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Qu Wenruo
8189197425
Unlike the bitmap usage inside raid56, for __extent_writepage_io() we handle the subpage submission not sector-by-sector, but for each dirty range we found. This is not a big deal normally, as the subpage complex code is already mostly optimized out by the compiler for x86_64. However for the sake of consistency and for the future of subpage sector-perfect compression support, this patch does: - Extract the sector submission code into submit_one_sector() - Add the needed code to extract the dirty bitmap for subpage case There is a small pitfall for non-subpage case, as we cleared page dirty before starting writeback, so we have to manually set the default dirty_bitmap to 1 for such case. - Use bitmap_and() to calculate the target sectors we need to submit This is done for both subpage and non-subpage cases, and will later be expanded to skip inline/compression ranges. For x86_64, the dirty bitmap will be fixed to 1, with the length of 1, so we're still doing the same workload per sector. For larger page sizes, the overhead will be a little larger, as previous we only need to do one extent_map lookup per-dirty-range, but now it will be one extent_map lookup per-sector. But that is the same frequency as x86_64, so we're just aligning the behavior to x86_64. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.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 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.