[PATCH V4 5/9] nvme: add sysfs attribute to change IO timeout per controller

[Maurizio Lombardi]

On Mon May 11, 2026 at 12:12 AM CEST, Sagi Grimberg wrote:
>
>
> On 08/05/2026 16:33, Maurizio Lombardi wrote:
>> Currently, there is no method to adjust the timeout values on a
>> per controller basis with nvme I/O queues.
>> Add an io_timeout attribute to nvme so that different nvme controllers
>> which may have different timeout requirements can have custom
>> I/O timeouts set.
>
> Why is this needed? Why not simply change the timeout on
> the namespaces themselves?

One reason is convenience, having an io_timeout default value at the
controller level means that a newly discovered or hot-plugged namespace
will automatically inherit the controller-specific timeout.

Additionally, for nvmeof, the controller allocates a dedicated I/O queue
(ctrl->connect_q) that doesn't have a block device representation.
The io_timeout attribute will allow userspace to change the timeout
for this internal queue.

Maurizio