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 | |
9 | struct ceph_pagelist *ceph_pagelist_alloc(gfp_t gfp_flags) |
10 | { |
11 | struct ceph_pagelist *pl; |
12 | |
13 | pl = kmalloc(size: sizeof(*pl), flags: gfp_flags); |
14 | if (!pl) |
15 | return NULL; |
16 | |
17 | INIT_LIST_HEAD(list: &pl->head); |
18 | pl->mapped_tail = NULL; |
19 | pl->length = 0; |
20 | pl->room = 0; |
21 | INIT_LIST_HEAD(list: &pl->free_list); |
22 | pl->num_pages_free = 0; |
23 | refcount_set(r: &pl->refcnt, n: 1); |
24 | |
25 | return pl; |
26 | } |
27 | EXPORT_SYMBOL(ceph_pagelist_alloc); |
28 | |
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 | |
38 | void ceph_pagelist_release(struct ceph_pagelist *pl) |
39 | { |
40 | if (!refcount_dec_and_test(r: &pl->refcnt)) |
41 | return; |
42 | ceph_pagelist_unmap_tail(pl); |
43 | while (!list_empty(head: &pl->head)) { |
44 | struct page *page = list_first_entry(&pl->head, struct page, |
45 | lru); |
46 | list_del(entry: &page->lru); |
47 | __free_page(page); |
48 | } |
49 | ceph_pagelist_free_reserve(pl); |
50 | kfree(objp: pl); |
51 | } |
52 | EXPORT_SYMBOL(ceph_pagelist_release); |
53 | |
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(entry: &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(new: &page->lru, head: &pl->head); |
70 | pl->mapped_tail = kmap(page); |
71 | return 0; |
72 | } |
73 | |
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 allocating. |
100 | * Returns: 0 on success, -ENOMEM on error. |
101 | */ |
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(new: &page->lru, head: &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. */ |
121 | int ceph_pagelist_free_reserve(struct ceph_pagelist *pl) |
122 | { |
123 | while (!list_empty(head: &pl->free_list)) { |
124 | struct page *page = list_first_entry(&pl->free_list, |
125 | struct page, lru); |
126 | list_del(entry: &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. */ |
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 | */ |
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(list: &page->lru, head: &pl->free_list); |
162 | ++pl->num_pages_free; |
163 | } |
164 | pl->room = c->room; |
165 | if (!list_empty(head: &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 | |