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18d758a2d8
In btrfs_io_context structure, we have a pointer raid_map, which indicates the logical bytenr for each stripe. But considering we always call sort_parity_stripes(), the result raid_map[] is always sorted, thus raid_map[0] is always the logical bytenr of the full stripe. So why we waste the space and time (for sorting) for raid_map? This patch will replace btrfs_io_context::raid_map with a single u64 number, full_stripe_start, by: - Replace btrfs_io_context::raid_map with full_stripe_start - Replace call sites using raid_map[0] to use full_stripe_start - Replace call sites using raid_map[i] to compare with nr_data_stripes. The benefits are: - Less memory wasted on raid_map It's sizeof(u64) * num_stripes vs sizeof(u64). It'll always save at least one u64, and the benefit grows larger with num_stripes. - No more weird alloc_btrfs_io_context() behavior As there is only one fixed size + one variable length array. Signed-off-by: Qu Wenruo <wqu@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.