dm: only initialize the request_queue once (3e6180f0) · Commits · 戴 / test

Commit ("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: ("dm: add full blk-mq support to request-based DM") Signed-off-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

Mike Snitzer <snitzer@redhat.com>

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)

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