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NFSv4: nfs4_state_manager() vs. nfs_server_remove_lists()

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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>
This commit is contained in:
Steve Dickson 2014-09-18 09:13:17 -04:00 committed by Trond Myklebust
parent f39c010479
commit 080af20cc9
1 changed files with 20 additions and 18 deletions
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38
fs/nfs/nfs4client.c
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@ -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;