mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

mm: introduce delete_from_page_cache() 

Presently we increase the page refcount in add_to_page_cache() but don't
decrease it in remove_from_page_cache().  Such asymmetry adds confusion,
requiring that callers notice it and a comment explaining why they release
a page reference.  It's not a good API.

A long time ago, Hugh tried it (http://lkml.org/lkml/2004/10/24/140) but
gave up because reiser4's drop_page() had to unlock the page between
removing it from page cache and doing the page_cache_release().  But now
the situation is changed.  I think at least things in current mainline
don't have any obstacles.  The problem is for out-of-mainline filesystems
- if they have done such things as reiser4, this patch could be a problem
but they will discover this at compile time since we remove
remove_from_page_cache().

This patch:

This function works as just wrapper remove_from_page_cache().  The
difference is that it decreases page references in itself.  So caller have
to make sure it has a page reference before calling.

This patch is ready for removing remove_from_page_cache().

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Edward Shishkin <edward.shishkin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim 2011-03-22 16:30:53 -07:00 committed by Linus Torvalds
parent ef6a3c6311
commit 97cecb5a25
2 changed files with 17 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/pagemap.h
View File

@ -455,6 +455,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
pgoff_t index, gfp_t gfp_mask);
int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
pgoff_t index, gfp_t gfp_mask);
extern void delete_from_page_cache(struct page *page);
extern void remove_from_page_cache(struct page *page);
extern void __remove_from_page_cache(struct page *page);
int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);

16
mm/filemap.c
View File

@ -155,6 +155,22 @@ void remove_from_page_cache(struct page *page)
}
EXPORT_SYMBOL(remove_from_page_cache);
/**
* delete_from_page_cache - delete page from page cache
* @page: the page which the kernel is trying to remove from page cache
*
* This must be called only on pages that have
* been verified to be in the page cache and locked.
* It will never put the page into the free list,
* the caller has a reference on the page.
*/
void delete_from_page_cache(struct page *page)
{
remove_from_page_cache(page);
page_cache_release(page);
}
EXPORT_SYMBOL(delete_from_page_cache);
static int sync_page(void *word)
{
struct address_space *mapping;