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Journal bucket is a circular buffer, the bucket can be like YYYNNNYY, which means the first valid journal in the 7th bucket, and the latest valid journal in third bucket, in this case, if we do not try we the zero index first, We may get a valid journal in the 7th bucket, then we call find_next_bit(bitmap,ca->sb.njournal_buckets, l + 1) to get the first invalid bucket after the 7th bucket, because all these buckets is valid, so no bit 1 in bitmap, thus find_next_bit() function would return with ca->sb.njournal_buckets (8). So, after that, bcache only read journal in 7th and 8the bucket, the first to the third buckets are lost. So, it is important to let developer know that, we need to try the zero index at first in the hash-search, and avoid any breaks in future's code modification. [ML: Fixed whitespace & formatting & file permissions] Signed-off-by: Tang Junhui <tang.junhui@zte.com.cn> Signed-off-by: Michael Lyle <mlyle@lyle.org> Reviewed-by: Michael Lyle <mlyle@lyle.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.