nvme-multipath: fix possible I/O hang when paths are updated
nvme_state_set_live() making a path available triggers requeue_work in order to resubmit requests that ended up on requeue_list when no paths were available. This requeue_work may race with concurrent nvme_ns_head_make_request() that do not observe the live path yet. Such concurrent requests may by made by either: - New IO submission. - Requeue_work triggered by nvme_failover_req() or another ana_work. A race may cause requeue_work capture the state of requeue_list before more requests get onto the list. These requests will stay on the list forever unless requeue_work is triggered again. In order to prevent such race, nvme_state_set_live() should synchronize_srcu(&head->srcu) before triggering the requeue_work and prevent nvme_ns_head_make_request referencing an old snapshot of the path list. Reviewed-by:Christoph Hellwig <hch@lst.de> Signed-off-by:
Anton Eidelman <anton@lightbitslabs.com> Signed-off-by:
Sagi Grimberg <sagi@grimberg.me> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
parent
500f9fba