From: Yu Kuai <yukuai3@huawei.com>

Include following APIs:
 - llbitmap_create
 - llbitmap_resize
 - llbitmap_load
 - llbitmap_destroy

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 drivers/md/md-llbitmap.c | 322 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 322 insertions(+)

diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
index 4d5f9a139a25..23283c4f7263 100644
--- a/drivers/md/md-llbitmap.c
+++ b/drivers/md/md-llbitmap.c
@@ -689,4 +689,326 @@ static void llbitmap_resume(struct llbitmap *llbitmap, int page_idx)
 	wake_up(&pctl->wait);
 }
 
+static int llbitmap_check_support(struct mddev *mddev)
+{
+	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
+		pr_notice("md/llbitmap: %s: array with journal cannot have bitmap\n",
+			  mdname(mddev));
+		return -EBUSY;
+	}
+
+	if (mddev->bitmap_info.space == 0) {
+		if (mddev->bitmap_info.default_space == 0) {
+			pr_notice("md/llbitmap: %s: no space for bitmap\n",
+				  mdname(mddev));
+			return -ENOSPC;
+		}
+	}
+
+	if (!mddev->persistent) {
+		pr_notice("md/llbitmap: %s: array must be persistent\n",
+			  mdname(mddev));
+		return -EOPNOTSUPP;
+	}
+
+	if (mddev->bitmap_info.file) {
+		pr_notice("md/llbitmap: %s: doesn't support bitmap file\n",
+			  mdname(mddev));
+		return -EOPNOTSUPP;
+	}
+
+	if (mddev->bitmap_info.external) {
+		pr_notice("md/llbitmap: %s: doesn't support external metadata\n",
+			  mdname(mddev));
+		return -EOPNOTSUPP;
+	}
+
+	if (mddev_is_dm(mddev)) {
+		pr_notice("md/llbitmap: %s: doesn't support dm-raid\n",
+			  mdname(mddev));
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int llbitmap_init(struct llbitmap *llbitmap)
+{
+	struct mddev *mddev = llbitmap->mddev;
+	sector_t blocks = mddev->resync_max_sectors;
+	unsigned long chunksize = MIN_CHUNK_SIZE;
+	unsigned long chunks = DIV_ROUND_UP(blocks, chunksize);
+	unsigned long space = mddev->bitmap_info.space << SECTOR_SHIFT;
+	int ret;
+
+	while (chunks > space) {
+		chunksize = chunksize << 1;
+		chunks = DIV_ROUND_UP(blocks, chunksize);
+	}
+
+	llbitmap->chunkshift = ffz(~chunksize);
+	llbitmap->chunksize = chunksize;
+	llbitmap->chunks = chunks;
+	mddev->bitmap_info.daemon_sleep = DEFAULT_DAEMON_SLEEP;
+
+	ret = llbitmap_cache_pages(llbitmap);
+	if (ret)
+		return ret;
+
+	llbitmap_state_machine(llbitmap, 0, llbitmap->chunks - 1, BitmapActionInit);
+	return 0;
+}
+
+static int llbitmap_read_sb(struct llbitmap *llbitmap)
+{
+	struct mddev *mddev = llbitmap->mddev;
+	unsigned long daemon_sleep;
+	unsigned long chunksize;
+	unsigned long events;
+	struct page *sb_page;
+	bitmap_super_t *sb;
+	int ret = -EINVAL;
+
+	if (!mddev->bitmap_info.offset) {
+		pr_err("md/llbitmap: %s: no super block found", mdname(mddev));
+		return -EINVAL;
+	}
+
+	sb_page = llbitmap_read_page(llbitmap, 0);
+	if (IS_ERR(sb_page)) {
+		pr_err("md/llbitmap: %s: read super block failed",
+		       mdname(mddev));
+		ret = -EIO;
+		goto out;
+	}
+
+	sb = kmap_local_page(sb_page);
+	if (sb->magic != cpu_to_le32(BITMAP_MAGIC)) {
+		pr_err("md/llbitmap: %s: invalid super block magic number",
+		       mdname(mddev));
+		goto out_put_page;
+	}
+
+	if (sb->version != cpu_to_le32(BITMAP_MAJOR_LOCKLESS)) {
+		pr_err("md/llbitmap: %s: invalid super block version",
+		       mdname(mddev));
+		goto out_put_page;
+	}
+
