• Liu Bo's avatar
    Btrfs: fix tree corruption after multi-thread snapshots and inode_cache flush · f1ebcc74
    Liu Bo authored
    The btrfs snapshotting code requires that once a root has been
    snapshotted, we don't change it during a commit.
    
    But there are two cases to lead to tree corruptions:
    
    1) multi-thread snapshots can commit serveral snapshots in a transaction,
       and this may change the src root when processing the following pending
       snapshots, which lead to the former snapshots corruptions;
    
    2) the free inode cache was changing the roots when it root the cache,
       which lead to corruptions.
    
    This fixes things by making sure we force COW the block after we create a
    snapshot during commiting a transaction, then any changes to the roots
    will result in COW, and we get all the fs roots and snapshot roots to be
    consistent.
    Signed-off-by: default avatarLiu Bo <liubo2009@cn.fujitsu.com>
    Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
    Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
    f1ebcc74
transaction.c 36.3 KB