tail(&page->lru, &pl->free_list);
114 ++pl->num_pages_free;
115 }
116 return 0;
117 }
118 EXPORT_SYMBOL(ceph_pagelist_reserve);
119
120 /* Free any pages that have been preallocated. */
ceph_pagelist_free_reserve(struct ceph_pagelist * pl)121 int ceph_pagelist_free_reserve(struct ceph_pagelist *pl)
122 {
123 while (!list_empty(&pl->free_list)) {
124 struct page *page = list_first_entry(&pl->free_list,
125 struct page, lru);
126 list_del(&page->lru);
127 __free_page(page);
128 --pl->num_pages_free;
129 }
130 BUG_ON(pl->num_pages_free);
131 return 0;
132 }
133 EXPORT_SYMBOL(ceph_pagelist_free_reserve);
134
135 /* Create a truncation point. */
ceph_pagelist_set_cursor(struct ceph_pagelist * pl,struct ceph_pagelist_cursor * c)136 void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
137 struct ceph_pagelist_cursor *c)
138 {
139 c->pl = pl;
140 c->page_lru = pl->head.prev;
141 c->room = pl->room;
142 }
143 EXPORT_SYMBOL(ceph_pagelist_set_cursor);
144
145 /* Truncate a pagelist to the given point. Move extra pages to reserve.
146 * This won't sleep.
147 * Returns: 0 on success,
148 * -EINVAL if the pagelist doesn't match the trunc point pagelist
149 */
ceph_pagelist_truncate(struct ceph_pagelist * pl,struct ceph_pagelist_cursor * c)150 int ceph_pagelist_truncate(struct ceph_pagelist *pl,
151 struct ceph_pagelist_cursor *c)
152 {
153 struct page *page;
154
155 if (pl != c->pl)
156 return -EINVAL;
157 ceph_pagelist_unmap_tail(pl);
158 while (pl->head.prev != c->page_lru) {
159 page = list_entry(pl->head.prev, struct page, lru);
160 /* move from pagelist to reserve */
161 list_move_tail(&page->lru, &pl->free_list);
162 ++pl->num_pages_free;
163 }
164 pl->room = c->room;
165 if (!list_empty(&pl->head)) {
166 page = list_entry(pl->head.prev, struct page, lru);
167 pl->mapped_tail = kmap(page);
168 }
169 return 0;
170 }
171 EXPORT_SYMBOL(ceph_pagelist_truncate);
172