commit ca0e05e4b15193aeba72b995e90de990db7f8304
Author: Dmitry Monakhov <dmonakhov@openvz.org>
Date:   Sun Aug 1 17:48:36 2010 -0400

    ext4: force block allocation on quota_off
    
    Perform full sync procedure so that any delayed allocation blocks are
    allocated so quota will be consistent.
    
    Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
    Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Index: linux-stage/fs/ext4/super.c
===================================================================
--- linux-stage.orig/fs/ext4/super.c	2012-06-26 09:37:06.039508000 +0200
+++ linux-stage/fs/ext4/super.c	2012-06-26 11:35:09.824099000 +0200
@@ -1104,6 +1104,7 @@ static int ext4_mark_dquot_dirty(struct
 static int ext4_write_info(struct super_block *sb, int type);
 static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 				char *path, int remount);
+static int ext4_quota_off(struct super_block *sb, int type, int remount);
 static int ext4_quota_on_mount(struct super_block *sb, int type);
 static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
 			       size_t len, loff_t off);
@@ -1173,7 +1174,7 @@ static const struct dquot_operations ext
 
 static const struct quotactl_ops ext4_qctl_operations = {
 	.quota_on	= ext4_quota_on,
-	.quota_off	= vfs_quota_off,
+	.quota_off	= ext4_quota_off,
 	.quota_sync	= vfs_quota_sync,
 	.get_info	= vfs_get_dqinfo,
 	.set_info	= vfs_set_dqinfo,
@@ -4578,6 +4579,28 @@ static int ext4_quota_on(struct super_bl
 	return err;
 }
 
+static int ext4_quota_off(struct super_block *sb, int type, int remount)
+{
+	struct quota_info *dqopt = sb_dqopt(sb);
+
+	mutex_lock(&dqopt->dqonoff_mutex);
+	if (!sb_any_quota_loaded(sb)) {
+		/* nothing to do */
+		mutex_unlock(&dqopt->dqonoff_mutex);
+		return 0;
+	}
+	mutex_unlock(&dqopt->dqonoff_mutex);
+
+	/* Force all delayed allocation blocks to be allocated. */
+	if (test_opt(sb, DELALLOC)) {
+		down_read(&sb->s_umount);
+		sync_filesystem(sb);
+		up_read(&sb->s_umount);
+	}
+
+	return vfs_quota_off(sb, type, remount);
+}
+
 /* Read data from quotafile - avoid pagecache and such because we cannot afford
  * acquiring the locks... As quota files are never truncated and quota code
  * itself serializes the operations (and noone else should touch the files)