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FS-Cache: Recruit a page flags for cache management

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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 <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
This commit is contained in:
David Howells 2009-04-03 16:42:36 +01:00
parent 03fb3d2af9
commit 266cf658ef
8 changed files with 58 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/splice.c
View File

@ -59,7 +59,8 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
*/
wait_on_page_writeback(page);
if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
if (page_has_private(page) &&
!try_to_release_page(page, GFP_KERNEL))
goto out_unlock;
/*

38
include/linux/page-flags.h
View File

@ -82,6 +82,7 @@ enum pageflags {
PG_arch_1,
PG_reserved,
PG_private, /* If pagecache, has fs-private data */
PG_private_2, /* If pagecache, has fs aux data */
PG_writeback, /* Page is under writeback */
#ifdef CONFIG_PAGEFLAGS_EXTENDED
PG_head, /* A head page */
@ -108,6 +109,12 @@ enum pageflags {
/* Filesystems */
PG_checked = PG_owner_priv_1,
/* Two page bits are conscripted by FS-Cache to maintain local caching
* state. These bits are set on pages belonging to the netfs's inodes
* when those inodes are being locally cached.
*/
PG_fscache = PG_private_2, /* page backed by cache */
/* XEN */
PG_pinned = PG_owner_priv_1,
PG_savepinned = PG_dirty,
@ -194,8 +201,6 @@ PAGEFLAG(Checked, checked) /* Used by some filesystems */
PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */
PAGEFLAG(SavePinned, savepinned); /* Xen */
PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
__SETPAGEFLAG(Private, private)
PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
__PAGEFLAG(SlobPage, slob_page)
@ -204,6 +209,16 @@ __PAGEFLAG(SlobFree, slob_free)
__PAGEFLAG(SlubFrozen, slub_frozen)
__PAGEFLAG(SlubDebug, slub_debug)
/*
* Private page markings that may be used by the filesystem that owns the page
* for its own purposes.
* - PG_private and PG_private_2 cause releasepage() and co to be invoked
*/
PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private)
__CLEARPAGEFLAG(Private, private)
PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2)
PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1)
/*
* Only test-and-set exist for PG_writeback. The unconditional operators are
* risky: they bypass page accounting.
@ -384,9 +399,10 @@ static inline void __ClearPageTail(struct page *page)
* these flags set. It they are, there is a problem.
*/
#define PAGE_FLAGS_CHECK_AT_FREE \
(1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
(1 << PG_lru | 1 << PG_locked | \
1 << PG_private | 1 << PG_private_2 | \
1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
__PG_UNEVICTABLE | __PG_MLOCKED)
/*
@ -397,4 +413,16 @@ static inline void __ClearPageTail(struct page *page)
#define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
#endif /* !__GENERATING_BOUNDS_H */
/**
* page_has_private - Determine if page has private stuff
* @page: The page to be checked
*
* Determine if a page has private stuff, indicating that release routines
* should be invoked upon it.
*/
#define page_has_private(page) \
((page)->flags & ((1 << PG_private) | \
(1 << PG_private_2)))
#endif /* PAGE_FLAGS_H */

3
mm/filemap.c
View File

@ -2463,6 +2463,9 @@ EXPORT_SYMBOL(generic_file_aio_write);
* (presumably at page->private). If the release was successful, return `1'.
* Otherwise return zero.
*
* This may also be called if PG_fscache is set on a page, indicating that the
* page is known to the local caching routines.
*
* The @gfp_mask argument specifies whether I/O may be performed to release
* this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
*