+	if (memcmp(sb->uuid, mddev->uuid, 16)) {
+		pr_err("md/llbitmap: %s: bitmap superblock UUID mismatch\n",
+		       mdname(mddev));
+		goto out_put_page;
+	}
+
+	if (mddev->bitmap_info.space == 0) {
+		int room = le32_to_cpu(sb->sectors_reserved);
+
+		if (room)
+			mddev->bitmap_info.space = room;
+		else
+			mddev->bitmap_info.space = mddev->bitmap_info.default_space;
+	}
+	llbitmap->flags = le32_to_cpu(sb->state);
+	if (test_and_clear_bit(BITMAP_FIRST_USE, &llbitmap->flags)) {
+		ret = llbitmap_init(llbitmap);
+		goto out_put_page;
+	}
+
+	chunksize = le32_to_cpu(sb->chunksize);
+	if (!is_power_of_2(chunksize)) {
+		pr_err("md/llbitmap: %s: chunksize not a power of 2",
+		       mdname(mddev));
+		goto out_put_page;
+	}
+
+	if (chunksize < DIV_ROUND_UP(mddev->resync_max_sectors,
+				     mddev->bitmap_info.space << SECTOR_SHIFT)) {
+		pr_err("md/llbitmap: %s: chunksize too small %lu < %llu / %lu",
+		       mdname(mddev), chunksize, mddev->resync_max_sectors,
+		       mddev->bitmap_info.space);
+		goto out_put_page;
+	}
+
+	daemon_sleep = le32_to_cpu(sb->daemon_sleep);
+	if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT / HZ) {
+		pr_err("md/llbitmap: %s: daemon sleep %lu period out of range",
+		       mdname(mddev), daemon_sleep);
+		goto out_put_page;
+	}
+
+	events = le64_to_cpu(sb->events);
+	if (events < mddev->events) {
+		pr_warn("md/llbitmap :%s: bitmap file is out of date (%lu < %llu) -- forcing full recovery",
+			mdname(mddev), events, mddev->events);
+		set_bit(BITMAP_STALE, &llbitmap->flags);
+	}
+
+	sb->sync_size = cpu_to_le64(mddev->resync_max_sectors);
+	mddev->bitmap_info.chunksize = chunksize;
+	mddev->bitmap_info.daemon_sleep = daemon_sleep;
+
+	llbitmap->chunksize = chunksize;
+	llbitmap->chunks = DIV_ROUND_UP(mddev->resync_max_sectors, chunksize);
+	llbitmap->chunkshift = ffz(~chunksize);
+	ret = llbitmap_cache_pages(llbitmap);
+
+out_put_page:
+	__free_page(sb_page);
+out:
+	kunmap_local(sb);
+	return ret;
+}
+
+static void llbitmap_pending_timer_fn(struct timer_list *t)
+{
+	struct llbitmap *llbitmap = from_timer(llbitmap, t, pending_timer);
+
+	if (work_busy(&llbitmap->daemon_work)) {
+		pr_warn("daemon_work not finished\n");
+		set_bit(BITMAP_DAEMON_BUSY, &llbitmap->flags);
+		return;
+	}
+
+	queue_work(md_llbitmap_io_wq, &llbitmap->daemon_work);
+}
+
+static void md_llbitmap_daemon_fn(struct work_struct *work)
+{
+	struct llbitmap *llbitmap =
+		container_of(work, struct llbitmap, daemon_work);
+	unsigned long start;
+	unsigned long end;
+	bool restart;
+	int idx;
+
+	if (llbitmap->mddev->degraded)
+		return;
+
+retry:
+	start = 0;
+	end = min(llbitmap->chunks, PAGE_SIZE - BITMAP_SB_SIZE) - 1;
+	restart = false;
+
+	for (idx = 0; idx < llbitmap->nr_pages; idx++) {
+		struct llbitmap_page_ctl *pctl = llbitmap->pctl[idx];
+
+		if (idx > 0) {
+			start = end + 1;
+			end = min(end + PAGE_SIZE, llbitmap->chunks - 1);
+		}
+
+		if (!test_bit(LLPageFlush, &pctl->flags) &&
+		    time_before(jiffies, pctl->expire)) {
+			restart = true;
+			continue;
+		}
+
+		llbitmap_suspend(llbitmap, idx);
+		llbitmap_state_machine(llbitmap, start, end, BitmapActionDaemon);
+		llbitmap_resume(llbitmap, idx);
+	}
+
+	/*
+	 * If the daemon took a long time to finish, retry to prevent missing
+	 * clearing dirty bits.
