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Commit 8f649c37 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent be1066bb

fs/nfs/delegation.c

+28 −14
Original line number Diff line number Diff line
@@ -129,21 +129,35 @@ static int nfs_delegation_claim_opens(struct inode *inode, const nfs4_stateid *s 
 */

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;

	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);

			clear_bit(NFS_DELEGATION_NEED_RECLAIM,

				  &delegation->flags);

			NFS_I(inode)->delegation_state = delegation->type;

	smp_wmb();

			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)