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| author | Mike Snitzer <snitzer@redhat.com> | 2014-12-18 05:08:12 +0300 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2015-02-09 21:06:47 +0300 |
| commit | e5863d9ad754926e7d3f38b43ac8bd48ef73b097 (patch) | |
| tree | 0e4d75672884b7dc93296beea8ddf3833b4d7f38 /drivers/md/dm-target.c | |
| parent | 466d89a6bcd500f64896b514f78b32e8d0b0303a (diff) | |
| download | linux-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-target.c')
| -rw-r--r-- | drivers/md/dm-target.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c index 242e3cec397a..925ec1b15e75 100644 --- a/drivers/md/dm-target.c +++ b/drivers/md/dm-target.c @@ -137,13 +137,26 @@ static int io_err_map_rq(struct dm_target *ti, struct request *clone, return -EIO; } +static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq, + union map_info *map_context, + struct request **clone) +{ + return -EIO; +} + +static void io_err_release_clone_rq(struct request *clone) +{ +} + static struct target_type error_target = { .name = "error", - .version = {1, 2, 0}, + .version = {1, 3, 0}, .ctr = io_err_ctr, .dtr = io_err_dtr, .map = io_err_map, .map_rq = io_err_map_rq, + .clone_and_map_rq = io_err_clone_and_map_rq, + .release_clone_rq = io_err_release_clone_rq, }; int __init dm_target_init(void) |