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0124855ff1
Currently the last_trans_committed field of struct btrfs_fs_info is modified and read without any locking or other protection. For example early in the fsync path, skip_inode_logging() is called which reads fs_info->last_trans_committed, but at the same time we can have a transaction commit completing and updating that field. In the case of an fsync this is harmless and any data race should be rare and at most cause an unnecessary logging of an inode. To avoid data race warnings from tools like KCSAN and other issues such as load and store tearing (amongst others, see [1]), create helpers to access the last_trans_committed field of struct btrfs_fs_info using READ_ONCE() and WRITE_ONCE(), and use these helpers everywhere. [1] https://lwn.net/Articles/793253/ Signed-off-by: Filipe Manana <fdmanana@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.