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Date: Wed, 22 Feb 2017 13:26:39 -0800
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 10/10] f2fs: return fs_trim if there is no
candidate
Hi Chao,
On 02/22, Chao Yu wrote:
> On 2016/12/31 2:51, Jaegeuk Kim wrote:
> > If there is no candidate to submit discard command during f2sf_trim_fs, let's
> > return without checkpoint.
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>
> Reviewed-by: Chao Yu <yuchao0@...wei.com>
>
> Please see comments below.
>
> > ---
> > fs/f2fs/checkpoint.c | 5 +++++
> > fs/f2fs/f2fs.h | 1 +
> > fs/f2fs/segment.c | 28 +++++++++++++++++++++++-----
> > 3 files changed, 29 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> > index 917b5c5053ae..ccea40763d9d 100644
> > --- a/fs/f2fs/checkpoint.c
> > +++ b/fs/f2fs/checkpoint.c
> > @@ -1249,6 +1249,11 @@ int write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> >
> > /* this is the case of multiple fstrims without any changes */
> > if (cpc->reason == CP_DISCARD) {
> > + if (!exist_trim_candidates(sbi, cpc)) {
> > + unblock_operations(sbi);
> > + goto out;
> > + }
> > +
> > if (NM_I(sbi)->dirty_nat_cnt == 0 &&
> > SIT_I(sbi)->dirty_sentries == 0 &&
> > prefree_segments(sbi) == 0) {
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index f2f40fce9d31..04d113f0d6bf 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -2119,6 +2119,7 @@ void release_discard_addrs(struct f2fs_sb_info *);
> > int npages_for_summary_flush(struct f2fs_sb_info *, bool);
> > void allocate_new_segments(struct f2fs_sb_info *);
> > int f2fs_trim_fs(struct f2fs_sb_info *, struct fstrim_range *);
> > +bool exist_trim_candidates(struct f2fs_sb_info *, struct cp_control *);
> > struct page *get_sum_page(struct f2fs_sb_info *, unsigned int);
> > void update_meta_page(struct f2fs_sb_info *, void *, block_t);
> > void write_meta_page(struct f2fs_sb_info *, struct page *);
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 9a38424c3c1f..82078734f379 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -836,7 +836,8 @@ static void __add_discard_entry(struct f2fs_sb_info *sbi,
> > SM_I(sbi)->nr_discards += end - start;
> > }
> >
> > -static void add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> > +static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc,
> > + bool check_only)
> > {
> > int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
> > int max_blocks = sbi->blocks_per_seg;
> > @@ -850,12 +851,12 @@ static void add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> > int i;
> >
> > if (se->valid_blocks == max_blocks || !f2fs_discard_en(sbi))
> > - return;
> > + return false;
> >
> > if (!force) {
> > if (!test_opt(sbi, DISCARD) || !se->valid_blocks ||
> > SM_I(sbi)->nr_discards >= SM_I(sbi)->max_discards)
> > - return;
> > + return false;
> > }
> >
> > /* SIT_VBLOCK_MAP_SIZE should be multiple of sizeof(unsigned long) */
> > @@ -873,8 +874,12 @@ static void add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> > && (end - start) < cpc->trim_minlen)
> > continue;
> >
> > + if (check_only)
> > + return true;
> > +
> > __add_discard_entry(sbi, cpc, se, start, end);
> > }
> > + return false;
> > }
> >
> > void release_discard_addrs(struct f2fs_sb_info *sbi)
> > @@ -1455,6 +1460,19 @@ static const struct segment_allocation default_salloc_ops = {
> > .allocate_segment = allocate_segment_by_default,
> > };
> >
> > +bool exist_trim_candidates(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> > +{
> > + __u64 trim_start = cpc->trim_start;
>
> bool has_candidate = false;
>
> > +
> > + mutex_lock(&SIT_I(sbi)->sentry_lock);
> > + for (; trim_start <= cpc->trim_end; trim_start++)
> > + if (add_discard_addrs(sbi, cpc, true))
> > + break;
>
> for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++)
> if (add_discard_addrs(sbi, cpc, true)) {
> has_candidate = true;
> break;
> }
Why do we need to do like this in which needs additional variable with multiple
assignment?
Thanks,
>
> cpc->trim_start = trim_start;
>
> > + mutex_unlock(&SIT_I(sbi)->sentry_lock);
> > +
> > + return trim_start <= cpc->trim_end;
>
> return has_candidate;
>
> Thanks,
>
> > +}
> > +
> > int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
> > {
> > __u64 start = F2FS_BYTES_TO_BLK(range->start);
> > @@ -2251,7 +2269,7 @@ void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> > /* add discard candidates */
> > if (cpc->reason != CP_DISCARD) {
> > cpc->trim_start = segno;
> > - add_discard_addrs(sbi, cpc);
> > + add_discard_addrs(sbi, cpc, false);
> > }
> >
> > if (to_journal) {
> > @@ -2289,7 +2307,7 @@ void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> > __u64 trim_start = cpc->trim_start;
> >
> > for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++)
> > - add_discard_addrs(sbi, cpc);
> > + add_discard_addrs(sbi, cpc, false);
> >
> > cpc->trim_start = trim_start;
> > }
> >
>
>
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