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Commit 8313b8e5 authored by NeilBrown's avatar NeilBrown
Browse files

md: fix problem when adding device to read-only array with bitmap. 



If an array is started degraded, and then the missing device
is found it can be re-added and a minimal bitmap-based recovery
will bring it fully up-to-date.

If the array is read-only a recovery would not be allowed.
But also if the array is read-only and the missing device was
present very recently, then there could be no need for any
recovery at all, so we simply include the device in the read-only
array without any recovery.

However... if the missing device was removed a little longer ago
it could be missing some updates, but if a bitmap is present it will
be conditionally accepted pending a bitmap-based update.  We don't
currently detect this case properly and will include that old
device into the read-only array with no recovery even though it really
needs a recovery.

This patch keeps track of whether a bitmap-based-recovery is really
needed or not in the new Bitmap_sync rdev flag.  If that is set,
then the device will not be added to a read-only array.

Cc: Andrei Warkentin <andreiw@vmware.com>
Fixes: d70ed2e4
Cc: stable@vger.kernel.org (3.2+)
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent e8b84915

drivers/md/md.c

+15 −3
Original line number Diff line number Diff line
@@ -1087,6 +1087,7 @@ static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev) 
	rdev->raid_disk = -1;

	clear_bit(Faulty, &rdev->flags);

	clear_bit(In_sync, &rdev->flags);

	clear_bit(Bitmap_sync, &rdev->flags);

	clear_bit(WriteMostly, &rdev->flags);



	if (mddev->raid_disks == 0) {
@@ -1165,6 +1166,8 @@ static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev) 
		 */

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

			return 0;

		if (ev1 < mddev->events)

			set_bit(Bitmap_sync, &rdev->flags);

	} else {

		if (ev1 < mddev->events)

			/* just a hot-add of a new device, leave raid_disk at -1 */
@@ -1573,6 +1576,7 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev) 
	rdev->raid_disk = -1;

	clear_bit(Faulty, &rdev->flags);

	clear_bit(In_sync, &rdev->flags);

	clear_bit(Bitmap_sync, &rdev->flags);

	clear_bit(WriteMostly, &rdev->flags);



	if (mddev->raid_disks == 0) {
@@ -1655,6 +1659,8 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev) 
		 */

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

			return 0;

		if (ev1 < mddev->events)

			set_bit(Bitmap_sync, &rdev->flags);

	} else {

		if (ev1 < mddev->events)

			/* just a hot-add of a new device, leave raid_disk at -1 */
@@ -2798,6 +2804,7 @@ slot_store(struct md_rdev *rdev, const char *buf, size_t len) 
		else

			rdev->saved_raid_disk = -1;

		clear_bit(In_sync, &rdev->flags);

		clear_bit(Bitmap_sync, &rdev->flags);

		err = rdev->mddev->pers->

			hot_add_disk(rdev->mddev, rdev);

		if (err) {
@@ -5770,6 +5777,7 @@ static int add_new_disk(struct mddev * mddev, mdu_disk_info_t *info) 
			    info->raid_disk < mddev->raid_disks) {

				rdev->raid_disk = info->raid_disk;

				set_bit(In_sync, &rdev->flags);

				clear_bit(Bitmap_sync, &rdev->flags);

			} else

				rdev->raid_disk = -1;

		} else
@@ -7716,7 +7724,8 @@ static int remove_and_add_spares(struct mddev *mddev, 
		if (test_bit(Faulty, &rdev->flags))

			continue;

		if (mddev->ro &&

		    rdev->saved_raid_disk < 0)

		    ! (rdev->saved_raid_disk >= 0 &&

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

			continue;



		rdev->recovery_offset = 0;
@@ -7797,9 +7806,12 @@ void md_check_recovery(struct mddev *mddev) 
			 * As we only add devices that are already in-sync,

			 * we can activate the spares immediately.

			 */

			clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);

			remove_and_add_spares(mddev, NULL);

			mddev->pers->spare_active(mddev);

			/* There is no thread, but we need to call

			 * ->spare_active and clear saved_raid_disk

			 */

			md_reap_sync_thread(mddev);

			clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);

			goto unlock;

		}

drivers/md/md.h

+3 −0
Original line number Diff line number Diff line
@@ -129,6 +129,9 @@ struct md_rdev { 
enum flag_bits {

	Faulty,			/* device is known to have a fault */

	In_sync,		/* device is in_sync with rest of array */

	Bitmap_sync,		/* ..actually, not quite In_sync.  Need a

				 * bitmap-based recovery to get fully in sync

				 */

	Unmerged,		/* device is being added to array and should

				 * be considerred for bvec_merge_fn but not

				 * yet for actual IO