NFS: Add read context retention for FS-Cache to call back with

Add read context retention so that FS-Cache can call back into NFS when a read operation on the cache fails EIO rather than reading data. This permits NFS to then fetch the data from the server instead using the appropriate security context. 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>

NFS: Add read context retention for FS-Cache to call back with
Add read context retention so that FS-Cache can call back into NFS when a read operation on the cache fails EIO rather than reading data. This permits NFS to then fetch the data from the server instead using the appropriate security context. 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>
David Howells
1 parent 545db45f0f
Showing 1 changed file with 26 additions and 0 deletions Side-by-side Diff
fs/nfs/fscache-index.c
@@ -292,6 +292,30 @@
 }
  
 /*
+ * Get an extra reference on a read context.
+ * - This function can be absent if the completion function doesn't require a
+ *   context.
+ * - The read context is passed back to NFS in the event that a data read on the
+ *   cache fails with EIO - in which case the server must be contacted to
+ *   retrieve the data, which requires the read context for security.
+ */
+static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
+{
+	get_nfs_open_context(context);
+}
+
+/*
+ * Release an extra reference on a read context.
+ * - This function can be absent if the completion function doesn't require a
+ *   context.
+ */
+static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
+{
+	if (context)
+		put_nfs_open_context(context);
+}
+
+/*
  * Define the inode object for FS-Cache.  This is used to describe an inode
  * object to fscache_acquire_cookie().  It is keyed by the NFS file handle for
  * an inode.
@@ -308,5 +332,7 @@
 	.get_aux	= nfs_fscache_inode_get_aux,
 	.check_aux	= nfs_fscache_inode_check_aux,
 	.now_uncached	= nfs_fscache_inode_now_uncached,
+	.get_context	= nfs_fh_get_context,
+	.put_context	= nfs_fh_put_context,
 };
...	...	@@ -292,6 +292,30 @@
292	292	}
293	293
294	294	/*
	295	+ * Get an extra reference on a read context.
	296	+ * - This function can be absent if the completion function doesn't require a
	297	+ * context.
	298	+ * - The read context is passed back to NFS in the event that a data read on the
	299	+ * cache fails with EIO - in which case the server must be contacted to
	300	+ * retrieve the data, which requires the read context for security.
	301	+ */
	302	+static void nfs_fh_get_context(void cookie_netfs_data, void context)
	303	+{
	304	+ get_nfs_open_context(context);
	305	+}
	306	+
	307	+/*
	308	+ * Release an extra reference on a read context.
	309	+ * - This function can be absent if the completion function doesn't require a
	310	+ * context.
	311	+ */
	312	+static void nfs_fh_put_context(void cookie_netfs_data, void context)
	313	+{
	314	+ if (context)
	315	+ put_nfs_open_context(context);
	316	+}
	317	+
	318	+/*
295	319	* Define the inode object for FS-Cache. This is used to describe an inode
296	320	* object to fscache_acquire_cookie(). It is keyed by the NFS file handle for
297	321	* an inode.
...	...	@@ -308,5 +332,7 @@
308	332	.get_aux = nfs_fscache_inode_get_aux,
309	333	.check_aux = nfs_fscache_inode_check_aux,
310	334	.now_uncached = nfs_fscache_inode_now_uncached,
	335	+ .get_context = nfs_fh_get_context,
	336	+ .put_context = nfs_fh_put_context,
311	337	};