On Fri, 2022-10-07 at 12:35 -0500, Benjamin Marzinski wrote: > nvme:tcp devices set BLK_MQ_F_BLOCKING (they are the only block > devices > which multipath supports that do so), meaning that block_mq expects > that > they can block at certain points while servicing a request. However, > due to the way device-mapper sets up its queue, it is not able to set > BLK_MQ_F_BLOCKING when it includes paths that set this flag. Patches > were written to address this issue but they were rejected upstream > > https://lore.kernel.org/linux-block/YcH%2FE4JNag0QYYAa@xxxxxxxxxxxxx/T/#t > > The proposed solution was to have multipath use the bio queue_mode > for > multipath devices that include nvme:tcp paths. Request-based dm-multipath is superior to bio-based in multiple ways. I thought that was consensus. It's sad that we need to make this clumsy workaround in user space while a much neater kernel-side approach would be available. > Multipathd currently doesn't handle queue_mode as well as it could. > Once > a multipath device is created, queue_mode cannot be changed, but > multipath doesn't enforce this. This patchset improves multipath's > handling of the queue_mode feature, and then makes sure that if a > multipath device includes a nvme:tcp path, it will have queue_mode > set to bio. > > Benjamin Marzinski (8): > libmultipath: cleanup remove_feature > libmultipath: cleanup add_feature > multipath tests: tests for adding and removing features > libmultipath: fix queue_mode feature handling > multipath tests: tests for reconcile_features_with_queue_mode > libmultipath: prepare proto_id for use by non-scsi devivces > libmultipath: get nvme path transport protocol > libmultipath: enforce queue_mode bio for nmve:tcp paths > > libmultipath/configure.c | 28 +- > libmultipath/discovery.c | 31 ++- > libmultipath/dmparser.c | 2 + > libmultipath/print.c | 6 +- > libmultipath/propsel.c | 55 ++++ > libmultipath/structs.c | 155 +++++------ > libmultipath/structs.h | 44 ++- > libmultipath/structs_vec.c | 7 + > multipath/multipath.conf.5 | 17 +- > multipathd/fpin_handlers.c | 2 +- > tests/Makefile | 4 +- > tests/features.c | 549 > +++++++++++++++++++++++++++++++++++++ > 12 files changed, 784 insertions(+), 116 deletions(-) > create mode 100644 tests/features.c > For the series: Reviewed-by: Martin Wilck <mwilck@xxxxxxxx> I have a few remarks and suggestions for additional improvement which I'll send as replies to the individual patches. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
