Re: [PATCH 2/2] xfs: fix broken bhold behavior in xrep_roll_ag_trans

Brian Foster
2019-04-25T11:17:02Z

On Wed, Apr 24, 2019 at 10:50:01PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> In xrep_roll_ag_trans, the transaction roll will always set sc->tp to
> the new transaction, even if committing the old one fails. A bare
> transaction roll leaves the buffer(s) locked but not joined to the new
> transaction, so it's not necessary to release the hold if the roll
> fails. Remove the incorrect xfs_trans_bhold_release calls.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Makes sense:

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

> fs/xfs/scrub/repair.c | 25 ++++++++-----------------
> 1 file changed, 8 insertions(+), 17 deletions(-)
>
> diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
> index 5e7e36cdf3d5..eb358f0f5e0a 100644
> --- a/fs/xfs/scrub/repair.c
> +++ b/fs/xfs/scrub/repair.c
> @@ -136,10 +136,16 @@ xrep_roll_ag_trans(
> if (sc->sa.agfl_bp)
> xfs_trans_bhold(sc->tp, sc->sa.agfl_bp);
>
> - /* Roll the transaction. */
> + /*
> + * Roll the transaction. We still own the buffer and the buffer lock
> + * regardless of whether or not the roll succeeds. If the roll fails,
> + * the buffers will be released during teardown on our way out of the
> + * kernel. If it succeeds, we join them to the new transaction and
> + * move on.
> + */
> error = xfs_trans_roll(&sc->tp);
> if (error)
> - goto out_release;
> + return error;
>
> /* Join AG headers to the new transaction. */
> if (sc->sa.agi_bp)
> @@ -150,21 +156,6 @@ xrep_roll_ag_trans(
> xfs_trans_bjoin(sc->tp, sc->sa.agfl_bp);
>
> return 0;
> -
> -out_release:
> - /*
> - * Rolling failed, so release the hold on the buffers. The
> - * buffers will be released during teardown on our way out
> - * of the kernel.
> - */
> - if (sc->sa.agi_bp)
> - xfs_trans_bhold_release(sc->tp, sc->sa.agi_bp);
> - if (sc->sa.agf_bp)
> - xfs_trans_bhold_release(sc->tp, sc->sa.agf_bp);
> - if (sc->sa.agfl_bp)
> - xfs_trans_bhold_release(sc->tp, sc->sa.agfl_bp);
> -
> - return error;
> }
>
> /*