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Message-ID: <CALTww29Y0jUGZBAaKVTDYQWRYAs_MxtriR7WjmDcxVqO77KRSQ@mail.gmail.com>
Date: Mon, 30 Dec 2024 13:01:05 +0800
From: Xiao Ni <xni@...hat.com>
To: Yu Kuai <yukuai1@...weicloud.com>
Cc: yukuai@...nel.org, song@...nel.org, linux-raid@...r.kernel.org,
linux-kernel@...r.kernel.org, yi.zhang@...wei.com, yangerkun@...wei.com,
"yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH v2 md-6.14 2/5] md/md-bitmap: remove the last parameter
for bimtap_ops->endwrite()
On Mon, Dec 23, 2024 at 3:50 PM Yu Kuai <yukuai1@...weicloud.com> wrote:
>
> Hi,
>
> 在 2024/12/23 15:31, Xiao Ni 写道:
> > On Wed, Dec 18, 2024 at 8:21 PM <yukuai@...nel.org> wrote:
> >>
> >> From: Yu Kuai <yukuai3@...wei.com>
> >>
> >> It is useless, because for the case IO failed for one rdev:
> >>
> >> - If badblocks is set and rdev is not faulty, there is no need to
> >> mark the bit as NEEDED;
> >
> >
> > Hi Kuai
> >
> > It's better to add some comments before here. Before this patch, it's
> > easy to understand. It needs to set bitmap bit when a write request
> > fails.
Hi Kuai
>
> This is not accurate, it's doesn't matter if IO fails or succeed, bit
> must be set if data is not consistent, either IO is not done yet, or the
> array is degaraded.
Sorry for the wrong words. I want to say bitmap NEEDED bit is set when
a write request fails. After this patch, we can't see the logic
directly. So it's a hidden logic. It's better to add more comments
here for future maintenance.
And I read the codes, R1BIO_Degraded, STRIPE_DEGRADED,
R10BIO_Degraded, these three flags are only used to tell bitmap if it
needs to set NEEDED bit. After this patch, it looks like these flags
are not useful anymore.
>
> > With this patch, there are some hidden logics here. To me, it's
> > not easy to maintain in the future. And in man mdadm, there is no-bbl
> > option, so it looks like an array may not have a bad block. And I
> > don't know how dmraid maintain badblock. So this patch needs to be
> > more careful.
>
> no-bbl is one of the option of mdadm --update, I think it means remove
> current badblock entries, not that disable badblocks.
>
> In kernel, badblocks is always enabled by default, and IO error will
> always try to set badblocks first. For example:
>
> - badblocks_init() is called from md_rdev_init(), and if
> badblocks_init() fails, the array can't be assembled.
> - The only thing stop rdev to record badblocks after IO failure is that
> rdev is faulty.
Yes, thanks for pointing out this.
>
> Thanks,
> Kuai
>
> >
> > Regards
> > Xiao
> >
> >> - If rdev is faulty, then mddev->degraded will be set, and we can use
> >> it to mard the bit as NEEDED;
> >>
> >> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> >> Signed-off-by: Yu Kuai <yukuai@...nel.org>
> >> ---
> >> drivers/md/md-bitmap.c | 19 ++++++++++---------
> >> drivers/md/md-bitmap.h | 2 +-
> >> drivers/md/raid1.c | 3 +--
> >> drivers/md/raid10.c | 3 +--
> >> drivers/md/raid5-cache.c | 3 +--
> >> drivers/md/raid5.c | 9 +++------
> >> 6 files changed, 17 insertions(+), 22 deletions(-)
> >>
> >> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> >> index 84fb4cc67d5e..b40a84b01085 100644
> >> --- a/drivers/md/md-bitmap.c
> >> +++ b/drivers/md/md-bitmap.c
> >> @@ -1726,7 +1726,7 @@ static int bitmap_startwrite(struct mddev *mddev, sector_t offset,
> >> }
> >>
> >> static void bitmap_endwrite(struct mddev *mddev, sector_t offset,
> >> - unsigned long sectors, bool success)
> >> + unsigned long sectors)
> >> {
> >> struct bitmap *bitmap = mddev->bitmap;
> >>
> >> @@ -1745,15 +1745,16 @@ static void bitmap_endwrite(struct mddev *mddev, sector_t offset,
> >> return;
> >> }
> >>
> >> - if (success && !bitmap->mddev->degraded &&
> >> - bitmap->events_cleared < bitmap->mddev->events) {
> >> - bitmap->events_cleared = bitmap->mddev->events;
> >> - bitmap->need_sync = 1;
> >> - sysfs_notify_dirent_safe(bitmap->sysfs_can_clear);
> >> - }
> >> -
> >> - if (!success && !NEEDED(*bmc))
> >> + if (!bitmap->mddev->degraded) {
> >> + if (bitmap->events_cleared < bitmap->mddev->events) {
> >> + bitmap->events_cleared = bitmap->mddev->events;