+	 */
+	if (test_and_clear_bit(BITMAP_DAEMON_BUSY, &llbitmap->flags))
+		goto retry;
+
+	/* If some page is dirty but not expired, setup timer again */
+	if (restart)
+		mod_timer(&llbitmap->pending_timer,
+			  jiffies + llbitmap->mddev->bitmap_info.daemon_sleep * HZ);
+}
+
+static int llbitmap_create(struct mddev *mddev)
+{
+	struct llbitmap *llbitmap;
+	int ret;
+
+	ret = llbitmap_check_support(mddev);
+	if (ret)
+		return ret;
+
+	llbitmap = kzalloc(sizeof(*llbitmap), GFP_KERNEL);
+	if (!llbitmap)
+		return -ENOMEM;
+
+	llbitmap->mddev = mddev;
+	llbitmap->io_size = bdev_logical_block_size(mddev->gendisk->part0);
+	llbitmap->bits_per_page = PAGE_SIZE / llbitmap->io_size;
+
+	timer_setup(&llbitmap->pending_timer, llbitmap_pending_timer_fn, 0);
+	INIT_WORK(&llbitmap->daemon_work, md_llbitmap_daemon_fn);
+	atomic_set(&llbitmap->behind_writes, 0);
+	init_waitqueue_head(&llbitmap->behind_wait);
+
+	mutex_lock(&mddev->bitmap_info.mutex);
+	mddev->bitmap = llbitmap;
+	ret = llbitmap_read_sb(llbitmap);
+	mutex_unlock(&mddev->bitmap_info.mutex);
+	if (ret)
+		goto err_out;
+
+	return 0;
+
+err_out:
+	kfree(llbitmap);
+	return ret;
+}
+
+static int llbitmap_resize(struct mddev *mddev, sector_t blocks, int chunksize)
+{
+	struct llbitmap *llbitmap = mddev->bitmap;
+	unsigned long chunks;
+
+	if (chunksize == 0)
+		chunksize = llbitmap->chunksize;
+
+	/* If there is enough space, leave the chunksize unchanged. */
+	chunks = DIV_ROUND_UP(blocks, chunksize);
+	while (chunks > mddev->bitmap_info.space << SECTOR_SHIFT) {
+		chunksize = chunksize << 1;
+		chunks = DIV_ROUND_UP(blocks, chunksize);
+	}
+
+	llbitmap->chunkshift = ffz(~chunksize);
+	llbitmap->chunksize = chunksize;
+	llbitmap->chunks = chunks;
+
+	return 0;
+}
+
+static int llbitmap_load(struct mddev *mddev)
+{
+	enum llbitmap_action action = BitmapActionReload;
+	struct llbitmap *llbitmap = mddev->bitmap;
+
+	if (test_and_clear_bit(BITMAP_STALE, &llbitmap->flags))
+		action = BitmapActionStale;
+
+	llbitmap_state_machine(llbitmap, 0, llbitmap->chunks - 1, action);
+	return 0;
+}
+
+static void llbitmap_destroy(struct mddev *mddev)
+{
+	struct llbitmap *llbitmap = mddev->bitmap;
+
+	if (!llbitmap)
+		return;
+
+	mutex_lock(&mddev->bitmap_info.mutex);
+
+	timer_delete_sync(&llbitmap->pending_timer);
+	flush_workqueue(md_llbitmap_io_wq);
+	flush_workqueue(md_llbitmap_unplug_wq);
+
+	mddev->bitmap = NULL;
+	llbitmap_free_pages(llbitmap);
+	kfree(llbitmap);
+	mutex_unlock(&mddev->bitmap_info.mutex);
+}
+
 #endif /* CONFIG_MD_LLBITMAP */
-- 
2.39.2

Hi Kuai

Is it better to put this patch before patch15. I'm reading patch15.
But I need to read this patch first to understand how llbitmap is
created and loaded. Then I can go to read the io related part.

Regards
Xiao

On Sat, May 24, 2025 at 2:18 PM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@huawei.com>
>
> Include following APIs:
>  - llbitmap_create
>  - llbitmap_resize
>  - llbitmap_load
>  - llbitmap_destroy
>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
>  drivers/md/md-llbitmap.c | 322 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 322 insertions(+)
>
> diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
> index 4d5f9a139a25..23283c4f7263 100644
> --- a/drivers/md/md-llbitmap.c
> +++ b/drivers/md/md-llbitmap.c
> @@ -689,4 +689,326 @@ static void llbitmap_resume(struct llbitmap *llbitmap, int page_idx)
>         wake_up(&pctl->wait);
>  }
>
> +static int llbitmap_check_support(struct mddev *mddev)
> +{
> +       if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
> +               pr_notice("md/llbitmap: %s: array with journal cannot have bitmap\n",
> +                         mdname(mddev));
> +               return -EBUSY;
> +       }
> +
> +       if (mddev->bitmap_info.space == 0) {
> +               if (mddev->bitmap_info.default_space == 0) {
> +                       pr_notice("md/llbitmap: %s: no space for bitmap\n",
> +                                 mdname(mddev));
> +                       return -ENOSPC;
> +               }
> +       }
> +
> +       if (!mddev->persistent) {
> +               pr_notice("md/llbitmap: %s: array must be persistent\n",
> +                         mdname(mddev));
> +               return -EOPNOTSUPP;
> +       }
> +
> +       if (mddev->bitmap_info.file) {
> +               pr_notice("md/llbitmap: %s: doesn't support bitmap file\n",
> +                         mdname(mddev));
> +               return -EOPNOTSUPP;
> +       }
> +
> +       if (mddev->bitmap_info.external) {
> +               pr_notice("md/llbitmap: %s: doesn't support external metadata\n",
> +                         mdname(mddev));
> +               return -EOPNOTSUPP;
> +       }
> +
> +       if (mddev_is_dm(mddev)) {
> +               pr_notice("md/llbitmap: %s: doesn't support dm-raid\n",
> +                         mdname(mddev));
> +               return -EOPNOTSUPP;
> +       }
> +
> +       return 0;
> +}
> +
