Hello, Here is the second version of the tree reading code which gets executed during mount. This goes a bit further than the previous posting in that it not only introduces a new function but also refactors the code which decides which backup root to use. Overall I think the semantics are now much cleaner and centralised in a single function - init_tree_roots rather than split between mount and backup root write out. The series starts gradually by simplifying find_newest_super_backup and its callers (patches 1-2). It then paves the way forward by introducing read_backup_rooti (patch 3) which supersedes (patch 4) next_root_backup, the latter is then removed (patch 6). While at it I also remove the unnecessary objectid mutex during mount (patch 5). The final 2 patches streamlines how btrfs_fs_info::backup_root_index is being initialised. This patchset has been tested by simulating (via btrfs-corrupt-block) corruption of the primary root and resorting to using usebackuproot mount option. I've also added a regression test to btrfs-progs that will follow shortly. Nikolay Borisov (8): btrfs: Cleanup and simplify find_newest_super_backup btrfs: Remove newest_gen argument from find_oldest_super_backup btrfs: Add read_backup_root btrfs: Factor out tree roots initialization during mount btrfs: Don't use objectid_mutex during mount btrfs: Remove unused next_root_backup function btrfs: Rename find_oldest_super_backup to init_backup_root_slot btrfs: Streamline btrfs_fs_info::backup_root_index semantics fs/btrfs/disk-io.c | 252 ++++++++++++++++++++------------------------- 1 file changed, 113 insertions(+), 139 deletions(-) -- 2.17.1
