diff options
| author | Mike Snitzer <snitzer@redhat.com> | 2014-12-17 21:08:12 -0500 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2015-02-09 13:06:47 -0500 |
| commit | e5863d9ad754926e7d3f38b43ac8bd48ef73b097 (patch) | |
| tree | 0e4d75672884b7dc93296beea8ddf3833b4d7f38 /drivers/md/dm.h | |
| parent | 466d89a6bcd500f64896b514f78b32e8d0b0303a (diff) | |
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.h | 8 |
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); |