• Josef Bacik's avatar
    Btrfs: keep dropped roots in cache until transaction commit · 2b9dbef2
    Josef Bacik authored
    When dropping a snapshot we need to account for the qgroup changes.  If we drop
    the snapshot in all one go then the backref code will fail to find blocks from
    the snapshot we dropped since it won't be able to find the root in the fs root
    cache.  This can lead to us failing to find refs from other roots that pointed
    at blocks in the now deleted root.  To handle this we need to not remove the fs
    roots from the cache until after we process the qgroup operations.  Do this by
    adding dropped roots to a list on the transaction, and letting the transaction
    remove the roots at the same time it drops the commit roots.  This will keep all
    of the backref searching code in sync properly, and fixes a problem Mark was
    seeing with snapshot delete and qgroups.  Thanks,
    Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
    Tested-by: default avatarHolger Hoffstätte <holger.hoffstaette@googlemail.com>
    Signed-off-by: default avatarChris Mason <clm@fb.com>