Re: [PATCH] xfs: cancel intents immediately if process_intents fails

[Brian Foster <bfoster@redhat.com>]

On Mon, Oct 19, 2020 at 09:29:17AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> If processing recovered log intent items fails, we need to cancel all
> the unprocessed recovered items immediately so that a subsequent AIL
> push in the bail out path won't get wedged on the pinned intent items
> that didn't get processed.
> 
> This can happen if the log contains (1) an intent that gets and releases
> an inode, (2) an intent that cannot be recovered successfully, and (3)
> some third intent item.  When recovery of (2) fails, we leave (3) pinned
> in memory.  Inode reclamation is called in the error-out path of
> xfs_mountfs before xfs_log_cancel_mount.  Reclamation calls
> xfs_ail_push_all_sync, which gets stuck waiting for (3).
> 
> Therefore, call xlog_recover_cancel_intents if _process_intents fails.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

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

>  fs/xfs/xfs_log_recover.c |    8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index a8289adc1b29..87886b7f77da 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -3446,6 +3446,14 @@ xlog_recover_finish(
>  		int	error;
>  		error = xlog_recover_process_intents(log);
>  		if (error) {
> +			/*
> +			 * Cancel all the unprocessed intent items now so that
> +			 * we don't leave them pinned in the AIL.  This can
> +			 * cause the AIL to livelock on the pinned item if
> +			 * anyone tries to push the AIL (inode reclaim does
> +			 * this) before we get around to xfs_log_mount_cancel.
> +			 */
> +			xlog_recover_cancel_intents(log);
>  			xfs_alert(log->l_mp, "Failed to recover intents");
>  			return error;
>  		}
>