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

[Hannes Reinecke <hare@suse.de>]

On 11/4/25 02:31, 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@kernel.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>   block/blk-zoned.c      | 141 +++++++++++++++++++++++++++++++++++++++++
>   include/linux/blkdev.h |   3 +
>   2 files changed, 144 insertions(+)
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
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