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Commit 07d84d10 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: Allow re-add to work on array without bitmaps 



When an array has a bitmap, a device can be removed and re-added and only
blocks changes since the removal (as recorded in the bitmap) will be resynced.

It should be possible to do a similar thing to arrays without bitmaps.  i.e.
if a device is removed and re-added and *no* changes have been made in the
interim, then the add should not require a resync.

This patch allows that option.  This means that when assembling an array one
device at a time (e.g.  during device discovery) the array can be enabled
read-only as soon as enough devices are available, but extra devices can still
be added without causing a resync.

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 3285edf1

drivers/md/md.c

+14 −11
Original line number Diff line number Diff line
@@ -737,6 +737,7 @@ 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);

	__u64 ev1 = md_event(sb);



	rdev->raid_disk = -1;

	rdev->flags = 0;
@@ -753,7 +754,7 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
		mddev->layout = sb->layout;

		mddev->raid_disks = sb->raid_disks;

		mddev->size = sb->size;

		mddev->events = md_event(sb);

		mddev->events = ev1;

		mddev->bitmap_offset = 0;

		mddev->default_bitmap_offset = MD_SB_BYTES >> 9;
@@ -802,7 +803,6 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev) 


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

		/* Insist on good event counter while assembling */

		__u64 ev1 = md_event(sb);

		++ev1;

		if (ev1 < mddev->events) 

			return -EINVAL;
@@ -810,11 +810,13 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
		/* 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 */

	} else {

		if (ev1 < mddev->events)

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

			return 0;

	}



	if (mddev->level != LEVEL_MULTIPATH) {

		desc = sb->disks + rdev->desc_nr;
@@ -1105,6 +1107,7 @@ static int super_1_load(mdk_rdev_t *rdev, mdk_rdev_t *refdev, int minor_version) 
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);

	__u64 ev1 = le64_to_cpu(sb->events);



	rdev->raid_disk = -1;

	rdev->flags = 0;
@@ -1120,7 +1123,7 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
		mddev->layout = le32_to_cpu(sb->layout);

		mddev->raid_disks = le32_to_cpu(sb->raid_disks);

		mddev->size = le64_to_cpu(sb->size)/2;

		mddev->events = le64_to_cpu(sb->events);

		mddev->events = ev1;

		mddev->bitmap_offset = 0;

		mddev->default_bitmap_offset = 1024 >> 9;
@@ -1154,7 +1157,6 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev) 


	} 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;
@@ -1162,12 +1164,13 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev) 
		/* 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 */

	} else {

		if (ev1 < mddev->events)

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

			return 0;



	}

	if (mddev->level != LEVEL_MULTIPATH) {

		int role;

		rdev->desc_nr = le32_to_cpu(sb->dev_number);

drivers/md/raid1.c

+6 −0
Original line number Diff line number Diff line
@@ -1625,6 +1625,12 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i 
	/* before building a request, check if we can skip these blocks..

	 * This call the bitmap_start_sync doesn't actually record anything

	 */

	if (mddev->bitmap == NULL &&

	    mddev->recovery_cp == MaxSector &&

	    conf->fullsync == 0) {

		*skipped = 1;

		return max_sector - sector_nr;

	}

	if (!bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&

	    !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {

		/* We can skip this block, and probably several more */