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
9struct 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}
27EXPORT_SYMBOL(ceph_pagelist_alloc);
28
29static 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
38void 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}
52EXPORT_SYMBOL(ceph_pagelist_release);
53
54static 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
74int 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}
96EXPORT_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 */
102int 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}
118EXPORT_SYMBOL(ceph_pagelist_reserve);
119
120/* Free any pages that have been preallocated. */
121int 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}
133EXPORT_SYMBOL(ceph_pagelist_free_reserve);
134
135/* Create a truncation point. */
136void 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}
143EXPORT_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 */
150int 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}
171EXPORT_SYMBOL(ceph_pagelist_truncate);
172