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Commit 6e20902e authored by Heinz Mauelshagen's avatar Heinz Mauelshagen Committed by Mike Snitzer
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dm raid: fix failed takeover/reshapes by keeping raid set frozen 



Superblock updates where bogus causing some takovers/reshapes to fail.

Introduce new runtime flag (RT_FLAG_KEEP_RS_FROZEN) to keep a raid set
frozen when a layout change was requested.  Userpace will immediately
reload the table w/o the flags requesting such change once they made it
to the superblocks and any change of recovery/reshape offsets has to be
avoided until after read.

Signed-off-by: default avatarHeinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 4257e085

drivers/md/dm-raid.c

+56 −29
Original line number Diff line number Diff line
@@ -190,6 +190,7 @@ struct raid_dev { 
#define RT_FLAG_RS_BITMAP_LOADED	2

#define RT_FLAG_UPDATE_SBS		3

#define RT_FLAG_RESHAPE_RS		4

#define RT_FLAG_KEEP_RS_FROZEN		5



/* Array elements of 64 bit needed for rebuild/write_mostly bits */

#define DISKS_ARRAY_ELEMS ((MAX_RAID_DEVICES + (sizeof(uint64_t) * 8 - 1)) / sizeof(uint64_t) / 8)
@@ -2727,6 +2728,7 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv) 
			return r;



		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);

		set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);

		rs_set_new(rs);

	} else if (rs_reshape_requested(rs)) {

		if (rs_is_reshaping(rs)) {
@@ -2767,13 +2769,19 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv) 
		 *           Would cause allocations in raid1->check_reshape

		 *           though, thus more issues with potential failures

		 */

		else if (rs_is_raid1(rs))

		else if (rs_is_raid1(rs)) {

			set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);

			rs->md.raid_disks = rs->raid_disks;

		}



		if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {

			set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);

			set_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags);

		}



		if (rs->md.raid_disks < rs->raid_disks)

			set_bit(MD_ARRAY_FIRST_USE, &rs->md.flags);



		set_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags);

		rs_set_cur(rs);

	} else

		rs_set_cur(rs);
@@ -3231,9 +3239,11 @@ static void raid_postsuspend(struct dm_target *ti) 
{

	struct raid_set *rs = ti->private;



	if (test_and_clear_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags)) {

		if (!rs->md.suspended)

			mddev_suspend(&rs->md);

		rs->md.ro = 1;

	clear_bit(RT_FLAG_RS_RESUMED, &rs->runtime_flags);

	}

}



static void attempt_restore_of_faulty_devices(struct raid_set *rs)
@@ -3308,6 +3318,18 @@ static int __load_dirty_region_bitmap(struct raid_set *rs) 
	return r;

}



/* Enforce updating all superblocks */

static void rs_update_sbs(struct raid_set *rs)

{

	struct mddev *mddev = &rs->md;

	int ro = mddev->ro;



	set_bit(MD_CHANGE_DEVS, &mddev->flags);

	mddev->ro = 0;

	md_update_sb(mddev, 1);

	mddev->ro = ro;

}



/*

 * Reshape changes raid algorithm of @rs to new one within personality

 * (e.g. raid6_zr -> raid6_nc), changes stripe size, adds/removes
@@ -3356,9 +3378,12 @@ static int rs_start_reshape(struct raid_set *rs) 
	if (!mddev->suspended)

		mddev_suspend(mddev);



	mddev->ro = 0;

	md_update_sb(mddev, 1);

	mddev->ro = 1;

	/*

	 * Now reshape got set up, update superblocks to

	 * reflect the fact so that a table reload will

	 * access proper superblock content in the ctr.

	 */

	rs_update_sbs(rs);



	return 0;

}
@@ -3375,22 +3400,12 @@ static int raid_preresume(struct dm_target *ti) 


	/*

	 * The superblocks need to be updated on disk if the

	 * array is new or __load_dirty_region_bitmap will overwrite them

	 * in core with old data.

	 *

	 * In case the array got modified (takeover/reshape/resize)

	 * or the data offsets on the component devices changed, they

	 * have to be updated as well.

	 *

	 * Have to switch to readwrite and back in order to

	 * allow for the superblock updates.

	 * array is new or new devices got added (thus zeroed

	 * out by userspace) or __load_dirty_region_bitmap

	 * will overwrite them in core with old data or fail.

	 */

	if (test_and_clear_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags)) {

		set_bit(MD_CHANGE_DEVS, &mddev->flags);

		mddev->ro = 0;

		md_update_sb(mddev, 1);

		mddev->ro = 1;

	}

	if (test_bit(RT_FLAG_UPDATE_SBS, &rs->runtime_flags))

		rs_update_sbs(rs);



	/*

	 * Disable/enable discard support on raid set after any
@@ -3449,15 +3464,27 @@ static void raid_resume(struct dm_target *ti) 
		 * devices are reachable again.

		 */

		attempt_restore_of_faulty_devices(rs);

	}



	} else {

		mddev->ro = 0;

		mddev->in_sync = 0;



		/*

		 * When passing in flags to the ctr, we expect userspace

		 * to reset them because they made it to the superblocks

		 * and reload the mapping anyway.

		 *

		 * -> only unfreeze recovery in case of a table reload or

		 *    we'll have a bogus recovery/reshape position

		 *    retrieved from the superblock by the ctr because

		 *    the ongoing recovery/reshape will change it after read.

		 */

		if (!test_bit(RT_FLAG_KEEP_RS_FROZEN, &rs->runtime_flags))

			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);



		if (mddev->suspended)

			mddev_resume(mddev);

	}

}



static struct target_type raid_target = {

	.name = "raid",