Commit 05256d98 authored by NeilBrown's avatar NeilBrown
Browse files

md/raid5: strengthen check on reshape_position at run. 



When reshaping, we work in units of the largest chunk size.
If changing from a larger to a smaller chunk size, that means we
reshape more than one stripe at a time.  So the required alignment
of reshape_position needs to take into account both the old
and new chunk size.

This means that both 'here_new' and 'here_old' are calculated with
respect to the same (maximum) chunk size, so testing if they are the
same when delta_disks is zero becomes pointless.

Signed-off-by: default avatarNeilBrown <neilb@suse.com>
parent 3cb5edf4

drivers/md/raid5.c

+14 −15
Original line number Diff line number Diff line
@@ -6688,6 +6688,8 @@ static int run(struct mddev *mddev) 
		sector_t here_new, here_old;

		int old_disks;

		int max_degraded = (mddev->level == 6 ? 2 : 1);

		int chunk_sectors;

		int new_data_disks;



		if (mddev->new_level != mddev->level) {

			printk(KERN_ERR "md/raid:%s: unsupported reshape "
@@ -6699,28 +6701,25 @@ static int run(struct mddev *mddev) 
		/* reshape_position must be on a new-stripe boundary, and one

		 * further up in new geometry must map after here in old

		 * geometry.

		 * If the chunk sizes are different, then as we perform reshape

		 * in units of the largest of the two, reshape_position needs

		 * be a multiple of the largest chunk size times new data disks.

		 */

		here_new = mddev->reshape_position;

		if (sector_div(here_new, mddev->new_chunk_sectors *

			       (mddev->raid_disks - max_degraded))) {

		chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);

		new_data_disks = mddev->raid_disks - max_degraded;

		if (sector_div(here_new, chunk_sectors * new_data_disks)) {

			printk(KERN_ERR "md/raid:%s: reshape_position not "

			       "on a stripe boundary\n", mdname(mddev));

			return -EINVAL;

		}

		reshape_offset = here_new * mddev->new_chunk_sectors;

		reshape_offset = here_new * chunk_sectors;

		/* here_new is the stripe we will write to */

		here_old = mddev->reshape_position;

		sector_div(here_old, mddev->chunk_sectors *

			   (old_disks-max_degraded));

		sector_div(here_old, chunk_sectors * (old_disks-max_degraded));

		/* here_old is the first stripe that we might need to read

		 * from */

		if (mddev->delta_disks == 0) {

			if ((here_new * mddev->new_chunk_sectors !=

			     here_old * mddev->chunk_sectors)) {

				printk(KERN_ERR "md/raid:%s: reshape position is"

				       " confused - aborting\n", mdname(mddev));

				return -EINVAL;

			}

			/* We cannot be sure it is safe to start an in-place

			 * reshape.  It is only safe if user-space is monitoring

			 * and taking constant backups.
@@ -6739,10 +6738,10 @@ static int run(struct mddev *mddev) 
				return -EINVAL;

			}

		} else if (mddev->reshape_backwards

		    ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=

		       here_old * mddev->chunk_sectors)

		    : (here_new * mddev->new_chunk_sectors >=

		       here_old * mddev->chunk_sectors + (-min_offset_diff))) {

		    ? (here_new * chunk_sectors + min_offset_diff <=

		       here_old * chunk_sectors)

		    : (here_new * chunk_sectors >=

		       here_old * chunk_sectors + (-min_offset_diff))) {

			/* Reading from the same stripe as writing to - bad */

			printk(KERN_ERR "md/raid:%s: reshape_position too early for "

			       "auto-recovery - aborting.\n",

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