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947a629988
[BACKGROUND] Although both btrfs metadata and data has their read time verification done at endio time (btrfs_validate_metadata_buffer() and btrfs_verify_data_csum()), metadata has extra verification, mostly parentness check including first key/transid/owner_root/level, done at read_tree_block() and btrfs_read_extent_buffer(). On the other hand, all the data verification is done at endio context. [ENHANCEMENT] This patch will make a new union in btrfs_bio, taking the space of the old data checksums, thus it will not increase the memory usage. With that extra btrfs_tree_parent_check inside btrfs_bio, we can just pass the check parameter into read_extent_buffer_pages(), and before submitting the bio, we can copy the check structure into btrfs_bio. And finally at endio time, we can grab btrfs_bio::parent_check and pass it to validate_extent_buffer(), to move the remaining checks into it. This brings the following benefits: - Much simpler btrfs_read_extent_buffer() Now it only needs to iterate through all mirrors. - Simpler read-time transid check Previously we go verify_parent_transid() after reading out the extent buffer. Now the transid check is done inside the endio function, no other code can modify the content. Thus no need to use the extent lock anymore. 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.