quota: Push dqio_sem down to ->write_dqblk()

Push down acquisition of dqio_sem into ->write_dqblk() callback. It will
allow quota formats to decide whether they need it or not.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/dquot.c

@@ -412,14 +412,14 @@ int dquot_acquire(struct dquot *dquot)
 	set_bit(DQ_READ_B, &dquot->dq_flags);
 	/* Instantiate dquot if needed */
 	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && !dquot->dq_off) {
-		down_write(&dqopt->dqio_sem);
 		ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
 		/* Write the info if needed */
 		if (info_dirty(&dqopt->info[dquot->dq_id.type])) {
+			down_write(&dqopt->dqio_sem);
 			ret2 = dqopt->ops[dquot->dq_id.type]->write_file_info(
 					dquot->dq_sb, dquot->dq_id.type);
+			up_write(&dqopt->dqio_sem);
 		}
-		up_write(&dqopt->dqio_sem);
 		if (ret < 0)
 			goto out_iolock;
 		if (ret2 < 0) {
@@ -456,13 +456,10 @@ int dquot_commit(struct dquot *dquot)
 	spin_unlock(&dq_list_lock);
 	/* Inactive dquot can be only if there was error during read/init
 	 * => we have better not writing it */
-	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
-		down_write(&dqopt->dqio_sem);
+	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
 		ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
-		up_write(&dqopt->dqio_sem);
-	} else {
+	else
 		ret = -EIO;
-	}
 out_lock:
 	mutex_unlock(&dquot->dq_lock);
 	return ret;

fs/quota/quota_v1.c

@@ -83,7 +83,9 @@ static int v1_commit_dqblk(struct dquot *dquot)
 	short type = dquot->dq_id.type;
 	ssize_t ret;
 	struct v1_disk_dqblk dqblk;
+	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
 
+	down_write(&dqopt->dqio_sem);
 	v1_mem2disk_dqblk(&dqblk, &dquot->dq_dqb);
 	if (((type == USRQUOTA) && uid_eq(dquot->dq_id.uid, GLOBAL_ROOT_UID)) ||
 	    ((type == GRPQUOTA) && gid_eq(dquot->dq_id.gid, GLOBAL_ROOT_GID))) {
@@ -97,6 +99,7 @@ static int v1_commit_dqblk(struct dquot *dquot)
 		ret = dquot->dq_sb->s_op->quota_write(dquot->dq_sb, type,
 			(char *)&dqblk, sizeof(struct v1_disk_dqblk),
 			v1_dqoff(from_kqid(&init_user_ns, dquot->dq_id)));
+	up_write(&dqopt->dqio_sem);
 	if (ret != sizeof(struct v1_disk_dqblk)) {
 		quota_error(dquot->dq_sb, "dquota write failed");
 		if (ret >= 0)

fs/quota/quota_v2.c

@@ -298,7 +298,15 @@ static int v2_read_dquot(struct dquot *dquot)
 
 static int v2_write_dquot(struct dquot *dquot)
 {
-	return qtree_write_dquot(sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv, dquot);
+	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
+	int ret;
+
+	down_write(&dqopt->dqio_sem);
+	ret = qtree_write_dquot(
+			sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv,
+			dquot);
+	up_write(&dqopt->dqio_sem);
+	return ret;
 }
 
 static int v2_release_dquot(struct dquot *dquot)