c0e0954e90
Fifo structure journal.pin is implemented by a cycle buffer, if the back index reaches highest location of the cycle buffer, it will be swapped to 0. Once the swapping happens, it means a smaller fifo index might be associated to a newer journal entry. So the btree node with oldest journal entry won't be selected in bch_btree_leaf_dirty() to reference the dirty B+tree leaf node. This problem may cause bcache journal won't protect unflushed oldest B+tree dirty leaf node in power failure, and this B+tree leaf node is possible to beinconsistent after reboot from power failure. This patch fixes the fifo index comparing logic in journal_pin_cmp(), to avoid potential corrupted B+tree leaf node when the back index of journal pin is swapped. Signed-off-by: Coly Li <colyli@suse.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.