Re: [PATCH 6/9] xfs: inode scrubber shouldn't bother with raw checks

[Brian Foster <bfoster@redhat.com>]

On Wed, Mar 14, 2018 at 05:30:07PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> The inode scrubber tries to _iget the inode prior to running checks.
> If that _iget call fails with corruption errors that's an automatic
> fail, regardless of whether it was the inode buffer read verifier,
> the ifork verifier, or the ifork formatter that errored out.
> 
> Therefore, get rid of the raw mode scrub code because it's not needed.
> Found by trying to fix some test failures in xfs/379 and xfs/415.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/scrub/inode.c |   98 +++++---------------------------------------------
>  1 file changed, 9 insertions(+), 89 deletions(-)
> 
> 
> diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
> index 21297be..0332a01 100644
> --- a/fs/xfs/scrub/inode.c
> +++ b/fs/xfs/scrub/inode.c
> @@ -515,72 +515,6 @@ xfs_scrub_dinode(
>  	}
>  }
>  
> -/* Map and read a raw inode. */
> -STATIC int
> -xfs_scrub_inode_map_raw(
> -	struct xfs_scrub_context	*sc,
> -	xfs_ino_t			ino,
> -	struct xfs_buf			**bpp,
> -	struct xfs_dinode		**dipp)
> -{
> -	struct xfs_imap			imap;
> -	struct xfs_mount		*mp = sc->mp;
> -	struct xfs_buf			*bp = NULL;
> -	struct xfs_dinode		*dip;
> -	int				error;
> -
> -	error = xfs_imap(mp, sc->tp, ino, &imap, XFS_IGET_UNTRUSTED);
> -	if (error == -EINVAL) {
> -		/*
> -		 * Inode could have gotten deleted out from under us;
> -		 * just forget about it.
> -		 */
> -		error = -ENOENT;
> -		goto out;
> -	}
> -	if (!xfs_scrub_process_error(sc, XFS_INO_TO_AGNO(mp, ino),
> -			XFS_INO_TO_AGBNO(mp, ino), &error))
> -		goto out;
> -
> -	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
> -			imap.im_blkno, imap.im_len, XBF_UNMAPPED, &bp,
> -			NULL);
> -	if (!xfs_scrub_process_error(sc, XFS_INO_TO_AGNO(mp, ino),
> -			XFS_INO_TO_AGBNO(mp, ino), &error))
> -		goto out;
> -
> -	/*
> -	 * Is this really an inode?  We disabled verifiers in the above
> -	 * xfs_trans_read_buf call because the inode buffer verifier
> -	 * fails on /any/ inode record in the inode cluster with a bad
> -	 * magic or version number, not just the one that we're
> -	 * checking.  Therefore, grab the buffer unconditionally, attach
> -	 * the inode verifiers by hand, and run the inode verifier only
> -	 * on the one inode we want.
> -	 */
> -	bp->b_ops = &xfs_inode_buf_ops;
> -	dip = xfs_buf_offset(bp, imap.im_boffset);
> -	if (xfs_dinode_verify(mp, ino, dip) != NULL ||
> -	    !xfs_dinode_good_version(mp, dip->di_version)) {
> -		xfs_scrub_ino_set_corrupt(sc, ino, bp);
> -		goto out_buf;
> -	}
> -
> -	/* ...and is it the one we asked for? */
> -	if (be32_to_cpu(dip->di_gen) != sc->sm->sm_gen) {
> -		error = -ENOENT;
> -		goto out_buf;
> -	}
> -
> -	*dipp = dip;
> -	*bpp = bp;
> -out:
> -	return error;
> -out_buf:
> -	xfs_trans_brelse(sc->tp, bp);
> -	return error;
> -}
> -
>  /*
>   * Make sure the finobt doesn't think this inode is free.
>   * We don't have to check the inobt ourselves because we got the inode via
> @@ -727,43 +661,29 @@ xfs_scrub_inode(
>  	struct xfs_scrub_context	*sc)
>  {
>  	struct xfs_dinode		di;
> -	struct xfs_buf			*bp = NULL;
> -	struct xfs_dinode		*dip;
> -	xfs_ino_t			ino;
>  	int				error = 0;
>  
> -	/* Did we get the in-core inode, or are we doing this manually? */
> -	if (sc->ip) {
> -		ino = sc->ip->i_ino;
> -		xfs_inode_to_disk(sc->ip, &di, 0);
> -		dip = &di;
> -	} else {
> -		/* Map & read inode. */
> -		ino = sc->sm->sm_ino;
> -		error = xfs_scrub_inode_map_raw(sc, ino, &bp, &dip);
> -		if (error || !bp)
> -			goto out;
> +	/* iget failed means automatic fail. */
> +	if (!sc->ip) {
> +		xfs_scrub_ino_set_corrupt(sc, sc->sm->sm_ino, NULL);
> +		return 0;
>  	}

Ok, so the setup function will attempt to lookup the inode number that's
passed in. If the lookup fails with a corruption error, we'd have ip ==
NULL but return 0 from that setup call because it's not a scrub
operational error. Hence, we get here without an inode and call it an fs
corruption. Seems fine as long as I'm following this correctly:

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  
> -	xfs_scrub_dinode(sc, bp, dip, ino);
> +	/* Scrub the inode core. */
> +	xfs_inode_to_disk(sc->ip, &di, 0);
> +	xfs_scrub_dinode(sc, NULL, &di, sc->ip->i_ino);
>  	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
>  		goto out;
>  
> -	/* Now let's do the things that require a live inode. */
> -	if (!sc->ip)
> -		goto out;
> -
>  	/*
>  	 * Look for discrepancies between file's data blocks and the reflink
>  	 * iflag.  We already checked the iflag against the file mode when
>  	 * we scrubbed the dinode.
>  	 */
>  	if (S_ISREG(VFS_I(sc->ip)->i_mode))
> -		xfs_scrub_inode_check_reflink_iflag(sc, ino, bp);
> +		xfs_scrub_inode_check_reflink_iflag(sc, sc->ip->i_ino, NULL);
>  
> -	xfs_scrub_inode_xref(sc, ino, dip);
> +	xfs_scrub_inode_xref(sc, sc->ip->i_ino, &di);
>  out:
> -	if (bp)
> -		xfs_trans_brelse(sc->tp, bp);
>  	return error;
>  }
> 
> --
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