85fa2c7743
xfs_rtallocate_extent_near() tries to find a free extent as close to a target bitmap block given by bbno as possible, which may be before or after bbno. Searching backwards has a complication: the realtime summary accounts for free space _starting_ in a bitmap block, but not straddling or ending in a bitmap block. So, when the negative search finds a free extent in the realtime summary, in order to end up closer to the target, it looks for the end of the free extent. For example, if bbno - 2 has a free extent, then it will check bbno - 1, then bbno - 2. But then if bbno - 3 has a free extent, it will check bbno - 1 again, then bbno - 2 again, and then bbno - 3. This results in a quadratic loop, which is completely pointless since the repeated checks won't find anything new. Fix it by remembering where we last checked up to and continue from there. This also obviates the need for a check of the realtime summary. Signed-off-by: Omar Sandoval <osandov@fb.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
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.