scsi: split scsi_nonblockable_ioctl

The calling conventions for this function are bad as it could return
-ENODEV both for a device not currently online and a not recognized ioctl.

Add a new scsi_ioctl_block_when_processing_errors function that wraps
scsi_block_when_processing_errors with the a special case for the
SG_SCSI_RESET ioctl command, and handle the SG_SCSI_RESET case itself
in scsi_ioctl.  All callers of scsi_ioctl now must call the above helper
to check for the EH state, so that the ioctl handler itself doesn't
have to.

Reported-by: Robert Elliott <Elliott@hp.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 2de44cc..3d5399e 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -549,6 +549,11 @@
 
 	mutex_lock(&sr_mutex);
 
+	ret = scsi_ioctl_block_when_processing_errors(sdev, cmd,
+			(mode & FMODE_NDELAY) != 0);
+	if (ret)
+		goto out;
+
 	/*
 	 * Send SCSI addressing ioctls directly to mid level, send other
 	 * ioctls to cdrom/block level.
@@ -564,16 +569,6 @@
 	if (ret != -ENOSYS)
 		goto out;
 
-	/*
-	 * ENODEV means that we didn't recognise the ioctl, or that we
-	 * cannot execute it in the current device state.  In either
-	 * case fall through to scsi_ioctl, which will return ENDOEV again
-	 * if it doesn't recognise the ioctl
-	 */
-	ret = scsi_nonblockable_ioctl(sdev, cmd, argp,
-					(mode & FMODE_NDELAY) != 0);
-	if (ret != -ENODEV)
-		goto out;
 	ret = scsi_ioctl(sdev, cmd, argp);
 
 out: