quota: Acquire dqio_sem for reading in vfs_load_quota_inode()

vfs_load_quota_inode() needs dqio_sem only for reading. In fact dqio_sem
is not needed there at all since the function can be called only during
quota on when quota file cannot be modified but let's leave the
protection there since it is logical and the path is in no way
performance critical.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ocfs2/quota_local.c

@@ -693,7 +693,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
 
 	/* We don't need the lock and we have to acquire quota file locks
 	 * which will later depend on this lock */
-	up_write(&sb_dqopt(sb)->dqio_sem);
+	up_read(&sb_dqopt(sb)->dqio_sem);
 	info->dqi_max_spc_limit = 0x7fffffffffffffffLL;
 	info->dqi_max_ino_limit = 0x7fffffffffffffffLL;
 	oinfo = kmalloc(sizeof(struct ocfs2_mem_dqinfo), GFP_NOFS);
@@ -772,7 +772,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
 		goto out_err;
 	}
 
-	down_write(&sb_dqopt(sb)->dqio_sem);
+	down_read(&sb_dqopt(sb)->dqio_sem);
 	return 0;
 out_err:
 	if (oinfo) {
@@ -786,7 +786,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
 		kfree(oinfo);
 	}
 	brelse(bh);
-	down_write(&sb_dqopt(sb)->dqio_sem);
+	down_read(&sb_dqopt(sb)->dqio_sem);
 	return -1;
 }
 

fs/quota/dquot.c

@@ -2331,15 +2331,15 @@ static int vfs_load_quota_inode(struct inode *inode, int type, int format_id,
 	dqopt->info[type].dqi_format = fmt;
 	dqopt->info[type].dqi_fmt_id = format_id;
 	INIT_LIST_HEAD(&dqopt->info[type].dqi_dirty_list);
-	down_write(&dqopt->dqio_sem);
+	down_read(&dqopt->dqio_sem);
 	error = dqopt->ops[type]->read_file_info(sb, type);
 	if (error < 0) {
-		up_write(&dqopt->dqio_sem);
+		up_read(&dqopt->dqio_sem);
 		goto out_file_init;
 	}
 	if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
 		dqopt->info[type].dqi_flags |= DQF_SYS_FILE;
-	up_write(&dqopt->dqio_sem);
+	up_read(&dqopt->dqio_sem);
 	spin_lock(&dq_state_lock);
 	dqopt->flags |= dquot_state_flag(flags, type);
 	spin_unlock(&dq_state_lock);