James Smart 834d3710a0 nvme-fc: reject reconnect if io queue count is reduced to zero
If:

 - A successful connect has occurred with an io queue count greater than
   zero and namespaces detected and running.
 - An error or something occurs which causes a termination of the prior
   association and then starts a reconnect,
 - The reconnect then creates a new controller, but for whatever reason,
   nvme_set_queue_count() results in io queue count set to zero.  This
   will skip io queue and tag set changes.
 - But... the controller will transition to live, calling
   nvme_start_ctrl, which calls nvme_start_queues(), which then releases
   I/Os into the transport which then sends them to the driver.

As there are no queues, things eventually hit the driver looking for a
handle, which was cleared when the original controller was reset, and it
can't proceed. Worst case, things progress, but everything fails.

In the failing scenario, the nvme_set_features(NVME_FEAT_NUM_QUEUES)
command actually failed with a NVME_SC_INTERNAL error.  For some reason,
although nvme_set_queue_count() saw the error and set io queue count to
zero, it doesn't return a failure status to the transport, which allows
the transport to continue using the controller.

Fix the problem by simply rejecting the new association if at least 1
I/O queue can't be created. The association reject will fail the
reconnect attempt and fall into the reconnect retry policy.

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: Jens Axboe <axboe@kernel.dk>
2019-03-13 12:05:40 -06:00
2018-10-31 08:54:14 -07:00
2019-01-04 14:27:09 -07:00
2019-02-10 14:42:20 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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