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-rw-r--r--net/ceph/pagelist.c106
1 files changed, 97 insertions, 9 deletions
diff --git a/net/ceph/pagelist.c b/net/ceph/pagelist.c
index 3b146cfac18..b8cbc456d0b 100644
--- a/net/ceph/pagelist.c
+++ b/net/ceph/pagelist.c
@@ -7,35 +7,42 @@
static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
{
- struct page *page = list_entry(pl->head.prev, struct page,
- lru);
- kunmap(page);
+ 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)
{
- if (pl->mapped_tail)
- ceph_pagelist_unmap_tail(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 = __page_cache_alloc(GFP_NOFS);
+ 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);
- if (pl->mapped_tail)
- ceph_pagelist_unmap_tail(pl);
pl->mapped_tail = kmap(page);
return 0;
}
@@ -63,3 +70,84 @@ int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t 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);