[PATCH 31/37] NFS: FS-Cache page management

David Howells
2008-02-08T17:14:13Z

FS-Cache page management for NFS. This includes hooking the releasing and
invalidation of pages marked with PG_fscache (aka PG_private_2) and waiting for
completion of the write-to-cache flag (PG_fscache_write aka PG_owner_priv_2).

Signed-off-by: David Howells <dhowells@redhat.com>
---

fs/nfs/file.c | 17 +++++++++++++----
fs/nfs/fscache.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/nfs/fscache.h | 22 ++++++++++++++++++++++
3 files changed, 84 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 26a073b..60db3ea 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -35,6 +35,7 @@
#include "delegation.h"
#include "internal.h"
#include "iostat.h"
+#include "fscache.h"

#define NFSDBG_FACILITY NFSDBG_FILE

@@ -358,7 +359,7 @@ static int nfs_write_end(struct file *file, struct address_space *mapping,
* Partially or wholly invalidate a page
* - Release the private state associated with a page if undergoing complete
* page invalidation
- * - Called if either PG_private or PG_private_2 is set on the page
+ * - Called if either PG_private or PG_fscache is set on the page
* - Caller holds page lock
*/
static void nfs_invalidate_page(struct page *page, unsigned long offset)
@@ -367,30 +368,35 @@ static void nfs_invalidate_page(struct page *page, unsigned long offset)
return;
/* Cancel any unstarted writes on this page */
nfs_wb_page_cancel(page->mapping->host, page);
+
+ nfs_fscache_invalidate_page(page, page->mapping->host);
}

/*
* Attempt to release the private state associated with a page
- * - Called if either PG_private or PG_private_2 is set on the page
+ * - Called if either PG_private or PG_fscache is set on the page
* - Caller holds page lock
* - Return true (may release page) or false (may not)
*/
static int nfs_release_page(struct page *page, gfp_t gfp)
{
/* If PagePrivate() is set, then the page is not freeable */
- return 0;
+ if (PagePrivate(page))
+ return 0;
+ return nfs_fscache_release_page(page, gfp);
}

/*
* Attempt to clear the private state associated with a page when an error
* occurs that requires the cached contents of an inode to be written back or
* destroyed
- * - Called if either PG_private or PG_private_2 is set on the page
+ * - Called if either PG_private or fscache is set on the page
* - Caller holds page lock
* - Return 0 if successful, -error otherwise
*/
static int nfs_launder_page(struct page *page)
{
+ wait_on_page_fscache_write(page);
return nfs_wb_page(page->mapping->host, page);
}

@@ -422,6 +428,9 @@ static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page)
int ret = -EINVAL;
struct address_space *mapping;

+ /* make sure the cache has finished storing the page */
+ wait_on_page_fscache_write(page);
+
lock_page(page);
mapping = page->mapping;
if (mapping != vma->vm_file->f_path.dentry->d_inode->i_mapping)
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index c0e0320..d475ff5 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -19,6 +19,7 @@
#include <linux/seq_file.h>

#include "internal.h"
+#include "iostat.h"
#include "fscache.h"

#define NFSDBG_FACILITY NFSDBG_FSCACHE
@@ -297,3 +298,51 @@ void nfs_fscache_attr_changed(struct inode *inode)
{
fscache_attr_changed(NFS_I(inode)->fscache);
}
+
+/*
+ * Release the caching state associated with a page, if the page isn't busy
+ * interacting with the cache.
+ * - Returns true (can release page) or false (page busy).
+ */
+int nfs_fscache_release_page(struct page *page, gfp_t gfp)
+{
+ if (PageFsCacheWrite(page)) {
+ if (!(gfp & __GFP_WAIT))
+ return 0;
+ wait_on_page_fscache_write(page);
+ }
+
+ if (PageFsCache(page)) {
+ struct nfs_inode *nfsi = NFS_I(page->mapping->host);
+
+ BUG_ON(!nfsi->fscache);
+
+ dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
+ nfsi->fscache, page, nfsi);
+
+ fscache_uncache_page(nfsi->fscache, page);
+ nfs_add_stats(page->mapping->host, NFSIOS_FSCACHE_UNCACHE, 1);
+ }
+
+ return 1;
+}
+
+/*
+ * Release the caching state associated with a page if undergoing complete page
+ * invalidation.
+ */
+void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
+{
+ struct nfs_inode *nfsi = NFS_I(inode);
+
+ BUG_ON(!nfsi->fscache);
+
+ dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
+ nfsi->fscache, page, nfsi);
+
+ wait_on_page_fscache_write(page);
+
+ BUG_ON(!PageLocked(page));
+ fscache_uncache_page(nfsi->fscache, page);
+ nfs_add_stats(page->mapping->host, NFSIOS_FSCACHE_UNCACHE, 1);
+}
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index d730ec8..1cb7d96 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -86,6 +86,21 @@ extern void nfs_fscache_set_inode_cookie(struct inode *, struct file *);
extern void nfs_fscache_renew_inode_cookie(struct inode *);
extern void nfs_fscache_attr_changed(struct inode *);

+extern void __nfs_fscache_invalidate_page(struct page *, struct inode *);
+extern int nfs_fscache_release_page(struct page *, gfp_t);
+
+/*
+ * release the caching state associated with a page if undergoing complete page
+ * invalidation
+ */
+static inline void nfs_fscache_invalidate_page(struct page *page,
+ struct inode *inode)
+{
+ if (PageFsCache(page))
+ __nfs_fscache_invalidate_page(page, inode);
+}
+
+
#else /* CONFIG_NFS_FSCACHE */
static inline int nfs_fscache_register(void) { return 0; }
static inline void nfs_fscache_unregister(void) {}
@@ -110,5 +125,12 @@ static inline void nfs_fscache_set_inode_cookie(struct inode *inode,
struct file *filp) {}
static inline void nfs_fscache_attr_changed(struct inode *inode) {}

+static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
+{
+ return 1; /* True: may release page */
+}
+static inline void nfs_fscache_invalidate_page(struct page *page,
+ struct inode *inode) {}
+
#endif /* CONFIG_NFS_FSCACHE */
#endif /* _NFS_FSCACHE_H */