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NFSv4: Fix the locking in nfs_inode_reclaim_delegation()

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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>
This commit is contained in:
Trond Myklebust 2010-05-01 12:36:18 -04:00
commit 8f649c3762
1 changed files with 28 additions and 14 deletions
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42
fs/nfs/delegation.c
View file

@ -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)