btrfs compressed reads try to always read the entire compressed chunk, even if only a subset is requested. Currently this is covered by the magic PSI accounting underneath submit_bio, but that is about to go away. Instead add manual psi_memstall_{enter,leave} annotations. Note that for readahead this really should be using readahead_expand, but the additionals reads are also done for plain ->read_folio where readahead_expand can't work, so this overall logic is left as-is for now. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: David Sterba <dsterba@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Link: https://lore.kernel.org/r/20220915094200.139713-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.
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