Re: [PATCH 01/18] xfs: pass an on-disk extent to xfs_bmbt_validate_extent

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

On Wed, Nov 01, 2017 at 09:58:55AM -0400, Brian Foster wrote:
> On Tue, Oct 31, 2017 at 02:15:20PM -0700, Darrick J. Wong wrote:
> > On Tue, Oct 31, 2017 at 01:53:12PM -0400, Brian Foster wrote:
> > > On Tue, Oct 31, 2017 at 04:22:13PM +0200, Christoph Hellwig wrote:
> > > > This prepares for getting rid of the current in-memory extent format.
> > > > 
> > > 
> > > Couldn't we port this function over to use whatever the new in-memory
> > > extent format is? IOW, just have the helper check for XFS_EXT_UNWRITTEN
> > > rather than the associated bit in the on-disk format..?
> > 
> > It's certainly possible, but in general verifiers are supposed to check
> > on-disk metadata before they end up in-core, and this would seem to get
> > us closer to that, right?
> > 
> 
> Yeah, but are any of these calls actually made in a buffer verifier
> path?

No.  They probably ought to be -- we can add them to the bmbt verifier and
the inode fork verifier (in the magical future when those exist :P), but
for now I think xfs_iread_extents is the closest we come to an "obvious"
place where we load disk data into/out of its in-core representation.

--D

> Brian
> 
> > --D
> > 
> > > Brian
> > > 
> > > > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > > > ---
> > > >  fs/xfs/libxfs/xfs_bmap.c       | 6 +++---
> > > >  fs/xfs/libxfs/xfs_bmap_btree.h | 4 ++--
> > > >  fs/xfs/libxfs/xfs_inode_fork.c | 9 ++++-----
> > > >  3 files changed, 9 insertions(+), 10 deletions(-)
> > > > 
> > > > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> > > > index f45f05c45e15..b2b6832b9e6b 100644
> > > > --- a/fs/xfs/libxfs/xfs_bmap.c
> > > > +++ b/fs/xfs/libxfs/xfs_bmap.c
> > > > @@ -1259,14 +1259,14 @@ xfs_iread_extents(
> > > >  		frp = XFS_BMBT_REC_ADDR(mp, block, 1);
> > > >  		for (j = 0; j < num_recs; j++, i++, frp++) {
> > > >  			xfs_bmbt_rec_host_t *trp = xfs_iext_get_ext(ifp, i);
> > > > -			trp->l0 = be64_to_cpu(frp->l0);
> > > > -			trp->l1 = be64_to_cpu(frp->l1);
> > > > -			if (!xfs_bmbt_validate_extent(mp, whichfork, trp)) {
> > > > +			if (!xfs_bmbt_validate_extent(mp, whichfork, frp)) {
> > > >  				XFS_ERROR_REPORT("xfs_bmap_read_extents(2)",
> > > >  						 XFS_ERRLEVEL_LOW, mp);
> > > >  				error = -EFSCORRUPTED;
> > > >  				goto out_brelse;
> > > >  			}
> > > > +			trp->l0 = be64_to_cpu(frp->l0);
> > > > +			trp->l1 = be64_to_cpu(frp->l1);
> > > >  			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
> > > >  		}
> > > >  		xfs_trans_brelse(tp, bp);
> > > > diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
> > > > index 6f891eeb88f6..2fbfe2a24b15 100644
> > > > --- a/fs/xfs/libxfs/xfs_bmap_btree.h
> > > > +++ b/fs/xfs/libxfs/xfs_bmap_btree.h
> > > > @@ -127,9 +127,9 @@ extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,
> > > >   * Check that the extent does not contain an invalid unwritten extent flag.
> > > >   */
> > > >  static inline bool xfs_bmbt_validate_extent(struct xfs_mount *mp, int whichfork,
> > > > -		struct xfs_bmbt_rec_host *ep)
> > > > +		struct xfs_bmbt_rec *ep)
> > > >  {
> > > > -	if (ep->l0 >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
> > > > +	if (get_unaligned_be64(&ep->l0) >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
> > > >  		return true;
> > > >  	if (whichfork == XFS_DATA_FORK &&
> > > >  	    xfs_sb_version_hasextflgbit(&mp->m_sb))
> > > > diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> > > > index bb63f38b97cc..abe601b48c9c 100644
> > > > --- a/fs/xfs/libxfs/xfs_inode_fork.c
> > > > +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> > > > @@ -371,13 +371,13 @@ xfs_iformat_extents(
> > > >  		dp = (xfs_bmbt_rec_t *) XFS_DFORK_PTR(dip, whichfork);
> > > >  		for (i = 0; i < nex; i++, dp++) {
> > > >  			xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
> > > > -			ep->l0 = get_unaligned_be64(&dp->l0);
> > > > -			ep->l1 = get_unaligned_be64(&dp->l1);
> > > > -			if (!xfs_bmbt_validate_extent(mp, whichfork, ep)) {
> > > > +			if (!xfs_bmbt_validate_extent(mp, whichfork, dp)) {
> > > >  				XFS_ERROR_REPORT("xfs_iformat_extents(2)",
> > > >  						 XFS_ERRLEVEL_LOW, mp);
> > > >  				return -EFSCORRUPTED;
> > > >  			}
> > > > +			ep->l0 = get_unaligned_be64(&dp->l0);
> > > > +			ep->l1 = get_unaligned_be64(&dp->l1);
> > > >  			trace_xfs_read_extent(ip, i, state, _THIS_IP_);
> > > >  		}
> > > >  	}
> > > > @@ -764,8 +764,6 @@ xfs_iextents_copy(
> > > >  	for (i = 0; i < nrecs; i++) {
> > > >  		xfs_bmbt_rec_host_t *ep = xfs_iext_get_ext(ifp, i);
> > > >  
> > > > -		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, ep));
> > > > -
> > > >  		start_block = xfs_bmbt_get_startblock(ep);
> > > >  		if (isnullstartblock(start_block)) {
> > > >  			/*
> > > > @@ -779,6 +777,7 @@ xfs_iextents_copy(
> > > >  		/* Translate to on disk format */
> > > >  		put_unaligned_be64(ep->l0, &dp->l0);
> > > >  		put_unaligned_be64(ep->l1, &dp->l1);
> > > > +		ASSERT(xfs_bmbt_validate_extent(ip->i_mount, whichfork, dp));
> > > >  
> > > >  		dp++;
> > > >  		copied++;
> > > > -- 
> > > > 2.14.2
> > > > 
> > > > --
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