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