From: Brian Foster <bfoster@redhat.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: sandeen@sandeen.net, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 3/3] xfs_repair: try to fill the AGFL before we fix the freelist
Date: Tue, 7 Jul 2020 10:13:08 -0400 [thread overview]
Message-ID: <20200707141308.GA55781@bfoster> (raw)
In-Reply-To: <20200707140708.GK7606@magnolia>
On Tue, Jul 07, 2020 at 07:07:08AM -0700, Darrick J. Wong wrote:
> On Tue, Jul 07, 2020 at 08:59:06AM -0400, Brian Foster wrote:
> > On Thu, Jul 02, 2020 at 08:27:09AM -0700, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <darrick.wong@oracle.com>
> > >
> > > In commit 9851fd79bfb1, we added a slight amount of slack to the free
> > > space btrees being reconstructed so that the initial fix_freelist call
> > > (which is run against a totally empty AGFL) would never have to split
> > > either free space btree in order to populate the free list.
> > >
> > > The new btree bulk loading code in xfs_repair can re-create this
> > > situation because it can set the slack values to zero if the filesystem
> > > is very full. However, these days repair has the infrastructure needed
> > > to ensure that overestimations of the btree block counts end up on the
> > > AGFL or get freed back into the filesystem at the end of phase 5.
> > >
> > > Fix this problem by reserving extra blocks in the bnobt reservation, and
> > > checking that there are enough overages in the bnobt/cntbt fakeroots to
> > > populate the AGFL with the minimum number of blocks it needs to handle a
> > > split in the bno/cnt/rmap btrees.
> > >
> > > Note that we reserve blocks for the new bnobt/cntbt/AGFL at the very end
> > > of the reservation steps in phase 5, so the extra allocation should not
> > > cause repair to fail if it can't find blocks for btrees.
> > >
> > > Fixes: 9851fd79bfb1 ("repair: AGFL rebuild fails if btree split required")
> > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > > ---
> > > repair/agbtree.c | 51 ++++++++++++++++++++++++++++++++++++++++++++-------
> > > 1 file changed, 44 insertions(+), 7 deletions(-)
> > >
> > >
> > > diff --git a/repair/agbtree.c b/repair/agbtree.c
> > > index de8015ec..9f64d54b 100644
> > > --- a/repair/agbtree.c
> > > +++ b/repair/agbtree.c
> > ...
> > > @@ -268,16 +288,33 @@ _("Unable to compute free space by length btree geometry, error %d.\n"), -error)
> > > btr_cnt->bload.nr_blocks;
> > >
> > > /* We don't need any more blocks, so we're done. */
> > > - if (delta_bno >= 0 && delta_cnt >= 0) {
> > > + if (delta_bno >= 0 && delta_cnt >= 0 &&
> > > + delta_bno + delta_cnt >= agfl_goal) {
> > > *extra_blocks = delta_bno + delta_cnt;
> > > break;
> > > }
> > >
> > > /* Allocate however many more blocks we need this time. */
> > > - if (delta_bno < 0)
> > > + if (delta_bno < 0) {
> > > reserve_btblocks(sc->mp, agno, btr_bno, -delta_bno);
> > > - if (delta_cnt < 0)
> > > + delta_bno = 0;
> > > + }
> > > + if (delta_cnt < 0) {
> > > reserve_btblocks(sc->mp, agno, btr_cnt, -delta_cnt);
> > > + delta_cnt = 0;
> > > + }
> > > +
> > > + /*
> > > + * Try to fill the bnobt cursor with extra blocks to populate
> > > + * the AGFL. If we don't get all the blocks we want, stop
> > > + * trying to fill the AGFL because the AG is totally out of
> > > + * space.
> > > + */
> > > + agfl_wanted = agfl_goal - (delta_bno + delta_cnt);
> > > + if (agfl_wanted > 0 &&
> > > + agfl_wanted != reserve_agblocks(sc->mp, agno, btr_bno,
> > > + agfl_wanted))
> > > + agfl_goal = 0;
> >
> > Nit: can we split off the function call so it's not embedded in the if
> > condition? With that tweak:
>
> It occurs to me that we don't care how much we fall short of the
> requested allocation. I could change reserve_agblocks to return true if
> it got all the blocks it was asked to get, and then that becomes:
>
> if (agfl_wanted > 0 &&
> !reserve_agblocks(sc->mp, agno, btr_bno, agfl_wanted)
> agfl_goal = 0;
>
> How does that sound?
>
Looks readable enough to me, thanks.
Brian
> --D
>
> > Reviewed-by: Brian Foster <bfoster@redhat.com>
> >
> > >
> > > /* Ok, now how many free space records do we have? */
> > > *nr_extents = count_bno_extents_blocks(agno, &num_freeblocks);
> > >
> >
>
next prev parent reply other threads:[~2020-07-07 14:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 15:26 [PATCH v2 0/3] xfs_repair: more fixes Darrick J. Wong
2020-07-02 15:26 ` [PATCH 1/3] xfs_repair: complain about ag header crc errors Darrick J. Wong
2020-07-06 22:53 ` Allison Collins
2020-07-08 6:36 ` Christoph Hellwig
2020-07-02 15:27 ` [PATCH 2/3] xfs_repair: simplify free space btree calculations in init_freespace_cursors Darrick J. Wong
2020-07-06 22:53 ` Allison Collins
2020-07-07 12:58 ` Brian Foster
2020-07-08 6:40 ` Christoph Hellwig
2020-07-02 15:27 ` [PATCH 3/3] xfs_repair: try to fill the AGFL before we fix the freelist Darrick J. Wong
2020-07-07 12:59 ` Brian Foster
2020-07-07 14:07 ` Darrick J. Wong
2020-07-07 14:13 ` Brian Foster [this message]
2020-07-08 15:34 ` [PATCH v2 " Darrick J. Wong
2020-07-09 13:37 ` Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200707141308.GA55781@bfoster \
--to=bfoster@redhat.com \
--cc=darrick.wong@oracle.com \
--cc=linux-xfs@vger.kernel.org \
--cc=sandeen@sandeen.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).