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Qu Wenruo
8e7e9c672f
Currently btrfs_subpage utilizes its atomic member @reader to manage the reader counter. However it is only utilized to prevent the page to be released/unlocked when we still have reads underway. In that use case, we don't really allow multiple readers on the same subpage sector. So here we can introduce a new locked bitmap to represent exactly which subpage range is locked for read. In theory we can remove btrfs_subpage::reader as it's just the set bits of the new locked bitmap. But unfortunately bitmap doesn't provide such handy API yet, so we still keep the reader counter. 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 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.