diff --git a/block/genhd.c b/block/genhd.c
index 430626e440f0..7bbfed05cecb 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -16,6 +16,7 @@
 #include <linux/kobj_map.h>
 #include <linux/buffer_head.h>
 #include <linux/mutex.h>
+#include <linux/idr.h>
 
 #include "blk.h"
 
@@ -24,6 +25,15 @@ static DEFINE_MUTEX(block_class_lock);
 struct kobject *block_depr;
 #endif
 
+/* for extended dynamic devt allocation, currently only one major is used */
+#define MAX_EXT_DEVT		(1 << MINORBITS)
+
+/* For extended devt allocation.  ext_devt_mutex prevents look up
+ * results from going away underneath its user.
+ */
+static DEFINE_MUTEX(ext_devt_mutex);
+static DEFINE_IDR(ext_devt_idr);
+
 static struct device_type disk_type;
 
 /**
@@ -288,6 +298,74 @@ EXPORT_SYMBOL(unregister_blkdev);
 
 static struct kobj_map *bdev_map;
 
+/**
+ * blk_alloc_devt - allocate a dev_t for a partition
+ * @part: partition to allocate dev_t for
+ * @gfp_mask: memory allocation flag
+ * @devt: out parameter for resulting dev_t
+ *
+ * Allocate a dev_t for block device.
+ *
+ * RETURNS:
+ * 0 on success, allocated dev_t is returned in *@devt.  -errno on
+ * failure.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
+{
+	struct gendisk *disk = part_to_disk(part);
+	int idx, rc;
+
+	/* in consecutive minor range? */
+	if (part->partno < disk->minors) {
+		*devt = MKDEV(disk->major, disk->first_minor + part->partno);
+		return 0;
+	}
+
+	/* allocate ext devt */
+	do {
+		if (!idr_pre_get(&ext_devt_idr, GFP_KERNEL))
+			return -ENOMEM;
+		rc = idr_get_new(&ext_devt_idr, part, &idx);
+	} while (rc == -EAGAIN);
+
+	if (rc)
+		return rc;
+
+	if (idx > MAX_EXT_DEVT) {
+		idr_remove(&ext_devt_idr, idx);
+		return -EBUSY;
+	}
+
+	*devt = MKDEV(BLOCK_EXT_MAJOR, idx);
+	return 0;
+}
+
+/**
+ * blk_free_devt - free a dev_t
+ * @devt: dev_t to free
+ *
+ * Free @devt which was allocated using blk_alloc_devt().
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void blk_free_devt(dev_t devt)
+{
+	might_sleep();
+
+	if (devt == MKDEV(0, 0))
+		return;
+
+	if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
+		mutex_lock(&ext_devt_mutex);
+		idr_remove(&ext_devt_idr, MINOR(devt));
+		mutex_unlock(&ext_devt_mutex);
+	}
+}
+
 /*
  * Register device numbers dev..(dev+range-1)
  * range must be nonzero
@@ -371,10 +449,27 @@ void unlink_gendisk(struct gendisk *disk)
  */
 struct gendisk *get_gendisk(dev_t devt, int *partno)
 {
-	struct kobject *kobj = kobj_lookup(bdev_map, devt, partno);
-	struct device *dev = kobj_to_dev(kobj);
+	struct gendisk *disk = NULL;
 
-	return  kobj ? dev_to_disk(dev) : NULL;
+	if (MAJOR(devt) != BLOCK_EXT_MAJOR) {
+		struct kobject *kobj;
+
+		kobj = kobj_lookup(bdev_map, devt, partno);
+		if (kobj)
+			disk = dev_to_disk(kobj_to_dev(kobj));
+	} else {
+		struct hd_struct *part;
+
+		mutex_lock(&ext_devt_mutex);
+		part = idr_find(&ext_devt_idr, MINOR(devt));
+		if (part && get_disk(part_to_disk(part))) {
+			*partno = part->partno;
+			disk = part_to_disk(part);
+		}
+		mutex_unlock(&ext_devt_mutex);
+	}
+
+	return disk;
 }
 
 /**
@@ -877,18 +972,30 @@ struct gendisk *alloc_disk(int minors)
 }
 
 struct gendisk *alloc_disk_node(int minors, int node_id)
+{
+	return alloc_disk_ext_node(minors, 0, node_id);
+}
+
+struct gendisk *alloc_disk_ext(int minors, int ext_minors)
+{
+	return alloc_disk_ext_node(minors, ext_minors, -1);
+}
+
+struct gendisk *alloc_disk_ext_node(int minors, int ext_minors, int node_id)
 {
 	struct gendisk *disk;
 
 	disk = kmalloc_node(sizeof(struct gendisk),
 				GFP_KERNEL | __GFP_ZERO, node_id);
 	if (disk) {
+		int tot_minors = minors + ext_minors;
+
 		if (!init_disk_stats(disk)) {
 			kfree(disk);
 			return NULL;
 		}
-		if (minors > 1) {
-			int size = (minors - 1) * sizeof(struct hd_struct *);
+		if (tot_minors > 1) {
+			int size = (tot_minors - 1) * sizeof(struct hd_struct *);
 			disk->__part = kmalloc_node(size,
 				GFP_KERNEL | __GFP_ZERO, node_id);
 			if (!disk->__part) {
@@ -898,6 +1005,7 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
 			}
 		}
 		disk->minors = minors;
+		disk->ext_minors = ext_minors;
 		rand_initialize_disk(disk);
 		disk->dev.class = &block_class;
 		disk->dev.type = &disk_type;
@@ -910,6 +1018,8 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
 
