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Re: [PATCH 034/119] xfs: teach rmapbt to support interval queries

To: Brian Foster <bfoster@xxxxxxxxxx>
Subject: Re: [PATCH 034/119] xfs: teach rmapbt to support interval queries
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Date: Fri, 8 Jul 2016 17:16:35 -0700
Cc: david@xxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, vishal.l.verma@xxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20160708183403.GF59278@xxxxxxxxxxxxxxx>
References: <146612627129.12839.3827886950949809165.stgit@xxxxxxxxxxxxxxxx> <146612649050.12839.2803288971604662823.stgit@xxxxxxxxxxxxxxxx> <20160708183403.GF59278@xxxxxxxxxxxxxxx>
User-agent: Mutt/1.5.24 (2015-08-30)
On Fri, Jul 08, 2016 at 02:34:03PM -0400, Brian Foster wrote:
> On Thu, Jun 16, 2016 at 06:21:30PM -0700, Darrick J. Wong wrote:
> > Now that the generic btree code supports querying all records within a
> > range of keys, use that functionality to allow us to ask for all the
> > extents mapped to a range of physical blocks.
> > 
> > v2: Move unwritten bit to rm_offset.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > ---
> >  fs/xfs/libxfs/xfs_rmap.c       |   43 
> > ++++++++++++++++++++++++++++++++++++++++
> >  fs/xfs/libxfs/xfs_rmap_btree.h |    9 ++++++++
> >  2 files changed, 52 insertions(+)
> > 
> > 
> > diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
> > index c6a5a0b..0e1721a 100644
> > --- a/fs/xfs/libxfs/xfs_rmap.c
> > +++ b/fs/xfs/libxfs/xfs_rmap.c
> > @@ -184,3 +184,46 @@ out_error:
> >     trace_xfs_rmap_alloc_extent_error(mp, agno, bno, len, false, oinfo);
> >     return error;
> >  }
> > +
> > +struct xfs_rmapbt_query_range_info {
> > +   xfs_rmapbt_query_range_fn       fn;
> > +   void                            *priv;
> > +};
> > +
> > +/* Format btree record and pass to our callback. */
> > +STATIC int
> > +xfs_rmapbt_query_range_helper(
> > +   struct xfs_btree_cur    *cur,
> > +   union xfs_btree_rec     *rec,
> > +   void                    *priv)
> > +{
> > +   struct xfs_rmapbt_query_range_info      *query = priv;
> > +   struct xfs_rmap_irec                    irec;
> > +   int                                     error;
> > +
> > +   error = xfs_rmapbt_btrec_to_irec(rec, &irec);
> > +   if (error)
> > +           return error;
> > +   return query->fn(cur, &irec, query->priv);
> > +}
> > +
> > +/* Find all rmaps between two keys. */
> > +int
> > +xfs_rmapbt_query_range(
> > +   struct xfs_btree_cur            *cur,
> > +   struct xfs_rmap_irec            *low_rec,
> > +   struct xfs_rmap_irec            *high_rec,
> > +   xfs_rmapbt_query_range_fn       fn,
> > +   void                            *priv)
> > +{
> > +   union xfs_btree_irec            low_brec;
> > +   union xfs_btree_irec            high_brec;
> > +   struct xfs_rmapbt_query_range_info      query;
> > +
> > +   low_brec.r = *low_rec;
> > +   high_brec.r = *high_rec;
> 
> Some checks or asserts that these are actually in order couldn't hurt.
> Otherwise looks good:

Ok.  If low_rec > high_rec then you'll get no results.  I'm not sure
if that's ok or if we should explicitly return -EINVAL for that case?

--D

> 
> Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> 
> > +   query.priv = priv;
> > +   query.fn = fn;
> > +   return xfs_btree_query_range(cur, &low_brec, &high_brec,
> > +                   xfs_rmapbt_query_range_helper, &query);
> > +}
> > diff --git a/fs/xfs/libxfs/xfs_rmap_btree.h b/fs/xfs/libxfs/xfs_rmap_btree.h
> > index 796071c..e926c6e 100644
> > --- a/fs/xfs/libxfs/xfs_rmap_btree.h
> > +++ b/fs/xfs/libxfs/xfs_rmap_btree.h
> > @@ -74,4 +74,13 @@ int xfs_rmap_free(struct xfs_trans *tp, struct xfs_buf 
> > *agbp,
> >               xfs_agnumber_t agno, xfs_agblock_t bno, xfs_extlen_t len,
> >               struct xfs_owner_info *oinfo);
> >  
> > +typedef int (*xfs_rmapbt_query_range_fn)(
> > +   struct xfs_btree_cur    *cur,
> > +   struct xfs_rmap_irec    *rec,
> > +   void                    *priv);
> > +
> > +int xfs_rmapbt_query_range(struct xfs_btree_cur *cur,
> > +           struct xfs_rmap_irec *low_rec, struct xfs_rmap_irec *high_rec,
> > +           xfs_rmapbt_query_range_fn fn, void *priv);
> > +
> >  #endif     /* __XFS_RMAP_BTREE_H__ */
> > 
> > _______________________________________________
> > xfs mailing list
> > xfs@xxxxxxxxxxx
> > http://oss.sgi.com/mailman/listinfo/xfs

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