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#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/ceph/pagelist.h>
static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
{
if (pl->mapped_tail) {
struct page *page = list_entry(pl->head.prev, struct page, lru);
kunmap(page);
pl->mapped_tail = NULL;
}
}
int ceph_pagelist_release(struct ceph_pagelist *pl)
{
ceph_pagelist_unmap_tail(pl);
while (!list_empty(&pl->head)) {
struct page *page = list_first_entry(&pl->head, struct page,
lru);
list_del(&page->lru);
__free_page(page);
}
ceph_pagelist_free_reserve(pl);
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_release);
static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
{
struct page *page;
if (!pl->num_pages_free) {
page = __page_cache_alloc(GFP_NOFS);
} else {
page = list_first_entry(&pl->free_list, struct page, lru);
list_del(&page->lru);
}
if (!page)
return -ENOMEM;
pl->room += PAGE_SIZE;
ceph_pagelist_unmap_tail(pl);
list_add_tail(&page->lru, &pl->head);
pl->mapped_tail = kmap(page);
return 0;
}
int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len)
{
while (pl->room < len) {
size_t bit = pl->room;
int ret;
memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK),
buf, bit);
pl->length += bit;
pl->room -= bit;
buf += bit;
len -= bit;
ret = ceph_pagelist_addpage(pl);
if (ret)
return ret;
}
memcpy(pl->mapped_tail + (pl->length & ~PAGE_CACHE_MASK), buf, len);
pl->length += len;
pl->room -= len;
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_append);
/**
* Allocate enough pages for a pagelist to append the given amount
* of data without without allocating.
* Returns: 0 on success, -ENOMEM on error.
*/
int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
{
if (space <= pl->room)
return 0;
space -= pl->room;
space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT; /* conv to num pages */
while (space > pl->num_pages_free) {
struct page *page = __page_cache_alloc(GFP_NOFS);
if (!page)
return -ENOMEM;
list_add_tail(&page->lru, &pl->free_list);
++pl->num_pages_free;
}
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_reserve);
/**
* Free any pages that have been preallocated.
*/
int ceph_pagelist_free_reserve(struct ceph_pagelist *pl)
{
while (!list_empty(&pl->free_list)) {
struct page *page = list_first_entry(&pl->free_list,
struct page, lru);
list_del(&page->lru);
__free_page(page);
--pl->num_pages_free;
}
BUG_ON(pl->num_pages_free);
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_free_reserve);
/**
* Create a truncation point.
*/
void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
struct ceph_pagelist_cursor *c)
{
c->pl = pl;
c->page_lru = pl->head.prev;
c->room = pl->room;
}
EXPORT_SYMBOL(ceph_pagelist_set_cursor);
/**
* Truncate a pagelist to the given point. Move extra pages to reserve.
* This won't sleep.
* Returns: 0 on success,
* -EINVAL if the pagelist doesn't match the trunc point pagelist
*/
int ceph_pagelist_truncate(struct ceph_pagelist *pl,
struct ceph_pagelist_cursor *c)
{
struct page *page;
if (pl != c->pl)
return -EINVAL;
ceph_pagelist_unmap_tail(pl);
while (pl->head.prev != c->page_lru) {
page = list_entry(pl->head.prev, struct page, lru);
list_del(&page->lru); /* remove from pagelist */
list_add_tail(&page->lru, &pl->free_list); /* add to reserve */
++pl->num_pages_free;
}
pl->room = c->room;
if (!list_empty(&pl->head)) {
page = list_entry(pl->head.prev, struct page, lru);
pl->mapped_tail = kmap(page);
}
return 0;
}
EXPORT_SYMBOL(ceph_pagelist_truncate);
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