Hello Christoph,
Thank you for the patch.
As you mentioned this patch allows scsi generic access to the
physical disks. I see this as potential data integrity issue if someone
does a write operation on a disk that belongs to a Logical RAID volume.
I would rather prevent all access to the disks using slave_alloc(). I
will be sending a patch shortly for review that implements
megasas_slave_alloc to block all direct access to the physical disks.
Regards,
Sumant
On Mon, 2006-02-06 at 15:05 +0100, Christoph Hellwig wrote:
> Chandra_Nelogal noticed that megaraid_sas currently exports all physical
> disks normally to the disk layer, which is obviously quite bad.
>
> The problems is that megaraid_sas is doing inquiry sniffing, and since
> 2.6.15 inquiry commands are sent down as one-element scatterlists on
> which the code in the driver doesn't work anymore. The right place to
> keep the scsi midlayer from attaching to a device is the slave_alloc
> method in the host template. To completely prevent attaching the method
> needs to return -ENXIO, but the patch below sets the no_uld_attach flag
> instead which prevents upper level drivers from attaching while still
> allowing scsi generic access to it, as in other raid HBA drivers.
>
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>
> Index: linux-2.6/drivers/scsi/megaraid/megaraid_sas.c
> ===================================================================
> --- linux-2.6.orig/drivers/scsi/megaraid/megaraid_sas.c 2006-02-04 13:35:00.000000000 +0100
> +++ linux-2.6/drivers/scsi/megaraid/megaraid_sas.c 2006-02-06 14:59:13.000000000 +0100
> @@ -707,6 +707,16 @@
> return 0;
> }
>
> +static int megasas_slave_configure(struct scsi_device *sdev)
> +{
> + /*
> + * Don't export physical disk devices to the disk driver.
> + */
> + if (sdev->channel < MEGASAS_MAX_PD_CHANNELS && sdev->type == TYPE_DISK)
> + sdev->no_uld_attach = 1;
> + return 0;
> +}
> +
> /**
> * megasas_wait_for_outstanding - Wait for all outstanding cmds
> * @instance: Adapter soft state
> @@ -857,6 +867,7 @@
> .module = THIS_MODULE,
> .name = "LSI Logic SAS based MegaRAID driver",
> .proc_name = "megaraid_sas",
> + .slave_configure = megasas_slave_configure,
> .queuecommand = megasas_queue_command,
> .eh_device_reset_handler = megasas_reset_device,
> .eh_bus_reset_handler = megasas_reset_bus_host,
> @@ -985,20 +996,6 @@
> break;
> }
>
> - /*
> - * Don't export physical disk devices to mid-layer.
> - */
> - if (!MEGASAS_IS_LOGICAL(cmd->scmd) &&
> - (hdr->cmd_status == MFI_STAT_OK) &&
> - (cmd->scmd->cmnd[0] == INQUIRY)) {
> -
> - if (((*(u8 *) cmd->scmd->request_buffer) & 0x1F) ==
> - TYPE_DISK) {
> - cmd->scmd->result = DID_BAD_TARGET << 16;
> - exception = 1;
> - }
> - }
> -
> case MFI_CMD_LD_READ:
> case MFI_CMD_LD_WRITE:
>
-
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