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  • Yan Zheng's avatar
    Btrfs: Improve space balancing code · f82d02d9
    Yan Zheng authored
    This patch improves the space balancing code to keep more sharing
    of tree blocks. The only case that breaks sharing of tree blocks is
    data extents get fragmented during balancing. The main changes in
    this patch are:
    Add a 'drop sub-tree' function. This solves the problem in old code
    that BTRFS_HEADER_FLAG_WRITTEN check breaks sharing of tree block.
    Remove relocation mapping tree. Relocation mappings are stored in
    struct btrfs_ref_path and updated dynamically during walking up/down
    the reference path. This reduces CPU usage and simplifies code.
    This patch also fixes a bug. Root items for reloc trees should be
    updated in btrfs_free_reloc_root.
    Signed-off-by: default avatarYan Zheng <>