scsi: Add reset ioctl capability to ULDs

Currently, the only way to issue a SCSI reset of any
type is to use the sg device.  By adding extra ioctls
to scsi_ioctl.c we enable this for all ULDs.

The slight complication is that scsi_ioctl() is usually
only called when the device has been checked not to be
undergoing eh recovery.  Resets may be issued in
this scenario if the user opens the device O_NONBLOCK.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/scsi_ioctl.c

@@ -20,6 +20,7 @@
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_ioctl.h>
 #include <scsi/scsi_request.h>
+#include <scsi/sg.h>
 
 #include "scsi_logging.h"
 
@@ -456,3 +457,51 @@ int scsi_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
 	}
 	return -EINVAL;
 }
+
+/*
+ * the scsi_nonblock_ioctl() function is designed for ioctls which may
+ * be executed even if the device is in recovery.
+ */
+int scsi_nonblockable_ioctl(struct scsi_device *sdev, int cmd,
+			    void __user *arg, struct file *filp)
+{
+	int val, result;
+
+	/* The first set of iocts may be executed even if we're doing
+	 * error processing, as long as the device was opened
+	 * non-blocking */
+	if (filp && filp->f_flags & O_NONBLOCK) {
+		if (test_bit(SHOST_RECOVERY,
+			     &sdev->host->shost_state))
+			return -ENODEV;
+	} else if (!scsi_block_when_processing_errors(sdev))
+		return -ENODEV;
+
+	switch (cmd) {
+	case SG_SCSI_RESET:
+		result = get_user(val, (int __user *)arg);
+		if (result)
+			return result;
+		if (val == SG_SCSI_RESET_NOTHING)
+			return 0;
+		switch (val) {
+		case SG_SCSI_RESET_DEVICE:
+			val = SCSI_TRY_RESET_DEVICE;
+			break;
+		case SG_SCSI_RESET_BUS:
+			val = SCSI_TRY_RESET_BUS;
+			break;
+		case SG_SCSI_RESET_HOST:
+			val = SCSI_TRY_RESET_HOST;
+			break;
+		default:
+			return -EINVAL;
+		}
+		if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
+			return -EACCES;
+		return (scsi_reset_provider(sdev, val) ==
+			SUCCESS) ? 0 : -EIO;
+	}
+	return -ENODEV;
+}
+EXPORT_SYMBOL(scsi_nonblockable_ioctl);

drivers/scsi/sd.c

@@ -574,8 +574,9 @@ static int sd_ioctl(struct inode * inode, struct file * filp,
 	 * may try and take the device offline, in which case all further
 	 * access to the device is prohibited.
 	 */
-	if (!scsi_block_when_processing_errors(sdp))
-		return -ENODEV;
+	error = scsi_nonblockable_ioctl(sdp, cmd, p, filp);
+	if (!scsi_block_when_processing_errors(sdp) || !error)
+		return error;
 
 	if (cmd == HDIO_GETGEO) {
 		if (!arg)

drivers/scsi/sr_ioctl.c

@@ -549,5 +549,17 @@ int sr_dev_ioctl(struct cdrom_device_info *cdi,
 		 unsigned int cmd, unsigned long arg)
 {
 	Scsi_CD *cd = cdi->handle;
+	int ret;
+	
+	ret = scsi_nonblockable_ioctl(cd->device, cmd,
+				      (void __user *)arg, NULL);
+	/*
+	 * 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
+	 */
+	if (ret != -ENODEV)
+		return ret;
 	return scsi_ioctl(cd->device, cmd, (void __user *)arg);
 }

drivers/scsi/st.c

@@ -3128,10 +3128,10 @@ static int st_ioctl(struct inode *inode, struct file *file,
 	 * may try and take the device offline, in which case all further
 	 * access to the device is prohibited.
 	 */
-	if (!scsi_block_when_processing_errors(STp->device)) {
-		retval = (-ENXIO);
+	retval = scsi_nonblockable_ioctl(STp->device, cmd_in, p, file);
+	if (!scsi_block_when_processing_errors(STp->device) || !retval)
 		goto out;
-	}
+
 	cmd_type = _IOC_TYPE(cmd_in);
 	cmd_nr = _IOC_NR(cmd_in);
 

include/scsi/scsi_ioctl.h

@@ -43,6 +43,8 @@ typedef struct scsi_fctargaddress {
 extern int scsi_ioctl(struct scsi_device *, int, void __user *);
 extern int scsi_ioctl_send_command(struct scsi_device *,
 				   struct scsi_ioctl_command __user *);
+extern int scsi_nonblockable_ioctl(struct scsi_device *sdev, int cmd,
+				   void __user *arg, struct file *filp);
 
 #endif /* __KERNEL__ */
 #endif /* _SCSI_IOCTL_H */