9e55a22fce
Currently, discad io is treated the same as normal write io, and for write behind case, io size is limited to: BIO_MAX_VECS * (PAGE_SIZE >> 9) For 0.5KB sector size and 4KB PAGE_SIZE, this is just 1MB. For consequence, if 'WriteMostly' is set to one of the underlying disks, then diskcard io will be splited into 1MB and it will take a long time for the diskcard to finish. Fix this problem by disable write behind for discard io. Reported-by: Roman Mamedov <rm@romanrm.net> Closes: https://lore.kernel.org/all/6a1165f7-c792-c054-b8f0-1ad4f7b8ae01@ultracoder.org/ Reported-and-tested-by: Kirill Kirilenko <kirill@ultracoder.org> Signed-off-by: Yu Kuai <yukuai3@huawei.com> Signed-off-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20231007112105.407449-1-yukuai1@huaweicloud.com
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.