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authorSteve Dickson <steved@redhat.com>2014-09-18 17:13:17 +0400
committerTrond Myklebust <trond.myklebust@primarydata.com>2014-09-18 21:04:21 +0400
commit080af20cc945d110f9912d01cf6b66f94a375b8d (patch)
treecd54ec58f700903855505a200834bf51761bd4b8
parentf39c01047994e66e7f3d89ddb4c6141f23349d8d (diff)
downloadlinux-080af20cc945d110f9912d01cf6b66f94a375b8d.tar.xz
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>
-rw-r--r--fs/nfs/nfs4client.c38
1 files changed, 20 insertions, 18 deletions
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 53e435a95260..ffdb28d86cf8 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -482,6 +482,16 @@ int nfs40_walk_client_list(struct nfs_client *new,
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 @@ int nfs40_walk_client_list(struct nfs_client *new,
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 @@ int nfs41_walk_client_list(struct nfs_client *new,
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 @@ int nfs41_walk_client_list(struct nfs_client *new,
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;