md: allow raid5_quiesce to work properly when reshape is happening. (64bd660b) · Commits · 戴 / test

The ->quiesce method is not supposed to stop resync/recovery/reshape, just normal IO. But in raid5 we don't have a way to know which stripes are being used for normal IO and which for resync etc, so we need to wait for all stripes to be idle to be sure that all writes have completed. However reshape keeps at least some stripe busy for an extended period of time, so a call to raid5_quiesce can block for several seconds needlessly. So arrange for reshape etc to pause briefly while raid5_quiesce is trying to quiesce the array so that the active_stripes count can drop to zero. Signed-off-by:

NeilBrown <neilb@suse.de>

drivers/md/raid5.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -3999,6 +3999,9 @@ static inline sector_t sync_request(mddev_t mddev, sector_t sector_nr, int ski
		return 0;
		}

		/* Allow raid5_quiesce to complete */
		wait_event(conf->wait_for_overlap, conf->quiesce != 2);

		if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
		return reshape_request(mddev, sector_nr, skipped);

		@@ -5104,12 +5107,18 @@ static void raid5_quiesce(mddev_t *mddev, int state)

		case 1: /* stop all writes */
		spin_lock_irq(&conf->device_lock);
		conf->quiesce = 1;
		/* '2' tells resync/reshape to pause so that all
		* active stripes can drain
		*/
		conf->quiesce = 2;
		wait_event_lock_irq(conf->wait_for_stripe,
		atomic_read(&conf->active_stripes) == 0 &&
		atomic_read(&conf->active_aligned_reads) == 0,
		conf->device_lock, /* nothing */);
		conf->quiesce = 1;
		spin_unlock_irq(&conf->device_lock);
		/* allow reshape to continue */
		wake_up(&conf->wait_for_overlap);
		break;

		case 0: /* re-enable writes */

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