a01b8f2252
We dont need to allocate an ifs in ->write_begin() for writes where the position and length completely overlap with the given folio. Therefore, such cases are skipped. Currently when the folio is uptodate, we only allocate ifs at writeback time (in iomap_writepage_map()). This is ok until now, but when we are going to add support for per-block dirty state bitmap in ifs, this could cause some performance degradation. The reason is that if we don't allocate ifs during ->write_begin(), then we will never mark the necessary dirty bits in ->write_end() call. And we will have to mark all the bits as dirty at the writeback time, that could cause the same write amplification and performance problems as it is now. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-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.