dm: fix reload failure of 0 path multipath mapping on blk-mq devices (15b94a69) · Commits · 戴 / test

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: ("dm table: train hybrid target type detection to select blk-mq if appropriate") Signed-off-by:

Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by:

Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-table.c

+9 −7

Original line number	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);

		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)
		{
		unsigned i;
		@@ -852,8 +858,7 @@ static int dm_table_set_type(struct dm_table *t)
		* Determine the type from the live device.
		* Default to bio-based if device is new.
		*/
		if (live_md_type == DM_TYPE_REQUEST_BASED \|\|
		live_md_type == DM_TYPE_MQ_REQUEST_BASED)
		if (__table_type_request_based(live_md_type))
		request_based = 1;
		else
		bio_based = 1;
		@@ -903,7 +908,7 @@ static int dm_table_set_type(struct dm_table *t)
		}
		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 */
		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)
		{
		unsigned table_type = dm_table_get_type(t);

		return (table_type == DM_TYPE_REQUEST_BASED \|\|
		table_type == DM_TYPE_MQ_REQUEST_BASED);
		return __table_type_request_based(dm_table_get_type(t));
		}

		bool dm_table_mq_request_based(struct dm_table *t)

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