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ublk_ch_release currently quiesces the device's request_queue while setting force_abort/fail_io. This avoids data races by preventing concurrent reads from the I/O path, but is not strictly needed - at this point, canceling is already set and guaranteed to be observed by any concurrently executing I/Os, so they will be handled properly even if the changes to force_abort/fail_io propagate to the I/O path later. Remove the quiesce/unquiesce calls from ublk_ch_release. This makes the writes to force_abort/fail_io concurrent with the reads in the I/O path, so make the accesses atomic. Before this change, the call to blk_mq_quiesce_queue was responsible for most (90%) of the runtime of ublk_ch_release. With that call eliminated, ublk_ch_release runs much faster. Here is a comparison of the total time spent in calls to ublk_ch_release when a server handling 128 devices exits, before and after this change: before: 1.11s after: 0.09s Signed-off-by: Uday Shankar <ushankar@purestorage.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20250808-ublk_quiesce2-v1-1-f87ade33fa3d@purestorage.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
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 reStructuredText 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.