linux/fs/ceph/pagelist.c
Sage Weil 58bb3b374b ceph: support ceph_pagelist for message payload
The ceph_pagelist is a simple list of whole pages, strung together via
their lru list_head.  It facilitates encoding to a "buffer" of unknown
size.  Allow its use in place of the ceph_msg page vector.

This will be used to fix the huge buffer preallocation woes of MDS
reconnection.

Signed-off-by: Sage Weil <sage@newdream.net>
2009-12-23 12:12:31 -08:00

55 lines
1.1 KiB
C

#include <linux/pagemap.h>
#include <linux/highmem.h>
#include "pagelist.h"
int ceph_pagelist_release(struct ceph_pagelist *pl)
{
if (pl->mapped_tail)
kunmap(pl->mapped_tail);
while (!list_empty(&pl->head)) {
struct page *page = list_first_entry(&pl->head, struct page,
lru);
list_del(&page->lru);
__free_page(page);
}
return 0;
}
static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
{
struct page *page = alloc_page(GFP_NOFS);
if (!page)
return -ENOMEM;
pl->room += PAGE_SIZE;
list_add_tail(&page->lru, &pl->head);
if (pl->mapped_tail)
kunmap(pl->mapped_tail);
pl->mapped_tail = kmap(page);
return 0;
}
int ceph_pagelist_append(struct ceph_pagelist *pl, 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;
}