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authorMike Snitzer <snitzer@redhat.com>2014-12-17 21:08:12 -0500
committerMike Snitzer <snitzer@redhat.com>2015-02-09 13:06:47 -0500
commite5863d9ad754926e7d3f38b43ac8bd48ef73b097 (patch)
tree0e4d75672884b7dc93296beea8ddf3833b4d7f38 /drivers/md/dm-target.c
parent466d89a6bcd500f64896b514f78b32e8d0b0303a (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-target.c')
-rw-r--r--drivers/md/dm-target.c15
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)