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

Su Yue
2024-08-19T08:28:57Z

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

> From: Yu Kuai <yukuai3@huawei.com>
>
> 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(-)