NFS: Propagate 'fsc' mount option through automounts

Propagate the NFS 'fsc' mount option through NFS automounts of various types.

This is now required as commit:

	commit c02d7adf8c5429727a98bad1d039bccad4c61c50
	Author: Trond Myklebust <Trond.Myklebust@netapp.com>
	Date:   Mon Jun 22 15:09:14 2009 -0400

	NFSv4: Replace nfs4_path_walk() with VFS path lookup in a private namespace

uses VFS-driven automounting to reach all submounts barring the root, thus
preventing fscaching from being enabled on any submount other than the root.

This patch gets around that by propagating the NFS_OPTION_FSCACHE flag across
automounts.  If a uniquifier is supplied to a mount then this is propagated to
all automounts of that mount too.

Signed-off-by: David Howells <dhowells@redhat.com>
[Trond: Fixed up the definition of nfs_fscache_get_super_cookie for the
        case of #undef CONFIG_NFS_FSCACHE]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 21 insertions, 4 deletions

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index 379be678cb7..70fad69eb95 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -58,17 +58,34 @@ void nfs_fscache_release_client_cookie(struct nfs_client *clp)
 /*
  * Get the cache cookie for an NFS superblock.  We have to handle
  * uniquification here because the cache doesn't do it for us.
+ *
+ * The default uniquifier is just an empty string, but it may be overridden
+ * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
+ * superblock across an automount point of some nature.
  */
-void nfs_fscache_get_super_cookie(struct super_block *sb,
-				  struct nfs_parsed_mount_data *data)
+void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq,
+				  struct nfs_clone_mount *mntdata)
 {
 	struct nfs_fscache_key *key, *xkey;
 	struct nfs_server *nfss = NFS_SB(sb);
 	struct rb_node **p, *parent;
-	const char *uniq = data->fscache_uniq ?: "";
 	int diff, ulen;
 
-	ulen = strlen(uniq);
+	if (uniq) {
+		ulen = strlen(uniq);
+	} else if (mntdata) {
+		struct nfs_server *mnt_s = NFS_SB(mntdata->sb);
+		if (mnt_s->fscache_key) {
+			uniq = mnt_s->fscache_key->key.uniquifier;
+			ulen = mnt_s->fscache_key->key.uniq_len;
+		}
+	}
+
+	if (!uniq) {
+		uniq = "";
+		ulen = 1;
+	}
+
 	key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
 	if (!key)
 		return;