diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index d460223b8e1d43b57f575eccb4c04ff4f5238745..7ae223ed152f6eaff9ed62c22dd8b31ef29f8cce 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -526,7 +526,7 @@ static inline int rsv_is_empty(struct ext4_reserve_window *rsv)
  * when setting the reservation window size through ioctl before the file
  * is open for write (needs block allocation).
  *
- * Needs truncate_mutex protection prior to call this function.
+ * Needs down_write(i_data_sem) protection prior to call this function.
  */
 void ext4_init_block_alloc_info(struct inode *inode)
 {
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ec5019fa552f96f4abcb821b1de6c6c989b3e43a..03d1bbb78a2ffac7f86016db6769578f6e107fe4 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1565,7 +1565,7 @@ static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
  * This routine returns max. credits that the extent tree can consume.
  * It should be OK for low-performance paths like ->writepage()
  * To allow many writing processes to fit into a single transaction,
- * the caller should calculate credits under truncate_mutex and
+ * the caller should calculate credits under i_data_sem and
  * pass the actual path.
  */
 int ext4_ext_calc_credits_for_insert(struct inode *inode,
@@ -2131,7 +2131,8 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 
 /*
  * Need to be called with
- * mutex_lock(&EXT4_I(inode)->truncate_mutex);
+ * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
+ * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
  */
 int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
 			ext4_lblk_t iblock,
@@ -2350,7 +2351,7 @@ void ext4_ext_truncate(struct inode * inode, struct page *page)
 	if (page)
 		ext4_block_truncate_page(handle, page, mapping, inode->i_size);
 
-	mutex_lock(&EXT4_I(inode)->truncate_mutex);
+	down_write(&EXT4_I(inode)->i_data_sem);
 	ext4_ext_invalidate_cache(inode);
 
 	/*
@@ -2386,7 +2387,7 @@ void ext4_ext_truncate(struct inode * inode, struct page *page)
 	if (inode->i_nlink)
 		ext4_orphan_del(handle, inode);
 
-	mutex_unlock(&EXT4_I(inode)->truncate_mutex);
+	up_write(&EXT4_I(inode)->i_data_sem);
 	ext4_journal_stop(handle);
 }
 
@@ -2450,7 +2451,7 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
 	 * modify 1 super block, 1 block bitmap and 1 group descriptor.
 	 */
 	credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + 3;
-	mutex_lock(&EXT4_I(inode)->truncate_mutex)
+	down_write((&EXT4_I(inode)->i_data_sem));
 retry:
 	while (ret >= 0 && ret < max_blocks) {
 		block = block + ret;
@@ -2507,7 +2508,7 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
 	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 		goto retry;
 
