On Tue, Oct 11, 2022 at 10:50:09AM -0400, Sasha Levin wrote: > From: Qu Wenruo <wqu@xxxxxxxx> > > [ Upstream commit d7f67ac9a928fa158a95573406eac0a887bbc28c ] > > [BUG] > When one user did a wrong attempt to clear block group tree, which can > not be done through mount option, by using "-o clear_cache,space_cache=v2", > it will cause the following error on a fs with block-group-tree feature: > > BTRFS info (device dm-1): force clearing of disk cache > BTRFS info (device dm-1): using free space tree > BTRFS info (device dm-1): clearing free space tree > BTRFS info (device dm-1): clearing compat-ro feature flag for FREE_SPACE_TREE (0x1) > BTRFS info (device dm-1): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2) > BTRFS error (device dm-1): block-group-tree feature requires fres-space-tree and no-holes > BTRFS error (device dm-1): super block corruption detected before writing it to disk > BTRFS: error (device dm-1) in write_all_supers:4318: errno=-117 Filesystem corrupted (unexpected superblock corruption detected) > BTRFS warning (device dm-1: state E): Skipping commit of aborted transaction. > > [CAUSE] > Although the dependency for block-group-tree feature is just an > artificial one (to reduce test matrix), we put the dependency check into > btrfs_validate_super(). > > This is too strict, and during space cache clearing, we will have a > window where free space tree is cleared, and we need to commit the super > block. > > In that window, we had block group tree without v2 cache, and triggered > the artificial dependency check. > > This is not necessary at all, especially for such a soft dependency. > > [FIX] > Introduce a new helper, btrfs_check_features(), to do all the runtime > limitation checks, including: > > - Unsupported incompat flags check > > - Unsupported compat RO flags check > > - Setting missing incompat flags > > - Artificial feature dependency checks > Currently only block group tree will rely on this. > > - Subpage runtime check for v1 cache > > With this helper, we can move quite some checks from > open_ctree()/btrfs_remount() into it, and just call it after > btrfs_parse_options(). > > Now "-o clear_cache,space_cache=v2" will not trigger the above error > anymore. > > Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> > Reviewed-by: David Sterba <dsterba@xxxxxxxx> > [ edit messages ] > Signed-off-by: David Sterba <dsterba@xxxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> Please drop this from the stable queue, it's for an unreleased feature (ETA 6.1).
