nvme reservation commands during controller reset

[Engel, Amit]

Hello, 
We test nvme reservation commands while controller reset and encounter a problem
The reservation cmd during controller reset fails on the host side with error code 0x370 (NVME_SC_HOST_PATH_ERROR)

based on the host code, nvme cli/ioctl commands are marked for failfast (no retry)
This is also the case for block layer user space API for persistent reservations (for example: IOC_PR_RESERVE)
host/core.c 'nvme_alloc_request' set the flag
req->cmd_flags |= REQ_FAILFAST_DRIVER

In case of path failover, the host will fail the cmd with status NVME_SC_HOST_PATH_ERROR
host/fabrics.c:

 blk_status_t nvmf_fail_nonready_command(struct nvme_ctrl *ctrl,
 >------->-------struct request *rq)
 {
 >-------if (ctrl->state != NVME_CTRL_DELETING &&
 >-------    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_HOST_PATH_ERROR;
 >-------blk_mq_start_request(rq);
 >-------nvme_complete_rq(rq);
 >-------return BLK_STS_OK;
 }

What is the reason for setting REQ_FAILFAST_DRIVER flag in nvme_alloc_request ?
The original intention was to mark only sync cmds as failfast ?

Thanks
Amit Engel