> +static int llbitmap_init(struct llbitmap *llbitmap)
> +{
> +       struct mddev *mddev = llbitmap->mddev;
> +       sector_t blocks = mddev->resync_max_sectors;
> +       unsigned long chunksize = MIN_CHUNK_SIZE;
> +       unsigned long chunks = DIV_ROUND_UP(blocks, chunksize);
> +       unsigned long space = mddev->bitmap_info.space << SECTOR_SHIFT;
> +       int ret;
> +
> +       while (chunks > space) {
> +               chunksize = chunksize << 1;
> +               chunks = DIV_ROUND_UP(blocks, chunksize);
> +       }
> +
> +       llbitmap->chunkshift = ffz(~chunksize);
> +       llbitmap->chunksize = chunksize;
> +       llbitmap->chunks = chunks;
> +       mddev->bitmap_info.daemon_sleep = DEFAULT_DAEMON_SLEEP;
> +
> +       ret = llbitmap_cache_pages(llbitmap);
> +       if (ret)
> +               return ret;
> +
> +       llbitmap_state_machine(llbitmap, 0, llbitmap->chunks - 1, BitmapActionInit);
> +       return 0;
> +}
> +
> +static int llbitmap_read_sb(struct llbitmap *llbitmap)
> +{
> +       struct mddev *mddev = llbitmap->mddev;
> +       unsigned long daemon_sleep;
> +       unsigned long chunksize;
> +       unsigned long events;
> +       struct page *sb_page;
> +       bitmap_super_t *sb;
> +       int ret = -EINVAL;
> +
> +       if (!mddev->bitmap_info.offset) {
> +               pr_err("md/llbitmap: %s: no super block found", mdname(mddev));
> +               return -EINVAL;
> +       }
> +
> +       sb_page = llbitmap_read_page(llbitmap, 0);
> +       if (IS_ERR(sb_page)) {
> +               pr_err("md/llbitmap: %s: read super block failed",
> +                      mdname(mddev));
> +               ret = -EIO;
> +               goto out;
> +       }
> +
> +       sb = kmap_local_page(sb_page);
> +       if (sb->magic != cpu_to_le32(BITMAP_MAGIC)) {
> +               pr_err("md/llbitmap: %s: invalid super block magic number",
> +                      mdname(mddev));
> +               goto out_put_page;
> +       }
> +
> +       if (sb->version != cpu_to_le32(BITMAP_MAJOR_LOCKLESS)) {
> +               pr_err("md/llbitmap: %s: invalid super block version",
> +                      mdname(mddev));
> +               goto out_put_page;
> +       }
> +
> +       if (memcmp(sb->uuid, mddev->uuid, 16)) {
> +               pr_err("md/llbitmap: %s: bitmap superblock UUID mismatch\n",
> +                      mdname(mddev));
> +               goto out_put_page;
> +       }
> +
> +       if (mddev->bitmap_info.space == 0) {
> +               int room = le32_to_cpu(sb->sectors_reserved);
> +
> +               if (room)
> +                       mddev->bitmap_info.space = room;
> +               else
> +                       mddev->bitmap_info.space = mddev->bitmap_info.default_space;
> +       }
> +       llbitmap->flags = le32_to_cpu(sb->state);
> +       if (test_and_clear_bit(BITMAP_FIRST_USE, &llbitmap->flags)) {
> +               ret = llbitmap_init(llbitmap);
> +               goto out_put_page;
> +       }
> +
> +       chunksize = le32_to_cpu(sb->chunksize);
> +       if (!is_power_of_2(chunksize)) {
> +               pr_err("md/llbitmap: %s: chunksize not a power of 2",
> +                      mdname(mddev));
> +               goto out_put_page;
> +       }
> +
> +       if (chunksize < DIV_ROUND_UP(mddev->resync_max_sectors,
> +                                    mddev->bitmap_info.space << SECTOR_SHIFT)) {
> +               pr_err("md/llbitmap: %s: chunksize too small %lu < %llu / %lu",
> +                      mdname(mddev), chunksize, mddev->resync_max_sectors,
> +                      mddev->bitmap_info.space);
> +               goto out_put_page;
> +       }
> +
> +       daemon_sleep = le32_to_cpu(sb->daemon_sleep);
> +       if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT / HZ) {
> +               pr_err("md/llbitmap: %s: daemon sleep %lu period out of range",
> +                      mdname(mddev), daemon_sleep);
> +               goto out_put_page;
> +       }
> +
> +       events = le64_to_cpu(sb->events);
> +       if (events < mddev->events) {
> +               pr_warn("md/llbitmap :%s: bitmap file is out of date (%lu < %llu) -- forcing full recovery",
> +                       mdname(mddev), events, mddev->events);
> +               set_bit(BITMAP_STALE, &llbitmap->flags);
> +       }
> +
> +       sb->sync_size = cpu_to_le64(mddev->resync_max_sectors);
> +       mddev->bitmap_info.chunksize = chunksize;
> +       mddev->bitmap_info.daemon_sleep = daemon_sleep;
> +
> +       llbitmap->chunksize = chunksize;
> +       llbitmap->chunks = DIV_ROUND_UP(mddev->resync_max_sectors, chunksize);
> +       llbitmap->chunkshift = ffz(~chunksize);
> +       ret = llbitmap_cache_pages(llbitmap);
> +
> +out_put_page:
> +       __free_page(sb_page);
> +out:
> +       kunmap_local(sb);
> +       return ret;
> +}
> +
> +static void llbitmap_pending_timer_fn(struct timer_list *t)
> +{
> +       struct llbitmap *llbitmap = from_timer(llbitmap, t, pending_timer);
