On Jun 25, 2007  19:15 +0530, Amit K. Arora wrote:

+#define FA_FL_DEALLOC	0x01 /* default is allocate */
+#define FA_FL_KEEP_SIZE	0x02 /* default is extend/shrink size */
+#define FA_FL_DEL_DATA	0x04 /* default is keep written data on DEALLOC */

In XFS one of the (many) ALLOC modes is to zero existing data on allocate.
For ext4 all this would mean is calling ext4_ext_mark_uninitialized() on
each extent.  For some workloads this would be much faster than truncate
and reallocate of all the blocks in a file.

In that light, please change the comment to /* default is keep existing data */
so that it doesn't imply this is only for DEALLOC.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.