Re: [PATCH 3/6] xfs_repair: enforce that inode btree chunks can't point to AG headers

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

On Thu, Dec 12, 2019 at 02:38:12PM -0600, Eric Sandeen wrote:
> On 12/4/19 11:04 AM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > xfs_repair has a very old check that evidently excuses the AG 0 inode
> > btrees pointing to blocks that are already marked XR_E_INUSE_FS* (e.g.
> > AG headers).  mkfs never formats filesystems that way and it looks like
> > an error, so purge the check.  After this, we always complain if inodes
> > overlap with AG headers because that should never happen.
> 
> So the only thing I can think here is that if you make a 64k block filesystem
> with a 512-byte inode size, you can actually get your first user-created
> inode in the range between first_prealloc and last_prealloc.  So that's
> maybe a clue.
> 
> But then we'd need something to mark all the blocks in that range as
> XR_E_INUSE_FS to justify the existence of the test you're removing here,
> and I can't make up any story or find anything in old code
> that indicates that was ever done.
> 
> Still, that's my best guess, that maybe the system preallocated inodes
> used to be marked as XR_E_INUSE_FS or something.  But then it's weird
> to code "if it's marked XR_E_INUSE_FS and it's in the preallocated
> inode range then re-mark it as XR_E_INO"
> 
> Maybe the prealloc inode range got calculated later or something...
> 
> </handwave>
> 
> Anyway, on to the nitpicking!
> 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  repair/globals.c    |    1 -
> >  repair/globals.h    |    1 -
> >  repair/scan.c       |   19 -------------------
> >  repair/xfs_repair.c |    7 -------
> >  4 files changed, 28 deletions(-)
> > 
> > 
> > diff --git a/repair/globals.c b/repair/globals.c
> > index dcd79ea4..8a60e706 100644
> > --- a/repair/globals.c
> > +++ b/repair/globals.c
> > @@ -73,7 +73,6 @@ int	lost_gquotino;
> >  int	lost_pquotino;
> >  
> >  xfs_agino_t	first_prealloc_ino;
> > -xfs_agino_t	last_prealloc_ino;
> >  xfs_agblock_t	bnobt_root;
> >  xfs_agblock_t	bcntbt_root;
> >  xfs_agblock_t	inobt_root;
> > diff --git a/repair/globals.h b/repair/globals.h
> > index 008bdd90..2ed5c894 100644
> > --- a/repair/globals.h
> > +++ b/repair/globals.h
> > @@ -114,7 +114,6 @@ extern int		lost_gquotino;
> >  extern int		lost_pquotino;
> >  
> >  extern xfs_agino_t	first_prealloc_ino;
> > -extern xfs_agino_t	last_prealloc_ino;
> >  extern xfs_agblock_t	bnobt_root;
> >  extern xfs_agblock_t	bcntbt_root;
> >  extern xfs_agblock_t	inobt_root;
> > diff --git a/repair/scan.c b/repair/scan.c
> > index c383f3aa..05707dd2 100644
> > --- a/repair/scan.c
> > +++ b/repair/scan.c
> > @@ -1645,13 +1645,6 @@ scan_single_ino_chunk(
> >  				break;
> >  			case XR_E_INUSE_FS:
> >  			case XR_E_INUSE_FS1:
> > -				if (agno == 0 &&
> > -				    ino + j >= first_prealloc_ino &&
> > -				    ino + j < last_prealloc_ino) {
> > -					set_bmap(agno, agbno, XR_E_INO);
> > -					break;
> > -				}
> > -				/* fall through */
> >  			default:
> >  				/* XXX - maybe should mark block a duplicate */
> >  				do_warn(
> > @@ -1782,18 +1775,6 @@ _("inode chunk claims untracked block, finobt block - agno %d, bno %d, inopb %d\
> >  				break;
> >  			case XR_E_INUSE_FS:
> >  			case XR_E_INUSE_FS1:
> 
> I guess there's no real reason to list a couple cases that all fall through
> to default:, I'd just remove them as well since they aren't any more special
> than the other unmentioned cases.
> 
> > -				if (agno == 0 &&
> > -				    ino + j >= first_prealloc_ino &&
> > -				    ino + j < last_prealloc_ino) {
> > -					do_warn(
> > -_("inode chunk claims untracked block, finobt block - agno %d, bno %d, inopb %d\n"),
> > -						agno, agbno, mp->m_sb.sb_inopblock);
> > -
> > -					set_bmap(agno, agbno, XR_E_INO);
> > -					suspect++;
> > -					break;
> > -				}
> > -				/* fall through */
> >  			default:
> >  				do_warn(
> >  _("inode chunk claims used block, finobt block - agno %d, bno %d, inopb %d\n"),
> > diff --git a/repair/xfs_repair.c b/repair/xfs_repair.c
> > index 9295673d..3e9059f3 100644
> > --- a/repair/xfs_repair.c
> > +++ b/repair/xfs_repair.c
> > @@ -460,13 +460,6 @@ calc_mkfs(xfs_mount_t *mp)
> >  		first_prealloc_ino = XFS_AGB_TO_AGINO(mp, fino_bno);
> >  	}
> >  
> > -	ASSERT(M_IGEO(mp)->ialloc_blks > 0);
> > -
> > -	if (M_IGEO(mp)->ialloc_blks > 1)
> > -		last_prealloc_ino = first_prealloc_ino + XFS_INODES_PER_CHUNK;
> > -	else
> > -		last_prealloc_ino = XFS_AGB_TO_AGINO(mp, fino_bno + 1);
> > -
> >  	/*
> >  	 * now the first 3 inodes in the system
> >  	 */
> > 
> 
> Otherwise I think I'm ok with this, I can't convince myself that there's any
> reason to keep it.
> 
> I can drop the extra cases if you agree.

Yeah, seems fine to me.

--D

> Reviewed-by: Eric Sandeen <sandeen@redhat.com>