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b63534c41e
Mark the plug with nowait == true, which will cause requests to avoid blocking on request allocation. If they do, we catch them and reissue them from a task_work based handler. Normally we can catch -EAGAIN directly, but the hard case is for split requests. As an example, the application issues a 512KB request. The block core will split this into 128KB if that's the max size for the device. The first request issues just fine, but we run into -EAGAIN for some latter splits for the same request. As the bio is split, we don't get to see the -EAGAIN until one of the actual reads complete, and hence we cannot handle it inline as part of submission. This does potentially cause re-reads of parts of the range, as the whole request is reissued. There's currently no better way to handle this. 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 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.