This patchset can be fetched from github: https://github.com/adam900710/linux/tree/refactor_delayed_ref_parameter
Which is based on previous delayed subtree scan patchset. (https://github.com/adam900710/linux/tree/qgroup_delayed_subtree) Current delayed ref interface has several problems: - Longer and longer parameter lists bytenr num_bytes parent ---- So far so good ref_root owner offset ---- I don't feel well now for_reloc ^^^^ This parameter only makes sense for qgroup code, but we need to pass the parameter a long way. This makes later expand on parameter list more and more tricky. - Different interpretation for the same parameter Above @owner for data ref is ino who owns this extent, while for tree ref, it's level. They are even in different size range. For level we only need 0~8, while for ino it's BTRFS_FIRST_FREE_OBJECTID~BTRFS_LAST_FREE_OBJECTID, so it's still possible to distinguish them, but it's never a straight-forward thing to grasp. And @offset doesn't even makes sense for tree ref. Such parameter reuse may look clever as an hidden union, but it destroys code readability. This patchset will change the way how we pass parameters for delayed ref. Instead of calling delayed ref interface like: ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, parent, ref_root, owner, offset); Or ret = btrfs_inc_extent_ref(trans, root, bytenr, nodesize, parent, level, ref_root, 0); We now call like: btrfs_init_generic_ref(&ref, bytenr, num_bytes, root->root_key.objectid, parent); btrfs_init_data_ref(&ref, ref_root, owner, offset); ret = btrfs_inc_extent_ref(trans, &ref); Or btrfs_init_generic_ref(&ref, bytenr, num_bytes, root->root_key.objectid, parent); btrfs_init_tree_ref(&ref, level, ref_root); ret = btrfs_inc_extent_ref(trans, &ref); To determine if a ref is tree or data, instead of calling like: if (owner < BTRFS_FIRST_FREE_OBJECTID) { } else { } We do it straight-forward: if (ref->type == BTRFS_REF_METADATA) { } else { } And for newer and minor new members, we don't need to add a new parameter to btrfs_add_delayed_tree|data_ref() or btrfs_inc_extent_ref(), just assign them after generic/data/tree init: btrfs_init_generic_ref(&ref, bytenr, num_bytes, root->root_key.objectid, parent); ref->real_root = root->root_key.objectid; ref->skip_qgroup = true; btrfs_init_data_ref(&ref, ref_root, owner, offset); ret = btrfs_inc_extent_ref(trans, &ref); This should improve the code readability and make later code easier to write. Furthermore, with the help of btrfs_ref::real_root parameter, qgroup can skip quit a lot of delayed tree/data ref for reloc tree, which result an obvious time save for balance: Test VM: - vRAM 8G - vCPU 8 - block dev vitrio-blk, 'unsafe' cache mode - host block 850evo Test workload - Copy 4G data from /usr/ to one subvolume - Create 16 snapshots of that subvolume, and modify 3 files in each snapshot - Enable quota, rescan - Time "btrfs balance start -m" | base (*) | w/ patchset | diff ------------------------------------------------------------- relocated | 22653 | 22673 | 0.0 % qgroup dirty | 122792 | 48360 | -60.6 % time | 24.494 | 11.606 | -52.6 % Changelog: v2: - Better documentation for btrfs_ref declaration - Rebase to newer delayed subtree rescan patchset - Add reviewed-by tags - Remove unnecessary ASSERT() for NULL pointer. Qu Wenruo (8): btrfs: delayed-ref: Introduce better documented delayed ref structures btrfs: extent-tree: Open-code process_func in __btrfs_mod_ref btrfs: delayed-ref: Use btrfs_ref to refactor btrfs_add_delayed_tree_ref() btrfs: delayed-ref: Use btrfs_ref to refactor btrfs_add_delayed_data_ref() btrfs: ref-verify: Use btrfs_ref to refactor btrfs_ref_tree_mod() btrfs: extent-tree: Use btrfs_ref to refactor add_pinned_bytes() btrfs: extent-tree: Use btrfs_ref to refactor btrfs_inc_extent_ref() btrfs: extent-tree: Use btrfs_ref to refactor btrfs_free_extent() fs/btrfs/ctree.h | 10 +-- fs/btrfs/delayed-ref.c | 40 ++++++--- fs/btrfs/delayed-ref.h | 126 +++++++++++++++++++++++++-- fs/btrfs/extent-tree.c | 189 ++++++++++++++++++++--------------------- fs/btrfs/file.c | 39 +++++---- fs/btrfs/inode.c | 23 +++-- fs/btrfs/ioctl.c | 15 ++-- fs/btrfs/ref-verify.c | 53 +++++++----- fs/btrfs/ref-verify.h | 10 +-- fs/btrfs/relocation.c | 67 +++++++++------ fs/btrfs/tree-log.c | 11 ++- 11 files changed, 374 insertions(+), 209 deletions(-) -- 2.19.2
