On 01/31, Chao Yu wrote:
> 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 outdated.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);
- remove
> >
> > @@ -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.
Agreed, and need to flush, only if we have multiple devices.
>
> >
> > + 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?
Yeah, so we need to wait end_io on synchronous paths like f2fs_sync_fs(1).
>
> Thanks,
>
> > +
> > release_ino_entry(sbi, false);
> >
> > if (unlikely(f2fs_cp_error(sbi)))
> >
