Index: linux-stage/fs/ext4/super.c
===================================================================
--- linux-stage.orig/fs/ext4/super.c	2011-03-11 15:46:27.000000000 +0800
+++ linux-stage/fs/ext4/super.c	2011-03-11 15:53:05.016701579 +0800
@@ -1400,9 +1400,47 @@
 static ssize_t ext4_quota_write(struct super_block *sb, int type,
 				const char *data, size_t len, loff_t off);
 
+static int ext4_dquot_initialize(struct inode *inode, int type)
+{
+	handle_t *handle;
+	int ret, err;
+
+	/* We may create quota structure so we need to reserve enough blocks */
+	handle = ext4_journal_start(inode, 2*EXT4_QUOTA_INIT_BLOCKS(inode->i_sb));
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+	ret = dquot_initialize(inode, type);
+	err = ext4_journal_stop(handle);
+	if (!ret)
+		ret = err;
+	return ret;
+}
+
+static int ext4_dquot_drop(struct inode *inode)
+{
+	handle_t *handle;
+	int ret, err;
+
+	/* We may delete quota structure so we need to reserve enough blocks */
+	handle = ext4_journal_start(inode, 2*EXT4_QUOTA_DEL_BLOCKS(inode->i_sb));
+	if (IS_ERR(handle)) {
+		/*
+		 * We call dquot_drop() anyway to at least release references
+		 * to quota structures so that umount does not hang.
+		 */
+		dquot_drop(inode);
+		return PTR_ERR(handle);
+	}
+	ret = dquot_drop(inode);
+	err = ext4_journal_stop(handle);
+	if (!ret)
+		ret = err;
+	return ret;
+}
+
 static const struct dquot_operations ext4_quota_operations = {
-	.initialize	= dquot_initialize,
-	.drop		= dquot_drop,
+	.initialize	= ext4_dquot_initialize,
+	.drop		= ext4_dquot_drop,
 	.alloc_space	= dquot_alloc_space,
 	.reserve_space	= dquot_reserve_space,
 	.claim_space	= dquot_claim_space,