On Fri, Oct 15, 2021 at 10:17:02AM +1100, Dave Chinner wrote: > On Thu, Oct 14, 2021 at 04:05:49PM -0700, Darrick J. Wong wrote: > > On Fri, Oct 15, 2021 at 09:48:13AM +1100, Dave Chinner wrote: > > > On Thu, Oct 14, 2021 at 01:17:00PM -0700, Darrick J. Wong wrote: > > > > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > > > > > > > During review of subsequent patches, Dave and I noticed that this > > > > function doesn't work quite right -- accessing cur->bc_ino depends on > > > > the ROOT_IN_INODE flag, not LONG_PTRS. Fix that and the parentheses > > > > isssue. While we're at it, remove the piece that accesses cur->bc_ag, > > > > because block 0 of an AG is never part of a btree. > > > > > > > > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> > > > > --- > > > > fs/xfs/scrub/trace.c | 7 ++++--- > > > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > > > > > > > > > diff --git a/fs/xfs/scrub/trace.c b/fs/xfs/scrub/trace.c > > > > index c0ef53fe6611..93c13763c15e 100644 > > > > --- a/fs/xfs/scrub/trace.c > > > > +++ b/fs/xfs/scrub/trace.c > > > > @@ -24,10 +24,11 @@ xchk_btree_cur_fsbno( > > > > if (level < cur->bc_nlevels && cur->bc_bufs[level]) > > > > return XFS_DADDR_TO_FSB(cur->bc_mp, > > > > xfs_buf_daddr(cur->bc_bufs[level])); > > > > - if (level == cur->bc_nlevels - 1 && cur->bc_flags & XFS_BTREE_LONG_PTRS) > > > > + > > > > + if (level == cur->bc_nlevels - 1 && > > > > + (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)) > > > > return XFS_INO_TO_FSB(cur->bc_mp, cur->bc_ino.ip->i_ino); > > > > > > Ok. > > > > > > > - if (!(cur->bc_flags & XFS_BTREE_LONG_PTRS)) > > > > - return XFS_AGB_TO_FSB(cur->bc_mp, cur->bc_ag.pag->pag_agno, 0); > > > > + > > > > > > But doesn't this break the tracing code on short pointers as the > > > tracing code does: > > > > > > TP_fast_assign( > > > xfs_fsblock_t fsbno = xchk_btree_cur_fsbno(cur, level); > > > ... > > > __entry->agno = XFS_FSB_TO_AGNO(cur->bc_mp, fsbno); > > > > > > > > > i.e. the tracing will no longer give the correct agno for per-ag > > > cursors that don't have any buffers attached to them at the current > > > level? > > > > Hmmm. By that logic, maybe we should get rid of the (level == > > cur->bc_nlevels - 1) check entirely so that any cursor without a buffer > > attached at that level will always provide *some* kind of breadcrumb to > > the tracepoints? > > Perhaps so. > > > I almost did that instead, except for the consideration that if you're > > tracing the online fsck code, you should /probably/ have at least one of > > xchk_stop/xrep_attempt/xchk_done included in the filter list so you can > > be certain of what the kernel is checking. > > It doesn't worry me how we resolve this - I just pointed it out > because it's not mentioned in the commit message and I wanted to > make sure it wasn't an oversight. If there are better ways to get > this information from tracepoints and XFS_FSB_TO_AGNO() does > something safe and obvious with NULLFSBLOCK (e.g. ends up as -1) > then as long as there's mention of this change in the commit message > I'm fine with it as it is. Ok. I'll add the following to the commit message: "Note: This changes the btree scrubber tracepoints behavior -- if the cursor has no buffer for a certain level, it will always report NULLFSBLOCK. It is assumed that anyone tracing the online fsck code will also be tracing xchk_start/xchk_done or otherwise be aware of what exactly is being scrubbed." --D > > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx
