03e51c4a74
blk_revalidate_disk_zones() implements checks of the zones of a zoned block device, verifying that the zone size is a power of 2 number of sectors, that all zones (except possibly the last one) have the same size and that zones cover the entire addressing space of the device. While these checks are appropriate to verify that well tested hardware devices have an adequate zone configurations, they lack in certain areas which may result in issues with emulated devices implemented with user drivers such as ublk or tcmu. Specifically, this function does not check if the device driver indicated support for the mandatory zone append writes, that is, if the device max_zone_append_sectors queue limit is set to a non-zero value. Additionally, invalid zones such as a zero length zone with a start sector equal to the device capacity will not be detected and result in out of bounds use of the zone bitmaps prepared with the callback function blk_revalidate_zone_cb(). Improve blk_revalidate_disk_zones() to address these inadequate checks, relying on the fact that all device drivers supporting zoned block devices must set the device zone size (chunk_sectors queue limit) and the max_zone_append_sectors queue limit before executing this function. The check for a non-zero max_zone_append_sectors value is done in blk_revalidate_disk_zones() before executing the zone report. The zone report callback function blk_revalidate_zone_cb() is also modified to add a check that a zone start is below the device capacity. The check that the zone size is a power of 2 number of sectors is moved to blk_revalidate_disk_zones() as the zone size is already known. Similarly, the number of zones of the device can be calculated in blk_revalidate_disk_zones() before executing the zone report. The kdoc comment for blk_revalidate_disk_zones() is also updated to mention that device drivers must set the device zone size and the max_zone_append_sectors queue limit before calling this function. Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230703024812.76778-6-dlemoal@kernel.org Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.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.