xfs: reverse the check on XFS_IOC_ZERO_RANGE

Reversing the check on XFS_IOC_ZERO_RANGE.

Range should be zeroed if the start is less than or equal to the end.
Signed-off-by: NAndrew Dahl <adahl@sgi.com>
Reviewed-by: NMark Tinguely <tinguely@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>

fs/xfs/xfs_vnodeops.c

@@ -2188,7 +2188,7 @@ xfs_change_file_space(
 	case XFS_IOC_ZERO_RANGE:
 		prealloc_type |= XFS_BMAPI_CONVERT;
 		end = round_down(startoffset + bf->l_len, PAGE_SIZE) - 1;
-		if (startoffset > end)
+		if (startoffset <= end)
 			truncate_pagecache_range(VFS_I(ip), startoffset, end);
 		/* FALLTHRU */
 	case XFS_IOC_RESVSP: