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. 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 -- 2.17.2 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
