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

[Brian Foster <bfoster@redhat.com>]

On Wed, Dec 04, 2019 at 09:04:43AM -0800, 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.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Strange.. This seems reasonable to me, but any idea on how this might
have been used in the past? The only thing I can see so far is that
perhaps if the superblock (blocksize/sectorsize) is corrupted, the
in-core state trees could be badly initialized such that the inode falls
into the "in use" state. Of course if that were the case the fs probably
has bigger problems..

Brian

>  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:
> -				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
>  	 */
>