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authorAnton Eidelman <anton@lightbitslabs.com>2019-10-18 11:32:50 -0700
committerJens Axboe <axboe@kernel.dk>2019-10-29 08:55:00 -0600
commitaf8fd0424713a2adb812d10d55e86718152cf656 (patch)
treed380bf2dfa237529aa7bbfafe8f650abe4e5cfa3 /drivers/nvme/host
parent044c1ab399afbe9f2ebef49a3204ef1509826dc7 (diff)
nvme-multipath: fix possible io hang after ctrl reconnect
The following scenario results in an IO hang: 1) ctrl completes a request with NVME_SC_ANA_TRANSITION. NVME_NS_ANA_PENDING bit in ns->flags is set and ana_work is triggered. 2) ana_work: nvme_read_ana_log() tries to get the ANA log page from the ctrl. This fails because ctrl disconnects. Therefore nvme_update_ns_ana_state() is not called and NVME_NS_ANA_PENDING bit in ns->flags is not cleared. 3) ctrl reconnects: nvme_mpath_init(ctrl,...) calls nvme_read_ana_log(ctrl, groups_only=true). However, nvme_update_ana_state() does not update namespaces because nr_nsids = 0 (due to groups_only mode). 4) scan_work calls nvme_validate_ns() finds the ns and re-validates OK. Result: The ctrl is now live but NVME_NS_ANA_PENDING bit in ns->flags is still set. Consequently ctrl will never be considered a viable path by __nvme_find_path(). IO will hang if ctrl is the only or the last path to the namespace. More generally, while ctrl is reconnecting, its ANA state may change. And because nvme_mpath_init() requests ANA log in groups_only mode, these changes are not propagated to the existing ctrl namespaces. This may result in a mal-function or an IO hang. Solution: nvme_mpath_init() will nvme_read_ana_log() with groups_only set to false. This will not harm the new ctrl case (no namespaces present), and will make sure the ANA state of namespaces gets updated after reconnect. Note: Another option would be for nvme_mpath_init() to invoke nvme_parse_ana_log(..., nvme_set_ns_ana_state) for each existing namespace. Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Anton Eidelman <anton@lightbitslabs.com> Signed-off-by: Keith Busch <kbusch@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/nvme/host')
-rw-r--r--drivers/nvme/host/multipath.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 30de7efef003..d320684d25b2 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -715,7 +715,7 @@ int nvme_mpath_init(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
goto out;
}
- error = nvme_read_ana_log(ctrl, true);
+ error = nvme_read_ana_log(ctrl, false);
if (error)
goto out_free_ana_log_buf;
return 0;