> +
> +       if (work_busy(&llbitmap->daemon_work)) {
> +               pr_warn("daemon_work not finished\n");
> +               set_bit(BITMAP_DAEMON_BUSY, &llbitmap->flags);
> +               return;
> +       }
> +
> +       queue_work(md_llbitmap_io_wq, &llbitmap->daemon_work);
> +}
> +
> +static void md_llbitmap_daemon_fn(struct work_struct *work)
> +{
> +       struct llbitmap *llbitmap =
> +               container_of(work, struct llbitmap, daemon_work);
> +       unsigned long start;
> +       unsigned long end;
> +       bool restart;
> +       int idx;
> +
> +       if (llbitmap->mddev->degraded)
> +               return;
> +
> +retry:
> +       start = 0;
> +       end = min(llbitmap->chunks, PAGE_SIZE - BITMAP_SB_SIZE) - 1;
> +       restart = false;
> +
> +       for (idx = 0; idx < llbitmap->nr_pages; idx++) {
> +               struct llbitmap_page_ctl *pctl = llbitmap->pctl[idx];
> +
> +               if (idx > 0) {
> +                       start = end + 1;
> +                       end = min(end + PAGE_SIZE, llbitmap->chunks - 1);
> +               }
> +
> +               if (!test_bit(LLPageFlush, &pctl->flags) &&
> +                   time_before(jiffies, pctl->expire)) {
> +                       restart = true;
> +                       continue;
> +               }
> +
> +               llbitmap_suspend(llbitmap, idx);
> +               llbitmap_state_machine(llbitmap, start, end, BitmapActionDaemon);
> +               llbitmap_resume(llbitmap, idx);
> +       }
> +
> +       /*
> +        * If the daemon took a long time to finish, retry to prevent missing
> +        * clearing dirty bits.
> +        */
> +       if (test_and_clear_bit(BITMAP_DAEMON_BUSY, &llbitmap->flags))
> +               goto retry;
> +
> +       /* If some page is dirty but not expired, setup timer again */
> +       if (restart)
> +               mod_timer(&llbitmap->pending_timer,
> +                         jiffies + llbitmap->mddev->bitmap_info.daemon_sleep * HZ);
> +}
> +
> +static int llbitmap_create(struct mddev *mddev)
> +{
> +       struct llbitmap *llbitmap;
> +       int ret;
> +
> +       ret = llbitmap_check_support(mddev);
> +       if (ret)
> +               return ret;
> +
> +       llbitmap = kzalloc(sizeof(*llbitmap), GFP_KERNEL);
> +       if (!llbitmap)
> +               return -ENOMEM;
> +
> +       llbitmap->mddev = mddev;
> +       llbitmap->io_size = bdev_logical_block_size(mddev->gendisk->part0);
> +       llbitmap->bits_per_page = PAGE_SIZE / llbitmap->io_size;
> +
> +       timer_setup(&llbitmap->pending_timer, llbitmap_pending_timer_fn, 0);
> +       INIT_WORK(&llbitmap->daemon_work, md_llbitmap_daemon_fn);
> +       atomic_set(&llbitmap->behind_writes, 0);
> +       init_waitqueue_head(&llbitmap->behind_wait);
> +
> +       mutex_lock(&mddev->bitmap_info.mutex);
> +       mddev->bitmap = llbitmap;
> +       ret = llbitmap_read_sb(llbitmap);
> +       mutex_unlock(&mddev->bitmap_info.mutex);
> +       if (ret)
> +               goto err_out;
> +
> +       return 0;
> +
> +err_out:
> +       kfree(llbitmap);
> +       return ret;
> +}
> +
> +static int llbitmap_resize(struct mddev *mddev, sector_t blocks, int chunksize)
> +{
> +       struct llbitmap *llbitmap = mddev->bitmap;
> +       unsigned long chunks;
> +
> +       if (chunksize == 0)
> +               chunksize = llbitmap->chunksize;
> +
> +       /* If there is enough space, leave the chunksize unchanged. */
> +       chunks = DIV_ROUND_UP(blocks, chunksize);
> +       while (chunks > mddev->bitmap_info.space << SECTOR_SHIFT) {
> +               chunksize = chunksize << 1;
> +               chunks = DIV_ROUND_UP(blocks, chunksize);
> +       }
> +
> +       llbitmap->chunkshift = ffz(~chunksize);
> +       llbitmap->chunksize = chunksize;
> +       llbitmap->chunks = chunks;
> +
> +       return 0;
> +}
> +
> +static int llbitmap_load(struct mddev *mddev)
> +{
> +       enum llbitmap_action action = BitmapActionReload;
> +       struct llbitmap *llbitmap = mddev->bitmap;
> +
> +       if (test_and_clear_bit(BITMAP_STALE, &llbitmap->flags))
> +               action = BitmapActionStale;
> +
> +       llbitmap_state_machine(llbitmap, 0, llbitmap->chunks - 1, action);
> +       return 0;
> +}
> +
> +static void llbitmap_destroy(struct mddev *mddev)
> +{
> +       struct llbitmap *llbitmap = mddev->bitmap;
> +
> +       if (!llbitmap)
> +               return;
> +
> +       mutex_lock(&mddev->bitmap_info.mutex);
> +
> +       timer_delete_sync(&llbitmap->pending_timer);
> +       flush_workqueue(md_llbitmap_io_wq);
> +       flush_workqueue(md_llbitmap_unplug_wq);
> +
> +       mddev->bitmap = NULL;
> +       llbitmap_free_pages(llbitmap);
> +       kfree(llbitmap);
> +       mutex_unlock(&mddev->bitmap_info.mutex);
> +}
> +
>  #endif /* CONFIG_MD_LLBITMAP */
> --
> 2.39.2
>

Hi,

在 2025/05/29 15:03, Xiao Ni 写道:
> Hi Kuai
> 
> Is it better to put this patch before patch15. I'm reading patch15.
