Re: [PATCH 4/7][TAKE5] support new modes in fallocate

[Timothy Shimmin <tes@xxxxxxx>]

Amit K. Arora wrote:
> > > > FA_FL_NO_MTIME  0x10 /* keep same mtime (default change on size, data change) */
> > > > FA_FL_NO_CTIME  0x20 /* keep same ctime (default change on size, data change) */
> > NACK to these aswell.  If i_size changes c/mtime need updates, if the size
> > doesn't chamge they don't.  No need to add more flags for this.
>
> This requirement was from the point of view of HSM applications. Hope
> you saw Andreas previous post and are keeping that in mind.
We use this capability in XFS at the moment.
I think this is mainly for DMF (HSM) but is done via the xfs handle interface
(xfs_open_by_handle) AFAICT.

This sets up a set of invisible operations (xfs_invis_file_operations).
xfs_file_ioctl_invis goes on to set IO_INVIS which goes on to set ATTR_DMI
which is then tested in xfs_change_file_space() (which handles XFS_IOC_RESVSP & 
friends)
for whether xfs_ichgtime(ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG)
is called or not.

--Tim