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

Eric Sandeen
2019-12-12T20:38:15Z

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.

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