Btrfs: check UUID tree during mount if required
If the filesystem was mounted with an old kernel that was not
aware of the UUID tree, this is detected by looking at the
uuid_tree_generation field of the superblock (similar to how
the free space cache is doing it). If a mismatch is detected
at mount time, a thread is started that does two things:
1. Iterate through the UUID tree, check each entry, delete those
entries that are not valid anymore (i.e., the subvol does not
exist anymore or the value changed).
2. Iterate through the root tree, for each found subvolume, add
the UUID tree entries for the subvolume (if they are not
already there).
This mechanism is also used to handle and repair errors that
happened during the initial creation and filling of the tree.
The update of the uuid_tree_generation field (which indicates
that the state of the UUID tree is up to date) is blocked until
all create and repair operations are successfully completed.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index e76237c..e0336b9 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1380,7 +1380,8 @@
super->root_level = root_item->level;
if (btrfs_test_opt(root, SPACE_CACHE))
super->cache_generation = root_item->generation;
- super->uuid_tree_generation = root_item->generation;
+ if (root->fs_info->update_uuid_tree_gen)
+ super->uuid_tree_generation = root_item->generation;
}
int btrfs_transaction_in_commit(struct btrfs_fs_info *info)