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With all the preparation patches already merged, it's pretty easy to enable large data folios: - Remove the ASSERT() on folio size in btrfs_end_repair_bio() - Add a helper to properly set the max folio order Currently due to several call sites that are fetching the bitmap content directly into an unsigned long, we can only support BITS_PER_LONG blocks for each bitmap. - Call the helper when reading/creating an inode The support has the following limitations: - No large folios for data reloc inode The relocation code still requires page sized folio. But it's not that hot nor common compared to regular buffered ios. Will be improved in the future. - Requires CONFIG_BTRFS_EXPERIMENTAL - Will require all folio related operations to check if it needs the extra btrfs_subpage structure Now any folio larger than block size will need btrfs_subpage structure handling. Unfortunately I do not have a physical machine for performance test, but if everything goes like XFS/EXT4, it should mostly bring single digits percentage performance improvement in the real world. Although I believe there are still quite some optimizations to be done, let's focus on testing the current large data folio support first. 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.