[PATCH v2 1/8] nvme-fabrics: allow to queue requests for live queues

[Sagi Grimberg]

Right now we are failing requests based on the controller
state (which is checked inline in nvmf_check_ready) however
we should definitely accept requests if the queue is live.

When entering controller reset, we transition the controller
into NVME_CTRL_RESETTING, and then return BLK_STS_RESOURCE for
non-mpath requests (have blk_noretry_request set).

This is also the case for NVME_REQ_USER for the wrong reason.
There shouldn't be any reason for us to reject this I/O in a
controller reset. We do want to prevent passthru commands on
the admin queue because we need the controller to fully initialize
first before we let user passthru admin commands to be issued.

In a non-mpath setup, this means that the requests will simply
be requeued over and over forever not allowing the q_usage_counter
to drop its final reference, causing controller reset to hang
if running concurrently with heavy I/O.

While we are at it, remove the redundant NVME_CTRL_NEW case, which
should never see any I/O as it must first transition to
NVME_CTRL_CONNECTING.

Fixes: 35897b920c8a ("nvme-fabrics: fix and refine state checks in __nvmf_check_ready")
Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
---
 drivers/nvme/host/fabrics.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
index 4ec4829d6233..8575724734e0 100644
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -565,10 +565,14 @@ bool __nvmf_check_ready(struct nvme_ctrl *ctrl, struct request *rq,
 	struct nvme_request *req = nvme_req(rq);
 
 	/*
-	 * If we are in some state of setup or teardown only allow
-	 * internally generated commands.
+	 * currently we have a problem sending passthru commands
+	 * on the admin_q if the controller is not LIVE because we can't
+	 * make sure that they are going out after the admin connect,
+	 * controller enable and/or other commands in the initialization
+	 * sequence. until the controller will be LIVE, fail with
+	 * BLK_STS_RESOURCE so that they will be rescheduled.
 	 */
-	if (!blk_rq_is_passthrough(rq) || (req->flags & NVME_REQ_USERCMD))
+	if (rq->q == ctrl->admin_q && (req->flags & NVME_REQ_USERCMD))
 		return false;
 
 	/*
@@ -576,9 +580,8 @@ bool __nvmf_check_ready(struct nvme_ctrl *ctrl, struct request *rq,
 	 * which is require to set the queue live in the appropinquate states.
 	 */
 	switch (ctrl->state) {
-	case NVME_CTRL_NEW:
 	case NVME_CTRL_CONNECTING:
-		if (nvme_is_fabrics(req->cmd) &&
+		if (blk_rq_is_passthrough(rq) && nvme_is_fabrics(req->cmd) &&
 		    req->cmd->fabrics.fctype == nvme_fabrics_type_connect)
 			return true;
 		break;
-- 
2.25.1