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Commit 15b94a69 authored by Junichi Nomura's avatar Junichi Nomura Committed by Mike Snitzer
Browse files

dm: fix reload failure of 0 path multipath mapping on blk-mq devices 



dm-multipath accepts 0 path mapping.

  # echo '0 2097152 multipath 0 0 0 0' | dmsetup create newdev

Such a mapping can be used to release underlying devices while still
holding requests in its queue until working paths come back.

However, once the multipath device is created over blk-mq devices,
it rejects reloading of 0 path mapping:

  # echo '0 2097152 multipath 0 0 1 1 queue-length 0 1 1 /dev/sda 1' \
      | dmsetup create mpath1
  # echo '0 2097152 multipath 0 0 0 0' | dmsetup load mpath1
  device-mapper: reload ioctl on mpath1 failed: Invalid argument
  Command failed

With following kernel message:
  device-mapper: ioctl: can't change device type after initial table load.

DM tries to inherit the current table type using dm_table_set_type()
but it doesn't work as expected because of unnecessary check about
whether the target type is hybrid or not.

Hybrid type is for targets that work as either request-based or bio-based
and not required for blk-mq or non blk-mq checking.

Fixes: 65803c20 ("dm table: train hybrid target type detection to select blk-mq if appropriate")
Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent e5d8de32

drivers/md/dm-table.c

+9 −7
Original line number Original line Diff line number Diff line
@@ -820,6 +820,12 @@ void dm_consume_args(struct dm_arg_set *as, unsigned num_args) 
}

}

EXPORT_SYMBOL(dm_consume_args);

EXPORT_SYMBOL(dm_consume_args);





static bool __table_type_request_based(unsigned table_type)

{

	return (table_type == DM_TYPE_REQUEST_BASED ||

		table_type == DM_TYPE_MQ_REQUEST_BASED);

}



static int dm_table_set_type(struct dm_table *t)

static int dm_table_set_type(struct dm_table *t)

{

{

	unsigned i;

	unsigned i;
@@ -852,8 +858,7 @@ static int dm_table_set_type(struct dm_table *t) 
		 * Determine the type from the live device.

		 * Determine the type from the live device.

		 * Default to bio-based if device is new.

		 * Default to bio-based if device is new.

		 */

		 */

		if (live_md_type == DM_TYPE_REQUEST_BASED ||

		if (__table_type_request_based(live_md_type))

		    live_md_type == DM_TYPE_MQ_REQUEST_BASED)

			request_based = 1;

			request_based = 1;

		else

		else

			bio_based = 1;

			bio_based = 1;
@@ -903,7 +908,7 @@ static int dm_table_set_type(struct dm_table *t) 
			}

			}

		t->type = DM_TYPE_MQ_REQUEST_BASED;

		t->type = DM_TYPE_MQ_REQUEST_BASED;





	} else if (hybrid && list_empty(devices) && live_md_type != DM_TYPE_NONE) {

	} else if (list_empty(devices) && __table_type_request_based(live_md_type)) {

		/* inherit live MD type */

		/* inherit live MD type */

		t->type = live_md_type;

		t->type = live_md_type;
@@ -925,10 +930,7 @@ struct target_type *dm_table_get_immutable_target_type(struct dm_table *t) 




bool dm_table_request_based(struct dm_table *t)

bool dm_table_request_based(struct dm_table *t)

{

{

	unsigned table_type = dm_table_get_type(t);

	return __table_type_request_based(dm_table_get_type(t));



	return (table_type == DM_TYPE_REQUEST_BASED ||

		table_type == DM_TYPE_MQ_REQUEST_BASED);

}

}





bool dm_table_mq_request_based(struct dm_table *t)

bool dm_table_mq_request_based(struct dm_table *t)