On 2018/1/31 14:39, 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 outdated.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>
> Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
> ---
> Change log from v3:
> - further review comments are applied from Jaegeuk and Chao
> - Tested on this patch (without multiple-device): mount, boot Android with f2fs userdata and make fragment
> - If any problem with this patch or I miss something, please kindly share your comments, thanks :)
> 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 | 67 ++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 46 insertions(+), 21 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 14d2fed..916dc72 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -1158,6 +1158,39 @@ static void update_ckpt_flags(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> spin_unlock_irqrestore(&sbi->cp_lock, flags);
> }
>
> +static void commit_checkpoint(struct f2fs_sb_info *sbi,
> + void *src, block_t blk_addr)
> +{
> + struct writeback_control wbc = {
> + .for_reclaim = 0,
> + };
> +
> + /*
> + * pagevec_lookup_tag and lock_page again will take
> + * some extra time. Therefore, update_meta_pages and
> + * sync_meta_pages are combined in this function.
> + */
> + 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 if NOBARRIER is not set) */
> + f2fs_submit_merged_write(sbi, META_FLUSH);
> +}
> +
> static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> {
> struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
> @@ -1260,16 +1293,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> }
> }
>
> - /* need to wait for end_io results */
> - wait_on_all_pages_writeback(sbi);
> - if (unlikely(f2fs_cp_error(sbi)))
> - return -EIO;
> -
> - /* flush all device cache */
> - err = f2fs_flush_device_cache(sbi);
> - if (err)
> - return err;
> -
> /* write out checkpoint buffer at block 0 */
> update_meta_page(sbi, ckpt, start_blk++);
>
> @@ -1297,15 +1320,6 @@ 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);
> -
> - if (unlikely(f2fs_cp_error(sbi)))
> - return -EIO;
> -
> filemap_fdatawait_range(NODE_MAPPING(sbi), 0, LLONG_MAX);
> filemap_fdatawait_range(META_MAPPING(sbi), 0, LLONG_MAX);
>
> @@ -1313,12 +1327,23 @@ 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);
> +
> + /* flush all device cache */
> + err = f2fs_flush_device_cache(sbi);
> + if (err)
> + return err;
>
> /* wait for previous submitted meta pages writeback */
> wait_on_all_pages_writeback(sbi);
Move f2fs_flush_device_cache here? since meta area can cross the multiple
devices, we should make sure all metadata were in device cache at least, and
then trigger the flush.
>
> + if (unlikely(f2fs_cp_error(sbi)))
> + return -EIO;
> +
> + /* barrier and flush checkpoint cp pack 2 page if it can */
> + commit_checkpoint(sbi, ckpt, start_blk);
Jaegeuk, are we really allow to make critical do_checkpoint which is on path of
fsync()/sync() be asynchronous?
Thanks,
> +
> release_ino_entry(sbi, false);
>
> if (unlikely(f2fs_cp_error(sbi)))
>
