NFS: Store pages from an NFS inode into a local cache

Store pages from an NFS inode into the cache data storage object associated
with that inode.

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>

fs/nfs/fscache.c

@@ -493,3 +493,31 @@ int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 
 	return ret;
 }
+
+/*
+ * Store a newly fetched page in fscache
+ * - PG_fscache must be set on the page
+ */
+void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
+{
+	int ret;
+
+	dfprintk(FSCACHE,
+		 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
+		 NFS_I(inode)->fscache, page, page->index, page->flags, sync);
+
+	ret = fscache_write_page(NFS_I(inode)->fscache, page, GFP_KERNEL);
+	dfprintk(FSCACHE,
+		 "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
+		 page, page->index, page->flags, ret);
+
+	if (ret != 0) {
+		fscache_uncache_page(NFS_I(inode)->fscache, page);
+		nfs_add_fscache_stats(inode,
+				      NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL, 1);
+		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED, 1);
+	} else {
+		nfs_add_fscache_stats(inode,
+				      NFSIOS_FSCACHE_PAGES_WRITTEN_OK, 1);
+	}
+}

fs/nfs/fscache.h

@@ -91,6 +91,7 @@ extern int __nfs_readpage_from_fscache(struct nfs_open_context *,
 extern int __nfs_readpages_from_fscache(struct nfs_open_context *,
 					struct inode *, struct address_space *,
 					struct list_head *, unsigned *);
+extern void __nfs_readpage_to_fscache(struct inode *, struct page *, int);
 
 /*
  * wait for a page to complete writing to the cache
@@ -140,6 +141,19 @@ static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 	return -ENOBUFS;
 }
 
+/*
+ * Store a page newly fetched from the server in an inode data storage object
+ * in the cache.
+ */
+static inline void nfs_readpage_to_fscache(struct inode *inode,
+					   struct page *page,
+					   int sync)
+{
+	if (PageFsCache(page))
+		__nfs_readpage_to_fscache(inode, page, sync);
+}
+
+
 #else /* CONFIG_NFS_FSCACHE */
 static inline int nfs_fscache_register(void) { return 0; }
 static inline void nfs_fscache_unregister(void) {}
@@ -184,6 +198,8 @@ static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 {
 	return -ENOBUFS;
 }
+static inline void nfs_readpage_to_fscache(struct inode *inode,
+					   struct page *page, int sync) {}
 
 #endif /* CONFIG_NFS_FSCACHE */
 #endif /* _NFS_FSCACHE_H */

fs/nfs/read.c

@@ -140,6 +140,11 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
 
 static void nfs_readpage_release(struct nfs_page *req)
 {
+	struct inode *d_inode = req->wb_context->path.dentry->d_inode;
+
+	if (PageUptodate(req->wb_page))
+		nfs_readpage_to_fscache(d_inode, req->wb_page, 0);
+
 	unlock_page(req->wb_page);
 
 	dprintk("NFS: read done (%s/%Ld %d@%Ld)\n",