4.19-stable review patch. If anyone has any objections, please let me know.
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From: James Smart jsmart2021@gmail.com
[ Upstream commit 783f4a4408e1251d17f333ad56abac24dde988b9 ]
When an io is rejected by nvmf_check_ready() due to validation of the controller state, the nvmf_fail_nonready_command() will normally return BLK_STS_RESOURCE to requeue and retry. However, if the controller is dying or the I/O is marked for NVMe multipath, the I/O is failed so that the controller can terminate or so that the io can be issued on a different path. Unfortunately, as this reject point is before the transport has accepted the command, blk-mq ends up completing the I/O and never calls nvme_complete_rq(), which is where multipath may preserve or re-route the I/O. The end result is, the device user ends up seeing an EIO error.
Example: single path connectivity, controller is under load, and a reset is induced. An I/O is received:
a) while the reset state has been set but the queues have yet to be stopped; or b) after queues are started (at end of reset) but before the reconnect has completed.
The I/O finishes with an EIO status.
This patch makes the following changes:
- Adds the HOST_PATH_ERROR pathing status from TP4028 - Modifies the reject point such that it appears to queue successfully, but actually completes the io with the new pathing status and calls nvme_complete_rq(). - nvme_complete_rq() recognizes the new status, avoids resetting the controller (likely was already done in order to get this new status), and calls the multipather to clear the current path that errored. This allows the next command (retry or new command) to select a new path if there is one.
Signed-off-by: James Smart jsmart2021@gmail.com Reviewed-by: Sagi Grimberg sagi@grimberg.me Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/nvme/host/fabrics.c | 7 +++++-- drivers/nvme/host/multipath.c | 7 +++++++ include/linux/nvme.h | 1 + 3 files changed, 13 insertions(+), 2 deletions(-)
--- a/drivers/nvme/host/fabrics.c +++ b/drivers/nvme/host/fabrics.c @@ -552,8 +552,11 @@ blk_status_t nvmf_fail_nonready_command( ctrl->state != NVME_CTRL_DEAD && !blk_noretry_request(rq) && !(rq->cmd_flags & REQ_NVME_MPATH)) return BLK_STS_RESOURCE; - nvme_req(rq)->status = NVME_SC_ABORT_REQ; - return BLK_STS_IOERR; + + nvme_req(rq)->status = NVME_SC_HOST_PATH_ERROR; + blk_mq_start_request(rq); + nvme_complete_rq(rq); + return BLK_STS_OK; } EXPORT_SYMBOL_GPL(nvmf_fail_nonready_command);
--- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -77,6 +77,13 @@ void nvme_failover_req(struct request *r queue_work(nvme_wq, &ns->ctrl->ana_work); } break; + case NVME_SC_HOST_PATH_ERROR: + /* + * Temporary transport disruption in talking to the controller. + * Try to send on a new path. + */ + nvme_mpath_clear_current_path(ns); + break; default: /* * Reset the controller for any non-ANA error as we don't know --- a/include/linux/nvme.h +++ b/include/linux/nvme.h @@ -1241,6 +1241,7 @@ enum { NVME_SC_ANA_PERSISTENT_LOSS = 0x301, NVME_SC_ANA_INACCESSIBLE = 0x302, NVME_SC_ANA_TRANSITION = 0x303, + NVME_SC_HOST_PATH_ERROR = 0x370,
NVME_SC_DNR = 0x4000, };