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Commit 3e6180f0 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Mike Snitzer
Browse files

dm: only initialize the request_queue once 

Commit bfebd1cd ("dm: add full blk-mq support to request-based DM")
didn't properly account for the need to short-circuit re-initializing
DM's blk-mq request_queue if it was already initialized.

Otherwise, reloading a blk-mq request-based DM table (either manually
or via multipathd) resulted in errors, see:
 https://www.redhat.com/archives/dm-devel/2015-April/msg00132.html



Fix is to only initialize the request_queue on the initial table load
(when the mapped_device type is assigned).

This is better than having dm_init_request_based_blk_mq_queue() return
early if the queue was already initialized because it elevates the
constraint to a more meaningful location in DM core.  As such the
pre-existing early return in dm_init_request_based_queue() can now be
removed.

Fixes: bfebd1cd ("dm: add full blk-mq support to request-based DM")
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent b787f68c

drivers/md/dm-ioctl.c

+9 −8
Original line number Diff line number Diff line
@@ -1298,14 +1298,9 @@ static int table_load(struct dm_ioctl *param, size_t param_size) 
		goto err_unlock_md_type;

	}



	if (dm_get_md_type(md) == DM_TYPE_NONE)

	if (dm_get_md_type(md) == DM_TYPE_NONE) {

		/* Initial table load: acquire type of table. */

		dm_set_md_type(md, dm_table_get_type(t));

	else if (dm_get_md_type(md) != dm_table_get_type(t)) {

		DMWARN("can't change device type after initial table load.");

		r = -EINVAL;

		goto err_unlock_md_type;

	}



		/* setup md->queue to reflect md's type (may block) */

		r = dm_setup_md_queue(md);
@@ -1313,6 +1308,12 @@ static int table_load(struct dm_ioctl *param, size_t param_size) 
			DMWARN("unable to set up device queue for new table.");

			goto err_unlock_md_type;

		}

	} else if (dm_get_md_type(md) != dm_table_get_type(t)) {

		DMWARN("can't change device type after initial table load.");

		r = -EINVAL;

		goto err_unlock_md_type;

	}



	dm_unlock_md_type(md);



	/* stage inactive table */

drivers/md/dm.c

+0 −3
Original line number Diff line number Diff line
@@ -2662,9 +2662,6 @@ static int dm_init_request_based_queue(struct mapped_device *md) 
{

	struct request_queue *q = NULL;



	if (md->queue->elevator)

		return 0;



	/* Fully initialize the queue */

	q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);

	if (!q)