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Date: Thu, 02 Apr 2009 00:03:52 +0100
From: David Howells <dhowells@...hat.com>
To: viro@...IV.linux.org.uk
Cc: dhowells@...hat.com, nfsv4@...ux-nfs.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 06/43] FS-Cache: Recruit a couple of page flags for cache
management [ver #46]
Recruit a couple of page flags to aid in cache management. The following extra
flags are defined:
(1) PG_fscache (PG_private_2)
The marked page is backed by a local cache and is pinning resources in the
cache driver.
(2) PG_fscache_write (PG_owner_priv_2)
The marked page is being written to the local cache. The page may not be
modified whilst this is in progress.
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@...hat.com>
Acked-by: Steve Dickson <steved@...hat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@...app.com>
---
fs/splice.c | 3 ++-
include/linux/page-flags.h | 41 ++++++++++++++++++++++++++++++++++++-----
include/linux/pagemap.h | 14 ++++++++++++++
mm/filemap.c | 18 ++++++++++++++++++
mm/migrate.c | 10 +++++-----
mm/readahead.c | 9 +++++----
mm/swap.c | 4 ++--
mm/truncate.c | 10 +++++-----
mm/vmscan.c | 6 +++---
9 files changed, 90 insertions(+), 25 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index 4ed0ba4..dd727d4 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -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;
/*
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 9d99e74..0633e06 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -79,9 +79,11 @@ enum pageflags {
PG_active,
PG_slab,
PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
+ PG_owner_priv_2, /* Owner use. fs may use in pagecache */
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 +110,13 @@ 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 */
+ PG_fscache_write = PG_owner_priv_2, /* page being written to cache */
+
/* XEN */
PG_pinned = PG_owner_priv_1,
PG_savepinned = PG_dirty,
@@ -194,8 +203,6 @@ 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)
@@ -205,6 +212,17 @@ __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)
+PAGEFLAG(OwnerPriv2, owner_priv_2) TESTSCFLAG(OwnerPriv2, owner_priv_2)
+
+/*
* Only test-and-set exist for PG_writeback. The unconditional operators are
* risky: they bypass page accounting.
*/
@@ -384,9 +402,10 @@ 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 +416,16 @@ 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 */
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 01ca085..d15e21e 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -379,6 +379,20 @@ static inline void wait_on_page_writeback(struct page *page)
extern void end_page_writeback(struct page *page);
+/**
+ * wait_on_page_owner_priv_2 - Wait for PG_owner_priv_2 to become clear
+ * @page: The page to monitor
+ *
+ * Wait for a PG_owner_priv_2 to become clear on the specified page.
+ */
+static inline void wait_on_page_owner_priv_2(struct page *page)
+{
+ if (PageOwnerPriv2(page))
+ wait_on_page_bit(page, PG_owner_priv_2);
+}
+
+extern void end_page_owner_priv_2(struct page *page);
+
/*
* Fault a userspace page into pagetables. Return non-zero on a fault.
*
diff --git a/mm/filemap.c b/mm/filemap.c
index 126d397..f8ae118 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -603,6 +603,21 @@ void end_page_writeback(struct page *page)
EXPORT_SYMBOL(end_page_writeback);
/**
+ * end_page_owner_priv_2 - Clear PG_owner_priv_2 and wake up any waiters
+ * @page: the page
+ *
+ * Clear PG_owner_priv_2 and wake up any processes waiting for that event.
+ */
+void end_page_owner_priv_2(struct page *page)
+{
+ if (!TestClearPageOwnerPriv2(page))
+ BUG();
+ smp_mb__after_clear_bit();
+ wake_up_page(page, PG_owner_priv_2);
+}
+EXPORT_SYMBOL(end_page_owner_priv_2);
+
+/**
* __lock_page - get a lock on the page, assuming we need to sleep to get it
* @page: the page to lock
*
@@ -2463,6 +2478,9 @@ 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).
*
diff --git a/mm/migrate.c b/mm/migrate.c
index a9eff3f..068655d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -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
diff --git a/mm/readahead.c b/mm/readahead.c
index 6be9275..133b6d5 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -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;
diff --git a/mm/swap.c b/mm/swap.c
index 6e83084..bede23c 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -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);
}
diff --git a/mm/truncate.c b/mm/truncate.c
index 1229211..55206fa 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -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 */
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 06e7269..4252449 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -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) {
--
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