> But I need to read this patch first to understand how llbitmap is
> created and loaded. Then I can go to read the io related part.

Never mind, I'll merge patch 15-23 into one single patch in the next
version, it's better for review.

Thanks,
Kuai

> 
> Regards
> Xiao
> 
> On Sat, May 24, 2025 at 2:18 PM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>>
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> Include following APIs:
>>   - llbitmap_create
>>   - llbitmap_resize
>>   - llbitmap_load
>>   - llbitmap_destroy
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> ---
>>   drivers/md/md-llbitmap.c | 322 +++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 322 insertions(+)
>>
>> diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
>> index 4d5f9a139a25..23283c4f7263 100644
>> --- a/drivers/md/md-llbitmap.c
>> +++ b/drivers/md/md-llbitmap.c
>> @@ -689,4 +689,326 @@ static void llbitmap_resume(struct llbitmap *llbitmap, int page_idx)
>>          wake_up(&pctl->wait);
>>   }
>>
>> +static int llbitmap_check_support(struct mddev *mddev)
>> +{
>> +       if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
>> +               pr_notice("md/llbitmap: %s: array with journal cannot have bitmap\n",
>> +                         mdname(mddev));
>> +               return -EBUSY;
>> +       }
>> +
>> +       if (mddev->bitmap_info.space == 0) {
>> +               if (mddev->bitmap_info.default_space == 0) {
>> +                       pr_notice("md/llbitmap: %s: no space for bitmap\n",
>> +                                 mdname(mddev));
>> +                       return -ENOSPC;
>> +               }
>> +       }
>> +
>> +       if (!mddev->persistent) {
>> +               pr_notice("md/llbitmap: %s: array must be persistent\n",
>> +                         mdname(mddev));
>> +               return -EOPNOTSUPP;
>> +       }
>> +
>> +       if (mddev->bitmap_info.file) {
>> +               pr_notice("md/llbitmap: %s: doesn't support bitmap file\n",
>> +                         mdname(mddev));
>> +               return -EOPNOTSUPP;
>> +       }
>> +
>> +       if (mddev->bitmap_info.external) {
>> +               pr_notice("md/llbitmap: %s: doesn't support external metadata\n",
>> +                         mdname(mddev));
>> +               return -EOPNOTSUPP;
>> +       }
>> +
>> +       if (mddev_is_dm(mddev)) {
>> +               pr_notice("md/llbitmap: %s: doesn't support dm-raid\n",
>> +                         mdname(mddev));
>> +               return -EOPNOTSUPP;
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +static int llbitmap_init(struct llbitmap *llbitmap)
>> +{
>> +       struct mddev *mddev = llbitmap->mddev;
>> +       sector_t blocks = mddev->resync_max_sectors;
>> +       unsigned long chunksize = MIN_CHUNK_SIZE;
>> +       unsigned long chunks = DIV_ROUND_UP(blocks, chunksize);
>> +       unsigned long space = mddev->bitmap_info.space << SECTOR_SHIFT;
>> +       int ret;
>> +
>> +       while (chunks > space) {
>> +               chunksize = chunksize << 1;
>> +               chunks = DIV_ROUND_UP(blocks, chunksize);
>> +       }
>> +
>> +       llbitmap->chunkshift = ffz(~chunksize);
>> +       llbitmap->chunksize = chunksize;
>> +       llbitmap->chunks = chunks;
>> +       mddev->bitmap_info.daemon_sleep = DEFAULT_DAEMON_SLEEP;
>> +
>> +       ret = llbitmap_cache_pages(llbitmap);
>> +       if (ret)
>> +               return ret;
>> +
>> +       llbitmap_state_machine(llbitmap, 0, llbitmap->chunks - 1, BitmapActionInit);
>> +       return 0;
>> +}
>> +
>> +static int llbitmap_read_sb(struct llbitmap *llbitmap)
>> +{
>> +       struct mddev *mddev = llbitmap->mddev;
>> +       unsigned long daemon_sleep;
>> +       unsigned long chunksize;
>> +       unsigned long events;
>> +       struct page *sb_page;
>> +       bitmap_super_t *sb;
>> +       int ret = -EINVAL;
>> +
>> +       if (!mddev->bitmap_info.offset) {
>> +               pr_err("md/llbitmap: %s: no super block found", mdname(mddev));
>> +               return -EINVAL;
>> +       }
>> +
>> +       sb_page = llbitmap_read_page(llbitmap, 0);
>> +       if (IS_ERR(sb_page)) {
>> +               pr_err("md/llbitmap: %s: read super block failed",
>> +                      mdname(mddev));
>> +               ret = -EIO;
>> +               goto out;
>> +       }
>> +
>> +       sb = kmap_local_page(sb_page);
>> +       if (sb->magic != cpu_to_le32(BITMAP_MAGIC)) {
>> +               pr_err("md/llbitmap: %s: invalid super block magic number",
>> +                      mdname(mddev));
>> +               goto out_put_page;
>> +       }
>> +
>> +       if (sb->version != cpu_to_le32(BITMAP_MAJOR_LOCKLESS)) {
