Re: [PATCH 1/3] xfs_scrub: detect infinite loops when scanning inodes

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Jan 08, 2021 at 10:28:04PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> During an inode scan (aka phase 3) when we're scanning the inode btree
> to find files to check, make sure that each invocation of inumbers
> actually gives us an inobt record with a startino that's at least as
> large as what we asked for so that we always make forward progress.

Heh, this should have gone in the random fixes series.  Sigh...

--D

> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  scrub/inodes.c |   16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> 
> diff --git a/scrub/inodes.c b/scrub/inodes.c
> index bdc12df3..4550db83 100644
> --- a/scrub/inodes.c
> +++ b/scrub/inodes.c
> @@ -119,6 +119,7 @@ scan_ag_inodes(
>  	struct scrub_ctx	*ctx = (struct scrub_ctx *)wq->wq_ctx;
>  	struct xfs_bulkstat	*bs;
>  	struct xfs_inumbers	*inumbers;
> +	uint64_t		nextino = cvt_agino_to_ino(&ctx->mnt, agno, 0);
>  	int			i;
>  	int			error;
>  	int			stale_count = 0;
> @@ -153,6 +154,21 @@ scan_ag_inodes(
>  	/* Find the inode chunk & alloc mask */
>  	error = -xfrog_inumbers(&ctx->mnt, ireq);
>  	while (!error && !si->aborted && ireq->hdr.ocount > 0) {
> +		/*
> +		 * Make sure that we always make forward progress while we
> +		 * scan the inode btree.
> +		 */
> +		if (nextino > inumbers->xi_startino) {
> +			str_corrupt(ctx, descr,
> +	_("AG %u inode btree is corrupt near agino %lu, got %lu"), agno,
> +				cvt_ino_to_agino(&ctx->mnt, nextino),
> +				cvt_ino_to_agino(&ctx->mnt,
> +						ireq->inumbers[0].xi_startino));
> +			si->aborted = true;
> +			break;
> +		}
> +		nextino = ireq->hdr.ino;
> +
>  		/*
>  		 * We can have totally empty inode chunks on filesystems where
>  		 * there are more than 64 inodes per block.  Skip these.
>