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authorMike Snitzer <snitzer@redhat.com>2014-12-18 05:08:12 +0300
committerMike Snitzer <snitzer@redhat.com>2015-02-09 21:06:47 +0300
commite5863d9ad754926e7d3f38b43ac8bd48ef73b097 (patch)
tree0e4d75672884b7dc93296beea8ddf3833b4d7f38 /drivers/md/dm.h
parent466d89a6bcd500f64896b514f78b32e8d0b0303a (diff)
downloadlinux-e5863d9ad754926e7d3f38b43ac8bd48ef73b097.tar.xz
dm: allocate requests in target when stacking on blk-mq devices
For blk-mq request-based DM the responsibility of allocating a cloned request is transfered from DM core to the target type. Doing so enables the cloned request to be allocated from the appropriate blk-mq request_queue's pool (only the DM target, e.g. multipath, can know which block device to send a given cloned request to). Care was taken to preserve compatibility with old-style block request completion that requires request-based DM _not_ acquire the clone request's queue lock in the completion path. As such, there are now 2 different request-based DM target_type interfaces: 1) the original .map_rq() interface will continue to be used for non-blk-mq devices -- the preallocated clone request is passed in from DM core. 2) a new .clone_and_map_rq() and .release_clone_rq() will be used for blk-mq devices -- blk_get_request() and blk_put_request() are used respectively from these hooks. dm_table_set_type() was updated to detect if the request-based target is being stacked on blk-mq devices, if so DM_TYPE_MQ_REQUEST_BASED is set. DM core disallows switching the DM table's type after it is set. This means that there is no mixing of non-blk-mq and blk-mq devices within the same request-based DM table. [This patch was started by Keith and later heavily modified by Mike] Tested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm.h')
-rw-r--r--drivers/md/dm.h8
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 84b0f9e4ba6c..84d79784b866 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -34,9 +34,10 @@
/*
* Type of table and mapped_device's mempool
*/
-#define DM_TYPE_NONE 0
-#define DM_TYPE_BIO_BASED 1
-#define DM_TYPE_REQUEST_BASED 2
+#define DM_TYPE_NONE 0
+#define DM_TYPE_BIO_BASED 1
+#define DM_TYPE_REQUEST_BASED 2
+#define DM_TYPE_MQ_REQUEST_BASED 3
/*
* List of devices that a metadevice uses and should open/close.
@@ -73,6 +74,7 @@ int dm_table_any_busy_target(struct dm_table *t);
unsigned dm_table_get_type(struct dm_table *t);
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_mq_request_based(struct dm_table *t);
void dm_table_free_md_mempools(struct dm_table *t);
struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);