Re: [PATCH RFC -next v2 00/41] md/md-bitmap: introduce bitmap_operations and make structure internel

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On Wed 14 Aug 2024 at 15:10, Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Changes in v2:
- add patch 1-8 to prevent dereference bitmap directly, and the last
 patch to make bitmap structure internel.
 - use plain function alls "bitmap_ops->xxx()" directly;

The background is that currently bitmap is using a global spin_lock, cauing lock contention and huge IO performance degration for all raid
levels.

However, it's impossible to implement a new lock free bitmap with current situation that md-bitmap exposes the internal implementation with lots of exported apis. Hence bitmap_operations is invented, to describe bitmap core implementation, and a new bitmap can be introduced with a new bitmap_operations, we only need to switch to the new one
during initialization.

Is the new bitmap in plan?

And with this we can build bitmap as kernel module, but that's not
our concern for now.

Noted I just compile this patchset, not tested yet.


I've looked through the patchset almostly. The changes are quite
straightforward. IMO, it's good timing to test it and drop RFC in next
version.

Yu Kuai (41):
md/raid1: use md_bitmap_wait_behind_writes() in raid1_read_request()
  md/md-bitmap: replace md_bitmap_status() with a new helper
    md_bitmap_get_stats()
md: use new helper md_bitmap_get_stats() in update_array_info()
  md/md-bitmap: add 'events_cleared' into struct md_bitmap_stats
  md/md-bitmap: add 'sync_size' into struct md_bitmap_stats
  md/md-bitmap: add 'file_pages' into struct md_bitmap_stats
md/md-bitmap: add 'behind_writes' and 'behind_wait' into struct
    md_bitmap_stats
md/md-cluster: use helper md_bitmap_get_stats() to get pages in
    resize_bitmaps()
  md/md-bitmap: add a new helper md_bitmap_set_pages()
  md/md-bitmap: introduce struct bitmap_operations
  md/md-bitmap: simplify md_bitmap_create() + md_bitmap_load()
  md/md-bitmap: merge md_bitmap_create() into bitmap_operations
  md/md-bitmap: merge md_bitmap_load() into bitmap_operations
  md/md-bitmap: merge md_bitmap_destroy() into bitmap_operations
  md/md-bitmap: merge md_bitmap_flush() into bitmap_operations
  md/md-bitmap: make md_bitmap_print_sb() internal
md/md-bitmap: merge md_bitmap_update_sb() into bitmap_operations
  md/md-bitmap: merge md_bitmap_status() into bitmap_operations
  md/md-bitmap: remove md_bitmap_setallbits()
  md/md-bitmap: merge bitmap_write_all() into bitmap_operations
md/md-bitmap: merge md_bitmap_dirty_bits() into bitmap_operations md/md-bitmap: merge md_bitmap_startwrite() into bitmap_operations md/md-bitmap: merge md_bitmap_endwrite() into bitmap_operations md/md-bitmap: merge md_bitmap_start_sync() into bitmap_operations md/md-bitmap: remove the parameter 'aborted' for md_bitmap_end_sync() md/md-bitmap: merge md_bitmap_end_sync() into bitmap_operations md/md-bitmap: merge md_bitmap_close_sync() into bitmap_operations md/md-bitmap: mrege md_bitmap_cond_end_sync() into bitmap_operations
  md/md-bitmap: merge md_bitmap_sync_with_cluster() into
    bitmap_operations
md/md-bitmap: merge md_bitmap_unplug_async() into md_bitmap_unplug()
  md/md-bitmap: merge bitmap_unplug() into bitmap_operations
md/md-bitmap: merge md_bitmap_daemon_work() into bitmap_operations
  md/md-bitmap: pass in mddev directly for md_bitmap_resize()
  md/md-bitmap: merge md_bitmap_resize() into bitmap_operations
md/md-bitmap: merge get_bitmap_from_slot() into bitmap_operations
  md/md-bitmap: merge md_bitmap_copy_from_slot() into struct
    bitmap_operation.
  md/md-bitmap: merge md_bitmap_set_pages() into struct
    bitmap_operations
  md/md-bitmap: merge md_bitmap_free() into bitmap_operations
  md/md-bitmap: merge md_bitmap_wait_behind_writes() into
    bitmap_operations
  md/md-bitmap: merge md_bitmap_enabled() into bitmap_operations
  md/md-bitmap: make in memory structure internal

 drivers/md/dm-raid.c     |   7 +-
drivers/md/md-bitmap.c | 561 +++++++++++++++++++++++++++++----------
 drivers/md/md-bitmap.h   | 272 ++++---------------
 drivers/md/md-cluster.c  |  79 +++---
 drivers/md/md.c          | 133 ++++++----
 drivers/md/md.h          |   3 +-
 drivers/md/raid1-10.c    |   9 +-
 drivers/md/raid1.c       |  78 +++---
 drivers/md/raid10.c      |  73 ++---
 drivers/md/raid5-cache.c |   8 +-
 drivers/md/raid5.c       |  62 ++---
 11 files changed, 731 insertions(+), 554 deletions(-)




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