Re: [PATCH 4/8] xfs: factor debug code out of xlog_state_do_callback()

Darrick J. Wong
2019-09-05T15:32:12Z

On Thu, Sep 05, 2019 at 06:47:13PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> Start making this function readable by lifting the debug code into
> a conditional function.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
> fs/xfs/xfs_log.c | 79 +++++++++++++++++++++++++++---------------------
> 1 file changed, 44 insertions(+), 35 deletions(-)
>
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index 8380ed065608..2904bf0d17f3 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -2628,6 +2628,48 @@ xlog_get_lowest_lsn(
> return lowest_lsn;
> }
>
> +#ifdef DEBUG
> +/*
> + * Make one last gasp attempt to see if iclogs are being left in limbo. If the
> + * above loop finds an iclog earlier than the current iclog and in one of the
> + * syncing states, the current iclog is put into DO_CALLBACK and the callbacks
> + * are deferred to the completion of the earlier iclog. Walk the iclogs in order
> + * and make sure that no iclog is in DO_CALLBACK unless an earlier iclog is in
> + * one of the syncing states.
> + *
> + * Note that SYNCING|IOERROR is a valid state so we cannot just check for
> + * ic_state == SYNCING.
> + */
> +static void
> +xlog_state_callback_check_state(
> + struct xlog *log)
> +{
> + struct xlog_in_core *first_iclog = log->l_iclog;
> + struct xlog_in_core *iclog = first_iclog;
> +
> + do {
> + ASSERT(iclog->ic_state != XLOG_STATE_DO_CALLBACK);
> + /*
> + * Terminate the loop if iclogs are found in states
> + * which will cause other threads to clean up iclogs.
> + *
> + * SYNCING - i/o completion will go through logs
> + * DONE_SYNC - interrupt thread should be waiting for
> + * l_icloglock
> + * IOERROR - give up hope all ye who enter here
> + */
> + if (iclog->ic_state == XLOG_STATE_WANT_SYNC ||
> + iclog->ic_state & XLOG_STATE_SYNCING ||

Code like this make my eyes twitch (Does ic_state track mutually
exclusive state? Or is it state flags? I think it's the second!),
but as this is simply refactoring debugging code...

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

--D

> + iclog->ic_state == XLOG_STATE_DONE_SYNC ||
> + iclog->ic_state == XLOG_STATE_IOERROR )
> + break;
> + iclog = iclog->ic_next;
> + } while (first_iclog != iclog);
> +}
> +#else
> +#define xlog_state_callback_check_state(l) ((void)0)
> +#endif
> +
> STATIC void
> xlog_state_do_callback(
> struct xlog *log,
> @@ -2802,41 +2844,8 @@ xlog_state_do_callback(
> }
> } while (!ioerrors && loopdidcallbacks);
>
> -#ifdef DEBUG
> - /*
> - * Make one last gasp attempt to see if iclogs are being left in limbo.
> - * If the above loop finds an iclog earlier than the current iclog and
> - * in one of the syncing states, the current iclog is put into
> - * DO_CALLBACK and the callbacks are deferred to the completion of the
> - * earlier iclog. Walk the iclogs in order and make sure that no iclog
> - * is in DO_CALLBACK unless an earlier iclog is in one of the syncing
> - * states.
> - *
> - * Note that SYNCING|IOABORT is a valid state so we cannot just check
> - * for ic_state == SYNCING.
> - */
> - if (funcdidcallbacks) {
> - first_iclog = iclog = log->l_iclog;
> - do {
> - ASSERT(iclog->ic_state != XLOG_STATE_DO_CALLBACK);
> - /*
> - * Terminate the loop if iclogs are found in states
> - * which will cause other threads to clean up iclogs.
> - *
> - * SYNCING - i/o completion will go through logs
> - * DONE_SYNC - interrupt thread should be waiting for
> - * l_icloglock
> - * IOERROR - give up hope all ye who enter here
> - */
> - if (iclog->ic_state == XLOG_STATE_WANT_SYNC ||
> - iclog->ic_state & XLOG_STATE_SYNCING ||
> - iclog->ic_state == XLOG_STATE_DONE_SYNC ||
> - iclog->ic_state == XLOG_STATE_IOERROR )
> - break;
> - iclog = iclog->ic_next;
> - } while (first_iclog != iclog);
> - }
> -#endif
> + if (funcdidcallbacks)
> + xlog_state_callback_check_state(log);
>
> if (log->l_iclog->ic_state & (XLOG_STATE_ACTIVE|XLOG_STATE_IOERROR))
> wake_up_all(&log->l_flush_wait);
> --
> 2.23.0.rc1
>