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526d10061b
Commit bc58ba9468 ("block: add sysfs file for controlling io stats
accounting") allowed users to turn off disk stat accounting completely
by checking if queue flag QUEUE_FLAG_IO_STAT is set. In dm, this flag
is neither set nor checked: so block-core's io stats are continuously
counted and cannot be turned off.
Add support for turning off block-core's io stats accounting for dm.
Set QUEUE_FLAG_IO_STAT for dm's request_queue. If QUEUE_FLAG_IO_STAT
is set when an io starts, record the need for block core's io stats by
setting the DM_IO_BLK_STAT dm_io flag to avoid io stats being disabled
in the middle of the io.
DM statistics (dm-stats) is independent of block-core's io stats and
remains unchanged.
Signed-off-by: Li Nan <linan122@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@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
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In order to build the documentation, use ``make htmldocs`` or
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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.