Re: [PATCH 6/8] xfs: factor common AIL item deletion code

Darrick J. Wong
2020-03-26T05:10:08Z

On Wed, Mar 25, 2020 at 12:42:03PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> Factor the common AIL deletion code that does all the wakeups into a
> helper so we only have one copy of this somewhat tricky code to
> interface with all the wakeups necessary when the LSN of the log
> tail changes.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

This call site didn't have a wake_up_all and now it does; is that going
to make a difference? I /think/ the answer is that this function
usually puts things on the AIL so we won't trigger the ail_empty wakeup;
and if the AIL was previously empty and we didn't match any log items
(such that it's still empty) then it's fine to wake up anyone who was
waiting for the ail to clear out?

If so,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> fs/xfs/xfs_inode_item.c | 12 +----------
> fs/xfs/xfs_trans_ail.c | 48 ++++++++++++++++++++++-------------------
> fs/xfs/xfs_trans_priv.h | 4 +++-
> 3 files changed, 30 insertions(+), 34 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
> index 4a3d13d4a0228..bd8c368098707 100644
> --- a/fs/xfs/xfs_inode_item.c
> +++ b/fs/xfs/xfs_inode_item.c
> @@ -742,17 +742,7 @@ xfs_iflush_done(
> xfs_clear_li_failed(blip);
> }
> }
> -
> - if (mlip_changed) {
> - if (!XFS_FORCED_SHUTDOWN(ailp->ail_mount))
> - xlog_assign_tail_lsn_locked(ailp->ail_mount);
> - if (list_empty(&ailp->ail_head))
> - wake_up_all(&ailp->ail_empty);
> - }
> - spin_unlock(&ailp->ail_lock);
> -
> - if (mlip_changed)
> - xfs_log_space_wake(ailp->ail_mount);
> + xfs_ail_update_finish(ailp, mlip_changed);
> }
>
> /*
> diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
> index 2ef0dfbfb303d..26d2e7928121c 100644
> --- a/fs/xfs/xfs_trans_ail.c
> +++ b/fs/xfs/xfs_trans_ail.c
> @@ -681,6 +681,27 @@ xfs_ail_push_all_sync(
> finish_wait(&ailp->ail_empty, &wait);
> }
>
> +void
> +xfs_ail_update_finish(
> + struct xfs_ail *ailp,
> + bool do_tail_update) __releases(ailp->ail_lock)
> +{
> + struct xfs_mount *mp = ailp->ail_mount;
> +
> + if (!do_tail_update) {
> + spin_unlock(&ailp->ail_lock);
> + return;
> + }
> +
> + if (!XFS_FORCED_SHUTDOWN(mp))
> + xlog_assign_tail_lsn_locked(mp);
> +
> + if (list_empty(&ailp->ail_head))
> + wake_up_all(&ailp->ail_empty);
> + spin_unlock(&ailp->ail_lock);
> + xfs_log_space_wake(mp);
> +}
> +
> /*
> * xfs_trans_ail_update - bulk AIL insertion operation.
> *
> @@ -740,15 +761,7 @@ xfs_trans_ail_update_bulk(
> if (!list_empty(&tmp))
> xfs_ail_splice(ailp, cur, &tmp, lsn);
>
> - if (mlip_changed) {
> - if (!XFS_FORCED_SHUTDOWN(ailp->ail_mount))
> - xlog_assign_tail_lsn_locked(ailp->ail_mount);
> - spin_unlock(&ailp->ail_lock);
> -
> - xfs_log_space_wake(ailp->ail_mount);
> - } else {
> - spin_unlock(&ailp->ail_lock);
> - }
> + xfs_ail_update_finish(ailp, mlip_changed);
> }
>
> bool
> @@ -792,10 +805,10 @@ void
> xfs_trans_ail_delete(
> struct xfs_ail *ailp,
> struct xfs_log_item *lip,
> - int shutdown_type) __releases(ailp->ail_lock)
> + int shutdown_type)
> {
> struct xfs_mount *mp = ailp->ail_mount;
> - bool mlip_changed;
> + bool need_update;
>
> if (!test_bit(XFS_LI_IN_AIL, &lip->li_flags)) {
> spin_unlock(&ailp->ail_lock);
> @@ -808,17 +821,8 @@ xfs_trans_ail_delete(
> return;
> }
>
> - mlip_changed = xfs_ail_delete_one(ailp, lip);
> - if (mlip_changed) {
> - if (!XFS_FORCED_SHUTDOWN(mp))
> - xlog_assign_tail_lsn_locked(mp);
> - if (list_empty(&ailp->ail_head))
> - wake_up_all(&ailp->ail_empty);
> - }
> -
> - spin_unlock(&ailp->ail_lock);
> - if (mlip_changed)
> - xfs_log_space_wake(ailp->ail_mount);
> + need_update = xfs_ail_delete_one(ailp, lip);
> + xfs_ail_update_finish(ailp, need_update);
> }
>
> int
> diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h
> index 2e073c1c4614f..64ffa746730e4 100644
> --- a/fs/xfs/xfs_trans_priv.h
> +++ b/fs/xfs/xfs_trans_priv.h
> @@ -92,8 +92,10 @@ xfs_trans_ail_update(
> }
>
> bool xfs_ail_delete_one(struct xfs_ail *ailp, struct xfs_log_item *lip);
> +void xfs_ail_update_finish(struct xfs_ail *ailp, bool do_tail_update)
> + __releases(ailp->ail_lock);
> void xfs_trans_ail_delete(struct xfs_ail *ailp, struct xfs_log_item *lip,
> - int shutdown_type) __releases(ailp->ail_lock);
> + int shutdown_type);
>
> static inline void
> xfs_trans_ail_remove(
> --
> 2.26.0.rc2
>