>> +               pr_err("md/llbitmap: %s: invalid super block version",
>> +                      mdname(mddev));
>> +               goto out_put_page;
>> +       }
>> +
>> +       if (memcmp(sb->uuid, mddev->uuid, 16)) {
>> +               pr_err("md/llbitmap: %s: bitmap superblock UUID mismatch\n",
>> +                      mdname(mddev));
>> +               goto out_put_page;
>> +       }
>> +
>> +       if (mddev->bitmap_info.space == 0) {
>> +               int room = le32_to_cpu(sb->sectors_reserved);
>> +
>> +               if (room)
>> +                       mddev->bitmap_info.space = room;
>> +               else
>> +                       mddev->bitmap_info.space = mddev->bitmap_info.default_space;
>> +       }
>> +       llbitmap->flags = le32_to_cpu(sb->state);
>> +       if (test_and_clear_bit(BITMAP_FIRST_USE, &llbitmap->flags)) {
>> +               ret = llbitmap_init(llbitmap);
>> +               goto out_put_page;
>> +       }
>> +
>> +       chunksize = le32_to_cpu(sb->chunksize);
>> +       if (!is_power_of_2(chunksize)) {
>> +               pr_err("md/llbitmap: %s: chunksize not a power of 2",
>> +                      mdname(mddev));
>> +               goto out_put_page;
>> +       }
>> +
>> +       if (chunksize < DIV_ROUND_UP(mddev->resync_max_sectors,
>> +                                    mddev->bitmap_info.space << SECTOR_SHIFT)) {
>> +               pr_err("md/llbitmap: %s: chunksize too small %lu < %llu / %lu",
>> +                      mdname(mddev), chunksize, mddev->resync_max_sectors,
>> +                      mddev->bitmap_info.space);
>> +               goto out_put_page;
>> +       }
>> +
>> +       daemon_sleep = le32_to_cpu(sb->daemon_sleep);
>> +       if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT / HZ) {
>> +               pr_err("md/llbitmap: %s: daemon sleep %lu period out of range",
>> +                      mdname(mddev), daemon_sleep);
>> +               goto out_put_page;
>> +       }
>> +
>> +       events = le64_to_cpu(sb->events);
>> +       if (events < mddev->events) {
>> +               pr_warn("md/llbitmap :%s: bitmap file is out of date (%lu < %llu) -- forcing full recovery",
>> +                       mdname(mddev), events, mddev->events);
>> +               set_bit(BITMAP_STALE, &llbitmap->flags);
>> +       }
>> +
>> +       sb->sync_size = cpu_to_le64(mddev->resync_max_sectors);
>> +       mddev->bitmap_info.chunksize = chunksize;
>> +       mddev->bitmap_info.daemon_sleep = daemon_sleep;
>> +
>> +       llbitmap->chunksize = chunksize;
>> +       llbitmap->chunks = DIV_ROUND_UP(mddev->resync_max_sectors, chunksize);
>> +       llbitmap->chunkshift = ffz(~chunksize);
>> +       ret = llbitmap_cache_pages(llbitmap);
>> +
>> +out_put_page:
>> +       __free_page(sb_page);
>> +out:
>> +       kunmap_local(sb);
>> +       return ret;
>> +}
>> +
>> +static void llbitmap_pending_timer_fn(struct timer_list *t)
>> +{
>> +       struct llbitmap *llbitmap = from_timer(llbitmap, t, pending_timer);
>> +
>> +       if (work_busy(&llbitmap->daemon_work)) {
>> +               pr_warn("daemon_work not finished\n");
>> +               set_bit(BITMAP_DAEMON_BUSY, &llbitmap->flags);
>> +               return;
>> +       }
>> +
>> +       queue_work(md_llbitmap_io_wq, &llbitmap->daemon_work);
>> +}
>> +
>> +static void md_llbitmap_daemon_fn(struct work_struct *work)
>> +{
>> +       struct llbitmap *llbitmap =
>> +               container_of(work, struct llbitmap, daemon_work);
>> +       unsigned long start;
>> +       unsigned long end;
>> +       bool restart;
>> +       int idx;
>> +
>> +       if (llbitmap->mddev->degraded)
>> +               return;
>> +
>> +retry:
>> +       start = 0;
>> +       end = min(llbitmap->chunks, PAGE_SIZE - BITMAP_SB_SIZE) - 1;
>> +       restart = false;
>> +
>> +       for (idx = 0; idx < llbitmap->nr_pages; idx++) {
>> +               struct llbitmap_page_ctl *pctl = llbitmap->pctl[idx];
>> +
>> +               if (idx > 0) {
>> +                       start = end + 1;
>> +                       end = min(end + PAGE_SIZE, llbitmap->chunks - 1);
>> +               }
>> +
>> +               if (!test_bit(LLPageFlush, &pctl->flags) &&
>> +                   time_before(jiffies, pctl->expire)) {
>> +                       restart = true;
>> +                       continue;
>> +               }
>> +
>> +               llbitmap_suspend(llbitmap, idx);
>> +               llbitmap_state_machine(llbitmap, start, end, BitmapActionDaemon);
>> +               llbitmap_resume(llbitmap, idx);
>> +       }
>> +
>> +       /*
>> +        * If the daemon took a long time to finish, retry to prevent missing
>> +        * clearing dirty bits.
