Commit 41158c7e authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: optimise reconstruction when re-adding a recently failed drive. 



When an array is degraded, bit in the intent-bitmap are never cleared.  So if
a recently failed drive is re-added, we only need to reconstruct the block
that are still reflected in the bitmap.

This patch adds support for this re-adding.

Signed-off-by: default avatarNeil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 289e99e8

drivers/md/md.c

+55 −16
Original line number Diff line number Diff line
@@ -577,6 +577,8 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
	mdp_disk_t *desc;

	mdp_super_t *sb = (mdp_super_t *)page_address(rdev->sb_page);



	rdev->raid_disk = -1;

	rdev->in_sync = 0;

	if (mddev->raid_disks == 0) {

		mddev->major_version = 0;

		mddev->minor_version = sb->minor_version;
@@ -607,16 +609,24 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
		memcpy(mddev->uuid+12,&sb->set_uuid3, 4);



		mddev->max_disks = MD_SB_DISKS;

	} else {

		__u64 ev1;

		ev1 = md_event(sb);

	} else if (mddev->pers == NULL) {

		/* Insist on good event counter while assembling */

		__u64 ev1 = md_event(sb);

		++ev1;

		if (ev1 < mddev->events) 

			return -EINVAL;

	}

	} else if (mddev->bitmap) {

		/* if adding to array with a bitmap, then we can accept an

		 * older device ... but not too old.

		 */

		__u64 ev1 = md_event(sb);

		if (ev1 < mddev->bitmap->events_cleared)

			return 0;

	} else /* just a hot-add of a new device, leave raid_disk at -1 */

		return 0;



	if (mddev->level != LEVEL_MULTIPATH) {

		rdev->raid_disk = -1;

		rdev->in_sync = rdev->faulty = 0;

		rdev->faulty = 0;

		desc = sb->disks + rdev->desc_nr;



		if (desc->state & (1<<MD_DISK_FAULTY))
@@ -626,7 +636,8 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
			rdev->in_sync = 1;

			rdev->raid_disk = desc->raid_disk;

		}

	}

	} else /* MULTIPATH are always insync */

		rdev->in_sync = 1;

	return 0;

}
@@ -868,6 +879,8 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
{

	struct mdp_superblock_1 *sb = (struct mdp_superblock_1*)page_address(rdev->sb_page);



	rdev->raid_disk = -1;

	rdev->in_sync = 0;

	if (mddev->raid_disks == 0) {

		mddev->major_version = 1;

		mddev->patch_version = 0;
@@ -885,13 +898,21 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
		memcpy(mddev->uuid, sb->set_uuid, 16);



		mddev->max_disks =  (4096-256)/2;

	} else {

		__u64 ev1;

		ev1 = le64_to_cpu(sb->events);

	} else if (mddev->pers == NULL) {

		/* Insist of good event counter while assembling */

		__u64 ev1 = le64_to_cpu(sb->events);

		++ev1;

		if (ev1 < mddev->events)

			return -EINVAL;

	}

	} else if (mddev->bitmap) {

		/* If adding to array with a bitmap, then we can accept an

		 * older device, but not too old.

		 */

		__u64 ev1 = le64_to_cpu(sb->events);

		if (ev1 < mddev->bitmap->events_cleared)

			return 0;

	} else /* just a hot-add of a new device, leave raid_disk at -1 */

		return 0;



	if (mddev->level != LEVEL_MULTIPATH) {

		int role;
@@ -899,14 +920,10 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
		role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);

		switch(role) {

		case 0xffff: /* spare */

			rdev->in_sync = 0;

			rdev->faulty = 0;

			rdev->raid_disk = -1;

			break;

		case 0xfffe: /* faulty */

			rdev->in_sync = 0;

			rdev->faulty = 1;

			rdev->raid_disk = -1;

			break;

		default:

			rdev->in_sync = 1;
@@ -914,7 +931,9 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
			rdev->raid_disk = role;

			break;

		}

	}

	} else /* MULTIPATH are always insync */

		rdev->in_sync = 1;



	return 0;

}
@@ -2155,6 +2174,18 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info) 
				PTR_ERR(rdev));

			return PTR_ERR(rdev);

		}

		/* set save_raid_disk if appropriate */

		if (!mddev->persistent) {

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

			    info->raid_disk < mddev->raid_disks)

				rdev->raid_disk = info->raid_disk;

			else

				rdev->raid_disk = -1;

		} else

			super_types[mddev->major_version].

				validate_super(mddev, rdev);

		rdev->saved_raid_disk = rdev->raid_disk;



		rdev->in_sync = 0; /* just to be sure */

		rdev->raid_disk = -1;

		err = bind_rdev_to_array(rdev, mddev);
@@ -3706,6 +3737,14 @@ void md_check_recovery(mddev_t *mddev) 
				mddev->pers->spare_active(mddev);

			}

			md_update_sb(mddev);



			/* if array is no-longer degraded, then any saved_raid_disk

			 * information must be scrapped

			 */

			if (!mddev->degraded)

				ITERATE_RDEV(mddev,rdev,rtmp)

					rdev->saved_raid_disk = -1;



			mddev->recovery = 0;

			/* flag recovery needed just to double check */

			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);

drivers/md/raid1.c

+6 −1
Original line number Diff line number Diff line
@@ -811,9 +811,12 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev) 
{

	conf_t *conf = mddev->private;

	int found = 0;

	int mirror;

	int mirror = 0;

	mirror_info_t *p;



	if (rdev->saved_raid_disk >= 0 &&

	    conf->mirrors[rdev->saved_raid_disk].rdev == NULL)

		mirror = rdev->saved_raid_disk;

	for (mirror=0; mirror < mddev->raid_disks; mirror++)

		if ( !(p=conf->mirrors+mirror)->rdev) {
@@ -830,6 +833,8 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev) 
			p->head_position = 0;

			rdev->raid_disk = mirror;

			found = 1;

			if (rdev->saved_raid_disk != mirror)

				conf->fullsync = 1;

			p->rdev = rdev;

			break;

		}

include/linux/raid/md_k.h

+4 −0
Original line number Diff line number Diff line
@@ -183,6 +183,10 @@ struct mdk_rdev_s 


	int desc_nr;			/* descriptor index in the superblock */

	int raid_disk;			/* role of device in array */

	int saved_raid_disk;		/* role that device used to have in the

					 * array and could again if we did a partial

					 * resync from the bitmap

					 */



	atomic_t	nr_pending;	/* number of pending requests.

					 * only maintained for arrays that

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