Commit 3be260cc authored by NeilBrown's avatar NeilBrown
Browse files

md/linear: remove rcu protections in favour of suspend/resume 



The use of 'rcu' to protect accesses to ->private_data so that
the ->private_data could be updated predates the introduction
of mddev_suspend/mddev_resume.
These are a cleaner mechanism for providing stability while
swapping in a new ->private data - it is used by level_store()
to support changing of raid levels.

So get rid of the RCU stuff and just use mddev_suspend, mddev_resume.

As these function call ->quiesce(), we add an empty function for
linear just like for raid0.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 64590f45

drivers/md/linear.c

+14 −30
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector) 


	lo = 0;

	hi = mddev->raid_disks - 1;

	conf = rcu_dereference(mddev->private);

	conf = mddev->private;



	/*

	 * Binary Search
@@ -70,7 +70,6 @@ static int linear_mergeable_bvec(struct mddev *mddev, 
	int maxbytes = biovec->bv_len;

	struct request_queue *subq;



	rcu_read_lock();

	dev0 = which_dev(mddev, sector);

	maxsectors = dev0->end_sector - sector;

	subq = bdev_get_queue(dev0->rdev->bdev);
@@ -80,7 +79,6 @@ static int linear_mergeable_bvec(struct mddev *mddev, 
		maxbytes = min(maxbytes, subq->merge_bvec_fn(subq, bvm,

							     biovec));

	}

	rcu_read_unlock();



	if (maxsectors < bio_sectors)

		maxsectors = 0;
@@ -101,15 +99,13 @@ static int linear_congested(struct mddev *mddev, int bits) 
	struct linear_conf *conf;

	int i, ret = 0;



	rcu_read_lock();

	conf = rcu_dereference(mddev->private);

	conf = mddev->private;



	for (i = 0; i < mddev->raid_disks && !ret ; i++) {

		struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);

		ret |= bdi_congested(&q->backing_dev_info, bits);

	}



	rcu_read_unlock();

	return ret;

}
@@ -118,12 +114,10 @@ static sector_t linear_size(struct mddev *mddev, sector_t sectors, int raid_disk 
	struct linear_conf *conf;

	sector_t array_sectors;



	rcu_read_lock();

	conf = rcu_dereference(mddev->private);

	conf = mddev->private;

	WARN_ONCE(sectors || raid_disks,

		  "%s does not support generic reshape\n", __func__);

	array_sectors = conf->array_sectors;

	rcu_read_unlock();



	return array_sectors;

}
@@ -243,33 +237,22 @@ static int linear_add(struct mddev *mddev, struct md_rdev *rdev) 
	if (!newconf)

		return -ENOMEM;



	oldconf = rcu_dereference_protected(mddev->private,

					    lockdep_is_held(

						    &mddev->reconfig_mutex));

	mddev_suspend(mddev);

	oldconf = mddev->private;

	mddev->raid_disks++;

	rcu_assign_pointer(mddev->private, newconf);

	mddev->private = newconf;

	md_set_array_sectors(mddev, linear_size(mddev, 0, 0));

	set_capacity(mddev->gendisk, mddev->array_sectors);

	mddev_resume(mddev);

	revalidate_disk(mddev->gendisk);

	kfree_rcu(oldconf, rcu);

	kfree(oldconf);

	return 0;

}



static int linear_stop (struct mddev *mddev)

{

	struct linear_conf *conf =

		rcu_dereference_protected(mddev->private,

					  lockdep_is_held(

						  &mddev->reconfig_mutex));

	struct linear_conf *conf = mddev->private;



	/*

	 * We do not require rcu protection here since

	 * we hold reconfig_mutex for both linear_add and

	 * linear_stop, so they cannot race.

	 * We should make sure any old 'conf's are properly

	 * freed though.

	 */

	rcu_barrier();

	blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/

	kfree(conf);

	mddev->private = NULL;
@@ -290,16 +273,12 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio) 
	}



	do {

		rcu_read_lock();



		tmp_dev = which_dev(mddev, bio->bi_iter.bi_sector);

		start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;

		end_sector = tmp_dev->end_sector;

		data_offset = tmp_dev->rdev->data_offset;

		bio->bi_bdev = tmp_dev->rdev->bdev;



		rcu_read_unlock();



		if (unlikely(bio->bi_iter.bi_sector >= end_sector ||

			     bio->bi_iter.bi_sector < start_sector))

			goto out_of_bounds;
@@ -346,6 +325,10 @@ static void linear_status (struct seq_file *seq, struct mddev *mddev) 
	seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);

}



static void linear_quiesce(struct mddev *mddev, int state)

{

}



static struct md_personality linear_personality =

{

	.name		= "linear",
@@ -357,6 +340,7 @@ static struct md_personality linear_personality = 
	.status		= linear_status,

	.hot_add_disk	= linear_add,

	.size		= linear_size,

	.quiesce	= linear_quiesce,

	.congested	= linear_congested,

	.mergeable_bvec	= linear_mergeable_bvec,

};

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