NFS: Add an asynchronous delegreturn operation for use in nfs_clear_inode
Otherwise, there is a potential deadlock if the last dput() from an NFSv4
close() or other asynchronous operation leads to nfs_clear_inode calling
the synchronous delegreturn.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index b03dcd8..2dead8d 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -174,11 +174,11 @@
return status;
}
-static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation)
+static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
{
int res = 0;
- res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid);
+ res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
nfs_free_delegation(delegation);
return res;
}
@@ -208,7 +208,7 @@
up_read(&clp->cl_sem);
nfs_msync_inode(inode);
- return nfs_do_return_delegation(inode, delegation);
+ return nfs_do_return_delegation(inode, delegation, 1);
}
static struct nfs_delegation *nfs_detach_delegation_locked(struct nfs_inode *nfsi, const nfs4_stateid *stateid)
@@ -228,6 +228,27 @@
return NULL;
}
+/*
+ * This function returns the delegation without reclaiming opens
+ * or protecting against delegation reclaims.
+ * It is therefore really only safe to be called from
+ * nfs4_clear_inode()
+ */
+void nfs_inode_return_delegation_noreclaim(struct inode *inode)
+{
+ struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
+ struct nfs_inode *nfsi = NFS_I(inode);
+ struct nfs_delegation *delegation;
+
+ if (rcu_dereference(nfsi->delegation) != NULL) {
+ spin_lock(&clp->cl_lock);
+ delegation = nfs_detach_delegation_locked(nfsi, NULL);
+ spin_unlock(&clp->cl_lock);
+ if (delegation != NULL)
+ nfs_do_return_delegation(inode, delegation, 0);
+ }
+}
+
int nfs_inode_return_delegation(struct inode *inode)
{
struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
@@ -388,7 +409,7 @@
nfs_msync_inode(inode);
if (delegation != NULL)
- nfs_do_return_delegation(inode, delegation);
+ nfs_do_return_delegation(inode, delegation, 1);
iput(inode);
module_put_and_exit(0);
}