Commit d562b0c4 authored by NeilBrown's avatar NeilBrown
Browse files

md: add ->takeover method for raid5 to be able to take over raid1 



The RAID1 must have two drives and be a suitable size to
be a multiple of a chunksize that isn't too small.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 245f46c2

drivers/md/raid5.c

+48 −0
Original line number Diff line number Diff line
@@ -4884,6 +4884,53 @@ static void raid5_quiesce(mddev_t *mddev, int state) 
	}

}





static void *raid5_takeover_raid1(mddev_t *mddev)

{

	int chunksect;



	if (mddev->raid_disks != 2 ||

	    mddev->degraded > 1)

		return ERR_PTR(-EINVAL);



	/* Should check if there are write-behind devices? */



	chunksect = 64*2; /* 64K by default */



	/* The array must be an exact multiple of chunksize */

	while (chunksect && (mddev->array_sectors & (chunksect-1)))

		chunksect >>= 1;



	if ((chunksect<<9) < STRIPE_SIZE)

		/* array size does not allow a suitable chunk size */

		return ERR_PTR(-EINVAL);



	mddev->new_level = 5;

	mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;

	mddev->new_chunk = chunksect << 9;



	return setup_conf(mddev);

}





static void *raid5_takeover(mddev_t *mddev)

{

	/* raid5 can take over:

	 *  raid0 - if all devices are the same - make it a raid4 layout

	 *  raid1 - if there are two drives.  We need to know the chunk size

	 *  raid4 - trivial - just use a raid4 layout.

	 *  raid6 - Providing it is a *_6 layout

	 *

	 * For now, just do raid1

	 */



	if (mddev->level == 1)

		return raid5_takeover_raid1(mddev);



	return ERR_PTR(-EINVAL);

}





static struct mdk_personality raid5_personality;



static void *raid6_takeover(mddev_t *mddev)
@@ -4975,6 +5022,7 @@ static struct mdk_personality raid5_personality = 
	.start_reshape  = raid5_start_reshape,

#endif

	.quiesce	= raid5_quiesce,

	.takeover	= raid5_takeover,

};



static struct mdk_personality raid4_personality =