f2fs: quota: decrease the lock granularity of statfs_project

According to fs/quota/dquot.c, `dq_data_lock' protects mem_dqinfo
structures and modifications of dquot pointers in the inode, and
`dquot->dq_dqb_lock' protects data from dq_dqb.

We should use dquot->dq_dqb_lock in statfs_project instead of
dq_dat_lock.
Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/super.c

@@ -1117,7 +1117,7 @@ static int f2fs_statfs_project(struct super_block *sb,
 	dquot = dqget(sb, qid);
 	if (IS_ERR(dquot))
 		return PTR_ERR(dquot);
-	spin_lock(&dq_data_lock);
+	spin_lock(&dquot->dq_dqb_lock);
 
 	limit = (dquot->dq_dqb.dqb_bsoftlimit ?
 		 dquot->dq_dqb.dqb_bsoftlimit :
@@ -1140,7 +1140,7 @@ static int f2fs_statfs_project(struct super_block *sb,
 			 (buf->f_files - dquot->dq_dqb.dqb_curinodes) : 0;
 	}
 
-	spin_unlock(&dq_data_lock);
+	spin_unlock(&dquot->dq_dqb_lock);
 	dqput(dquot);
 	return 0;
 }