Re: [PATCH 4/7] xfs: add support for free space btree staging cursors

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

On Mon, Mar 16, 2020 at 08:29:42AM -0400, Brian Foster wrote:
> On Sun, Mar 15, 2020 at 04:51:06PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Add support for btree staging cursors for the free space btrees.  This
> > is needed both for online repair and also to convert xfs_repair to use
> > btree bulk loading.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/libxfs/xfs_alloc_btree.c |   98 +++++++++++++++++++++++++++++++--------
> >  fs/xfs/libxfs/xfs_alloc_btree.h |    7 +++
> >  2 files changed, 86 insertions(+), 19 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/libxfs/xfs_alloc_btree.c b/fs/xfs/libxfs/xfs_alloc_btree.c
> > index a28041fdf4c0..93792ee7924e 100644
> > --- a/fs/xfs/libxfs/xfs_alloc_btree.c
> > +++ b/fs/xfs/libxfs/xfs_alloc_btree.c
> ...
> > @@ -485,36 +520,61 @@ xfs_allocbt_init_cursor(
> ...
> >  
> > +/*
> > + * Install a new free space btree root.  Caller is responsible for invalidating
> > + * and freeing the old btree blocks.
> > + */
> > +void
> > +xfs_allocbt_commit_staged_btree(
> > +	struct xfs_btree_cur	*cur,
> > +	struct xfs_trans	*tp,
> > +	struct xfs_buf		*agbp)
> > +{
> > +	struct xfs_agf		*agf = agbp->b_addr;
> > +	struct xbtree_afakeroot	*afake = cur->bc_ag.afake;
> > +
> > +	ASSERT(cur->bc_flags & XFS_BTREE_STAGING);
> > +
> > +	agf->agf_roots[cur->bc_btnum] = cpu_to_be32(afake->af_root);
> > +	agf->agf_levels[cur->bc_btnum] = cpu_to_be32(afake->af_levels);
> > +	xfs_alloc_log_agf(tp, agbp, XFS_AGF_ROOTS | XFS_AGF_LEVELS);
> > +
> > +	if (cur->bc_btnum == XFS_BTNUM_BNO) {
> > +		xfs_btree_commit_afakeroot(cur, tp, agbp, &xfs_bnobt_ops);
> > +	} else {
> > +		cur->bc_flags |= XFS_BTREE_LASTREC_UPDATE;
> 
> Any reason this is set here and not at init time for the staging cursor?

Originally it was so that ->update_lastrec couldn't get called, but
since you're not supposed to be calling the regular btree operations
anyway I suppose it doesn't matter if the flag is set in staging
cursors... will fix.

--D

> Brian
> 
> > +		xfs_btree_commit_afakeroot(cur, tp, agbp, &xfs_cntbt_ops);
> > +	}
> > +}
> > +
> >  /*
> >   * Calculate number of records in an alloc btree block.
> >   */
> > diff --git a/fs/xfs/libxfs/xfs_alloc_btree.h b/fs/xfs/libxfs/xfs_alloc_btree.h
> > index c9305ebb69f6..047f09f0be3c 100644
> > --- a/fs/xfs/libxfs/xfs_alloc_btree.h
> > +++ b/fs/xfs/libxfs/xfs_alloc_btree.h
> > @@ -13,6 +13,7 @@
> >  struct xfs_buf;
> >  struct xfs_btree_cur;
> >  struct xfs_mount;
> > +struct xbtree_afakeroot;
> >  
> >  /*
> >   * Btree block header size depends on a superblock flag.
> > @@ -48,8 +49,14 @@ struct xfs_mount;
> >  extern struct xfs_btree_cur *xfs_allocbt_init_cursor(struct xfs_mount *,
> >  		struct xfs_trans *, struct xfs_buf *,
> >  		xfs_agnumber_t, xfs_btnum_t);
> > +struct xfs_btree_cur *xfs_allocbt_stage_cursor(struct xfs_mount *mp,
> > +		struct xbtree_afakeroot *afake, xfs_agnumber_t agno,
> > +		xfs_btnum_t btnum);
> >  extern int xfs_allocbt_maxrecs(struct xfs_mount *, int, int);
> >  extern xfs_extlen_t xfs_allocbt_calc_size(struct xfs_mount *mp,
> >  		unsigned long long len);
> >  
> > +void xfs_allocbt_commit_staged_btree(struct xfs_btree_cur *cur,
> > +		struct xfs_trans *tp, struct xfs_buf *agbp);
> > +
> >  #endif	/* __XFS_ALLOC_BTREE_H__ */
> > 
>