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