Index: linux-stage/fs/ext4/ext4.h
===================================================================
--- linux-stage.orig/fs/ext4/ext4.h	2012-08-07 11:52:38.994200699 -0700
+++ linux-stage/fs/ext4/ext4.h	2012-08-07 12:28:19.497442862 -0700
@@ -706,6 +707,9 @@
 	__u32	i_dtime;
 	ext4_fsblk_t	i_file_acl;
 
+	/* following fields for parallel directory operations -bzzz */
+	struct semaphore i_append_sem;
+
 	/*
 	 * i_block_group is the number of the block group which contains
 	 * this file's inode.  Constant across the lifetime of the inode,
Index: linux-stage/fs/ext4/namei.c
===================================================================
--- linux-stage.orig/fs/ext4/namei.c	2012-08-07 11:52:38.992199430 -0700
+++ linux-stage/fs/ext4/namei.c	2012-08-07 12:27:24.845281099 -0700
@@ -53,6 +53,11 @@
 					ext4_lblk_t *block, int *err)
 {
 	struct buffer_head *bh;
+	struct ext4_inode_info *ei = EXT4_I(inode);
+
+	/* with parallel dir operations all appends
+	* have to be serialized -bzzz */
+	down(&ei->i_append_sem);
 
 	*block = inode->i_size >> inode->i_sb->s_blocksize_bits;
 
@@ -65,7 +70,9 @@
 			brelse(bh);
 			bh = NULL;
 		}
+		ei->i_disksize = inode->i_size;
 	}
+	up(&ei->i_append_sem);
 	return bh;
 }
 
Index: linux-stage/fs/ext4/super.c
===================================================================
--- linux-stage.orig/fs/ext4/super.c	2012-08-07 11:52:39.009197356 -0700
+++ linux-stage/fs/ext4/super.c	2012-08-07 12:28:29.499112997 -0700
@@ -749,6 +749,7 @@
 
 	ei->vfs_inode.i_version = 1;
 	ei->vfs_inode.i_data.writeback_index = 0;
+	sema_init(&ei->i_append_sem, 1);
 	memset(&ei->i_cached_extent, 0, sizeof(struct ext4_ext_cache));
 	INIT_LIST_HEAD(&ei->i_prealloc_list);
 	spin_lock_init(&ei->i_prealloc_lock);