udf: Fix off-by-one error when discarding preallocation

The condition determining whether the preallocation can be used had
an off-by-one error so we didn't discard preallocation when new
allocation was just following it. This can then confuse code in
inode_getblk().

CC: stable@vger.kernel.org
Fixes: 16d05565 ("udf: Discard preallocation before extending file with a hole")
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/inode.c

@@ -361,7 +361,7 @@ static int udf_map_block(struct inode *inode, struct udf_map_rq *map)
 	 * Block beyond EOF and prealloc extents? Just discard preallocation
 	 * as it is not useful and complicates things.
 	 */
-	if (((loff_t)map->lblk) << inode->i_blkbits > iinfo->i_lenExtents)
+	if (((loff_t)map->lblk) << inode->i_blkbits >= iinfo->i_lenExtents)
 		udf_discard_prealloc(inode);
 	udf_clear_extent_cache(inode);
 	err = inode_getblk(inode, map);