NFS: FS-Cache page management

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>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 8b4299a0ad61..e29613a8cbd2 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -83,6 +83,31 @@ extern void nfs_fscache_zap_inode_cookie(struct inode *);
 extern void nfs_fscache_set_inode_cookie(struct inode *, struct file *);
 extern void nfs_fscache_reset_inode_cookie(struct inode *);
 
+extern void __nfs_fscache_invalidate_page(struct page *, struct inode *);
+extern int nfs_fscache_release_page(struct page *, gfp_t);
+
+/*
+ * wait for a page to complete writing to the cache
+ */
+static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
+                                                  struct page *page)
+{
+        if (PageFsCache(page))
+                fscache_wait_on_page_write(nfsi->fscache, page);
+}
+
+/*
+ * 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) {}
@@ -104,5 +129,14 @@ static inline void nfs_fscache_set_inode_cookie(struct inode *inode,
                                                 struct file *filp) {}
 static inline void nfs_fscache_reset_inode_cookie(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) {}
+static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
+                                                  struct page *page) {}
+
 #endif /* CONFIG_NFS_FSCACHE */
 #endif /* _NFS_FSCACHE_H */