FS-Cache: Recruit a page flags for cache management

Recruit a page flag to aid in cache management.  The following extra flag is
defined:

 (1) PG_fscache (PG_private_2)

     The marked page is backed by a local cache and is pinning resources in the
     cache driver.

If PG_fscache is set, then things that checked for PG_private will now also
check for that.  This includes things like truncation and page invalidation.
The function page_has_private() had been added to make the checks for both
PG_private and PG_private_2 at the same time.

Signed-off-by: David Howells <[email protected]>
Acked-by: Steve Dickson <[email protected]>
Acked-by: Trond Myklebust <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Acked-by: Al Viro <[email protected]>
Tested-by: Daire Byrne <[email protected]>
This commit is contained in:
David Howells 2009-04-03 16:42:36 +01:00
commit 266cf658ef
8 changed files with 58 additions and 25 deletions

View file

@ -33,14 +33,15 @@ EXPORT_SYMBOL_GPL(file_ra_state_init);
/*
* see if a page needs releasing upon read_cache_pages() failure
* - the caller of read_cache_pages() may have set PG_private before calling,
* such as the NFS fs marking pages that are cached locally on disk, thus we
* need to give the fs a chance to clean up in the event of an error
* - the caller of read_cache_pages() may have set PG_private or PG_fscache
* before calling, such as the NFS fs marking pages that are cached locally
* on disk, thus we need to give the fs a chance to clean up in the event of
* an error
*/
static void read_cache_pages_invalidate_page(struct address_space *mapping,
struct page *page)
{
if (PagePrivate(page)) {
if (page_has_private(page)) {
if (!trylock_page(page))
BUG();
page->mapping = mapping;