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The 512B buffer sector_buf field of struct ata_port is used for scanning devices as well as during error recovery with ata EH. This buffer is thus useless if a port does not have a device connected to it. And also given that commands using this buffer are issued to devices, and not to ports, move this buffer definition from struct ata_port to struct ata_device. This change slightly increases system memory usage for systems using a port-multiplier as in that case we do not need a per-device buffer for scanning devices (PMP does not allow parallel scanning) nor for EH (as when entering EH we are guaranteed that all commands to all devices connected to the PMP have completed or have been aborted). However, this change reduces memory usage on systems that have many ports with only few devices rives connected, which is a much more common use case than the PMP use case. Suggested-by: Niklas Cassel <cassel@kernel.org> Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Niklas Cassel <cassel@kernel.org>
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.