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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 08:59:06 -0400	[thread overview]
Message-ID: <20200707125906.GB37141@bfoster> (raw)
In-Reply-To: <159370362968.3579756.14752877317465395252.stgit@magnolia>

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:

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);
> 


  reply	other threads:[~2020-07-07 12:59 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 [this message]
2020-07-07 14:07     ` Darrick J. Wong
2020-07-07 14:13       ` Brian Foster
2020-07-08 15:34   ` [PATCH v2 " Darrick J. Wong
2020-07-09 13:37     ` Christoph Hellwig

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