[PATCH 2/2] nfsd: change algorithm for selecting the client_tracking_ops

[Jeff Layton <jlayton@redhat.com>]

If the legacy tracking dir exists, use that. Next try the usermodehelper
upcall. It should succeed or fail quickly, so trying it first should be
harmless. If that fails, fall back to using nfsdcld.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/nfsd/nfs4recover.c | 36 +++++++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index d8e07d5..3584313 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -1067,17 +1067,35 @@ nfsd4_client_tracking_init(struct net *net)
 	int status;
 	struct path path;
 
-	if (!client_tracking_ops) {
-		client_tracking_ops = &nfsd4_cld_tracking_ops;
-		status = kern_path(nfs4_recoverydir(), LOOKUP_FOLLOW, &path);
-		if (!status) {
-			if (S_ISDIR(path.dentry->d_inode->i_mode))
-				client_tracking_ops =
-						&nfsd4_legacy_tracking_ops;
-			path_put(&path);
-		}
+	/* just run the init if it the method is already decided */
+	if (client_tracking_ops)
+		goto do_init;
+
+	/*
+	 * See if the recoverydir exists and is a directory. If it is,
+	 * then use the legacy ops.
+	 */
+	client_tracking_ops = &nfsd4_legacy_tracking_ops;
+	status = kern_path(nfs4_recoverydir(), LOOKUP_FOLLOW, &path);
+	if (!status) {
+		status = S_ISDIR(path.dentry->d_inode->i_mode);
+		path_put(&path);
+		if (status)
+			goto do_init;
 	}
 
+	/*
+	 * Next, try a UMH upcall. It should succeed or fail quickly, so
+	 * there's little harm in trying that first.
+	 */
+	client_tracking_ops = &nfsd4_umh_tracking_ops;
+	status = client_tracking_ops->init(net);
+	if (!status)
+		return status;
+
+	/* Finally, try to use nfsdcld */
+	client_tracking_ops = &nfsd4_cld_tracking_ops;
+do_init:
 	status = client_tracking_ops->init(net);
 	if (status) {
 		printk(KERN_WARNING "NFSD: Unable to initialize client "
-- 
1.7.11.4