From: Anton Eidelman anton.eidelman@gmail.com
[ Upstream commit a4a6f3c8f61c3cfbda4998ad94596059ad7e4332 ]
nvme_mpath_init_identify() invoked from nvme_init_identify() fetches a fresh ANA log from the ctrl. This is essential to have an up to date path states for both existing namespaces and for those scan_work may discover once the ctrl is up.
This happens in the following cases: 1) A new ctrl is being connected. 2) An existing ctrl is successfully reconnected. 3) An existing ctrl is being reset.
While in (1) ctrl->namespaces is empty, (2 & 3) may have namespaces, and nvme_read_ana_log() may call nvme_update_ns_ana_state().
This result in a hang when the ANA state of an existing namespace changes and makes the disk live: nvme_mpath_set_live() issues IO to the namespace through the ctrl, which does NOT have IO queues yet.
See sample hang below.
Solution: - nvme_update_ns_ana_state() to call set_live only if ctrl is live - nvme_read_ana_log() call from nvme_mpath_init_identify() therefore only fetches and parses the ANA log; any erros in this process will fail the ctrl setup as appropriate; - a separate function nvme_mpath_update() is called in nvme_start_ctrl(); this parses the ANA log without fetching it. At this point the ctrl is live, therefore, disks can be set live normally.
Sample failure: nvme nvme0: starting error recovery nvme nvme0: Reconnecting in 10 seconds... block nvme0n6: no usable path - requeuing I/O INFO: task kworker/u8:3:312 blocked for more than 122 seconds. Tainted: G E 5.14.5-1.el7.elrepo.x86_64 #1 Workqueue: nvme-wq nvme_tcp_reconnect_ctrl_work [nvme_tcp] Call Trace: __schedule+0x2a2/0x7e0 schedule+0x4e/0xb0 io_schedule+0x16/0x40 wait_on_page_bit_common+0x15c/0x3e0 do_read_cache_page+0x1e0/0x410 read_cache_page+0x12/0x20 read_part_sector+0x46/0x100 read_lba+0x121/0x240 efi_partition+0x1d2/0x6a0 bdev_disk_changed.part.0+0x1df/0x430 bdev_disk_changed+0x18/0x20 blkdev_get_whole+0x77/0xe0 blkdev_get_by_dev+0xd2/0x3a0 __device_add_disk+0x1ed/0x310 device_add_disk+0x13/0x20 nvme_mpath_set_live+0x138/0x1b0 [nvme_core] nvme_update_ns_ana_state+0x2b/0x30 [nvme_core] nvme_update_ana_state+0xca/0xe0 [nvme_core] nvme_parse_ana_log+0xac/0x170 [nvme_core] nvme_read_ana_log+0x7d/0xe0 [nvme_core] nvme_mpath_init_identify+0x105/0x150 [nvme_core] nvme_init_identify+0x2df/0x4d0 [nvme_core] nvme_init_ctrl_finish+0x8d/0x3b0 [nvme_core] nvme_tcp_setup_ctrl+0x337/0x390 [nvme_tcp] nvme_tcp_reconnect_ctrl_work+0x24/0x40 [nvme_tcp] process_one_work+0x1bd/0x360 worker_thread+0x50/0x3d0
Signed-off-by: Anton Eidelman anton@lightbitslabs.com Reviewed-by: Sagi Grimberg sagi@grimberg.me Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/nvme/host/core.c | 1 + drivers/nvme/host/multipath.c | 25 +++++++++++++++++++++++-- drivers/nvme/host/nvme.h | 4 ++++ 3 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 5785f6abf194..0390897828d9 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -4409,6 +4409,7 @@ void nvme_start_ctrl(struct nvme_ctrl *ctrl) if (ctrl->queue_count > 1) { nvme_queue_scan(ctrl); nvme_start_queues(ctrl); + nvme_mpath_update(ctrl); } } EXPORT_SYMBOL_GPL(nvme_start_ctrl); diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index 99c2307b04e2..e3e419b2e223 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -598,8 +598,17 @@ static void nvme_update_ns_ana_state(struct nvme_ana_group_desc *desc, ns->ana_grpid = le32_to_cpu(desc->grpid); ns->ana_state = desc->state; clear_bit(NVME_NS_ANA_PENDING, &ns->flags); - - if (nvme_state_is_live(ns->ana_state)) + /* + * nvme_mpath_set_live() will trigger I/O to the multipath path device + * and in turn to this path device. However we cannot accept this I/O + * if the controller is not live. This may deadlock if called from + * nvme_mpath_init_identify() and the ctrl will never complete + * initialization, preventing I/O from completing. For this case we + * will reprocess the ANA log page in nvme_mpath_update() once the + * controller is ready. + */ + if (nvme_state_is_live(ns->ana_state) && + ns->ctrl->state == NVME_CTRL_LIVE) nvme_mpath_set_live(ns); }
@@ -686,6 +695,18 @@ static void nvme_ana_work(struct work_struct *work) nvme_read_ana_log(ctrl); }
+void nvme_mpath_update(struct nvme_ctrl *ctrl) +{ + u32 nr_change_groups = 0; + + if (!ctrl->ana_log_buf) + return; + + mutex_lock(&ctrl->ana_lock); + nvme_parse_ana_log(ctrl, &nr_change_groups, nvme_update_ana_state); + mutex_unlock(&ctrl->ana_lock); +} + static void nvme_anatt_timeout(struct timer_list *t) { struct nvme_ctrl *ctrl = from_timer(ctrl, t, anatt_timer); diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 9b095ee01364..a629b18ee79a 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -771,6 +771,7 @@ void nvme_mpath_add_disk(struct nvme_ns *ns, struct nvme_id_ns *id); void nvme_mpath_remove_disk(struct nvme_ns_head *head); int nvme_mpath_init_identify(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id); void nvme_mpath_init_ctrl(struct nvme_ctrl *ctrl); +void nvme_mpath_update(struct nvme_ctrl *ctrl); void nvme_mpath_uninit(struct nvme_ctrl *ctrl); void nvme_mpath_stop(struct nvme_ctrl *ctrl); bool nvme_mpath_clear_current_path(struct nvme_ns *ns); @@ -845,6 +846,9 @@ static inline int nvme_mpath_init_identify(struct nvme_ctrl *ctrl, "Please enable CONFIG_NVME_MULTIPATH for full support of multi-port devices.\n"); return 0; } +static inline void nvme_mpath_update(struct nvme_ctrl *ctrl) +{ +} static inline void nvme_mpath_uninit(struct nvme_ctrl *ctrl) { }