Commit f6b6ec5c authored by Shaohua Li's avatar Shaohua Li Committed by NeilBrown
Browse files

raid5-cache: add journal hot add/remove support 



Add support for journal disk hot add/remove. Mostly trival checks in md
part. The raid5 part is a little tricky. For hot-remove, we can't wait
pending write as it's called from raid5d. The wait will cause deadlock.
We simplily fail the hot-remove. A hot-remove retry can success
eventually since if journal disk is faulty all pending write will be
failed and finish. For hot-add, since an array supporting journal but
without journal disk will be marked read-only, we are safe to hot add
journal without stopping IO (should be read IO, while journal only
handles write IO).

Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.com>
parent 9ebc6ef1

drivers/md/md.c

+30 −12
Original line number Diff line number Diff line
@@ -2055,8 +2055,9 @@ static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev) 
		return -EEXIST;



	/* make sure rdev->sectors exceeds mddev->dev_sectors */

	if (rdev->sectors && (mddev->dev_sectors == 0 ||

			rdev->sectors < mddev->dev_sectors)) {

	if (!test_bit(Journal, &rdev->flags) &&

	    rdev->sectors &&

	    (mddev->dev_sectors == 0 || rdev->sectors < mddev->dev_sectors)) {

		if (mddev->pers) {

			/* Cannot change size, so fail

			 * If mddev->level <= 0, then we don't care
@@ -2087,7 +2088,8 @@ static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev) 
		}

	}

	rcu_read_unlock();

	if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {

	if (!test_bit(Journal, &rdev->flags) &&

	    mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {

		printk(KERN_WARNING "md: %s: array is limited to %d devices\n",

		       mdname(mddev), mddev->max_disks);

		return -EBUSY;
@@ -6044,8 +6046,23 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info) 
		else

			clear_bit(WriteMostly, &rdev->flags);



		if (info->state & (1<<MD_DISK_JOURNAL))

		if (info->state & (1<<MD_DISK_JOURNAL)) {

			struct md_rdev *rdev2;

			bool has_journal = false;



			/* make sure no existing journal disk */

			rdev_for_each(rdev2, mddev) {

				if (test_bit(Journal, &rdev2->flags)) {

					has_journal = true;

					break;

				}

			}

			if (has_journal) {

				export_rdev(rdev);

				return -EBUSY;

			}

			set_bit(Journal, &rdev->flags);

		}

		/*

		 * check whether the device shows up in other nodes

		 */
@@ -8181,18 +8198,19 @@ static int remove_and_add_spares(struct mddev *mddev, 
			continue;

		if (test_bit(Faulty, &rdev->flags))

			continue;

		if (test_bit(Journal, &rdev->flags))

			continue;

		if (!test_bit(Journal, &rdev->flags)) {

			if (mddev->ro &&

			    ! (rdev->saved_raid_disk >= 0 &&

			       !test_bit(Bitmap_sync, &rdev->flags)))

				continue;



			rdev->recovery_offset = 0;

		}

		if (mddev->pers->

		    hot_add_disk(mddev, rdev) == 0) {

			if (sysfs_link_rdev(mddev, rdev))

				/* failure here is OK */;

			if (!test_bit(Journal, &rdev->flags))

				spares++;

			md_new_event(mddev);

			set_bit(MD_CHANGE_DEVS, &mddev->flags);

drivers/md/raid5-cache.c

+12 −4
Original line number Diff line number Diff line
@@ -799,10 +799,18 @@ void r5l_quiesce(struct r5l_log *log, int state) 


bool r5l_log_disk_error(struct r5conf *conf)

{

	struct r5l_log *log;

	bool ret;

	/* don't allow write if journal disk is missing */

	if (!conf->log)

		return test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);

	return test_bit(Faulty, &conf->log->rdev->flags);

	rcu_read_lock();

	log = rcu_dereference(conf->log);



	if (!log)

		ret = test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);

	else

		ret = test_bit(Faulty, &log->rdev->flags);

	rcu_read_unlock();

	return ret;

}



struct r5l_recovery_ctx {
@@ -1165,7 +1173,7 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev) 
	if (r5l_load_log(log))

		goto error;



	conf->log = log;

	rcu_assign_pointer(conf->log, log);

	return 0;

error:

	md_unregister_thread(&log->reclaim_thread);

drivers/md/raid5.c

+26 −8
Original line number Diff line number Diff line
@@ -7139,14 +7139,19 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev) 
	struct disk_info *p = conf->disks + number;



	print_raid5_conf(conf);

	if (test_bit(Journal, &rdev->flags)) {

	if (test_bit(Journal, &rdev->flags) && conf->log) {

		struct r5l_log *log;

		/*

		 * journal disk is not removable, but we need give a chance to

		 * update superblock of other disks. Otherwise journal disk

		 * will be considered as 'fresh'

		 * we can't wait pending write here, as this is called in

		 * raid5d, wait will deadlock.

		 */

		set_bit(MD_CHANGE_DEVS, &mddev->flags);

		return -EINVAL;

		if (atomic_read(&mddev->writes_pending))

			return -EBUSY;

		log = conf->log;

		conf->log = NULL;

		synchronize_rcu();

		r5l_exit_log(log);

		return 0;

	}

	if (rdev == p->rdev)

		rdevp = &p->rdev;
@@ -7210,8 +7215,21 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev) 
	int first = 0;

	int last = conf->raid_disks - 1;



	if (test_bit(Journal, &rdev->flags))

		return -EINVAL;

	if (test_bit(Journal, &rdev->flags)) {

		char b[BDEVNAME_SIZE];

		if (conf->log)

			return -EBUSY;



		rdev->raid_disk = 0;

		/*

		 * The array is in readonly mode if journal is missing, so no

		 * write requests running. We should be safe

		 */

		r5l_init_log(conf, rdev);

		printk(KERN_INFO"md/raid:%s: using device %s as journal\n",

		       mdname(mddev), bdevname(rdev->bdev, b));

		return 0;

	}

	if (mddev->recovery_disabled == conf->recovery_disabled)

		return -EBUSY;

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