Re: [PATCH] xfs: Allow user to kill fstrim process

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Thu, Apr 27, 2017 at 09:34:04AM -0500, Eric Sandeen wrote:
> On 4/27/17 3:39 AM, Lukas Czerner wrote:
> > fstrim can take really long time on big, slow device or on file system
> > with a lots of allocation groups. Currently there is no way for the user
> > to cancell the operation. This patch makes it possible for the user to
> > kill fstrim pocess by adding the check for fatal_signal_pending() in
> > xfs_trim_extents().
> 
> With this patch, it seems that if it is killed, then nothing is copied
> back to the user about the number of blocks trimmed before the kill.
> 
> Is that intentional?
> 
> I think it could be done in a way that the progress until the kill
> does get reported, and that might be more useful?

AFAICT ext4 doesn't report anything if somoene ERESTARTSYS's it...

> 
> Thanks,
> -Eric
> 
> > Signed-off-by: Lukas Czerner <lczerner@redhat.com>
> > Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
> > ---
> >  fs/xfs/xfs_discard.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
> > index d796ffa..6a05d27 100644
> > --- a/fs/xfs/xfs_discard.c
> > +++ b/fs/xfs/xfs_discard.c
> > @@ -132,6 +132,11 @@ xfs_trim_extents(
> >  		error = xfs_btree_decrement(cur, 0, &i);
> >  		if (error)
> >  			goto out_del_cursor;
> > +
> > +		if (fatal_signal_pending(current)) {

...but the process isn't going to be around to care anyway, right?

--D

> > +			error = -ERESTARTSYS;
> > +			goto out_del_cursor;
> > +		}
> >  	}
> >  
> >  out_del_cursor:
> > @@ -196,8 +201,11 @@ xfs_ioc_trim(
> >  	for (agno = start_agno; agno <= end_agno; agno++) {
> >  		error = xfs_trim_extents(mp, agno, start, end, minlen,
> >  					  &blocks_trimmed);
> > -		if (error)
> > +		if (error) {
> >  			last_error = error;
> > +			if (error == -ERESTARTSYS)
> > +				break;
> > +		}
> >  	}
> >  
> >  	if (last_error)
> > 
> --
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