diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 4917cf2..10ec463 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -581,6 +581,13 @@ Table of Ext4 specific ioctls
 			      behaviour may change in the future as it is
 			      not necessary and has been done this way only
 			      for sake of simplicity.
+
+ EXT4_IOC_RESIZE_FS	      Resize the filesystem to a new size.  The number
+			      of blocks of resized filesystem is passed in via
+			      64 bit integer argument.  The kernel allocates
+			      bitmaps and inode table, the userspace tool thus
+			      just passes the new number of blocks.
+
 ..............................................................................
 
 References
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index a062ab3..477137f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -583,6 +583,7 @@ enum {
  /* note ioctl 11 reserved for filesystem-independent FIEMAP ioctl */
 #define EXT4_IOC_ALLOC_DA_BLKS		_IO('f', 12)
 #define EXT4_IOC_MOVE_EXT		_IOWR('f', 15, struct move_extent)
+#define EXT4_IOC_RESIZE_FS		_IOW('f', 16, __u64)
 
 #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
 /*
@@ -1932,6 +1933,7 @@ extern int ext4_group_add(struct super_block *sb,
 extern int ext4_group_extend(struct super_block *sb,
 				struct ext4_super_block *es,
 				ext4_fsblk_t n_blocks_count);
+extern int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count);
 
 /* super.c */
 extern void *ext4_kvmalloc(size_t size, gfp_t flags);
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index a567968..cfe95f2 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -331,6 +331,44 @@ mext_out:
 		return err;
 	}
 
+	case EXT4_IOC_RESIZE_FS: {
+		ext4_fsblk_t n_blocks_count;
+		struct super_block *sb = inode->i_sb;
+		int err = 0, err2 = 0;
+
+		if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+			       EXT4_FEATURE_RO_COMPAT_BIGALLOC)) {
+			ext4_msg(sb, KERN_ERR,
+				 "Online resizing not supported with bigalloc");
+			return -EOPNOTSUPP;
+		}
+
+		err = ext4_resize_begin(sb);
+		if (err)
+			return err;
+
+		if (copy_from_user(&n_blocks_count, (__u64 __user *)arg,
+				   sizeof(__u64)))
+			return -EFAULT;
+
+		err = mnt_want_write(filp->f_path.mnt);
+		if (err)
+			return err;
+
+		err = ext4_resize_fs(sb, n_blocks_count);
+		if (EXT4_SB(sb)->s_journal) {
+			jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
+			err2 = jbd2_journal_flush(EXT4_SB(sb)->s_journal);
+			jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+		}
+		if (err == 0)
+			err = err2;
+		mnt_drop_write(filp->f_path.mnt);
+		ext4_resize_end(sb);
+
+		return err;
+	}
+
 	case FITRIM:
 	{
 		struct request_queue *q = bdev_get_queue(sb->s_bdev);
@@ -429,6 +467,7 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	}
 	case EXT4_IOC_MOVE_EXT:
 	case FITRIM:
+	case EXT4_IOC_RESIZE_FS:
 		break;
 	default:
 		return -ENOIOCTLCMD;
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index bfca158..6e0af4b 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1439,6 +1439,68 @@ exit:
 	return err;
 }
 
