Here is pretty straight forward attempt of handling REQ_NOWAIT for bio-based and stacked devices. They are marked with flag queue->limits.nowait_requests which tells that queue method make_request() handles REQ_NOWAIT or doesn't delay requests, and all backend devices do the same. As a example second/third patches add support into md-raid0 and dm-linear. --- Konstantin Khlebnikov (3): block: add flag 'nowait_requests' into queue limits md/raid0: enable REQ_NOWAIT dm: add support for REQ_NOWAIT and enable for target dm-linear drivers/md/dm-linear.c | 5 +++-- drivers/md/dm-table.c | 3 +++ drivers/md/dm.c | 4 +++- drivers/md/raid0.c | 3 +++ include/linux/device-mapper.h | 6 ++++++ 5 files changed, 18 insertions(+), 3 deletions(-) -- Signature -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel