Re: [PATCH 2/3] xfs: don't fail unwritten extent conversion on writeback due to edquot

[Brian Foster <bfoster@redhat.com>]

On Mon, May 18, 2020 at 05:49:17PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> During writeback, it's possible for the quota block reservation in
> xfs_iomap_write_unwritten to fail with EDQUOT because we hit the quota
> limit.  This causes writeback errors for data that was already written
> to disk, when it's not even guaranteed that the bmbt will expand to
> exceed the quota limit.  Irritatingly, this condition is reported to
> userspace as EIO by fsync, which is confusing.
> 
> We wrote the data, so allow the reservation.  That might put us slightly
> above the hard limit, but it's better than losing data after a write.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/xfs_iomap.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> 
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index bb590a267a7f..ac970b13b1f8 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -563,7 +563,7 @@ xfs_iomap_write_unwritten(
>  		xfs_trans_ijoin(tp, ip, 0);
>  
>  		error = xfs_trans_reserve_quota_nblks(tp, ip, resblks, 0,
> -				XFS_QMOPT_RES_REGBLKS);
> +				XFS_QMOPT_RES_REGBLKS | XFS_QMOPT_FORCE_RES);
>  		if (error)
>  			goto error_on_bmapi_transaction;
>  
>