10
mm/migrate.c
View File

@ -250,7 +250,7 @@ out:
* The number of remaining references must be:
* 1 for anonymous pages without a mapping
* 2 for pages with a mapping
* 3 for pages with a mapping and PagePrivate set.
* 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
*/
static int migrate_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page)
@ -270,7 +270,7 @@ static int migrate_page_move_mapping(struct address_space *mapping,
pslot = radix_tree_lookup_slot(&mapping->page_tree,
page_index(page));
expected_count = 2 + !!PagePrivate(page);
expected_count = 2 + !!page_has_private(page);
if (page_count(page) != expected_count ||
(struct page *)radix_tree_deref_slot(pslot) != page) {
spin_unlock_irq(&mapping->tree_lock);
@ -386,7 +386,7 @@ EXPORT_SYMBOL(fail_migrate_page);
/*
* Common logic to directly migrate a single page suitable for
* pages that do not use PagePrivate.
* pages that do not use PagePrivate/PagePrivate2.
*
* Pages are locked upon entry and exit.
*/
@ -522,7 +522,7 @@ static int fallback_migrate_page(struct address_space *mapping,
* Buffers may be managed in a filesystem specific way.
* We must have no buffers or drop them.
*/
if (PagePrivate(page) &&
if (page_has_private(page) &&
!try_to_release_page(page, GFP_KERNEL))
return -EAGAIN;
@ -655,7 +655,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
* free the metadata, so the page can be freed.
*/
if (!page->mapping) {
if (!PageAnon(page) && PagePrivate(page)) {
if (!PageAnon(page) && page_has_private(page)) {
/*
* Go direct to try_to_free_buffers() here because
* a) that's what try_to_release_page() would do anyway

9
mm/readahead.c
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;

4
mm/swap.c
View File

@ -448,8 +448,8 @@ void pagevec_strip(struct pagevec *pvec)
for (i = 0; i < pagevec_count(pvec); i++) {
struct page *page = pvec->pages[i];
if (PagePrivate(page) && trylock_page(page)) {
if (PagePrivate(page))
if (page_has_private(page) && trylock_page(page)) {
if (page_has_private(page))
try_to_release_page(page, 0);
unlock_page(page);
}

10
mm/truncate.c
View File

@ -50,7 +50,7 @@ void do_invalidatepage(struct page *page, unsigned long offset)
static inline void truncate_partial_page(struct page *page, unsigned partial)
{
zero_user_segment(page, partial, PAGE_CACHE_SIZE);
if (PagePrivate(page))
if (page_has_private(page))
do_invalidatepage(page, partial);
}
@ -99,7 +99,7 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
if (page->mapping != mapping)
return;
if (PagePrivate(page))
if (page_has_private(page))
do_invalidatepage(page, 0);
cancel_dirty_page(page, PAGE_CACHE_SIZE);
@ -126,7 +126,7 @@ invalidate_complete_page(struct address_space *mapping, struct page *page)
if (page->mapping != mapping)
return 0;
if (PagePrivate(page) && !try_to_release_page(page, 0))
if (page_has_private(page) && !try_to_release_page(page, 0))
return 0;
clear_page_mlock(page);
@ -348,7 +348,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
if (page->mapping != mapping)
return 0;
if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
return 0;
spin_lock_irq(&mapping->tree_lock);
@ -356,7 +356,7 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
goto failed;
clear_page_mlock(page);
BUG_ON(PagePrivate(page));
BUG_ON(page_has_private(page));
__remove_from_page_cache(page);
spin_unlock_irq(&mapping->tree_lock);
page_cache_release(page); /* pagecache ref */

6
mm/vmscan.c
View File

@ -283,7 +283,7 @@ static inline int page_mapping_inuse(struct page *page)
static inline int is_page_cache_freeable(struct page *page)
{
return page_count(page) - !!PagePrivate(page) == 2;
return page_count(page) - !!page_has_private(page) == 2;
}
static int may_write_to_queue(struct backing_dev_info *bdi)
@ -367,7 +367,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
* Some data journaling orphaned pages can have
* page->mapping == NULL while being dirty with clean buffers.
*/
if (PagePrivate(page)) {
if (page_has_private(page)) {
if (try_to_free_buffers(page)) {
ClearPageDirty(page);
printk("%s: orphaned page\n", __func__);
@ -727,7 +727,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
* process address space (page_count == 1) it can be freed.
* Otherwise, leave the page on the LRU so it is swappable.
*/
if (PagePrivate(page)) {
if (page_has_private(page)) {
if (!try_to_release_page(page, sc->gfp_mask))
goto activate_locked;
if (!mapping && page_count(page) == 1) {