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authorTrond Myklebust <Trond.Myklebust@netapp.com>2010-05-01 12:36:18 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2010-05-01 12:36:18 -0400
commit8f649c376254755f2261a693b3d48d09126218dc (patch)
tree818338eca6dea5c7e022a3a6df51c3b2aa9e54b7
parentbe1066bbcd443a65df312fdecea7e4959adedb45 (diff)
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NFSv4: Fix the locking in nfs_inode_reclaim_delegation()
Ensure that we correctly rcu-dereference the delegation itself, and that we protect against removal while we're changing the contents. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-rw-r--r--fs/nfs/delegation.c42
1 files changed, 28 insertions, 14 deletions
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 15671245c6e..8d9ec494a94 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -129,21 +129,35 @@ again:
*/
void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
{
- struct nfs_delegation *delegation = NFS_I(inode)->delegation;
- struct rpc_cred *oldcred;
+ struct nfs_delegation *delegation;
+ struct rpc_cred *oldcred = NULL;
- if (delegation == NULL)
- return;
- memcpy(delegation->stateid.data, res->delegation.data,
- sizeof(delegation->stateid.data));
- delegation->type = res->delegation_type;
- delegation->maxsize = res->maxsize;
- oldcred = delegation->cred;
- delegation->cred = get_rpccred(cred);
- clear_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
- NFS_I(inode)->delegation_state = delegation->type;
- smp_wmb();
- put_rpccred(oldcred);
+ rcu_read_lock();
+ delegation = rcu_dereference(NFS_I(inode)->delegation);
+ if (delegation != NULL) {
+ spin_lock(&delegation->lock);
+ if (delegation->inode != NULL) {
+ memcpy(delegation->stateid.data, res->delegation.data,
+ sizeof(delegation->stateid.data));
+ delegation->type = res->delegation_type;
+ delegation->maxsize = res->maxsize;
+ oldcred = delegation->cred;
+ delegation->cred = get_rpccred(cred);
+ clear_bit(NFS_DELEGATION_NEED_RECLAIM,
+ &delegation->flags);
+ NFS_I(inode)->delegation_state = delegation->type;
+ spin_unlock(&delegation->lock);
+ put_rpccred(oldcred);
+ rcu_read_unlock();
+ } else {
+ /* We appear to have raced with a delegation return. */
+ spin_unlock(&delegation->lock);
+ rcu_read_unlock();
+ nfs_inode_set_delegation(inode, cred, res);
+ }
+ } else {
+ rcu_read_unlock();
+ }
}
static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)