Re: [Drbd-dev] [PATCH 12/23] sd: handle REQ_UNMAP

[Bart Van Assche <Bart.VanAssche@sandisk.com>]

On Thu, 2017-03-23 at 10:33 -0400, Christoph Hellwig wrote:
> Try to use a write same with unmap bit variant if the device supports it
> and the caller asks for it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/scsi/sd.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index b6f70a09a301..ca96bb33471b 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -871,6 +871,16 @@ static int sd_setup_write_zeroes_cmnd(struct scsi_cmnd *cmd)
>  			return BLKPREP_INVALID;
>  		return sd_setup_ata_trim_cmnd(cmd);
>  	}
> +
> +	if (rq->cmd_flags & REQ_UNMAP) {
> +		switch (sdkp->provisioning_mode) {
> +		case SD_LBP_WS16:
> +			return sd_setup_write_same16_cmnd(cmd, true);
> +		case SD_LBP_WS10:
> +			return sd_setup_write_same10_cmnd(cmd, true);
> +		}
> +	}
> +
>  	if (sdp->no_write_same)
>  		return BLKPREP_INVALID;
>  	if (sdkp->ws16 || sector > 0xffffffff || nr_sectors > 0xffff)

Users can change the provisioning mode from user space from SD_LBP_WS16 into
SD_LBP_WS10 so I'm not sure it's safe to skip the (sdkp->ws16 || sector >
0xffffffff || nr_sectors > 0xffff) check if REQ_UNMAP is set.

Bart.