From: Anton Eidelman anton@lightbitslabs.com
[ Upstream commit af8fd0424713a2adb812d10d55e86718152cf656 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvme/host/multipath.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index 30de7efef0035..d320684d25b20 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;