md: perform async updates for metadata where possible. (060b0689) · Commits · 戴 / test

When adding devices to, or removing device from, an array we need to update the metadata. However we don't need to do it synchronously as data integrity doesn't depend on these changes being recorded instantly. So avoid the synchronous call to md_update_sb and just set a flag so that the thread will do it. This can reduce the number of updates performed when lots of devices are being added or removed. Signed-off-by:

NeilBrown <neilb@suse.com> Signed-off-by:

Shaohua Li <shli@fb.com>

drivers/md/md.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -2599,8 +2599,10 @@ state_store(struct md_rdev rdev, const char buf, size_t len)

		if (err == 0) {
		md_kick_rdev_from_array(rdev);
		if (mddev->pers)
		md_update_sb(mddev, 1);
		if (mddev->pers) {
		set_bit(MD_CHANGE_DEVS, &mddev->flags);
		md_wakeup_thread(mddev->thread);
		}
		md_new_event(mddev);
		}
		}
		@@ -6175,6 +6177,10 @@ kick_rdev:
		md_cluster_ops->remove_disk(mddev, rdev);

		md_kick_rdev_from_array(rdev);
		set_bit(MD_CHANGE_DEVS, &mddev->flags);
		if (mddev->thread)
		md_wakeup_thread(mddev->thread);
		else
		md_update_sb(mddev, 1);
		md_new_event(mddev);

		@@ -6240,6 +6246,8 @@ static int hot_add_disk(struct mddev *mddev, dev_t dev)

		rdev->raid_disk = -1;

		set_bit(MD_CHANGE_DEVS, &mddev->flags);
		if (!mddev->thread)
		md_update_sb(mddev, 1);
		/*
		* Kick recovery, maybe this spare has to be added to the

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