diff --git a/block/genhd.c b/block/genhd.c
index e2f6790..90327a4 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -154,7 +154,7 @@ struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
 		part = rcu_dereference(ptbl->part[piter->idx]);
 		if (!part)
 			continue;
-		if (!part->nr_sects &&
+		if (!part_nr_sects_read(part) &&
 		    !(piter->flags & DISK_PITER_INCL_EMPTY) &&
 		    !(piter->flags & DISK_PITER_INCL_EMPTY_PART0 &&
 		      piter->idx == 0))
@@ -191,7 +191,7 @@ EXPORT_SYMBOL_GPL(disk_part_iter_exit);
 static inline int sector_in_part(struct hd_struct *part, sector_t sector)
 {
 	return part->start_sect <= sector &&
-		sector < part->start_sect + part->nr_sects;
+		sector < part->start_sect + part_nr_sects_read(part);
 }
 
 /**
@@ -760,8 +760,8 @@ void __init printk_all_partitions(void)
 
 			printk("%s%s %10llu %s %s", is_part0 ? "" : "  ",
 			       bdevt_str(part_devt(part), devt_buf),
-			       (unsigned long long)part->nr_sects >> 1,
-			       disk_name(disk, part->partno, name_buf), uuid);
+			       (unsigned long long)part_nr_sects_read(part) >> 1
+			       , disk_name(disk, part->partno, name_buf), uuid);
 			if (is_part0) {
 				if (disk->driverfs_dev != NULL &&
 				    disk->driverfs_dev->driver != NULL)
@@ -852,7 +852,7 @@ static int show_partition(struct seq_file *seqf, void *v)
 	while ((part = disk_part_iter_next(&piter)))
 		seq_printf(seqf, "%4d  %7d %10llu %s\n",
 			   MAJOR(part_devt(part)), MINOR(part_devt(part)),
-			   (unsigned long long)part->nr_sects >> 1,
+			   (unsigned long long)part_nr_sects_read(part) >> 1,
 			   disk_name(sgp, part->partno, buf));
 	disk_part_iter_exit(&piter);
 
diff --git a/block/ioctl.c b/block/ioctl.c
index 1124cd2..d5de971 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -12,12 +12,13 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
 {
 	struct block_device *bdevp;
 	struct gendisk *disk;
-	struct hd_struct *part;
+	struct hd_struct *part, *lpart;
 	struct blkpg_ioctl_arg a;
 	struct blkpg_partition p;
 	struct disk_part_iter piter;
-	long long start, length;
+	long long start, length, size, orig_length, new_length;
 	int partno;
+	loff_t bdev_size;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
@@ -91,6 +92,75 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
 			bdput(bdevp);
 
 			return 0;
+		case BLKPG_EXTEND_PARTITION:
+			/* length here represents increase in partition size */
+			size = p.length >> 9;
+
+			part = disk_get_part(disk, partno);
+			if (!part)
+				return -ENXIO;
+			bdevp = bdget(part_devt(part));
+			disk_put_part(part);
+			if (!bdevp)
+				return -ENOMEM;
+
+			mutex_lock(&bdevp->bd_mutex);
+			mutex_lock_nested(&bdev->bd_mutex, 1);
+
+			start = part->start_sect;
+			orig_length = part->nr_sects;
+			new_length = orig_length + size;
+
+			if (new_length < orig_length || new_length < 0) {
+				mutex_unlock(&bdev->bd_mutex);
+				mutex_unlock(&bdevp->bd_mutex);
+				bdput(bdevp);
+				return -EINVAL;
+			}
+
+			/* check for fit in a hd_struct */
+			if (sizeof(sector_t) == sizeof(long) &&
+			    sizeof(long long) > sizeof(long)) {
+				long plength = new_length;
+				if (plength != length || plength < 0) {
+					mutex_unlock(&bdev->bd_mutex);
+					mutex_unlock(&bdevp->bd_mutex);
+					bdput(bdevp);
+					return -EINVAL;
+				}
+			}
+
+			/* overlap? */
+			disk_part_iter_init(&piter, disk,
+					    DISK_PITER_INCL_EMPTY);
+			while ((lpart = disk_part_iter_next(&piter))) {
+
+				/* This is partition being extended */
+				if (lpart->start_sect == part->start_sect)
+					continue;
+
+				if (!(start + new_length <= lpart->start_sect ||
+				    start >= lpart->start_sect + lpart->nr_sects
+					)) {
+					disk_part_iter_exit(&piter);
+					mutex_unlock(&bdev->bd_mutex);
+					mutex_unlock(&bdevp->bd_mutex);
+					bdput(bdevp);
+					return -EBUSY;
+				}
+			}
+			disk_part_iter_exit(&piter);
+			if (!extend_partition(disk, partno, size)) {
+				/* Update bdev->bd_inode size */
+				bdev_size = i_size_read(bdevp->bd_inode);
+				i_size_write(bdevp->bd_inode,
+						bdev_size + (size << 9));
+			}
+			mutex_unlock(&bdev->bd_mutex);
+			mutex_unlock(&bdevp->bd_mutex);
+			bdput(bdevp);
+
+			return 0;
 		default:
 			return -EINVAL;
 	}
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index e3c63d1..5d462d6 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -21,6 +21,7 @@
 #include <linux/ctype.h>
 #include <linux/genhd.h>
 #include <linux/blktrace_api.h>
+#include <linux/seqlock.h>
 
