Re: [PATCH 5.15.y] block: fix revalidate performance regression

[Greg KH <greg@kroah.com>]

On Tue, Jun 06, 2023 at 08:13:49AM +0900, Damien Le Moal wrote:
> commit 47fe1c3064c6bc1bfa3c032ff78e603e5dd6e5bc upstream.
> 
> The scsi driver function sd_read_block_characteristics() always calls
> blk_queue_set_zoned() to set a disk zoned model correctly, in case the
> device model changed. This is done even for regular disks to set the
> zoned model to BLK_ZONED_NONE and free any zone related resources if the
> drive previously was zoned.
> 
> This behavior significantly impact the time it takes to revalidate disks
> on a large system as the call to blk_queue_clear_zone_settings() done
> from blk_queue_set_zoned() for the BLK_ZONED_NONE case results in the
> device request queued to be frozen, even if there are no zone resources
> to free.
> 
> Avoid this overhead for non-zoned devices by not calling
> blk_queue_clear_zone_settings() in blk_queue_set_zoned() if the device
> model was already set to BLK_ZONED_NONE, which is always the case for
> regular devices.
> 
> Reported by: Brian Bunker <brian@purestorage.com>
> Fixes: 508aebb80527 ("block: introduce blk_queue_clear_zone_settings()")
> Cc: stable@vger.kernel.org
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> Reviewed-by: Ming Lei <ming.lei@redhat.com>
> Link: https://lore.kernel.org/r/20230529073237.1339862-1-dlemoal@kernel.org
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
>  block/blk-settings.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Thanks, now queued up.

greg k-h