On Mon, Apr 19, 2021 at 04:41:02PM +0900, Johannes Thumshirn wrote: > +void btrfs_reclaim_bgs_work(struct work_struct *work) > +{ > + struct btrfs_fs_info *fs_info = > + container_of(work, struct btrfs_fs_info, reclaim_bgs_work); > + struct btrfs_block_group *bg; > + struct btrfs_space_info *space_info; > + int ret; > + > + if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags)) > + return; > + > + if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) > + return; > + > + mutex_lock(&fs_info->reclaim_bgs_lock); > + spin_lock(&fs_info->unused_bgs_lock); > + while (!list_empty(&fs_info->reclaim_bgs)) { > + bg = list_first_entry(&fs_info->reclaim_bgs, > + struct btrfs_block_group, > + bg_list); > + list_del_init(&bg->bg_list); > + > + space_info = bg->space_info; > + spin_unlock(&fs_info->unused_bgs_lock); > + > + /* Don't want to race with allocators so take the groups_sem */ > + down_write(&space_info->groups_sem); > + > + spin_lock(&bg->lock); > + if (bg->reserved || bg->pinned || bg->ro) { > + /* > + * We want to bail if we made new allocations or have > + * outstanding allocations in this block group. We do > + * the ro check in case balance is currently acting on > + * this block group. > + */ > + spin_unlock(&bg->lock); > + up_write(&space_info->groups_sem); > + goto next; > + } > + spin_unlock(&bg->lock); > + > + /* Get out fast, in case we're unmounting the FS. */ > + if (btrfs_fs_closing(fs_info)) { > + up_write(&space_info->groups_sem); > + goto next; > + } > + > + ret = inc_block_group_ro(bg, 0); > + up_write(&space_info->groups_sem); > + if (ret < 0) > + goto next; > + > + btrfs_info(fs_info, "reclaiming chunk %llu", bg->start);
This could state the bg usage ratio, bg->used / bg->length . > + trace_btrfs_reclaim_block_group(bg); > + ret = btrfs_relocate_chunk(fs_info, bg->start); > + if (ret) > + btrfs_err(fs_info, "error relocating chunk %llu", > + bg->start); > + > +next: > + btrfs_put_block_group(bg); > + spin_lock(&fs_info->unused_bgs_lock); > + } > + spin_unlock(&fs_info->unused_bgs_lock); > + mutex_unlock(&fs_info->reclaim_bgs_lock); > + btrfs_exclop_finish(fs_info); > +}