NFSv4: nfs4_state_manager() vs. nfs_server_remove_lists()
There is a race between nfs4_state_manager() and
nfs_server_remove_lists() that happens during a nfsv3 mount.
The v3 mount notices there is already a supper block so
nfs_server_remove_lists() called which uses the nfs_client_lock
spin lock to synchronize access to the client list.
At the same time nfs4_state_manager() is running through
the client list looking for work to do, using the same
lock. When nfs4_state_manager() wins the race to the
list, a v3 client pointer is found and not ignored
properly which causes the panic.
Moving some protocol checks before the state checking
avoids the panic.
CC: Stable Tree <stable@vger.kernel.org>
Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 53e435a..ffdb28d 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -482,6 +482,16 @@
spin_lock(&nn->nfs_client_lock);
list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
+
+ if (pos->rpc_ops != new->rpc_ops)
+ continue;
+
+ if (pos->cl_proto != new->cl_proto)
+ continue;
+
+ if (pos->cl_minorversion != new->cl_minorversion)
+ continue;
+
/* If "pos" isn't marked ready, we can't trust the
* remaining fields in "pos" */
if (pos->cl_cons_state > NFS_CS_READY) {
@@ -501,15 +511,6 @@
if (pos->cl_cons_state != NFS_CS_READY)
continue;
- if (pos->rpc_ops != new->rpc_ops)
- continue;
-
- if (pos->cl_proto != new->cl_proto)
- continue;
-
- if (pos->cl_minorversion != new->cl_minorversion)
- continue;
-
if (pos->cl_clientid != new->cl_clientid)
continue;
@@ -622,6 +623,16 @@
spin_lock(&nn->nfs_client_lock);
list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
+
+ if (pos->rpc_ops != new->rpc_ops)
+ continue;
+
+ if (pos->cl_proto != new->cl_proto)
+ continue;
+
+ if (pos->cl_minorversion != new->cl_minorversion)
+ continue;
+
/* 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
@@ -647,15 +658,6 @@
if (pos->cl_cons_state != NFS_CS_READY)
continue;
- if (pos->rpc_ops != new->rpc_ops)
- continue;
-
- if (pos->cl_proto != new->cl_proto)
- continue;
-
- if (pos->cl_minorversion != new->cl_minorversion)
- continue;
-
if (!nfs4_match_clientids(pos, new))
continue;