Re: [PATCH v3 2/4] xfs: refactor xfsaild_push loop into helper

["Darrick J. Wong" <djwong@kernel.org>]

On Sun, Mar 08, 2026 at 06:28:07PM +0000, Yuto Ohnuki wrote:
> Factor the loop body of xfsaild_push() into a separate
> xfsaild_process_logitem() helper to improve readability.
> 
> This is a pure code movement with no functional change. The
> subsequent patch to fix a use-after-free in the AIL push path
> depends on this refactoring.
> 
> Cc: <stable@vger.kernel.org> # v5.9
> Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com>

Seems like a reasonable hoist to reduce the length of the function, but
in ordering the patches this way (cleanup, then bugfixes) the hoist also
has to be backported to 5.10/5.15/6.1/6.6/6.12/6.18/6.19.

--D

> ---
>  fs/xfs/xfs_trans_ail.c | 116 +++++++++++++++++++++++------------------
>  1 file changed, 64 insertions(+), 52 deletions(-)
> 
> diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
> index 923729af4206..ac747804e1d6 100644
> --- a/fs/xfs/xfs_trans_ail.c
> +++ b/fs/xfs/xfs_trans_ail.c
> @@ -458,6 +458,69 @@ xfs_ail_calc_push_target(
>  	return target_lsn;
>  }
>  
> +static void
> +xfsaild_process_logitem(
> +	struct xfs_ail		*ailp,
> +	struct xfs_log_item	*lip,
> +	xfs_lsn_t		lsn,
> +	int			*stuck,
> +	int			*flushing)
> +{
> +	struct xfs_mount	*mp = ailp->ail_log->l_mp;
> +	int			lock_result;
> +
> +	/*
> +	 * Note that iop_push may unlock and reacquire the AIL lock. We
> +	 * rely on the AIL cursor implementation to be able to deal with
> +	 * the dropped lock.
> +	 */
> +	lock_result = xfsaild_push_item(ailp, lip);
> +	switch (lock_result) {
> +	case XFS_ITEM_SUCCESS:
> +		XFS_STATS_INC(mp, xs_push_ail_success);
> +		trace_xfs_ail_push(lip);
> +
> +		ailp->ail_last_pushed_lsn = lsn;
> +		break;
> +
> +	case XFS_ITEM_FLUSHING:
> +		/*
> +		 * The item or its backing buffer is already being
> +		 * flushed.  The typical reason for that is that an
> +		 * inode buffer is locked because we already pushed the
> +		 * updates to it as part of inode clustering.
> +		 *
> +		 * We do not want to stop flushing just because lots
> +		 * of items are already being flushed, but we need to
> +		 * re-try the flushing relatively soon if most of the
> +		 * AIL is being flushed.
> +		 */
> +		XFS_STATS_INC(mp, xs_push_ail_flushing);
> +		trace_xfs_ail_flushing(lip);
> +
> +		(*flushing)++;
> +		ailp->ail_last_pushed_lsn = lsn;
> +		break;
> +
> +	case XFS_ITEM_PINNED:
> +		XFS_STATS_INC(mp, xs_push_ail_pinned);
> +		trace_xfs_ail_pinned(lip);
> +
> +		(*stuck)++;
> +		ailp->ail_log_flush++;
> +		break;
> +	case XFS_ITEM_LOCKED:
> +		XFS_STATS_INC(mp, xs_push_ail_locked);
> +		trace_xfs_ail_locked(lip);
> +
> +		(*stuck)++;
> +		break;
> +	default:
> +		ASSERT(0);
> +		break;
> +	}
> +}
> +
>  static long
>  xfsaild_push(
>  	struct xfs_ail		*ailp)
> @@ -505,62 +568,11 @@ xfsaild_push(
>  
>  	lsn = lip->li_lsn;
>  	while ((XFS_LSN_CMP(lip->li_lsn, ailp->ail_target) <= 0)) {
> -		int	lock_result;
>  
>  		if (test_bit(XFS_LI_FLUSHING, &lip->li_flags))
>  			goto next_item;
>  
> -		/*
> -		 * Note that iop_push may unlock and reacquire the AIL lock.  We
> -		 * rely on the AIL cursor implementation to be able to deal with
> -		 * the dropped lock.
> -		 */
> -		lock_result = xfsaild_push_item(ailp, lip);
> -		switch (lock_result) {
> -		case XFS_ITEM_SUCCESS:
> -			XFS_STATS_INC(mp, xs_push_ail_success);
> -			trace_xfs_ail_push(lip);
> -
> -			ailp->ail_last_pushed_lsn = lsn;
> -			break;
> -
> -		case XFS_ITEM_FLUSHING:
> -			/*
> -			 * The item or its backing buffer is already being
> -			 * flushed.  The typical reason for that is that an
> -			 * inode buffer is locked because we already pushed the
> -			 * updates to it as part of inode clustering.
> -			 *
> -			 * We do not want to stop flushing just because lots
> -			 * of items are already being flushed, but we need to
> -			 * re-try the flushing relatively soon if most of the
> -			 * AIL is being flushed.
> -			 */
> -			XFS_STATS_INC(mp, xs_push_ail_flushing);
> -			trace_xfs_ail_flushing(lip);
> -
> -			flushing++;
> -			ailp->ail_last_pushed_lsn = lsn;
> -			break;
> -
> -		case XFS_ITEM_PINNED:
> -			XFS_STATS_INC(mp, xs_push_ail_pinned);
> -			trace_xfs_ail_pinned(lip);
> -
> -			stuck++;
> -			ailp->ail_log_flush++;
> -			break;
> -		case XFS_ITEM_LOCKED:
> -			XFS_STATS_INC(mp, xs_push_ail_locked);
> -			trace_xfs_ail_locked(lip);
> -
> -			stuck++;
> -			break;
> -		default:
> -			ASSERT(0);
> -			break;
> -		}
> -
> +		xfsaild_process_logitem(ailp, lip, lsn, &stuck, &flushing);
>  		count++;
>  
>  		/*
> -- 
> 2.50.1
> 
> 
> 
> 
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