[PATCH] get_gendisk() prototype change

get_gendisk() now takes dev_t (instead of kdev_t) and gets an additional
argument - int *part.  Set to 0 for non-partitioned, partition number
for partititoned.  Callers updated.  Yes, I hate passing return values
that way ;-/  We need that since old "minor(dev) - disk->first_minor"
doesn't work for stuff with non-trivial numbers (e.g. floppy) and
get_gendisk() really has to return both gendisk and partition number.
Fortunately, amount of callers of gendisk() is about to drop RSN big way...

drivers/block/blkpg.c

@@ -69,8 +69,7 @@ int add_partition(struct block_device *bdev, struct blkpg_partition *p)
 	struct gendisk *g;
 	long long ppstart, pplength;
 	long pstart, plength;
-	int i;
-	kdev_t dev = to_kdev_t(bdev->bd_dev);
+	int part, i;
 
 	/* convert bytes to sectors, check for fit in a hd_struct */
 	ppstart = (p->start >> 9);
@@ -82,7 +81,7 @@ int add_partition(struct block_device *bdev, struct blkpg_partition *p)
 		return -EINVAL;
 
 	/* find the drive major */
-	g = get_gendisk(dev);
+	g = get_gendisk(bdev->bd_dev, &part);
 	if (!g)
 		return -ENXIO;
 
@@ -91,6 +90,8 @@ int add_partition(struct block_device *bdev, struct blkpg_partition *p)
 	/* drive and partition number OK? */
 	if (bdev != bdev->bd_contains)
 		return -EINVAL;
+	if (part)
+		BUG();
 	if (p->pno <= 0 || p->pno >= (1 << g->minor_shift))
 		return -EINVAL;
 
@@ -123,17 +124,19 @@ int add_partition(struct block_device *bdev, struct blkpg_partition *p)
  */
 int del_partition(struct block_device *bdev, struct blkpg_partition *p)
 {
-	kdev_t dev = to_kdev_t(bdev->bd_dev);
 	struct gendisk *g;
 	struct block_device *bdevp;
+	int part;
 	int holder;
 
 	/* find the drive major */
-	g = get_gendisk(dev);
+	g = get_gendisk(bdev->bd_dev, &part);
 	if (!g)
 		return -ENXIO;
 	if (bdev != bdev->bd_contains)
 		return -EINVAL;
+	if (part)
+		BUG();
 	if (p->pno <= 0 || p->pno >= (1 << g->minor_shift))
   		return -EINVAL;
 
@@ -142,7 +145,7 @@ int del_partition(struct block_device *bdev, struct blkpg_partition *p)
 		return -ENXIO;
 
 	/* partition in use? Incomplete check for now. */
-	bdevp = bdget(MKDEV(major(dev), minor(dev) + p->pno));
+	bdevp = bdget(MKDEV(g->major, g->first_minor + p->pno));
 	if (!bdevp)
 		return -ENOMEM;
 	if (bd_claim(bdevp, &holder) < 0) {

drivers/block/genhd.c

@@ -108,13 +108,14 @@ void unlink_gendisk(struct gendisk *disk)
  * information for the given device @dev.
  */
 struct gendisk *
-get_gendisk(kdev_t dev)
+get_gendisk(dev_t dev, int *part)
 {
 	struct gendisk *disk;
 	struct list_head *p;
-	int major = major(dev);
-	int minor = minor(dev);
+	int major = MAJOR(dev);
+	int minor = MINOR(dev);
 
+	*part = 0;
 	read_lock(&gendisk_lock);
 	if (gendisks[major].get) {
 		disk = gendisks[major].get(minor);
@@ -128,6 +129,7 @@ get_gendisk(kdev_t dev)
 		if (disk->first_minor + (1<<disk->minor_shift) <= minor)
 			continue;
 		read_unlock(&gendisk_lock);
+		*part = minor - disk->first_minor;
 		return disk;
 	}
 	read_unlock(&gendisk_lock);

fs/block_dev.c

@@ -526,6 +526,7 @@ int check_disk_change(struct block_device *bdev)
 	struct block_device_operations * bdops = bdev->bd_op;
 	kdev_t dev = to_kdev_t(bdev->bd_dev);
 	struct gendisk *disk;
+	int part;
 
 	if (bdops->check_media_change == NULL)
 		return 0;
@@ -535,7 +536,7 @@ int check_disk_change(struct block_device *bdev)
 	if (invalidate_device(dev, 0))
 		printk("VFS: busy inodes on changed media.\n");
 
