ceturtd., 2021. g. 18. marts, plkst. 01:49 — lietotājs Qu Wenruo (<[email protected]>) rakstīja: > > > > On 2021/3/18 上午5:03, Dāvis Mosāns wrote: > > trešd., 2021. g. 17. marts, plkst. 12:28 — lietotājs Qu Wenruo > > (<[email protected]>) rakstīja: > >> > >> > >> > >> On 2021/3/17 上午9:29, Dāvis Mosāns wrote: > >>> trešd., 2021. g. 17. marts, plkst. 03:18 — lietotājs Dāvis Mosāns > >>> (<[email protected]>) rakstīja: > >>>> > >>>> Currently if there's any corruption at all in extent tree > >>>> (eg. even single bit) then mounting will fail with: > >>>> "failed to read block groups: -5" (-EIO) > >>>> It happens because we immediately abort on first error when > >>>> searching in extent tree for block groups. > >>>> > >>>> Now with this patch if `ignorebadroots` option is specified > >>>> then we handle such case and continue by removing already > >>>> created block groups and creating dummy block groups. > >>>> > >>>> Signed-off-by: Dāvis Mosāns <[email protected]> > >>>> --- > >>>> fs/btrfs/block-group.c | 14 ++++++++++++++ > >>>> fs/btrfs/disk-io.c | 4 ++-- > >>>> fs/btrfs/disk-io.h | 2 ++ > >>>> 3 files changed, 18 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c > >>>> index 48ebc106a606..827a977614b3 100644 > >>>> --- a/fs/btrfs/block-group.c > >>>> +++ b/fs/btrfs/block-group.c > >>>> @@ -2048,6 +2048,20 @@ int btrfs_read_block_groups(struct btrfs_fs_info > >>>> *info) > >>>> ret = check_chunk_block_group_mappings(info); > >>>> error: > >>>> btrfs_free_path(path); > >>>> + > >>>> + if (ret == -EIO && btrfs_test_opt(info, IGNOREBADROOTS)) { > >>>> + btrfs_put_block_group_cache(info); > >>>> + btrfs_stop_all_workers(info); > >>>> + btrfs_free_block_groups(info); > >>>> + ret = btrfs_init_workqueues(info, NULL); > >>>> + if (ret) > >>>> + return ret; > >>>> + ret = btrfs_init_space_info(info); > >>>> + if (ret) > >>>> + return ret; > >>>> + return fill_dummy_bgs(info); > >> > >> When we hit bad things in extent tree, we should ensure we're mounting > >> the fs RO, or we can't continue. > >> > >> And we should also refuse to mount back to RW if we hit such case, so > >> that we don't need anything complex, just ignore the whole extent tree > >> and create the dummy block groups. > >> > > > > That's what we're doing here, `ignorebadroots` implies RO mount and > > without specifying it doesn't mount at all. > > > >>> > >>> This isn't that nice, but I don't really know how to properly clean up > >>> everything related to already created block groups so this was easiest > >>> way. It seems to work fine. > >>> But looks like need to do something about replay log aswell because if > >>> it's not disabled then it fails with: > >>> > >>> [ 1397.246869] BTRFS info (device sde): start tree-log replay > >>> [ 1398.218685] BTRFS warning (device sde): sde checksum verify failed > >>> on 21057127661568 wanted 0xd1506ed9 found 0x22ab750a level 0 > >>> [ 1398.218803] BTRFS warning (device sde): sde checksum verify failed > >>> on 21057127661568 wanted 0xd1506ed9 found 0x7dd54bb9 level 0 > >>> [ 1398.218813] BTRFS: error (device sde) in __btrfs_free_extent:3054: > >>> errno=-5 IO failure > >>> [ 1398.218828] BTRFS: error (device sde) in > >>> btrfs_run_delayed_refs:2124: errno=-5 IO failure > >>> [ 1398.219002] BTRFS: error (device sde) in btrfs_replay_log:2254: > >>> errno=-5 IO failure (Failed to recover log tree) > >>> [ 1398.229048] BTRFS error (device sde): open_ctree failed > >> > >> This is because we shouldn't allow to do anything write to the fs if we > >> have anything wrong in extent tree. > >> > > > > This is happening when mounting read-only. My assumption is that it > > only tries to replay in memory without writing anything to disk. > > > > We lacks the check on log tree. > > Normally for such forced RO mount, log replay is not allowed. > > We should output a warning to prompt user to use nologreplay, and reject > the mount. >
I'm not familiar with log replay but couldn't there be something useful (ignoring ref counts) that would still be worth replaying in memory?
