• Josef Bacik's avatar
    Btrfs: remove empty block groups automatically · 47ab2a6c
    Josef Bacik authored
    One problem that has plagued us is that a user will use up all of his space with
    data, remove a bunch of that data, and then try to create a bunch of small files
    and run out of space.  This happens because all the chunks were allocated for
    data since the metadata requirements were so low.  But now there's a bunch of
    empty data block groups and not enough metadata space to do anything.  This
    patch solves this problem by automatically deleting empty block groups.  If we
    notice the used count go down to 0 when deleting or on mount notice that a block
    group has a used count of 0 then we will queue it to be deleted.
    
    When the cleaner thread runs we will double check to make sure the block group
    is still empty and then we will delete it.  This patch has the side effect of no
    longer having a bunch of BUG_ON()'s in the chunk delete code, which will be
    helpful for both this and relocate.  Thanks,
    Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
    Signed-off-by: default avatarChris Mason <clm@fb.com>
    47ab2a6c
disk-io.c 113 KB