[ide] add ide_{un}register_region()

Add ide_{un}register_region() and fix ide-{tape,scsi}.c to register
block device number ranges.  In ata_probe() only probe for modules.

Behavior is unchanged because:
* if driver is already loaded and attached to drive ata_probe()
  is not called et all
* if driver is loaded by ata_probe() it will register new number range
  for a drive and this range will be found by kobj_lookup()

If this is not clear please read http://lwn.net/Articles/25711/
and see drivers/base/map.c.

This patch makes it possible to move drive->disk allocation from
ide-probe.c to device drivers.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

4 files changed, 54 insertions, 17 deletions

diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index 2b8c8f86edbd00..4f25501bc758b8 100644
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -1214,8 +1214,6 @@ static int ata_lock(dev_t dev, void *data)
 	return 0;
 }
 
-extern ide_driver_t idedefault_driver;
-
 static struct kobject *ata_probe(dev_t dev, int *part, void *data)
 {
 	ide_hwif_t *hwif = data;
@@ -1223,24 +1221,53 @@ static struct kobject *ata_probe(dev_t dev, int *part, void *data)
 	ide_drive_t *drive = &hwif->drives[unit];
 	if (!drive->present)
 		return NULL;
-	if (drive->driver == &idedefault_driver) {
-		if (drive->media == ide_disk)
-			(void) request_module("ide-disk");
-		if (drive->scsi)
-			(void) request_module("ide-scsi");
-		if (drive->media == ide_cdrom || drive->media == ide_optical)
-			(void) request_module("ide-cd");
-		if (drive->media == ide_tape)
-			(void) request_module("ide-tape");
-		if (drive->media == ide_floppy)
-			(void) request_module("ide-floppy");
-	}
-	if (drive->driver == &idedefault_driver)
-		return NULL;
+
+	if (drive->media == ide_disk)
+		request_module("ide-disk");
+	if (drive->scsi)
+		request_module("ide-scsi");
+	if (drive->media == ide_cdrom || drive->media == ide_optical)
+		request_module("ide-cd");
+	if (drive->media == ide_tape)
+		request_module("ide-tape");
+	if (drive->media == ide_floppy)
+		request_module("ide-floppy");
+
+	return NULL;
+}
+
+static struct kobject *exact_match(dev_t dev, int *part, void *data)
+{
+	struct gendisk *p = data;
 	*part &= (1 << PARTN_BITS) - 1;
-	return get_disk(drive->disk);
+	return &p->kobj;
 }
 
+static int exact_lock(dev_t dev, void *data)
+{
+	struct gendisk *p = data;
+
+	if (!get_disk(p))
+		return -1;
+	return 0;
+}
+
+void ide_register_region(struct gendisk *disk)
+{
+	blk_register_region(MKDEV(disk->major, disk->first_minor),
+			    disk->minors, NULL, exact_match, exact_lock, disk);
+}
+
+EXPORT_SYMBOL_GPL(ide_register_region);
+
+void ide_unregister_region(struct gendisk *disk)
+{
+	blk_unregister_region(MKDEV(disk->major, disk->first_minor),
+			      disk->minors);
+}
+
+EXPORT_SYMBOL_GPL(ide_unregister_region);
+
 static int alloc_disks(ide_hwif_t *hwif)
 {
 	unsigned int unit;
diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 8802679c3eff90..41513c4b27fe7f 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -4687,6 +4687,8 @@ static int idetape_cleanup (ide_drive_t *drive)
 	DRIVER(drive)->busy = 0;
 	(void) ide_unregister_subdriver(drive);
 
+	ide_unregister_region(drive->disk);
+
 	ide_tape_put(tape);
 
 	return 0;
@@ -4878,6 +4880,7 @@ static int idetape_attach (ide_drive_t *drive)
 	g->number = devfs_register_tape(drive->devfs_name);
 	g->fops = &idetape_block_ops;
 	g->private_data = tape;
+	ide_register_region(g);
 
 	return 0;
 failed:
diff --git a/drivers/scsi/ide-scsi.c b/drivers/scsi/ide-scsi.c
index 805cccd042b671..fc7e999ec46310 100644
--- a/drivers/scsi/ide-scsi.c
+++ b/drivers/scsi/ide-scsi.c
@@ -723,6 +723,8 @@ static int idescsi_cleanup (ide_drive_t *drive)
 	if (ide_unregister_subdriver(drive))
 		return 1;
 
+	ide_unregister_region(g);
+
 	drive->driver_data = NULL;
 	g->private_data = NULL;
 	g->fops = ide_fops;
@@ -1120,12 +1122,14 @@ static int idescsi_attach(ide_drive_t *drive)
 		idescsi_setup (drive, idescsi);
 		g->fops = &idescsi_ops;
 		g->private_data = idescsi;
+		ide_register_region(g);
 		err = scsi_add_host(host, &drive->gendev);
 		if (!err) {
 			scsi_scan_host(host);
 			return 0;
 		}
 		/* fall through on error */
+		ide_unregister_region(g);
 		ide_unregister_subdriver(drive);
 	}
 
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 58d91a9d533256..329dcc754d868a 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1442,6 +1442,9 @@ extern int ide_hwif_request_regions(ide_hwif_t *hwif);
 extern void ide_hwif_release_regions(ide_hwif_t* hwif);
 extern void ide_unregister (unsigned int index);
 
+void ide_register_region(struct gendisk *);
+void ide_unregister_region(struct gendisk *);
+
 void ide_undecoded_slave(ide_hwif_t *);
 
 int probe_hwif_init_with_fixup(ide_hwif_t *, void (*)(ide_hwif_t *));