 #include "check.h"
 
@@ -234,7 +235,7 @@ ssize_t part_size_show(struct device *dev,
 		       struct device_attribute *attr, char *buf)
 {
 	struct hd_struct *p = dev_to_part(dev);
-	return sprintf(buf, "%llu\n",(unsigned long long)p->nr_sects);
+	return sprintf(buf, "%llu\n",(unsigned long long)part_nr_sects_read(p));
 }
 
 static ssize_t part_ro_show(struct device *dev,
@@ -408,6 +409,69 @@ void delete_partition(struct gendisk *disk, int partno)
 	hd_struct_put(part);
 }
 
+#if BITS_PER_LONG == 32 && defined(CONFIG_LBDAF)
+static inline void part_nr_sects_write_begin(struct seqcount_t *seq)
+{
+	write_seqcount_begin(&seq);
+}
+
+static inline void part_nr_sects_write_end(struct seqcount_t *seq)
+{
+	write_seqcount_end(&seq);
+}
+
+/*
+ * Any access of part->nr_sects which is not protected by partition
+ * bd_mutex or gendisk bdev bd_mutex, hould be done using this accessor
+ * function.
+ */
+sector_t part_nr_sects_read(struct hd_struct *part)
+{
+	sector_t nr_sects;
+        unsigned seq;
+
+        do {
+                seq = read_seqcount_begin(&part->seq);
+                nr_sects = part->nr_sects;
+        } while (read_seqcount_retry(&part->seq, seq));
+
+        return nr_sects;
+}
+#else
+static inline void part_nr_sects_write_begin(seqcount_t *seq) {}
+static inline void part_nr_sects_write_end(seqcount_t *seq) {}
+sector_t part_nr_sects_read(struct hd_struct *part)
+{
+	return part->nr_sects;
+}
+#endif
+
+int extend_partition(struct gendisk *disk, int partno, sector_t size)
+{
+	struct disk_part_tbl *ptbl = disk->part_tbl;
+	struct hd_struct *part;
+	unsigned long flags;
+
+	if (partno >= ptbl->len)
+		return 1;
+
+	part = ptbl->part[partno];
+	if (!part)
+		return 1;
+
+	/*
+	 * It is called with mutex held for writer mutual exclusion. Disabling
+	 * interrupts to protect against a reader in interrupt/softirq
+	 * context. Is it not needed?
+	 */
+	local_irq_save(flags);
+	part_nr_sects_write_begin(&part->seq);
+	part->nr_sects += size;
+	part_nr_sects_write_end(&part->seq);
+	local_irq_restore(flags);
+	return 0;
+}
+
 static ssize_t whole_disk_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
diff --git a/include/linux/blkpg.h b/include/linux/blkpg.h
index faf8a45..2a7bce9 100644
--- a/include/linux/blkpg.h
+++ b/include/linux/blkpg.h
@@ -40,6 +40,7 @@ struct blkpg_ioctl_arg {
 /* The subfunctions (for the op field) */
 #define BLKPG_ADD_PARTITION	1
 #define BLKPG_DEL_PARTITION	2
+#define BLKPG_EXTEND_PARTITION	3
 
 /* Sizes of name fields. Unused at present. */
 #define BLKPG_DEVNAMELTH	64
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 02fa469..81c12d2 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -98,7 +98,13 @@ struct partition_meta_info {
 
 struct hd_struct {
 	sector_t start_sect;
+	/*
+	 * nr_sects is protected by sequence counter. One might extend a
+	 * partition while IO is happening to it and update of nr_sects
+	 * can be non-atomic on 32bit machines with 64bit sector_t.
+	 */
 	sector_t nr_sects;
+	seqcount_t seq;
 	sector_t alignment_offset;
 	unsigned int discard_alignment;
 	struct device __dev;
@@ -600,8 +606,10 @@ extern struct hd_struct * __must_check add_partition(struct gendisk *disk,
 						     struct partition_meta_info
 						       *info);
 extern void __delete_partition(struct hd_struct *);
+extern int extend_partition(struct gendisk *disk, int partno, sector_t size);
 extern void delete_partition(struct gendisk *, int);
 extern void printk_all_partitions(void);
+extern sector_t part_nr_sects_read(struct hd_struct *part);
 
 extern struct gendisk *alloc_disk_node(int minors, int node_id);
 extern struct gendisk *alloc_disk(int minors);
