Re: [PATCH 1/5] xfs: store inode btree block counts in AGI header

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, Aug 31, 2020 at 03:06:37PM -0400, Brian Foster wrote:
> On Thu, Aug 27, 2020 at 07:36:37PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Add a btree block usage counters for both inode btrees to the AGI header
> > so that we don't have to walk the entire finobt at mount time to create
> > the per-AG reservations.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/libxfs/xfs_ag.c           |    4 ++++
> >  fs/xfs/libxfs/xfs_format.h       |   18 +++++++++++++++++-
> >  fs/xfs/libxfs/xfs_ialloc.c       |    1 +
> >  fs/xfs/libxfs/xfs_ialloc_btree.c |   21 +++++++++++++++++++++
> >  fs/xfs/xfs_ondisk.h              |    2 +-
> >  fs/xfs/xfs_super.c               |    4 ++++
> >  6 files changed, 48 insertions(+), 2 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
> > index 8cf73fe4338e..65d443c787d0 100644
> > --- a/fs/xfs/libxfs/xfs_ag.c
> > +++ b/fs/xfs/libxfs/xfs_ag.c
> > @@ -333,6 +333,10 @@ xfs_agiblock_init(
> >  	}
> >  	for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
> >  		agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
> > +	if (xfs_sb_version_hasinobtcounts(&mp->m_sb)) {
> > +		agi->agi_iblocks = cpu_to_be32(1);
> > +		agi->agi_fblocks = cpu_to_be32(1);
> > +	}
> 
> With independent tree counters, shouldn't we be checking for hasfinobt()
> for such finobt changes?

DOH.  Yes, it should, now that hasinobtcounts() no longer requires
hasfinobt.  I'll fix that.

> >  }
> >  
> >  typedef void (*aghdr_init_work_f)(struct xfs_mount *mp, struct xfs_buf *bp,
> ...
> > diff --git a/fs/xfs/libxfs/xfs_ialloc_btree.c b/fs/xfs/libxfs/xfs_ialloc_btree.c
> > index 3c8aebc36e64..ee9d407ab9da 100644
> > --- a/fs/xfs/libxfs/xfs_ialloc_btree.c
> > +++ b/fs/xfs/libxfs/xfs_ialloc_btree.c
> > @@ -67,6 +67,25 @@ xfs_finobt_set_root(
> >  			   XFS_AGI_FREE_ROOT | XFS_AGI_FREE_LEVEL);
> >  }
> >  
> > +/* Update the inode btree block counter for this btree. */
> > +static inline void
> > +xfs_inobt_mod_blockcount(
> > +	struct xfs_btree_cur	*cur,
> > +	int			howmuch)
> > +{
> > +	struct xfs_buf		*agbp = cur->bc_ag.agbp;
> > +	struct xfs_agi		*agi = agbp->b_addr;
> > +
> > +	if (!xfs_sb_version_hasinobtcounts(&cur->bc_mp->m_sb))
> > +		return;
> > +
> > +	if (cur->bc_btnum == XFS_BTNUM_FINO)
> > +		be32_add_cpu(&agi->agi_fblocks, howmuch);
> > +	else
> > +		be32_add_cpu(&agi->agi_iblocks, howmuch);
> > +	xfs_ialloc_log_agi(cur->bc_tp, agbp, XFS_AGI_IBLOCKS);
> 
> Similarly, I thought we were going to be logging them separately as
> well..? It seems odd to log an unused field in the finobt=0 case. Hm?

...and that.  Thank you for catching that.

--D

> Brian
> 
> > +}
> > +
> >  STATIC int
> >  __xfs_inobt_alloc_block(
> >  	struct xfs_btree_cur	*cur,
> > @@ -102,6 +121,7 @@ __xfs_inobt_alloc_block(
> >  
> >  	new->s = cpu_to_be32(XFS_FSB_TO_AGBNO(args.mp, args.fsbno));
> >  	*stat = 1;
> > +	xfs_inobt_mod_blockcount(cur, 1);
> >  	return 0;
> >  }
> >  
> > @@ -134,6 +154,7 @@ __xfs_inobt_free_block(
> >  	struct xfs_buf		*bp,
> >  	enum xfs_ag_resv_type	resv)
> >  {
> > +	xfs_inobt_mod_blockcount(cur, -1);
> >  	return xfs_free_extent(cur->bc_tp,
> >  			XFS_DADDR_TO_FSB(cur->bc_mp, XFS_BUF_ADDR(bp)), 1,
> >  			&XFS_RMAP_OINFO_INOBT, resv);
> > diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
> > index 5f04d8a5ab2a..acb9b737fe6b 100644
> > --- a/fs/xfs/xfs_ondisk.h
> > +++ b/fs/xfs/xfs_ondisk.h
> > @@ -23,7 +23,7 @@ xfs_check_ondisk_structs(void)
> >  	XFS_CHECK_STRUCT_SIZE(struct xfs_acl_entry,		12);
> >  	XFS_CHECK_STRUCT_SIZE(struct xfs_agf,			224);
> >  	XFS_CHECK_STRUCT_SIZE(struct xfs_agfl,			36);
> > -	XFS_CHECK_STRUCT_SIZE(struct xfs_agi,			336);
> > +	XFS_CHECK_STRUCT_SIZE(struct xfs_agi,			344);
> >  	XFS_CHECK_STRUCT_SIZE(struct xfs_bmbt_key,		8);
> >  	XFS_CHECK_STRUCT_SIZE(struct xfs_bmbt_rec,		16);
> >  	XFS_CHECK_STRUCT_SIZE(struct xfs_bmdr_block,		4);
> > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> > index 71ac6c1cdc36..c7ffcb57b586 100644
> > --- a/fs/xfs/xfs_super.c
> > +++ b/fs/xfs/xfs_super.c
> > @@ -1549,6 +1549,10 @@ xfs_fc_fill_super(
> >  		goto out_filestream_unmount;
> >  	}
> >  
> > +	if (xfs_sb_version_hasinobtcounts(&mp->m_sb))
> > +		xfs_warn(mp,
> > + "EXPERIMENTAL inode btree counters feature in use. Use at your own risk!");
> > +
> >  	error = xfs_mountfs(mp);
> >  	if (error)
> >  		goto out_filestream_unmount;
> > 
>