tree 9ff33ff8845855161cf117e79dd6038211c7975a
parent 5651cd3c43368873d0787b52acb2e0e08f3c5da4
author Sagi Grimberg <sagi@grimberg.me> 1559108945 -0700
committer Sagi Grimberg <sagi@grimberg.me> 1559239657 -0700

nvme-tcp: fix queue mapping when queue count is limited

When the controller supports less queues than requested, we
should make sure that queue mapping does the right thing and
not assume that all queues are available. This fixes a crash
when the controller supports less queues than requested.

The rules are:
1. if no write queues are requested, we assign the available queues
   to the default queue map. The default and read queue maps share the
   existing queues.
2. if write queues are requested:
  - first make sure that read queue map gets the requested
    nr_io_queues count
  - then grant the default queue map the minimum between the requested
    nr_write_queues and the remaining queues. If there are no available
    queues to dedicate to the default queue map, fallback to (1) and
    share all the queues in the existing queue map.

Also, provide a log indication on how we constructed the different
queue maps.

Reported-by: Harris, James R <james.r.harris@intel.com>
Tested-by: Jim Harris <james.r.harris@intel.com>
Cc: <stable@vger.kernel.org> # v5.0+
Suggested-by: Roy Shterman <roys@lightbitslabs.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>