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authorAnton Eidelman <anton@lightbitslabs.com>2019-08-12 23:00:36 +0300
committerJens Axboe <axboe@kernel.dk>2019-08-20 11:02:10 -0600
commit504db087aaccdb32af61539916409f7dca31ceb5 (patch)
treec33bb26ea03fc7350dd0fd6ac2b23bd93ab8ae99 /drivers
parent500f9fbadef86466a435726192f4ca4df7d94236 (diff)
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/nvme/host/multipath.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 888d4543894e..af831d3d15d0 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -428,6 +428,7 @@ static void nvme_mpath_set_live(struct nvme_ns *ns)
srcu_read_unlock(&head->srcu, srcu_idx);
}
+ synchronize_srcu(&ns->head->srcu);
kblockd_schedule_work(&ns->head->requeue_work);
}