ext4: fix quota charging for shared xattr blocks

ext4_xattr_block_set() calls dquot_alloc_block() to charge for an xattr
block when new references are made. However if dquot_initialize() hasn't
been called on an inode, request for charging is effectively ignored
because ext4_inode_info->i_dquot is not initialized yet.

Add dquot_initialize() to call paths that lead to ext4_xattr_block_set().

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index 9c6f768..dda22f4 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -44,6 +44,7 @@ void inode_sub_rsv_space(struct inode *inode, qsize_t number);
 void inode_reclaim_rsv_space(struct inode *inode, qsize_t number);
 
 int dquot_initialize(struct inode *inode);
+bool dquot_initialize_needed(struct inode *inode);
 void dquot_drop(struct inode *inode);
 struct dquot *dqget(struct super_block *sb, struct kqid qid);
 static inline struct dquot *dqgrab(struct dquot *dquot)
@@ -207,6 +208,11 @@ static inline int dquot_initialize(struct inode *inode)
 	return 0;
 }
 
+static inline bool dquot_initialize_needed(struct inode *inode)
+{
+	return false;
+}
+
 static inline void dquot_drop(struct inode *inode)
 {
 }