On 11/15/2016 04:37 PM, Mike Snitzer wrote:
On Tue, Nov 15 2016 at 6:35pm -0500,
Bart Van Assche <bart.vanassche@xxxxxxxxxxx> wrote:
If a single-queue dm device is stacked on top of multi-queue block
devices and map_tio_request() is called while there are no paths then
the request will be prepared for a single-queue path. If a path is
added after a request was prepared and before __multipath_map() is
called return DM_MAPIO_REQUEUE such that it gets unprepared and
reprepared as a blk-mq request.
This patch makes little sense to me. There isn't a scenario that I'm
aware of that would allow the request_queue to transition between old
.request_fn and new blk-mq.
The dm-table code should prevent this.
Hello Mike,
Are you aware that dm_table_determine_type() sets "all_blk_mq" to false
if there are no paths, even if the dm device is in blk-mq mode?
Bart.
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