On Wed, Oct 09, 2019 at 04:27:48PM +0200, Christoph Hellwig wrote:
> XLOG_STATE_DO_CALLBACK is only entered through XLOG_STATE_DONE_SYNC
> and just used in a single debug check. Remove the flag and thus
> simplify the calling conventions for xlog_state_do_callback and
> xlog_state_iodone_process_iclog.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/xfs_log.c | 76 +++++++------------------------------------
> fs/xfs/xfs_log_priv.h | 1 -
> 2 files changed, 11 insertions(+), 66 deletions(-)
>
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index 001a9586cb56..d158b6d56a26 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -2750,7 +2750,6 @@ static bool
> xlog_state_iodone_process_iclog(
> struct xlog *log,
> struct xlog_in_core *iclog,
> - struct xlog_in_core *completed_iclog,
> bool *ioerror)
> {
> xfs_lsn_t lowest_lsn;
> @@ -2768,17 +2767,16 @@ xlog_state_iodone_process_iclog(
> * Between marking a filesystem SHUTDOWN and stopping the log,
> * we do flush all iclogs to disk (if there wasn't a log I/O
> * error). So, we do want things to go smoothly in case of just
> - * a SHUTDOWN w/o a LOG_IO_ERROR.
> + * a SHUTDOWN w/o a LOG_IO_ERROR.
> */
> *ioerror = true;
> return false;
> case XLOG_STATE_DONE_SYNC:
> - case XLOG_STATE_DO_CALLBACK:
> /*
> - * Now that we have an iclog that is in either the DO_CALLBACK
> - * or DONE_SYNC states, do one more check here to see if we have
> - * chased our tail around. If this is not the lowest lsn iclog,
> - * then we will leave it for another completion to process.
> + * Now that we have an iclog that is in the DONE_SYNC state, do
> + * one more check here to see if we have chased our tail around.
> + * If this is not the lowest lsn iclog, then we will leave it
> + * for another completion to process.
> */
> header_lsn = be64_to_cpu(iclog->ic_header.h_lsn);
> lowest_lsn = xlog_get_lowest_lsn(log);
> @@ -2789,15 +2787,9 @@ xlog_state_iodone_process_iclog(
> default:
> /*
> * Can only perform callbacks in order. Since this iclog is not
> - * in the DONE_SYNC or DO_CALLBACK states, we skip the rest and
> - * just try to clean up. If we set our iclog to DO_CALLBACK, we
> - * will not process it when we retry since a previous iclog is
> - * in the CALLBACK and the state cannot change since we are
> - * holding l_icloglock.
> + * in the DONE_SYNC state, we skip the rest and just try to
> + * clean up.
> */
> - if (completed_iclog &&
> - (completed_iclog->ic_state == XLOG_STATE_DONE_SYNC))
> - completed_iclog->ic_state = XLOG_STATE_DO_CALLBACK;
> return true;
> }
> }
> @@ -2838,54 +2830,13 @@ xlog_state_do_iclog_callbacks(
> spin_unlock(&iclog->ic_callback_lock);
> }
>
> -#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.
> - */
> -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 ||
> - 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
So, uh... does this debugging functionality just disappear? Is it
unnecessary? It's not clear (to me anyway) why it's ok for the extra
checking to go away.
--D
> -
> STATIC void
> xlog_state_do_callback(
> struct xlog *log,
> - bool aborted,
> - struct xlog_in_core *ciclog)
> + bool aborted)
> {
> struct xlog_in_core *iclog;
> struct xlog_in_core *first_iclog;
> - bool did_callbacks = false;
> bool cycled_icloglock;
> bool ioerror;
> int flushcnt = 0;
> @@ -2909,7 +2860,7 @@ xlog_state_do_callback(
>
> do {
> if (xlog_state_iodone_process_iclog(log, iclog,
> - ciclog, &ioerror))
> + &ioerror))
> break;
>
> if (iclog->ic_state != XLOG_STATE_CALLBACK &&
> @@ -2929,8 +2880,6 @@ xlog_state_do_callback(
> iclog = iclog->ic_next;
> } while (first_iclog != iclog);
>
> - did_callbacks |= cycled_icloglock;
> -
> if (repeats > 5000) {
> flushcnt += repeats;
> repeats = 0;
> @@ -2940,9 +2889,6 @@ xlog_state_do_callback(
> }
> } while (!ioerror && cycled_icloglock);
>
> - if (did_callbacks)
> - xlog_state_callback_check_state(log);
> -
> if (log->l_iclog->ic_state == XLOG_STATE_ACTIVE ||
> log->l_iclog->ic_state == XLOG_STATE_IOERROR)
> wake_up_all(&log->l_flush_wait);
> @@ -2993,7 +2939,7 @@ xlog_state_done_syncing(
> */
> wake_up_all(&iclog->ic_write_wait);
> spin_unlock(&log->l_icloglock);
> - xlog_state_do_callback(log, aborted, iclog); /* also cleans log */
> + xlog_state_do_callback(log, aborted); /* also cleans log */
> } /* xlog_state_done_syncing */
>
>
> @@ -3987,7 +3933,7 @@ xfs_log_force_umount(
> spin_lock(&log->l_cilp->xc_push_lock);
> wake_up_all(&log->l_cilp->xc_commit_wait);
> spin_unlock(&log->l_cilp->xc_push_lock);
> - xlog_state_do_callback(log, true, NULL);
> + xlog_state_do_callback(log, true);
>
> /* return non-zero if log IOERROR transition had already happened */
> return retval;
> diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
> index bf076893f516..4f19375f6592 100644
> --- a/fs/xfs/xfs_log_priv.h
> +++ b/fs/xfs/xfs_log_priv.h
> @@ -45,7 +45,6 @@ enum xlog_iclog_state {
> XLOG_STATE_WANT_SYNC, /* Want to sync this iclog; no more writes */
> XLOG_STATE_SYNCING, /* This IC log is syncing */
> XLOG_STATE_DONE_SYNC, /* Done syncing to disk */
> - XLOG_STATE_DO_CALLBACK, /* Process callback functions */
> XLOG_STATE_CALLBACK, /* Callback functions now */
> XLOG_STATE_DIRTY, /* Dirty IC log, not ready for ACTIVE status */
> XLOG_STATE_IOERROR, /* IO error happened in sync'ing log */
> --
> 2.20.1
>
