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| author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2010-05-01 12:36:18 -0400 |
|---|---|---|
| committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2010-05-01 12:36:18 -0400 |
| commit | 8f649c376254755f2261a693b3d48d09126218dc (patch) | |
| tree | 818338eca6dea5c7e022a3a6df51c3b2aa9e54b7 /fs/nfs/delegation.c | |
| parent | be1066bbcd443a65df312fdecea7e4959adedb45 (diff) | |
| download | linux-8f649c376254755f2261a693b3d48d09126218dc.tar.bz2 | |
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>
Diffstat (limited to 'fs/nfs/delegation.c')
| -rw-r--r-- | fs/nfs/delegation.c | 42 |
1 files changed, 28 insertions, 14 deletions
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c index 15671245c6ee..8d9ec494a944 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) |