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>

include/scsi/scsi_ioctl.h

@@ -40,9 +40,9 @@ typedef struct scsi_fctargaddress {
 	unsigned char host_wwn[8]; // include NULL term.
 } Scsi_FCTargAddress;
 
+int scsi_ioctl_block_when_processing_errors(struct scsi_device *sdev,
+		int cmd, bool ndelay);
 extern int scsi_ioctl(struct scsi_device *, int, void __user *);
-extern int scsi_nonblockable_ioctl(struct scsi_device *sdev, int cmd,
-				   void __user *arg, int ndelay);
 
 #endif /* __KERNEL__ */
 #endif /* _SCSI_IOCTL_H */