On 01/25, Gaoxiang (OS) wrote:
> Previously, we attempt to flush the whole cp pack in a single bio,
> however, when suddenly powering off at this time, we could get into
> an extreme scenario that cp pack 1 page and cp pack 2 page are updated
> and latest, but payload or current summaries are still partially
> outdated. (see reliable write in the UFS specification)
>
> This patch submits the whole cp pack except cp pack 2 page at first,
> and then writes the cp pack 2 page with an extra independent
> bio with pre-io barrier.
>
> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
> ---
> Change log from v2:
> - Apply the review comments from Chao
> Change log from v1:
> - Apply the review comments from Chao
> - time data from "finish block_ops" to " finish checkpoint" (tested on ARM64 with TOSHIBA 128GB UFS):
> Before patch: 0.002273 0.001973 0.002789 0.005159 0.002050
> After patch: 0.002502 0.001624 0.002487 0.003049 0.002696
> fs/f2fs/checkpoint.c | 39 ++++++++++++++++++++++++++++++++++-----
> 1 file changed, 34 insertions(+), 5 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 14d2fed..c1f4b10 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -300,6 +300,33 @@ static int f2fs_write_meta_pages(struct address_space *mapping,
> return 0;
> }
>
> +static void commit_checkpoint(struct f2fs_sb_info *sbi,
> + void *src, block_t blk_addr)
> +{
> + struct writeback_control wbc = {
> + .for_reclaim = 0,
> + };
> + struct page *page = grab_meta_page(sbi, blk_addr);
> + int err;
> +
> + memcpy(page_address(page), src, PAGE_SIZE);
> + set_page_dirty(page);
> +
> + f2fs_wait_on_page_writeback(page, META, true);
> + f2fs_bug_on(sbi, PageWriteback(page));
> + if (unlikely(!clear_page_dirty_for_io(page)))
> + f2fs_bug_on(sbi, 1);
> +
> + /* writeout cp pack 2 page */
> + err = __f2fs_write_meta_page(page, &wbc, FS_CP_META_IO);
> + f2fs_bug_on(sbi, err);
> +
> + f2fs_put_page(page, 0);
> +
> + /* submit checkpoint with barrier */
> + f2fs_submit_merged_write(sbi, META_FLUSH);
> +}
> +
> long sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
> long nr_to_write, enum iostat_type io_type)
> {
> @@ -1297,9 +1324,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> start_blk += NR_CURSEG_NODE_TYPE;
> }
>
> - /* writeout checkpoint block */
> - update_meta_page(sbi, ckpt, start_blk);
> -
> /* wait for previous submitted node/meta pages writeback */
> wait_on_all_pages_writeback(sbi);
Then, we don't need to wait for this as well as wait_on_all_pages_writeback()
in the early stage in do_checkpoint()?
So, it seems like we can modify like below:
---
1. while (get_pages())
sync_meta_pages()
2. if (enabled_nat_bits())
while (get_pages())
sync_meta_pages()
3. wait_on_all_pages_writeback()
-> remove
4. f2fs_flush_device_cache()
5. update_meta_page() <- for first cp_block
6. update_meta_page()... <- payload
7. orphan writes
8. node_summary writes
9. update_meta_page() <- for last cp_block
-> remove
10. wait_on_all_pages_writeback()
----
Add) 11. commit_checkpoint()
- update_meta_page() <- for last cp_block
- sync_meta_pages(META_FLUSH)
We don't need to wait for page_writeback any more.
>
> @@ -1313,10 +1337,15 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> sbi->last_valid_block_count = sbi->total_valid_block_count;
> percpu_counter_set(&sbi->alloc_valid_block_count, 0);
>
> - /* Here, we only have one bio having CP pack */
> - sync_meta_pages(sbi, META_FLUSH, LONG_MAX, FS_CP_META_IO);
> + /* Here, we have one bio having CP pack except cp pack 2 page */
> + sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO);
>
> /* wait for previous submitted meta pages writeback */
> + if (!test_opt(sbi, NOBARRIER))
The above has nothing to do with this patch.
> + wait_on_all_pages_writeback(sbi);
> +
> + /* barrier and flush checkpoint cp pack 2 page */
> + commit_checkpoint(sbi, ckpt, start_blk);
> wait_on_all_pages_writeback(sbi);
>
> release_ino_entry(sbi, false);
> --
> 2.1.4
