ide: remove ->supports_dsc_overlap field from ide_driver_t

* Use drive->media and drive->scsi to check if ->dsc_overlap
  can be set by HDIO_SET_NICE ioctl in generic_ide_ioctl().

* Remove unused ->supports_dsc_overlap field from ide_driver_t.

There should be no functional changes caused by this patch.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-cd.c

@@ -1969,7 +1969,6 @@ static ide_driver_t ide_cdrom_driver = {
 	.remove			= ide_cd_remove,
 	.version		= IDECD_VERSION,
 	.media			= ide_cdrom,
-	.supports_dsc_overlap	= 1,
 	.do_request		= ide_cd_do_request,
 	.end_request		= ide_end_request,
 	.error			= __ide_error,

drivers/ide/ide-disk.c

@@ -980,7 +980,6 @@ static ide_driver_t idedisk_driver = {
 	.shutdown		= ide_device_shutdown,
 	.version		= IDEDISK_VERSION,
 	.media			= ide_disk,
-	.supports_dsc_overlap	= 0,
 	.do_request		= ide_do_rw_disk,
 	.end_request		= ide_end_request,
 	.error			= __ide_error,

drivers/ide/ide-floppy.c

@@ -1130,7 +1130,6 @@ static ide_driver_t idefloppy_driver = {
 	.remove			= ide_floppy_remove,
 	.version		= IDEFLOPPY_VERSION,
 	.media			= ide_floppy,
-	.supports_dsc_overlap	= 0,
 	.do_request		= idefloppy_do_request,
 	.end_request		= idefloppy_end_request,
 	.error			= __ide_error,

drivers/ide/ide-tape.c

@@ -2607,7 +2607,6 @@ static ide_driver_t idetape_driver = {
 	.remove			= ide_tape_remove,
 	.version		= IDETAPE_VERSION,
 	.media			= ide_tape,
-	.supports_dsc_overlap 	= 1,
 	.do_request		= idetape_do_request,
 	.end_request		= idetape_end_request,
 	.error			= __ide_error,

drivers/ide/ide.c

@@ -562,7 +562,6 @@ int generic_ide_ioctl(ide_drive_t *drive, struct file *file, struct block_device
 			unsigned int cmd, unsigned long arg)
 {
 	unsigned long flags;
-	ide_driver_t *drv;
 	int err = 0, (*getfunc)(ide_drive_t *), (*setfunc)(ide_drive_t *, int);
 
 	switch (cmd) {
@@ -612,12 +611,12 @@ int generic_ide_ioctl(ide_drive_t *drive, struct file *file, struct block_device
 			if (!capable(CAP_SYS_ADMIN)) return -EACCES;
 			if (arg != (arg & ((1 << IDE_NICE_DSC_OVERLAP) | (1 << IDE_NICE_1))))
 				return -EPERM;
-			drive->dsc_overlap = (arg >> IDE_NICE_DSC_OVERLAP) & 1;
-			drv = *(ide_driver_t **)bdev->bd_disk->private_data;
-			if (drive->dsc_overlap && !drv->supports_dsc_overlap) {
-				drive->dsc_overlap = 0;
+			if (((arg >> IDE_NICE_DSC_OVERLAP) & 1) &&
+			    (drive->media == ide_disk ||
+			     drive->media == ide_floppy ||
+			     drive->scsi))
 				return -EPERM;
-			}
+			drive->dsc_overlap = (arg >> IDE_NICE_DSC_OVERLAP) & 1;
 			drive->nice1 = (arg >> IDE_NICE_1) & 1;
 			return 0;
 		case HDIO_DRIVE_RESET:

drivers/scsi/ide-scsi.c

@@ -522,7 +522,6 @@ static ide_driver_t idescsi_driver = {
 	.remove			= ide_scsi_remove,
 	.version		= IDESCSI_VERSION,
 	.media			= ide_scsi,
-	.supports_dsc_overlap	= 0,
 	.do_request		= idescsi_do_request,
 	.end_request		= idescsi_end_request,
 	.error                  = idescsi_atapi_error,

include/linux/ide.h

@@ -912,7 +912,6 @@ enum {
 struct ide_driver_s {
 	const char			*version;
 	u8				media;
-	unsigned supports_dsc_overlap	: 1;
 	ide_startstop_t	(*do_request)(ide_drive_t *, struct request *, sector_t);
 	int		(*end_request)(ide_drive_t *, int, int);
 	ide_startstop_t	(*error)(ide_drive_t *, struct request *rq, u8, u8);