• Josef Bacik's avatar
    Btrfs: change how we unpin extents · 68b38550
    Josef Bacik authored
    We are racy with async block caching and unpinning extents.  This patch makes
    things much less complicated by only unpinning the extent if the block group is
    cached.  We check the block_group->cached var under the block_group->lock spin
    lock.  If it is set to BTRFS_CACHE_FINISHED then we update the pinned counters,
    and unpin the extent and add the free space back.  If it is not set to this, we
    start the caching of the block group so the next time we unpin extents we can
    unpin the extent.  This keeps us from racing with the async caching threads,
    lets us kill the fs wide async thread counter, and keeps us from having to set
    DELALLOC bits for every extent we hit if there are caching kthreads going.
    One thing that needed to be changed was btrfs_free_super_mirror_extents.  Now
    instead of just looking for LOCKED extents, we also look for DIRTY extents,
    since we could have left some extents pinned in the previous transaction that
    will never get freed now that we are unmounting, which would cause us to leak
    memory.  So btrfs_free_super_mirror_extents has been changed to
    btrfs_free_pinned_extents, and it will clear the extents locked for the super
    mirror, and any remaining pinned extents that may be present.  Thank you,
    Signed-off-by: default avatarJosef Bacik <jbacik@redhat.com>
    Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>