nvme: return queue busy for ENOMEM, not queue error

Signed-off-by: Jens Axboe <axboe@fb.com>
nvme: fix setting of admin command timeouts

We can pass it in through rq->timeout now.

Signed-off-by: Jens Axboe <axboe@fb.com>
nvme: reserve 1 tag on the admin queue for abort purposes

If we have this spare one, we can always rely on being able to
allocate one.

Signed-off-by: Jens Axboe <axboe@fb.com>
nvme: correct comment on call context of nvme_submit_req_queue()

Signed-off-by: Jens Axboe <axboe@fb.com>
NVMe: readd error message
NVMe: remove blk device 4k limitation

Left over from first patchset.
NVMe: move blk_queue_flush initialization

No need to move this around, as the queue flush doesn't require the
capacity to be known.
NVMe: remove double release of nvmeq->q_lock
NVMe: fix style
NVMe: fix style

Missed two newlines
NVMe: fix illegal RCU accesses
NVMe: readd cmd.timeout

Lost the cmd.timeout update when merging.