From 58bb3b374b07a2a43315213f00a48a5ffd6d0915 Mon Sep 17 00:00:00 2001 From: Sage Weil Date: Wed, 23 Dec 2009 12:12:31 -0800 Subject: 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 --- fs/ceph/pagelist.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 fs/ceph/pagelist.c (limited to 'fs/ceph/pagelist.c') diff --git a/fs/ceph/pagelist.c b/fs/ceph/pagelist.c new file mode 100644 index 00000000000..370e9369547 --- /dev/null +++ b/fs/ceph/pagelist.c @@ -0,0 +1,54 @@ + +#include +#include + +#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; +} -- cgit v1.2.3