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Message-ID: <0f5b4641-cd4a-dccc-6f13-f2fa3221dee1@huaweicloud.com>
Date: Thu, 29 May 2025 17:03:17 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Xiao Ni <xni@...hat.com>, Yu Kuai <yukuai1@...weicloud.com>
Cc: hch@....de, colyli@...nel.org, song@...nel.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-raid@...r.kernel.org, yi.zhang@...wei.com, yangerkun@...wei.com,
johnny.chenyi@...wei.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH 18/23] md/md-llbitmap: implement APIs to mange bitmap
lifetime
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@...weicloud.com> wrote:
>>
>> From: Yu Kuai <yukuai3@...wei.com>
>>
>> Include following APIs:
>> - llbitmap_create
>> - llbitmap_resize
>> - llbitmap_load
>> - llbitmap_destroy
>>
>> Signed-off-by: Yu Kuai <yukuai3@...wei.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
>>
>
>
> .
>
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