Re: [PATCH 11/30] xfs: scrub the shape of a metadata btree

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

On Mon, Oct 16, 2017 at 12:29:59PM +1100, Dave Chinner wrote:
> On Wed, Oct 11, 2017 at 06:41:56PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Create a function that can check the shape of a btree -- each block
> > passes basic inspection and all the pointers look ok.  In the next patch
> > we'll add the ability to check the actual keys and records stored within
> > the btree.  Add some helper functions so that we report detailed scrub
> > errors in a uniform manner in dmesg.  These are helper functions for
> > subsequent patches.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Minor thing:
> 
> >  /*
> > + * Check a btree pointer.  Returns true if it's ok to use this pointer.
> > + * Callers do not need to set the corrupt flag.
> > + */
> > +static bool
> > +xfs_scrub_btree_ptr_ok(
> > +	struct xfs_scrub_btree		*bs,
> > +	int				level,
> > +	union xfs_btree_ptr		*ptr)
> > +{
> > +	bool				res;
> > +
> > +	/* A btree rooted in an inode has no block pointer to the root. */
> > +	if ((bs->cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
> > +	    level == bs->cur->bc_nlevels)
> > +		return true;
> > +
> > +	/* Otherwise, check the pointers. */
> > +	if (bs->cur->bc_flags & XFS_BTREE_LONG_PTRS) {
> > +		res = xfs_btree_check_lptr(bs->cur, be64_to_cpu(ptr->l), level);
> > +		if (!res)
> > +			xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, level);
> > +	} else {
> > +		res = xfs_btree_check_sptr(bs->cur, be32_to_cpu(ptr->s), level);
> > +		if (!res)
> > +			xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, level);
> > +	}
> 
> We should already know what type of btree we are scrubbing, so I
> think this can be simplified to a single
> xfs_scrub_btree_set_corrupt() tracepoint.

Ok to both.

> > +STATIC int
> > +xfs_scrub_btree_get_block(
> > +	struct xfs_scrub_btree		*bs,
> > +	int				level,
> > +	union xfs_btree_ptr		*pp,
> > +	struct xfs_btree_block		**pblock,
> > +	struct xfs_buf			**pbp)
> > +{
> > +	void				*failed_at;
> > +	int				error;
> > +
> > +	error = xfs_btree_lookup_get_block(bs->cur, level, pp, pblock);
> > +	if (!xfs_scrub_btree_process_error(bs->sc, bs->cur, level, &error) ||
> > +	    !pblock)
> > +		return error;
> > +
> > +	xfs_btree_get_block(bs->cur, level, pbp);
> > +	if (bs->cur->bc_flags & XFS_BTREE_LONG_PTRS) {
> > +		failed_at = __xfs_btree_check_lblock(bs->cur, *pblock,
> > +				level, *pbp);
> > +		if (failed_at) {
> > +			xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, level);
> > +			return 0;
> > +		}
> > +	} else {
> > +		failed_at = __xfs_btree_check_sblock(bs->cur, *pblock,
> > +				 level, *pbp);
> > +		if (failed_at) {
> > +			xfs_scrub_btree_set_corrupt(bs->sc, bs->cur, level);
> > +			return 0;
> > +		}
> > +	}
> 
> And same here.
> 
> > diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
> > index a7c3361..414bbb8 100644
> > --- a/fs/xfs/scrub/common.h
> > +++ b/fs/xfs/scrub/common.h
> > @@ -21,6 +21,24 @@
> >  #define __XFS_SCRUB_COMMON_H__
> >  
> >  /*
> > + * We /could/ terminate a scrub/repair operation early.  If we're not
> > + * in a good place to continue (fatal signal, etc.) then bail out.
> > + * Note that we're careful not to make any judgements about *error.
> > + */
> > +static inline bool
> > +xfs_scrub_should_terminate(
> > +	struct xfs_scrub_context	*sc,
> > +	int				*error)
> > +{
> > +	if (fatal_signal_pending(current)) {
> > +		if (*error == 0)
> > +			*error = -EAGAIN;
> > +		return true;
> > +	}
> > +	return false;
> > +}
> 
> Probably should move that to the original scrub infrastructure
> patch.

Will do.  It's in this patch because (iirc) this is the first time
anything uses it.

--D

> Otherwise looks fine.
> 
> 
> Reviewed-by: Dave Chinner <dchinner@redhat.com>
> 
> -- 
> Dave Chinner
> david@fromorbit.com
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html