On 2018/1/26 6:06, Jaegeuk Kim wrote:
> 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 outdated.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
Would meta area across two devices? if it would, we need to wait all meta
be persisted in second device before f2fs_flush_device_cache?
>
> 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
9.1 sync_meta_pages(META) to make sure all meta IOs are issued.
>
> 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.
We only need to use wait_on_all_pages_writeback to keep writeback order of
previous metadata and last cp pack metadata if barrier is on?
Thanks,
>
>> + 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
>
> .
>
