NFSv4/4.1: Fix bugs in nfs4[01]_walk_client_list

It is unsafe to use list_for_each_entry_safe() here, because
when we drop the nn->nfs_client_lock, we pin the _current_ list
entry and ensure that it stays in the list, but we don't do the
same for the _next_ list entry. Use of list_for_each_entry() is
therefore the correct thing to do.

Also fix the refcounting in nfs41_walk_client_list().

Finally, ensure that the nfs_client has finished being initialised
and, in the case of NFSv4.1, that the session is set up.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Bryan Schumaker <bjschuma@netapp.com>
Cc: stable@vger.kernel.org [>= 3.7]

1 files changed, 28 insertions, 16 deletions

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index ac4fc9a8fdbc..c7b346f8cc44 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -300,7 +300,7 @@ int nfs40_walk_client_list(struct nfs_client *new,
                            struct rpc_cred *cred)
 {
         struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
-        struct nfs_client *pos, *n, *prev = NULL;
+        struct nfs_client *pos, *prev = NULL;
         struct nfs4_setclientid_res clid = {
                 .clientid       = new->cl_clientid,
                 .confirm        = new->cl_confirm,
@@ -308,10 +308,23 @@ int nfs40_walk_client_list(struct nfs_client *new,
         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) {
+        list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
                 /* If "pos" isn't marked ready, we can't trust the
                  * remaining fields in "pos" */
-                if (pos->cl_cons_state < NFS_CS_READY)
+                if (pos->cl_cons_state > NFS_CS_READY) {
+                        atomic_inc(&pos->cl_count);
+                        spin_unlock(&nn->nfs_client_lock);
+
+                        if (prev)
+                                nfs_put_client(prev);
+                        prev = pos;
+
+                        status = nfs_wait_client_init_complete(pos);
+                        spin_lock(&nn->nfs_client_lock);
+                        if (status < 0)
+                                continue;
+                }
+                if (pos->cl_cons_state != NFS_CS_READY)
                         continue;
 
                 if (pos->rpc_ops != new->rpc_ops)
@@ -423,16 +436,16 @@ int nfs41_walk_client_list(struct nfs_client *new,
                            struct rpc_cred *cred)
 {
         struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
-        struct nfs_client *pos, *n, *prev = NULL;
+        struct nfs_client *pos, *prev = NULL;
         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) {
+        list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
                 /* If "pos" isn't marked ready, we can't trust the
                  * remaining fields in "pos", especially the client
                  * ID and serverowner fields.  Wait for CREATE_SESSION
                  * to finish. */
-                if (pos->cl_cons_state < NFS_CS_READY) {
+                if (pos->cl_cons_state > NFS_CS_READY) {
                         atomic_inc(&pos->cl_count);
                         spin_unlock(&nn->nfs_client_lock);
 
@@ -440,18 +453,17 @@ int nfs41_walk_client_list(struct nfs_client *new,
                                 nfs_put_client(prev);
                         prev = pos;
 
-                        nfs4_schedule_lease_recovery(pos);
                         status = nfs_wait_client_init_complete(pos);
-                        if (status < 0) {
-                                nfs_put_client(pos);
-                                spin_lock(&nn->nfs_client_lock);
-                                continue;
+                        if (status == 0) {
+                                nfs4_schedule_lease_recovery(pos);
+                                status = nfs4_wait_clnt_recover(pos);
                         }
-                        status = pos->cl_cons_state;
                         spin_lock(&nn->nfs_client_lock);
                         if (status < 0)
                                 continue;
                 }
+                if (pos->cl_cons_state != NFS_CS_READY)
+                        continue;
 
                 if (pos->rpc_ops != new->rpc_ops)
                         continue;
@@ -469,17 +481,17 @@ int nfs41_walk_client_list(struct nfs_client *new,
                         continue;
 
                 atomic_inc(&pos->cl_count);
-                spin_unlock(&nn->nfs_client_lock);
+                *result = pos;
                 dprintk("NFS: <-- %s using nfs_client = %p ({%d})\n",
                         __func__, pos, atomic_read(&pos->cl_count));
-
-                *result = pos;
-                return 0;
+                break;
         }
 
         /* No matching nfs_client found. */
         spin_unlock(&nn->nfs_client_lock);
         dprintk("NFS: <-- %s status = %d\n", __func__, status);
+        if (prev)
+                nfs_put_client(prev);
         return status;
 }
 #endif  /* CONFIG_NFS_V4_1 */