From: Anand Jain <anand.jain@oracle.com>
Date: Thu, 12 Apr 2018 02:29:32 +0000 (+0800)
Subject: btrfs: document uuid_mutex uasge in read_chunk_tree
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=3dd0f7a3644eed9017f62ccd0067a91e8260d097;p=openwrt%2Fstaging%2Fblogic.git

btrfs: document uuid_mutex uasge in read_chunk_tree

read_chunk_tree() calls read_one_dev(), but for seed device we have
to search the fs_uuids list, so we need the uuid_mutex. Add a comment
comment, so that we can improve this part.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a382d53c560a..6eec1e3f9083 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6932,6 +6932,10 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 	if (!path)
 		return -ENOMEM;
 
+	/*
+	 * uuid_mutex is needed only if we are mounting a sprout FS
+	 * otherwise we don't need it.
+	 */
 	mutex_lock(&uuid_mutex);
 	mutex_lock(&fs_info->chunk_mutex);