RE: [EXTERNAL] [PATCH] scsi: storvsc: Handle PERSISTENT_RESERVE_IN truncation for Hyper-V vFC

[Long Li]

> -----Original Message-----
> From: Li Tian <litian@xxxxxxxxxx>
> Sent: Sunday, April 5, 2026 6:54 PM
> To: linux-scsi@xxxxxxxxxxxxxxx
> Cc: Li Tian <litian@xxxxxxxxxx>; KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang
> Zhang <haiyangz@xxxxxxxxxxxxx>; Wei Liu <wei.liu@xxxxxxxxxx>; Dexuan Cui
> <DECUI@xxxxxxxxxxxxx>; Long Li <longli@xxxxxxxxxxxxx>; James E.J. Bottomley
> <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>; Martin K. Petersen
> <martin.petersen@xxxxxxxxxx>; linux-hyperv@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: [EXTERNAL] [PATCH] scsi: storvsc: Handle PERSISTENT_RESERVE_IN
> truncation for Hyper-V vFC
> 
> The storvsc driver has become stricter in handling SRB status codes returned by
> the Hyper-V host. When using Virtual Fibre Channel (vFC) passthrough, the host
> may return SRB_STATUS_DATA_OVERRUN for PERSISTENT_RESERVE_IN
> commands if the allocation length in the CDB does not match the host's expected
> response size.
> 
> Currently, this status is treated as a fatal error, propagating
> Host_status=0x07 [DID_ERROR] to the SCSI mid-layer. This causes userspace
> storage utilities (such as sg_persist) to fail with transport errors, even when the
> host has actually returned the requested reservation data in the buffer.
> 
> Refactor the existing command-specific workarounds into a new helper function,
> storvsc_host_mishandles_cmd(), and add PERSISTENT_RESERVE_IN to the list of
> commands where SRB status errors should be suppressed for vFC devices. This
> ensures that the SCSI mid-layer processes the returned data buffer instead of
> terminating the command.
> 
> Signed-off-by: Li Tian <litian@xxxxxxxxxx>

Reviewed-by: Long Li <longli@xxxxxxxxxxxxx>


> ---
>  drivers/scsi/storvsc_drv.c | 32 +++++++++++++++++++++-----------
>  1 file changed, 21 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index
> ae1abab97835..6977ca8a0658 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -1131,6 +1131,26 @@ static void storvsc_command_completion(struct
> storvsc_cmd_request *cmd_request,
>  		kfree(payload);
>  }
> 
> +/*
> + * The current SCSI handling on the host side does not correctly handle:
> + * INQUIRY with page code 0x80, MODE_SENSE / MODE_SENSE_10 with
> cmd[2]
> +== 0x1c,
> + * and (for FC) MAINTENANCE_IN / PERSISTENT_RESERVE_IN passthrough.
> + */
> +static bool storvsc_host_mishandles_cmd(u8 opcode, struct hv_device
> +*device) {
> +	switch (opcode) {
> +	case INQUIRY:
> +	case MODE_SENSE:
> +	case MODE_SENSE_10:
> +		return true;
> +	case MAINTENANCE_IN:
> +	case PERSISTENT_RESERVE_IN:
> +		return hv_dev_is_fc(device);
> +	default:
> +		return false;
> +	}
> +}
> +
>  static void storvsc_on_io_completion(struct storvsc_device *stor_device,
>  				  struct vstor_packet *vstor_packet,
>  				  struct storvsc_cmd_request *request) @@ -
> 1141,22 +1161,12 @@ static void storvsc_on_io_completion(struct
> storvsc_device *stor_device,
>  	stor_pkt = &request->vstor_packet;
> 
>  	/*
> -	 * The current SCSI handling on the host side does
> -	 * not correctly handle:
> -	 * INQUIRY command with page code parameter set to 0x80
> -	 * MODE_SENSE and MODE_SENSE_10 command with cmd[2] == 0x1c
> -	 * MAINTENANCE_IN is not supported by HyperV FC passthrough
> -	 *
>  	 * Setup srb and scsi status so this won't be fatal.
>  	 * We do this so we can distinguish truly fatal failues
>  	 * (srb status == 0x4) and off-line the device in that case.
>  	 */
> 
> -	if ((stor_pkt->vm_srb.cdb[0] == INQUIRY) ||
> -	   (stor_pkt->vm_srb.cdb[0] == MODE_SENSE) ||
> -	   (stor_pkt->vm_srb.cdb[0] == MODE_SENSE_10) ||
> -	   (stor_pkt->vm_srb.cdb[0] == MAINTENANCE_IN &&
> -	   hv_dev_is_fc(device))) {
> +	if (storvsc_host_mishandles_cmd(stor_pkt->vm_srb.cdb[0], device)) {
>  		vstor_packet->vm_srb.scsi_status = 0;
>  		vstor_packet->vm_srb.srb_status = SRB_STATUS_SUCCESS;
>  	}
> --
> 2.53.0