>> +        */
>> +       if (test_and_clear_bit(BITMAP_DAEMON_BUSY, &llbitmap->flags))
>> +               goto retry;
>> +
>> +       /* If some page is dirty but not expired, setup timer again */
>> +       if (restart)
>> +               mod_timer(&llbitmap->pending_timer,
>> +                         jiffies + llbitmap->mddev->bitmap_info.daemon_sleep * HZ);
>> +}
>> +
>> +static int llbitmap_create(struct mddev *mddev)
>> +{
>> +       struct llbitmap *llbitmap;
>> +       int ret;
>> +
>> +       ret = llbitmap_check_support(mddev);
>> +       if (ret)
>> +               return ret;
>> +
>> +       llbitmap = kzalloc(sizeof(*llbitmap), GFP_KERNEL);
>> +       if (!llbitmap)
>> +               return -ENOMEM;
>> +
>> +       llbitmap->mddev = mddev;
>> +       llbitmap->io_size = bdev_logical_block_size(mddev->gendisk->part0);
>> +       llbitmap->bits_per_page = PAGE_SIZE / llbitmap->io_size;
>> +
>> +       timer_setup(&llbitmap->pending_timer, llbitmap_pending_timer_fn, 0);
>> +       INIT_WORK(&llbitmap->daemon_work, md_llbitmap_daemon_fn);
>> +       atomic_set(&llbitmap->behind_writes, 0);
>> +       init_waitqueue_head(&llbitmap->behind_wait);
>> +
>> +       mutex_lock(&mddev->bitmap_info.mutex);
>> +       mddev->bitmap = llbitmap;
>> +       ret = llbitmap_read_sb(llbitmap);
>> +       mutex_unlock(&mddev->bitmap_info.mutex);
>> +       if (ret)
>> +               goto err_out;
>> +
>> +       return 0;
>> +
>> +err_out:
>> +       kfree(llbitmap);
>> +       return ret;
>> +}
>> +
>> +static int llbitmap_resize(struct mddev *mddev, sector_t blocks, int chunksize)
>> +{
>> +       struct llbitmap *llbitmap = mddev->bitmap;
>> +       unsigned long chunks;
>> +
>> +       if (chunksize == 0)
>> +               chunksize = llbitmap->chunksize;
>> +
>> +       /* If there is enough space, leave the chunksize unchanged. */
>> +       chunks = DIV_ROUND_UP(blocks, chunksize);
>> +       while (chunks > mddev->bitmap_info.space << SECTOR_SHIFT) {
>> +               chunksize = chunksize << 1;
>> +               chunks = DIV_ROUND_UP(blocks, chunksize);
>> +       }
>> +
>> +       llbitmap->chunkshift = ffz(~chunksize);
>> +       llbitmap->chunksize = chunksize;
>> +       llbitmap->chunks = chunks;
>> +
>> +       return 0;
>> +}
>> +
>> +static int llbitmap_load(struct mddev *mddev)
>> +{
>> +       enum llbitmap_action action = BitmapActionReload;
>> +       struct llbitmap *llbitmap = mddev->bitmap;
>> +
>> +       if (test_and_clear_bit(BITMAP_STALE, &llbitmap->flags))
>> +               action = BitmapActionStale;
>> +
>> +       llbitmap_state_machine(llbitmap, 0, llbitmap->chunks - 1, action);
>> +       return 0;
>> +}
>> +
>> +static void llbitmap_destroy(struct mddev *mddev)
>> +{
>> +       struct llbitmap *llbitmap = mddev->bitmap;
>> +
>> +       if (!llbitmap)
>> +               return;
>> +
>> +       mutex_lock(&mddev->bitmap_info.mutex);
>> +
>> +       timer_delete_sync(&llbitmap->pending_timer);
>> +       flush_workqueue(md_llbitmap_io_wq);
>> +       flush_workqueue(md_llbitmap_unplug_wq);
>> +
>> +       mddev->bitmap = NULL;
>> +       llbitmap_free_pages(llbitmap);
>> +       kfree(llbitmap);
>> +       mutex_unlock(&mddev->bitmap_info.mutex);
>> +}
>> +
>>   #endif /* CONFIG_MD_LLBITMAP */
>> --
>> 2.39.2
>>
> 
> 
> .
>