-	disk = get_gendisk(dev);
+	disk = get_gendisk(bdev->bd_dev, &part);
 	if (bdops->revalidate)
 		bdops->revalidate(dev);
 	if (disk && disk->minor_shift)
@@ -546,11 +547,12 @@ int check_disk_change(struct block_device *bdev)
 int full_check_disk_change(struct block_device *bdev)
 {
 	int res = 0;
+	int n;
 	if (bdev->bd_contains != bdev)
 		BUG();
 	down(&bdev->bd_sem);
 	if (check_disk_change(bdev)) {
-		rescan_partitions(get_gendisk(to_kdev_t(bdev->bd_dev)), bdev);
+		rescan_partitions(get_gendisk(bdev->bd_dev, &n), bdev);
 		res = 1;
 	}
 	up(&bdev->bd_sem);
@@ -612,26 +614,24 @@ static int do_open(struct block_device *bdev, struct inode *inode, struct file *
 			__MOD_DEC_USE_COUNT(owner);
 	}
 	if (!bdev->bd_contains) {
-		unsigned minor = minor(dev);
-		struct gendisk *g = get_gendisk(dev);
+		int part;
+		struct gendisk *g = get_gendisk(bdev->bd_dev, &part);
 		bdev->bd_contains = bdev;
-		if (g) {
-			unsigned minor0 = g->first_minor;
-			if (minor != minor0) {
-				struct block_device *disk;
-				disk = bdget(MKDEV(major(dev), minor0));
-				ret = -ENOMEM;
-				if (!disk)
-					goto out1;
-				ret = blkdev_get(disk, file->f_mode, file->f_flags, BDEV_RAW);
-				if (ret)
-					goto out1;
-				bdev->bd_contains = disk;
-			}
+		if (g && part) {
+			struct block_device *disk;
+			disk = bdget(MKDEV(g->major, g->first_minor));
+			ret = -ENOMEM;
+			if (!disk)
+				goto out1;
+			ret = blkdev_get(disk, file->f_mode, file->f_flags, BDEV_RAW);
+			if (ret)
+				goto out1;
+			bdev->bd_contains = disk;
 		}
 	}
 	if (bdev->bd_contains == bdev) {
-		struct gendisk *g = get_gendisk(dev);
+		int part;
+		struct gendisk *g = get_gendisk(bdev->bd_dev, &part);
 
 		if (!bdev->bd_queue) {
 			struct blk_dev_struct *p = blk_dev + major(dev);
@@ -665,9 +665,10 @@ static int do_open(struct block_device *bdev, struct inode *inode, struct file *
 		down(&bdev->bd_contains->bd_sem);
 		bdev->bd_contains->bd_part_count++;
 		if (!bdev->bd_openers) {
-			struct gendisk *g = get_gendisk(dev);
+			int part;
+			struct gendisk *g = get_gendisk(bdev->bd_dev, &part);
 			struct hd_struct *p;
-			p = g->part + minor(dev) - g->first_minor - 1;
+			p = g->part + part - 1;
 			inode->i_data.backing_dev_info =
 			   bdev->bd_inode->i_data.backing_dev_info =
 			   bdev->bd_contains->bd_inode->i_data.backing_dev_info;
@@ -793,12 +794,14 @@ int blkdev_close(struct inode * inode, struct file * filp)
 
 static int blkdev_reread_part(struct block_device *bdev)
 {
-	kdev_t dev = to_kdev_t(bdev->bd_dev);
-	struct gendisk *disk = get_gendisk(dev);
+	int part;
+	struct gendisk *disk = get_gendisk(bdev->bd_dev, &part);
 	int res = 0;
 
 	if (!disk || !disk->minor_shift || bdev != bdev->bd_contains)
 		return -EINVAL;
+	if (part)
+		BUG();
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
 	if (down_trylock(&bdev->bd_sem))

fs/partitions/check.c

@@ -569,6 +569,7 @@ char *partition_name(dev_t dev)
 	static char nomem [] = "<nomem>";
 	struct dev_name *dname;
 	struct list_head *tmp;
+	int part;
 
 	list_for_each(tmp, &device_names) {
 		dname = list_entry(tmp, struct dev_name, list);
@@ -583,10 +584,10 @@ char *partition_name(dev_t dev)
 	/*
 	 * ok, add this new device name to the list
 	 */
-	hd = get_gendisk(to_kdev_t(dev));
+	hd = get_gendisk(dev, &part);
 	dname->name = NULL;
 	if (hd)
-		dname->name = disk_name(hd, MINOR(dev)-hd->first_minor, dname->namebuf);
+		dname->name = disk_name(hd, part, dname->namebuf);
 	if (!dname->name) {
 		sprintf(dname->namebuf, "[dev %s]", kdevname(to_kdev_t(dev)));
 		dname->name = dname->namebuf;

include/linux/genhd.h

@@ -95,7 +95,7 @@ struct gendisk {
 extern void add_disk(struct gendisk *disk);
 extern void del_gendisk(struct gendisk *gp);
 extern void unlink_gendisk(struct gendisk *gp);
-extern struct gendisk *get_gendisk(kdev_t dev);
+extern struct gendisk *get_gendisk(dev_t dev, int *part);
 static inline unsigned long get_start_sect(struct block_device *bdev)
 {
 	return bdev->bd_offset;
@@ -268,7 +268,8 @@ extern void blk_set_probe(int major, struct gendisk *(p)(int));
 
 static inline unsigned int disk_index (kdev_t dev)
 {
-	struct gendisk *g = get_gendisk(dev);
+	int part;
+	struct gendisk *g = get_gendisk(kdev_t_to_nr(dev), &part);
 	return g ? (minor(dev) >> g->minor_shift) : 0;
 }