+static int ext4_setup_next_flex_gd(struct super_block *sb,
+				    struct ext4_new_flex_group_data *flex_gd,
+				    ext4_fsblk_t n_blocks_count,
+				    unsigned long flexbg_size)
+{
+	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+	struct ext4_new_group_data *group_data = flex_gd->groups;
+	ext4_fsblk_t o_blocks_count;
+	ext4_group_t n_group;
+	ext4_group_t group;
+	ext4_group_t last_group;
+	ext4_grpblk_t last;
+	ext4_grpblk_t blocks_per_group;
+	unsigned long i;
+
+	blocks_per_group = EXT4_BLOCKS_PER_GROUP(sb);
+
+	o_blocks_count = ext4_blocks_count(es);
+
+	if (o_blocks_count == n_blocks_count)
+		return 0;
+
+	ext4_get_group_no_and_offset(sb, o_blocks_count, &group, &last);
+	BUG_ON(last);
+	ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &last);
+
+	last_group = group | (flexbg_size - 1);
+	if (last_group > n_group)
+		last_group = n_group;
+
+	flex_gd->count = last_group - group + 1;
+
+	for (i = 0; i < flex_gd->count; i++) {
+		int overhead;
+
+		group_data[i].group = group + i;
+		group_data[i].blocks_count = blocks_per_group;
+		overhead = ext4_bg_has_super(sb, group + i) ?
+			   (1 + ext4_bg_num_gdb(sb, group + i) +
+			    le16_to_cpu(es->s_reserved_gdt_blocks)) : 0;
+		group_data[i].free_blocks_count = blocks_per_group - overhead;
+		if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+					       EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
+			flex_gd->bg_flags[i] = EXT4_BG_BLOCK_UNINIT |
+					       EXT4_BG_INODE_UNINIT;
+	}
+
+	if (last_group == n_group &&
+	    EXT4_HAS_RO_COMPAT_FEATURE(sb,
+				       EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
+		/* We need to initialize block bitmap of last group. */
+		flex_gd->bg_flags[i - 1] &= ~EXT4_BG_BLOCK_UNINIT;
+
+	if ((last_group == n_group) && (last != blocks_per_group - 1)) {
+		group_data[i - 1].blocks_count = last + 1;
+		group_data[i - 1].free_blocks_count -= blocks_per_group-
+					last - 1;
+	}
+
+	return 1;
+}
+
 /* Add group descriptor data to an existing or new group descriptor block.
  * Ensure we handle all possible error conditions _before_ we start modifying
  * the filesystem, because we cannot abort the transaction and not have it
@@ -1838,3 +1900,116 @@ int ext4_group_extend(struct super_block *sb, struct ext4_super_block *es,
 exit_put:
 	return err;
 } /* ext4_group_extend */
+
+/*
+ * ext4_resize_fs() resizes a fs to new size specified by @n_blocks_count
+ *
+ * @sb: super block of the fs to be resized
+ * @n_blocks_count: the number of blocks resides in the resized fs
+ */
+int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
+{
+	struct ext4_new_flex_group_data *flex_gd = NULL;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	struct ext4_super_block *es = sbi->s_es;
+	struct buffer_head *bh;
+	struct inode *resize_inode;
+	ext4_fsblk_t o_blocks_count;
+	ext4_group_t o_group;
+	ext4_group_t n_group;
+	ext4_grpblk_t offset;
+	unsigned long n_desc_blocks;
+	unsigned long o_desc_blocks;
+	unsigned long desc_blocks;
+	int err = 0, flexbg_size = 1;
+
+	o_blocks_count = ext4_blocks_count(es);
+
+	if (test_opt(sb, DEBUG))
+		printk(KERN_DEBUG "EXT4-fs: resizing filesystem from %llu "
+		       "upto %llu blocks\n", o_blocks_count, n_blocks_count);
+
+	if (n_blocks_count < o_blocks_count) {
+		/* On-line shrinking not supported */
+		ext4_warning(sb, "can't shrink FS - resize aborted");
+		return -EINVAL;
+	}
+
+	if (n_blocks_count == o_blocks_count)
+		/* Nothing need to do */
+		return 0;
+
+	ext4_get_group_no_and_offset(sb, n_blocks_count - 1, &n_group, &offset);
+	ext4_get_group_no_and_offset(sb, o_blocks_count, &o_group, &offset);
+
+	n_desc_blocks = (n_group + EXT4_DESC_PER_BLOCK(sb)) /
+			EXT4_DESC_PER_BLOCK(sb);
+	o_desc_blocks = (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) /
+			EXT4_DESC_PER_BLOCK(sb);
+	desc_blocks = n_desc_blocks - o_desc_blocks;
+
+	if (desc_blocks &&
+	    (!EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_RESIZE_INODE) ||
+	     le16_to_cpu(es->s_reserved_gdt_blocks) < desc_blocks)) {
+		ext4_warning(sb, "No reserved GDT blocks, can't resize");
+		return -EPERM;
+	}
+
+	resize_inode = ext4_iget(sb, EXT4_RESIZE_INO);
+	if (IS_ERR(resize_inode)) {
+		ext4_warning(sb, "Error opening resize inode");
+		return PTR_ERR(resize_inode);
+	}
+
+	/* See if the device is actually as big as what was requested */
+	bh = sb_bread(sb, n_blocks_count - 1);
+	if (!bh) {
+		ext4_warning(sb, "can't read last block, resize aborted");
+		return -ENOSPC;
+	}
+	brelse(bh);
+
+	if (offset != 0) {
+		/* extend the last group */
+		ext4_grpblk_t add;
+		add = EXT4_BLOCKS_PER_GROUP(sb) - offset;
+		err = ext4_group_extend_no_check(sb, o_blocks_count, add);
+		if (err)
+			goto out;
+	}
+
+	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FLEX_BG) &&
+	    es->s_log_groups_per_flex)
+		flexbg_size = 1 << es->s_log_groups_per_flex;
+
+	o_blocks_count = ext4_blocks_count(es);
+	if (o_blocks_count == n_blocks_count)
+		goto out;
+
+	flex_gd = alloc_flex_gd(flexbg_size);
+	if (flex_gd == NULL) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	/* Add flex groups. Note that a regular group is a
+	 * flex group with 1 group.
+	 */
+	while (ext4_setup_next_flex_gd(sb, flex_gd, n_blocks_count,
+					      flexbg_size)) {
+		ext4_alloc_group_tables(sb, flex_gd, flexbg_size);
+		err = ext4_flex_group_add(sb, resize_inode, flex_gd);
+		if (unlikely(err))
+			break;
+	}
+
+out:
+	if (flex_gd)
+		free_flex_gd(flex_gd);
+
+	iput(resize_inode);
+	if (test_opt(sb, DEBUG))
+		printk(KERN_DEBUG "EXT4-fs: resized filesystem from %llu "
+		       "upto %llu blocks\n", o_blocks_count, n_blocks_count);
+	return err;
+}
