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.
Ming Lei
authored
In case of block device backend, if the backend supports write zeros, the loop device will set queue flag of QUEUE_FLAG_DISCARD. However, limits.discard_granularity isn't setup, and this way is wrong, see the following description in Documentation/ABI/testing/sysfs-block: A discard_granularity of 0 means that the device does not support discard functionality. Especially 9b15d109 ("block: improve discard bio alignment in __blkdev_issue_discard()") starts to take q->limits.discard_granularity for computing max discard sectors. And zero discard granularity may cause kernel oops, or fail discard request even though the loop queue claims discard support via QUEUE_FLAG_DISCARD. Fix the issue by setup discard granularity and alignment. Fixes: c52abf56 ("loop: Better discard support for block devices") Signed-off-by:Ming Lei <ming.lei@redhat.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Acked-by:
Coly Li <colyli@suse.de> Cc: Hannes Reinecke <hare@suse.com> Cc: Xiao Ni <xni@redhat.com> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Evan Green <evgreen@chromium.org> Cc: Gwendal Grignou <gwendal@chromium.org> Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Cc: Andrzej Pietrasiewicz <andrzej.p@collabora.com> Cc: Christoph Hellwig <hch@lst.de> Cc: <stable@vger.kernel.org> Signed-off-by:
Jens Axboe <axboe@kernel.dk>