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