-	mutex_unlock(&EXT4_I(inode)->truncate_mutex)
+	up_write((&EXT4_I(inode)->i_data_sem));
 	/*
 	 * Time to update the file size.
 	 * Update only when preallocation was requested beyond the file size.
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index a6b2aa14626eaadcdd7334367f3898af26a3caab..ac35ec58db55c9e9fe4b4d3effde74274b614b25 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -37,9 +37,9 @@ static int ext4_release_file (struct inode * inode, struct file * filp)
 	if ((filp->f_mode & FMODE_WRITE) &&
 			(atomic_read(&inode->i_writecount) == 1))
 	{
-		mutex_lock(&EXT4_I(inode)->truncate_mutex);
+		down_write(&EXT4_I(inode)->i_data_sem);
 		ext4_discard_reservation(inode);
-		mutex_unlock(&EXT4_I(inode)->truncate_mutex);
+		up_write(&EXT4_I(inode)->i_data_sem);
 	}
 	if (is_dx(inode) && filp->private_data)
 		ext4_htree_free_dir_info(filp->private_data);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 71c7ad0c6723abdc2601889fa68666ae0cf0cbda..a7eb8bb4bdd4afa7b864789e63dcca52df6cd0a8 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -308,7 +308,7 @@ static int ext4_block_to_path(struct inode *inode,
 		final = ptrs;
 	} else {
 		ext4_warning(inode->i_sb, "ext4_block_to_path",
-				"block %u > max",
+				"block %lu > max",
 				i_block + direct_blocks +
 				indirect_blocks + double_blocks);
 	}
@@ -345,7 +345,7 @@ static int ext4_block_to_path(struct inode *inode,
  *	the whole chain, all way to the data (returns %NULL, *err == 0).
  *
  *      Need to be called with
- *      mutex_lock(&EXT4_I(inode)->truncate_mutex)
+ *      down_read(&EXT4_I(inode)->i_data_sem)
  */
 static Indirect *ext4_get_branch(struct inode *inode, int depth,
 				 ext4_lblk_t  *offsets,
@@ -777,7 +777,8 @@ static int ext4_splice_branch(handle_t *handle, struct inode *inode,
  *
  *
  * Need to be called with
- * mutex_lock(&EXT4_I(inode)->truncate_mutex)
+ * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
+ * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
  */
 int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
 		ext4_lblk_t iblock, unsigned long maxblocks,
@@ -865,7 +866,7 @@ int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
 		err = ext4_splice_branch(handle, inode, iblock,
 					partial, indirect_blks, count);
 	/*
-	 * i_disksize growing is protected by truncate_mutex.  Don't forget to
+	 * i_disksize growing is protected by i_data_sem.  Don't forget to
 	 * protect it if you're about to implement concurrent
 	 * ext4_get_block() -bzzz
 	*/
@@ -895,6 +896,31 @@ int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
 
 #define DIO_CREDITS (EXT4_RESERVE_TRANS_BLOCKS + 32)
 
+int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
+			unsigned long max_blocks, struct buffer_head *bh,
+			int create, int extend_disksize)
+{
+	int retval;
+	if (create) {
+		down_write((&EXT4_I(inode)->i_data_sem));
+	} else {
+		down_read((&EXT4_I(inode)->i_data_sem));
+	}
+	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
+		retval =  ext4_ext_get_blocks(handle, inode, block, max_blocks,
+				bh, create, extend_disksize);
+	} else {
+		retval = ext4_get_blocks_handle(handle, inode, block,
+				max_blocks, bh, create, extend_disksize);
+	}
+	if (create) {
+		up_write((&EXT4_I(inode)->i_data_sem));
+	} else {
+		up_read((&EXT4_I(inode)->i_data_sem));
+	}
+	return retval;
+}
+
 static int ext4_get_block(struct inode *inode, sector_t iblock,
 			struct buffer_head *bh_result, int create)
 {
@@ -1399,7 +1425,7 @@ static int jbd2_journal_dirty_data_fn(handle_t *handle, struct buffer_head *bh)
  *	ext4_file_write() -> generic_file_write() -> __alloc_pages() -> ...
  *
  * Same applies to ext4_get_block().  We will deadlock on various things like
- * lock_journal and i_truncate_mutex.
+ * lock_journal and i_data_sem
  *
  * Setting PF_MEMALLOC here doesn't work - too many internal memory
  * allocations fail.
@@ -2325,7 +2351,7 @@ void ext4_truncate(struct inode *inode)
 	 * From here we block out all ext4_get_block() callers who want to
 	 * modify the block allocation tree.
 	 */
-	mutex_lock(&ei->truncate_mutex);
+	down_write(&ei->i_data_sem);
 
 	if (n == 1) {		/* direct blocks */
 		ext4_free_data(handle, inode, NULL, i_data+offsets[0],
@@ -2389,7 +2415,7 @@ void ext4_truncate(struct inode *inode)
 
 	ext4_discard_reservation(inode);
 
-	mutex_unlock(&ei->truncate_mutex);
+	up_write(&ei->i_data_sem);
 	inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
 	ext4_mark_inode_dirty(handle, inode);
 
