Re: [PATCH v2] xfs: use per-AG reservations for the finobt

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

On Tue, Jan 24, 2017 at 03:02:47PM +0100, Christoph Hellwig wrote:
> On Mon, Jan 23, 2017 at 11:28:47AM -0800, Darrick J. Wong wrote:
> > I also want to warn more loudly about AGs that don't actually have
> > enough space to handle the reservation.
> 
> > > +			xfs_warn(mp,
> > > +"Per-AG reservation for finobt failed.  File System may run out of space.\n");
> > > +			mp->m_inotbt_nores = true;
> > > +		}
> 
> Any suggestion for a better warning than this one?  Except for this
> bit I'm ready to resend the series.

I'd just print out:

"Per-AG reservation for AG ${agno} failed.  Filesystem may run out of space."

if any of the (now three) invocations of __xfs_ag_resv_init() returns
ENOSPC, since the AG is more than 98% full.  Some day, a sysadmin could
then use the fsmap data to identify which inodes are using the most
space in that AG and arrange to migrate/remove/etc the data to another
AG.

--D