Re: [PATCH v5 01/11] block: improve handling of all zones reset operation

[Hannes Reinecke <hare@suse.de>]

On 5/25/21 11:24 PM, Damien Le Moal wrote:
> SCSI, ZNS and null_blk zoned devices support resetting all zones using
> a single command (REQ_OP_ZONE_RESET_ALL), as indicated using the device
> request queue flag QUEUE_FLAG_ZONE_RESETALL. This flag is not set for
> device mapper targets creating zoned devices. In this case, a user
> request for resetting all zones of a device is processed in
> blkdev_zone_mgmt() by issuing a REQ_OP_ZONE_RESET operation for each
> zone of the device. This leads to different behaviors of the
> BLKRESETZONE ioctl() depending on the target device support for the
> reset all operation. E.g.
> 
> blkzone reset /dev/sdX
> 
> will reset all zones of a SCSI device using a single command that will
> ignore conventional, read-only or offline zones.
> 
> But a dm-linear device including conventional, read-only or offline
> zones cannot be reset in the same manner as some of the single zone
> reset operations issued by blkdev_zone_mgmt() will fail. E.g.:
> 
> blkzone reset /dev/dm-Y
> blkzone: /dev/dm-0: BLKRESETZONE ioctl failed: Remote I/O error
> 
> To simplify applications and tools development, unify the behavior of
> the all-zone reset operation by modifying blkdev_zone_mgmt() to not
> issue a zone reset operation for conventional, read-only and offline
> zones, thus mimicking what an actual reset-all device command does on a
> device supporting REQ_OP_ZONE_RESET_ALL. This emulation is done using
> the new function blkdev_zone_reset_all_emulated(). The zones needing a
> reset are identified using a bitmap that is initialized using a zone
> report. Since empty zones do not need a reset, also ignore these zones.
> The function blkdev_zone_reset_all() is introduced for block devices
> natively supporting reset all operations. blkdev_zone_mgmt() is modified
> to call either function to execute an all zone reset request.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> [hch: split into multiple functions]
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> ---
>   block/blk-zoned.c | 119 +++++++++++++++++++++++++++++++++++-----------
>   1 file changed, 92 insertions(+), 27 deletions(-)
> 
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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