NFSv4: Fix handling of revoked delegations by setattr

Currently, _nfs4_do_setattr() will use the delegation stateid if no
writeable open file stateid is available.
If the server revokes that delegation stateid, then the call to
nfs4_handle_exception() will fail to handle the error due to the
lack of a struct nfs4_state, and will just convert the error into
an EIO.

This patch just removes the requirement that we must have a
struct nfs4_state in order to invalidate the delegation and
retry.

Reported-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -304,9 +304,13 @@ static int nfs4_handle_exception(struct nfs_server *server, int errorcode, struc
 		case -NFS4ERR_DELEG_REVOKED:
 		case -NFS4ERR_ADMIN_REVOKED:
 		case -NFS4ERR_BAD_STATEID:
+			if (inode != NULL && nfs4_have_delegation(inode, FMODE_READ)) {
+				nfs_remove_bad_delegation(inode);
+				exception->retry = 1;
+				break;
+			}
 			if (state == NULL)
 				break;
-			nfs_remove_bad_delegation(state->inode);
 			ret = nfs4_schedule_stateid_recovery(server, state);
 			if (ret < 0)
 				break;