 EXPORT_SYMBOL(alloc_disk);
 EXPORT_SYMBOL(alloc_disk_node);
+EXPORT_SYMBOL(alloc_disk_ext);
+EXPORT_SYMBOL(alloc_disk_ext_node);
 
 struct kobject *get_disk(struct gendisk *disk)
 {
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index c442f0aadac3..0d4b7f28f13f 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -333,6 +333,7 @@ void delete_partition(struct gendisk *disk, int partno)
 	if (!part)
 		return;
 
+	blk_free_devt(part_devt(part));
 	rcu_assign_pointer(disk->__part[partno-1], NULL);
 	kobject_put(part->holder_dir);
 	device_del(&part->dev);
@@ -352,6 +353,7 @@ int add_partition(struct gendisk *disk, int partno,
 		  sector_t start, sector_t len, int flags)
 {
 	struct hd_struct *p;
+	dev_t devt = MKDEV(0, 0);
 	int err;
 
 	if (disk->__part[partno - 1])
@@ -378,11 +380,15 @@ int add_partition(struct gendisk *disk, int partno,
 			 "%s%d", disk->dev.bus_id, partno);
 
 	device_initialize(&p->dev);
-	p->dev.devt = MKDEV(disk->major, disk->first_minor + partno);
 	p->dev.class = &block_class;
 	p->dev.type = &part_type;
 	p->dev.parent = &disk->dev;
 
+	err = blk_alloc_devt(p, &devt);
+	if (err)
+		goto out_put;
+	p->dev.devt = devt;
+
 	/* delay uevent until 'holders' subdir is created */
 	p->dev.uevent_suppress = 1;
 	err = device_add(&p->dev);
@@ -419,6 +425,7 @@ out_del:
 	device_del(&p->dev);
 out_put:
 	put_device(&p->dev);
+	blk_free_devt(devt);
 	return err;
 }
 
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index ac8a901f2002..6fc532424062 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -113,13 +113,15 @@ struct hd_struct {
 #define GENHD_FL_FAIL				64
 
 struct gendisk {
-	/* major, first_minor and minors are input parameters only,
-	 * don't use directly.  Use disk_devt() and disk_max_parts().
+	/* major, first_minor, minors and ext_minors are input
+	 * parameters only, don't use directly.  Use disk_devt() and
+	 * disk_max_parts().
 	 */
 	int major;			/* major number of driver */
 	int first_minor;
 	int minors;                     /* maximum number of minors, =1 for
                                          * disks that can't be partitioned. */
+	int ext_minors;			/* number of extended dynamic minors */
 
 	char disk_name[32];		/* name of major driver */
 
@@ -167,7 +169,7 @@ static inline struct gendisk *part_to_disk(struct hd_struct *part)
 
 static inline int disk_max_parts(struct gendisk *disk)
 {
-	return disk->minors - 1;
+	return disk->minors + disk->ext_minors - 1;
 }
 
 static inline dev_t disk_devt(struct gendisk *disk)
@@ -554,6 +556,8 @@ struct unixware_disklabel {
 #define ADDPART_FLAG_RAID	1
 #define ADDPART_FLAG_WHOLEDISK	2
 
+extern int blk_alloc_devt(struct hd_struct *part, dev_t *devt);
+extern void blk_free_devt(dev_t devt);
 extern dev_t blk_lookup_devt(const char *name, int partno);
 extern char *disk_name (struct gendisk *hd, int partno, char *buf);
 
@@ -564,6 +568,9 @@ extern void printk_all_partitions(void);
 
 extern struct gendisk *alloc_disk_node(int minors, int node_id);
 extern struct gendisk *alloc_disk(int minors);
+extern struct gendisk *alloc_disk_ext_node(int minors, int ext_minrs,
+					   int node_id);
+extern struct gendisk *alloc_disk_ext(int minors, int ext_minors);
 extern struct kobject *get_disk(struct gendisk *disk);
 extern void put_disk(struct gendisk *disk);
 extern void blk_register_region(dev_t devt, unsigned long range,
diff --git a/include/linux/major.h b/include/linux/major.h
index 53d5fafd85c3..88249452b935 100644
--- a/include/linux/major.h
+++ b/include/linux/major.h
@@ -170,4 +170,6 @@
 
 #define VIOTAPE_MAJOR		230
 
+#define BLOCK_EXT_MAJOR		259
+
 #endif