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index e7f894bdb4202359974088ba5c1f14585a43fc03..c0e5b8cf635c65aec9db57e0163308ae4808ed29 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -199,7 +199,7 @@ int ext4_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
 		 * need to allocate reservation structure for this inode
 		 * before set the window size
 		 */
-		mutex_lock(&ei->truncate_mutex);
+		down_write(&ei->i_data_sem);
 		if (!ei->i_block_alloc_info)
 			ext4_init_block_alloc_info(inode);
 
@@ -207,7 +207,7 @@ int ext4_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
 			struct ext4_reserve_window_node *rsv = &ei->i_block_alloc_info->rsv_window_node;
 			rsv->rsv_goal_size = rsv_window_size;
 		}
-		mutex_unlock(&ei->truncate_mutex);
+		up_write(&ei->i_data_sem);
 		return 0;
 	}
 	case EXT4_IOC_GROUP_EXTEND: {
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index effd375ece8049b55135c6444df3c31e6be557ab..c7305443e1004ec154d9c0b733fe94e166187ecf 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -593,7 +593,7 @@ static void init_once(struct kmem_cache *cachep, void *foo)
 #ifdef CONFIG_EXT4DEV_FS_XATTR
 	init_rwsem(&ei->xattr_sem);
 #endif
-	mutex_init(&ei->truncate_mutex);
+	init_rwsem(&ei->i_data_sem);
 	inode_init_once(&ei->vfs_inode);
 }
 
diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index 583049c1d366120aabd20ffd0da0b16e64d148ab..300cc5a5adb95a714fb7dd9a9ec05c5a9beb6d8a 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -1107,27 +1107,10 @@ extern void ext4_ext_init(struct super_block *);
 extern void ext4_ext_release(struct super_block *);
 extern long ext4_fallocate(struct inode *inode, int mode, loff_t offset,
 			  loff_t len);
-static inline int
-ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
-			unsigned long max_blocks, struct buffer_head *bh,
-			int create, int extend_disksize)
-{
-	int retval;
-	mutex_lock(&EXT4_I(inode)->truncate_mutex);
-	if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
-		retval = ext4_ext_get_blocks(handle, inode,
-						(ext4_lblk_t)block, max_blocks,
-						bh, create, extend_disksize);
-	} else {
-		retval = ext4_get_blocks_handle(handle, inode,
-						(ext4_lblk_t)block, max_blocks,
-						bh, create, extend_disksize);
-	}
-	mutex_unlock(&EXT4_I(inode)->truncate_mutex);
-	return retval;
-}
-
-
+extern int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode,
+			sector_t block, unsigned long max_blocks,
+			struct buffer_head *bh, int create,
+			int extend_disksize);
 #endif	/* __KERNEL__ */
 
 #endif	/* _LINUX_EXT4_FS_H */
diff --git a/include/linux/ext4_fs_i.h b/include/linux/ext4_fs_i.h
index f1cd4934e46f3284a77c03043d4f7b55afed91af..4377d249d3789700b114189413f053833d70cb26 100644
--- a/include/linux/ext4_fs_i.h
+++ b/include/linux/ext4_fs_i.h
@@ -139,16 +139,16 @@ struct ext4_inode_info {
 	__u16 i_extra_isize;
 
 	/*
-	 * truncate_mutex is for serialising ext4_truncate() against
+	 * i_data_sem is for serialising ext4_truncate() against
 	 * ext4_getblock().  In the 2.4 ext2 design, great chunks of inode's
 	 * data tree are chopped off during truncate. We can't do that in
 	 * ext4 because whenever we perform intermediate commits during
 	 * truncate, the inode and all the metadata blocks *must* be in a
 	 * consistent state which allows truncation of the orphans to restart
 	 * during recovery.  Hence we must fix the get_block-vs-truncate race
-	 * by other means, so we have truncate_mutex.
+	 * by other means, so we have i_data_sem.
 	 */
-	struct mutex truncate_mutex;
+	struct rw_semaphore i_data_sem;
 	struct inode vfs_inode;
 
 	unsigned long i_ext_generation;