> >> + bitmap->need_sync = 1;
> >> + sysfs_notify_dirent_safe(
> >> + bitmap->sysfs_can_clear);
> >> + }
> >> + } else if (!NEEDED(*bmc)) {
> >> *bmc |= NEEDED_MASK;
> >> + }
> >>
> >> if (COUNTER(*bmc) == COUNTER_MAX)
> >> wake_up(&bitmap->overflow_wait);
> >> diff --git a/drivers/md/md-bitmap.h b/drivers/md/md-bitmap.h
> >> index e87a1f493d3c..31c93019c76b 100644
> >> --- a/drivers/md/md-bitmap.h
> >> +++ b/drivers/md/md-bitmap.h
> >> @@ -92,7 +92,7 @@ struct bitmap_operations {
> >> int (*startwrite)(struct mddev *mddev, sector_t offset,
> >> unsigned long sectors);
> >> void (*endwrite)(struct mddev *mddev, sector_t offset,
> >> - unsigned long sectors, bool success);
> >> + unsigned long sectors);
> >> bool (*start_sync)(struct mddev *mddev, sector_t offset,
> >> sector_t *blocks, bool degraded);
> >> void (*end_sync)(struct mddev *mddev, sector_t offset, sector_t *blocks);
> >> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> >> index 15ba7a001f30..81dff2cea0db 100644
> >> --- a/drivers/md/raid1.c
> >> +++ b/drivers/md/raid1.c
> >> @@ -423,8 +423,7 @@ static void close_write(struct r1bio *r1_bio)
> >> if (test_bit(R1BIO_BehindIO, &r1_bio->state))
> >> mddev->bitmap_ops->end_behind_write(mddev);
> >> /* clear the bitmap if all writes complete successfully */
> >> - mddev->bitmap_ops->endwrite(mddev, r1_bio->sector, r1_bio->sectors,
> >> - !test_bit(R1BIO_Degraded, &r1_bio->state));
> >> + mddev->bitmap_ops->endwrite(mddev, r1_bio->sector, r1_bio->sectors);
> >> md_write_end(mddev);
> >> }
> >>
> >> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> >> index c3a93b2a26a6..3dc0170125b2 100644
> >> --- a/drivers/md/raid10.c
> >> +++ b/drivers/md/raid10.c
> >> @@ -429,8 +429,7 @@ static void close_write(struct r10bio *r10_bio)
> >> struct mddev *mddev = r10_bio->mddev;
> >>
> >> /* clear the bitmap if all writes complete successfully */
> >> - mddev->bitmap_ops->endwrite(mddev, r10_bio->sector, r10_bio->sectors,
> >> - !test_bit(R10BIO_Degraded, &r10_bio->state));
> >> + mddev->bitmap_ops->endwrite(mddev, r10_bio->sector, r10_bio->sectors);
> >> md_write_end(mddev);
> >> }
> >>
> >> diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
> >> index 4c7ecdd5c1f3..ba4f9577c737 100644
> >> --- a/drivers/md/raid5-cache.c
> >> +++ b/drivers/md/raid5-cache.c
> >> @@ -314,8 +314,7 @@ void r5c_handle_cached_data_endio(struct r5conf *conf,
> >> set_bit(R5_UPTODATE, &sh->dev[i].flags);
> >> r5c_return_dev_pending_writes(conf, &sh->dev[i]);
> >> conf->mddev->bitmap_ops->endwrite(conf->mddev,
> >> - sh->sector, RAID5_STRIPE_SECTORS(conf),
> >> - !test_bit(STRIPE_DEGRADED, &sh->state));
> >> + sh->sector, RAID5_STRIPE_SECTORS(conf));
> >> }
> >> }
> >> }
> >> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> >> index 93cc7e252dd4..6eb2841ce28c 100644
> >> --- a/drivers/md/raid5.c
> >> +++ b/drivers/md/raid5.c
> >> @@ -3664,8 +3664,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
> >> }
> >> if (bitmap_end)
> >> conf->mddev->bitmap_ops->endwrite(conf->mddev,
> >> - sh->sector, RAID5_STRIPE_SECTORS(conf),
> >> - false);
> >> + sh->sector, RAID5_STRIPE_SECTORS(conf));
> >> bitmap_end = 0;
> >> /* and fail all 'written' */
> >> bi = sh->dev[i].written;
> >> @@ -3711,8 +3710,7 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
> >> }
> >> if (bitmap_end)
> >> conf->mddev->bitmap_ops->endwrite(conf->mddev,
> >> - sh->sector, RAID5_STRIPE_SECTORS(conf),
> >> - false);
> >> + sh->sector, RAID5_STRIPE_SECTORS(conf));
> >> /* If we were in the middle of a write the parity block might
> >> * still be locked - so just clear all R5_LOCKED flags
> >> */
> >> @@ -4062,8 +4060,7 @@ static void handle_stripe_clean_event(struct r5conf *conf,
> >> wbi = wbi2;
> >> }
> >> conf->mddev->bitmap_ops->endwrite(conf->mddev,
> >> - sh->sector, RAID5_STRIPE_SECTORS(conf),
> >> - !test_bit(STRIPE_DEGRADED, &sh->state));
> >> + sh->sector, RAID5_STRIPE_SECTORS(conf));
> >> if (head_sh->batch_head) {
> >> sh = list_first_entry(&sh->batch_list,
> >> struct stripe_head,
> >> --
> >> 2.43.0
> >>
> >>
> >
> >
> > .
> >
>
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