NFSv4: Fix NFSv4 trunking discovery

If walking the list in nfs4[01]_walk_client_list fails, then the most
likely explanation is that the server dropped the clientid before we
actually managed to confirm it. As long as our nfs_client is the very
last one in the list to be tested, the caller can be assured that this
is the case when the final return value is NFS4ERR_STALE_CLIENTID.

Reported-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org [>=3.7]
Tested-by: Ben Greear <greearb@candelatech.com>

2 files changed, 9 insertions, 25 deletions

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 65a290a73065..2f21f17fb16c 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -352,14 +352,8 @@ int nfs40_walk_client_list(struct nfs_client *new,
         }
         spin_unlock(&nn->nfs_client_lock);
 
+        /* No match found. The server lost our clientid */
 out:
-        /*
-         * No matching nfs_client found.  This should be impossible,
-         * because the new nfs_client has already been added to
-         * nfs_client_list by nfs_get_client().
-         *
-         * Don't BUG(), since the caller is holding a mutex.
-         */
         if (prev)
                 nfs_put_client(prev);
         dprintk("NFS: <-- %s status = %d\n", __func__, status);
@@ -430,7 +424,7 @@ int nfs41_walk_client_list(struct nfs_client *new,
 {
         struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
         struct nfs_client *pos, *n, *prev = NULL;
-        int error;
+        int status = -NFS4ERR_STALE_CLIENTID;
 
         spin_lock(&nn->nfs_client_lock);
         list_for_each_entry_safe(pos, n, &nn->nfs_client_list, cl_share_link) {
@@ -446,8 +440,8 @@ int nfs41_walk_client_list(struct nfs_client *new,
                                 nfs_put_client(prev);
                         prev = pos;
 
-                        error = nfs_wait_client_init_complete(pos);
-                        if (error < 0) {
+                        status = nfs_wait_client_init_complete(pos);
+                        if (status < 0) {
                                 nfs_put_client(pos);
                                 spin_lock(&nn->nfs_client_lock);
                                 continue;
@@ -480,16 +474,10 @@ int nfs41_walk_client_list(struct nfs_client *new,
                 return 0;
         }
 
-        /*
-         * No matching nfs_client found.  This should be impossible,
-         * because the new nfs_client has already been added to
-         * nfs_client_list by nfs_get_client().
-         *
-         * Don't BUG(), since the caller is holding a mutex.
-         */
+        /* No matching nfs_client found. */
         spin_unlock(&nn->nfs_client_lock);
-        pr_err("NFS: %s Error: no matching nfs_client found\n", __func__);
-        return -NFS4ERR_STALE_CLIENTID;
+        dprintk("NFS: <-- %s status = %d\n", __func__, status);
+        return status;
 }
 #endif  /* CONFIG_NFS_V4_1 */
 
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 9448c579d41a..f72561ca6895 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -136,16 +136,11 @@ int nfs40_discover_server_trunking(struct nfs_client *clp,
         clp->cl_confirm = clid.confirm;
 
         status = nfs40_walk_client_list(clp, result, cred);
-        switch (status) {
-        case -NFS4ERR_STALE_CLIENTID:
-                set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
-        case 0:
+        if (status == 0) {
                 /* Sustain the lease, even if it's empty.  If the clientid4
                  * goes stale it's of no use for trunking discovery. */
                 nfs4_schedule_state_renewal(*result);
-                break;
         }
-
 out:
         return status;
 }
@@ -1863,6 +1858,7 @@ again:
         case -ETIMEDOUT:
         case -EAGAIN:
                 ssleep(1);
+        case -NFS4ERR_STALE_CLIENTID:
                 dprintk("NFS: %s after status %d, retrying\n",
                         __func__, status);
                 goto again;