[PATCH v2 8/9] btrfs: consolidate uuid memcmp in btrfs_validate_super

[Anand Jain <anand.jain@oracle.com>]

There are three ways the fsid is validated in btrfs_validate_super():

First, it verifies that super_copy::fsid is the same as fs_devices::fsid.
Second, if the metadata_uuid flag is set, it verifies if
 super_copy::metadata_uuid and fs_devices::metadata_uuid are the same.
Third, a few lines below, often missed out, it verifies if dev_item::fsid
 is the same as fs_devices::metadata_uuid.

The function btrfs_validate_super() contains multiple if-statements with
memcmp() to check UUIDs. This patch consolidates them into a single
location.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v2: None.

 fs/btrfs/disk-io.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 6681e82900b0..d09f767c7bda 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2392,6 +2392,14 @@ int btrfs_validate_super(struct btrfs_fs_info *fs_info,
 		ret = -EINVAL;
 	}
 
+	if (memcmp(fs_info->fs_devices->metadata_uuid, sb->dev_item.fsid,
+		   BTRFS_FSID_SIZE) != 0) {
+		btrfs_err(fs_info,
+			"dev_item UUID does not match metadata fsid: %pU != %pU",
+			fs_info->fs_devices->metadata_uuid, sb->dev_item.fsid);
+		ret = -EINVAL;
+	}
+
 	/*
 	 * Artificial requirement for block-group-tree to force newer features
 	 * (free-space-tree, no-holes) so the test matrix is smaller.
@@ -2404,14 +2412,6 @@ int btrfs_validate_super(struct btrfs_fs_info *fs_info,
 		ret = -EINVAL;
 	}
 
-	if (memcmp(fs_info->fs_devices->metadata_uuid, sb->dev_item.fsid,
-		   BTRFS_FSID_SIZE) != 0) {
-		btrfs_err(fs_info,
-			"dev_item UUID does not match metadata fsid: %pU != %pU",
-			fs_info->fs_devices->metadata_uuid, sb->dev_item.fsid);
-		ret = -EINVAL;
-	}
-
 	/*
 	 * Hint to catch really bogus numbers, bitflips or so, more exact checks are
 	 * done later
-- 
2.38.1