On Wed, Aug 01, 2018 at 09:19:38AM -0400, Brian Foster wrote:
> The current transaction allocation code conditionally initializes
> the ->t_dfops indirection pointer. Transaction commit/cancel check
> the validity of the pointer to determine whether to finish/cancel
> the internal dfops.
>
> This disallows the ability to use the internal dfops list as a
> temporary container (via xfs_trans_alloc_empty()). Refactor
> transaction allocation to always initialize ->t_dfops and check
> permanent reservation state on transaction commit/cancel.
>
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
> fs/xfs/xfs_trans.c | 19 +++++++++----------
> 1 file changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
> index 7bf5c1202719..12b6ad1558e6 100644
> --- a/fs/xfs/xfs_trans.c
> +++ b/fs/xfs/xfs_trans.c
> @@ -281,13 +281,7 @@ xfs_trans_alloc(
> INIT_LIST_HEAD(&tp->t_items);
> INIT_LIST_HEAD(&tp->t_busy);
> tp->t_firstblock = NULLFSBLOCK;
> - /*
> - * We only roll transactions with permanent log reservation. Don't init
> - * ->t_dfops to skip attempts to finish or cancel an empty dfops with a
> - * non-permanent res.
> - */
> - if (resp->tr_logflags & XFS_TRANS_PERM_LOG_RES)
> - xfs_defer_init(tp, &tp->t_dfops_internal);
> + xfs_defer_init(tp, &tp->t_dfops_internal);
>
> error = xfs_trans_reserve(tp, resp, blocks, rtextents);
> if (error) {
> @@ -931,8 +925,13 @@ __xfs_trans_commit(
>
> trace_xfs_trans_commit(tp, _RET_IP_);
>
> - /* finish deferred items on final commit */
> - if (!regrant && tp->t_dfops) {
> + /*
> + * Finish deferred items on final commit. Only permanent transactions
> + * should ever have deferred ops.
> + */
> + WARN_ON_ONCE(xfs_defer_has_unfinished_work(tp->t_dfops) &&
> + !(tp->t_flags & XFS_TRANS_PERM_LOG_RES));
> + if (!regrant && (tp->t_flags & XFS_TRANS_PERM_LOG_RES)) {
> error = xfs_defer_finish_noroll(&tp);
> if (error) {
> xfs_defer_cancel(tp);
> @@ -1029,7 +1028,7 @@ xfs_trans_cancel(
>
> trace_xfs_trans_cancel(tp, _RET_IP_);
>
> - if (tp->t_dfops)
> + if (tp->t_flags & XFS_TRANS_PERM_LOG_RES)
> xfs_defer_cancel(tp);
>
> /*
> --
> 2.17.1
>
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