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NFSv4: nfs4_state_manager() vs. nfs_server_remove_lists()

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commit 080af20cc9 upstream.

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.

Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Steve Dickson
2014-09-18 09:13:17 -04:00
committed by Greg Kroah-Hartman
parent 47415d5452
commit 648d333d7d
1 changed files with 20 additions and 18 deletions
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38
fs/nfs/nfs4client.c
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@@ -311,6 +311,16 @@ 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) {
@@ -330,15 +340,6 @@ 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;
@@ -444,6 +445,16 @@ 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
@@ -469,15 +480,6 @@ 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;