[PATCH v3 09/15] block: introduce blkdev_get_zone_info()

[Chaitanya Kulkarni]

On 11/3/25 17:31, Damien Le Moal wrote:
> Introduce the function blkdev_get_zone_info() to obtain a single zone
> information from cached zone data, that is, either from the zone write
> plug for the target zone if it exists and from the disk zones_cond
> array otherwise.
>
> Since sequential zones that do not have a zone write plug are either
> full, empty or in a bad state (read-only or offline), the zone write
> pointer can be inferred from the zone condition cached in the disk
> zones_cond array. For sequential zones that have a zone write plug, the
> zone condition and zone write pointer are obtained from the condition
> and write pointer offset managed with the zone write plug. This allows
> obtaining the information for a zone much more quickly than having to
> execute a report zones command on the device.
>
> blkdev_get_zone_info() falls back to using a regular zone report if the
> target zone is flagged as needing an update with the
> BLK_ZONE_WPLUG_NEED_WP_UPDATE flag, or if the target device does not
> use zone write plugs (i.e. a device mapper device). In this case, the
> new function blkdev_report_zone_fallback() is used and the zone
> condition is reported consistantly with the cahced report, that is, the
> BLK_ZONE_COND_ACTIVE condition is used in place of the implicit open,
> explicit open and closed conditions. This is achieved by adding the
> .report_active field to struct blk_report_zones_args and by having
> disk_report_zone() sets the correct zone condition if .report_active is
> true.
>
> In preparation for using blkdev_get_zone_info() in upcoming file systems
> changes, also export this function as a GPL symbol.
>
> Signed-off-by: Damien Le Moal<dlemoal at kernel.org>
> Reviewed-by: Christoph Hellwig<hch at lst.de>
> Reviewed-by: Johannes Thumshirn<johannes.thumshirn at wdc.com>


Looks good.

Reviewed-by: Chaitanya Kulkarni <kch at nvidia.com>

-ck