[XFS] fix inode leak in xfs_iget_core()

If the radix_tree_preload() fails, we need to destroy the inode we just
read in before trying again. This could leak xfs_vnode structures when
there is memory pressure. Noticed by Christoph Hellwig.

SGI-PV: 977823
SGI-Modid: xfs-linux-melb:xfs-kern:30606a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>

fs/xfs/xfs_iget.c

@@ -235,6 +235,7 @@ xfs_iget_core(
 	 */
 	new_icl = kmem_zone_alloc(xfs_icluster_zone, KM_SLEEP);
 	if (radix_tree_preload(GFP_KERNEL)) {
+		xfs_idestroy(ip);
 		delay(1);
 		goto again;
 	}