Commit e38b0432 authored by Logan Gunthorpe's avatar Logan Gunthorpe Committed by Song Liu
Browse files

md/raid5: Annotate rdev/replacement accesses when nr_pending is elevated 



There are a number of accesses to __rcu variables that should be safe
because nr_pending in the disk is known to be elevated.

Create a wrapper around rcu_dereference_protected() to annotate these
accesses and verify that nr_pending is non-zero.

This fixes a number of sparse warnings.

Signed-off-by: default avatarLogan Gunthorpe <logang@deltatee.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarSong Liu <song@kernel.org>
parent b0920ede

drivers/md/raid5.c

+19 −9
Original line number Diff line number Diff line
@@ -2648,6 +2648,16 @@ static void shrink_stripes(struct r5conf *conf) 
	conf->slab_cache = NULL;

}



/*

 * This helper wraps rcu_dereference_protected() and can be used when

 * it is known that the nr_pending of the rdev is elevated.

 */

static struct md_rdev *rdev_pend_deref(struct md_rdev __rcu *rdev)

{

	return rcu_dereference_protected(rdev,

			atomic_read(&rcu_access_pointer(rdev)->nr_pending));

}



static void raid5_end_read_request(struct bio * bi)

{

	struct stripe_head *sh = bi->bi_private;
@@ -2674,9 +2684,9 @@ static void raid5_end_read_request(struct bio * bi) 
		 * In that case it moved down to 'rdev'.

		 * rdev is not removed until all requests are finished.

		 */

		rdev = conf->disks[i].replacement;

		rdev = rdev_pend_deref(conf->disks[i].replacement);

	if (!rdev)

		rdev = conf->disks[i].rdev;

		rdev = rdev_pend_deref(conf->disks[i].rdev);



	if (use_new_offset(conf, sh))

		s = sh->sector + rdev->new_data_offset;
@@ -2790,11 +2800,11 @@ static void raid5_end_write_request(struct bio *bi) 


	for (i = 0 ; i < disks; i++) {

		if (bi == &sh->dev[i].req) {

			rdev = conf->disks[i].rdev;

			rdev = rdev_pend_deref(conf->disks[i].rdev);

			break;

		}

		if (bi == &sh->dev[i].rreq) {

			rdev = conf->disks[i].replacement;

			rdev = rdev_pend_deref(conf->disks[i].replacement);

			if (rdev)

				replacement = 1;

			else
@@ -2802,7 +2812,7 @@ static void raid5_end_write_request(struct bio *bi) 
				 * replaced it.  rdev is not removed

				 * until all requests are finished.

				 */

				rdev = conf->disks[i].rdev;

				rdev = rdev_pend_deref(conf->disks[i].rdev);

			break;

		}

	}
@@ -5210,23 +5220,23 @@ static void handle_stripe(struct stripe_head *sh) 
			struct r5dev *dev = &sh->dev[i];

			if (test_and_clear_bit(R5_WriteError, &dev->flags)) {

				/* We own a safe reference to the rdev */

				rdev = conf->disks[i].rdev;

				rdev = rdev_pend_deref(conf->disks[i].rdev);

				if (!rdev_set_badblocks(rdev, sh->sector,

							RAID5_STRIPE_SECTORS(conf), 0))

					md_error(conf->mddev, rdev);

				rdev_dec_pending(rdev, conf->mddev);

			}

			if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {

				rdev = conf->disks[i].rdev;

				rdev = rdev_pend_deref(conf->disks[i].rdev);

				rdev_clear_badblocks(rdev, sh->sector,

						     RAID5_STRIPE_SECTORS(conf), 0);

				rdev_dec_pending(rdev, conf->mddev);

			}

			if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {

				rdev = conf->disks[i].replacement;

				rdev = rdev_pend_deref(conf->disks[i].replacement);

				if (!rdev)

					/* rdev have been moved down */

					rdev = conf->disks[i].rdev;

					rdev = rdev_pend_deref(conf->disks[i].rdev);

				rdev_clear_badblocks(rdev, sh->sector,

						     RAID5_STRIPE_SECTORS(conf), 0);

				rdev_dec_pending(rdev, conf->mddev);