ocfs2: Fix NULL pointer deref when writing local dquot

commit_dqblk() can write quota info to global file. That is actually a bad
thing to do because if we are just modifying local quota file, we are not
prepared (do not hold proper locks, do not have transaction credits) to do
a modification of the global quota file. So do not use commit_dqblk() and
instead call our writing function directly.

Acked-by: Joel Becker <Joel.Becker@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ocfs2/quota.h b/fs/ocfs2/quota.h
index 903ffa93..196fcb5 100644
--- a/fs/ocfs2/quota.h
+++ b/fs/ocfs2/quota.h
@@ -109,6 +109,7 @@
 				struct buffer_head **bh);
 int ocfs2_create_local_dquot(struct dquot *dquot);
 int ocfs2_local_release_dquot(handle_t *handle, struct dquot *dquot);
+int ocfs2_local_write_dquot(struct dquot *dquot);
 
 extern const struct dquot_operations ocfs2_quota_operations;
 extern struct quota_format_type ocfs2_quota_format;