Commit 2652a1bd authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

md: factor out the rdev overlaps check from rdev_size_store 



This splits the code into nicely readable chunks and also avoids
the refcount inc/dec manipulations.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarLogan Gunthorpe <logang@deltatee.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 33b614e3

drivers/md/md.c

+39 −45
Original line number Diff line number Diff line
@@ -3343,14 +3343,33 @@ rdev_size_show(struct md_rdev *rdev, char *page) 
	return sprintf(page, "%llu\n", (unsigned long long)rdev->sectors / 2);

}



static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)

static int md_rdevs_overlap(struct md_rdev *a, struct md_rdev *b)

{

	/* check if two start/length pairs overlap */

	if (s1+l1 <= s2)

		return 0;

	if (s2+l2 <= s1)

		return 0;

	return 1;

	if (a->data_offset + a->sectors <= b->data_offset)

		return false;

	if (b->data_offset + b->sectors <= a->data_offset)

		return false;

	return true;

}



static bool md_rdev_overlaps(struct md_rdev *rdev)

{

	struct mddev *mddev;

	struct md_rdev *rdev2;



	spin_lock(&all_mddevs_lock);

	list_for_each_entry(mddev, &all_mddevs, all_mddevs) {

		rdev_for_each(rdev2, mddev) {

			if (rdev != rdev2 && rdev->bdev == rdev2->bdev &&

			    md_rdevs_overlap(rdev, rdev2)) {

				spin_unlock(&all_mddevs_lock);

				return true;

			}

		}

	}

	spin_unlock(&all_mddevs_lock);

	return false;

}



static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
@@ -3402,47 +3421,22 @@ rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len) 
		return -EINVAL; /* component must fit device */



	rdev->sectors = sectors;

	if (sectors > oldsectors && my_mddev->external) {

		/* Need to check that all other rdevs with the same

		 * ->bdev do not overlap.  'rcu' is sufficient to walk

		 * the rdev lists safely.

		 * This check does not provide a hard guarantee, it

		 * just helps avoid dangerous mistakes.

		 */

		struct mddev *mddev;

		int overlap = 0;

		struct list_head *tmp;



		rcu_read_lock();

		for_each_mddev(mddev, tmp) {

			struct md_rdev *rdev2;



			rdev_for_each(rdev2, mddev)

				if (rdev->bdev == rdev2->bdev &&

				    rdev != rdev2 &&

				    overlaps(rdev->data_offset, rdev->sectors,

					     rdev2->data_offset,

					     rdev2->sectors)) {

					overlap = 1;

					break;

				}

			if (overlap) {

				mddev_put(mddev);

				break;

			}

		}

		rcu_read_unlock();

		if (overlap) {

			/* Someone else could have slipped in a size

			 * change here, but doing so is just silly.

			 * We put oldsectors back because we *know* it is

			 * safe, and trust userspace not to race with

			 * itself

	/*

	 * Check that all other rdevs with the same bdev do not overlap.  This

	 * check does not provide a hard guarantee, it just helps avoid

	 * dangerous mistakes.

	 */

	if (sectors > oldsectors && my_mddev->external &&

	    md_rdev_overlaps(rdev)) {

		/*

		 * Someone else could have slipped in a size change here, but

		 * doing so is just silly.  We put oldsectors back because we

		 * know it is safe, and trust userspace not to race with itself.

		 */

		rdev->sectors = oldsectors;

		return -EBUSY;

	}

	}

	return len;

}