Re: [PATCH v3] f2fs: fix a missing discard prefree segments

[Jaegeuk Kim <jaegeuk@kernel.org>]

On 12/22, heyunlei wrote:
> Hi Jaegeuk,
> 
> On 2016/12/22 2:04, Jaegeuk Kim wrote:
> > On 12/21, Yunlei He wrote:
> > > If userspace issue a fstrim with a range not involve prefree segments,
> > > it will reuse these segments without discard. This patch fix it.
> > > 
> > > Signed-off-by: Yunlei He <heyunlei@huawei.com>
> > > ---
> > >  fs/f2fs/segment.c | 9 +++++++--
> > >  1 file changed, 7 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > > index 0738f48..e0fff28 100644
> > > --- a/fs/f2fs/segment.c
> > > +++ b/fs/f2fs/segment.c
> > > @@ -916,9 +916,13 @@ void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> > > 
> > >  		dirty_i->nr_dirty[PRE] -= end - start;
> > > 
> > > -		if (force || !test_opt(sbi, DISCARD))
> > > +		if (!test_opt(sbi, DISCARD))
> > >  			continue;
> > > 
> > > +		if (force && start >= cpc->trim_start &&
> > > +					(end -1) <= cpc->trim_end)
> > > +				continue;
> > > +
> > >  		if (!test_opt(sbi, LFS) || sbi->segs_per_sec == 1) {
> > >  			f2fs_issue_discard(sbi, START_BLOCK(sbi, start),
> > >  				(end - start) << sbi->log_blocks_per_seg);
> > > @@ -2263,7 +2267,8 @@ void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> > >  	f2fs_bug_on(sbi, sit_i->dirty_sentries);
> > >  out:
> > >  	if (cpc->reason == CP_DISCARD) {
> > > -		for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++)
> > > +		__u64 trim_start = cpc->trim_start;
> > > +		for (; trim_start <= cpc->trim_end; trim_start++)
> > 
> > BTW, why do we need this?
> > The below add_discard_addrs() will use cpc->trim_start.
> 
> Here, we need to reserve the original value of cpc->trim_start, because
> we will use it as a boundary judgement for skipping prefree segments
> discard.  How about this:

Looks good to me. :)
Could you send v4?

Thanks,

> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 0738f48..30cd445 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -916,9 +916,13 @@ void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> 
>                 dirty_i->nr_dirty[PRE] -= end - start;
> 
> -               if (force || !test_opt(sbi, DISCARD))
> +               if (!test_opt(sbi, DISCARD))
>                         continue;
> 
> +               if (force && start >= cpc->trim_start &&
> +                                       (end -1) <= cpc->trim_end)
> +                               continue;
> +
>                 if (!test_opt(sbi, LFS) || sbi->segs_per_sec == 1) {
>                         f2fs_issue_discard(sbi, START_BLOCK(sbi, start),
>                                 (end - start) << sbi->log_blocks_per_seg);
> @@ -2263,8 +2267,11 @@ void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>         f2fs_bug_on(sbi, sit_i->dirty_sentries);
>  out:
>         if (cpc->reason == CP_DISCARD) {
> +               __u64 trim_start = cpc->trim_start;
>                 for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++)
>                         add_discard_addrs(sbi, cpc);
> +
> +               cpc->trim_start = trim_start;
>         }
>         mutex_unlock(&sit_i->sentry_lock);
> 
> Thanks,
> 
> > 
> > Thanks,
> > 
> > >  			add_discard_addrs(sbi, cpc);
> > >  	}
> > >  	mutex_unlock(&sit_i->sentry_lock);
> > > --
> > > 2.10.1
> > > 
> > > 
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> > 
> > .
> > 

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