Re: [PATCH 2/2] xfs: fix finobt btree block recovery ordering

[Brian Foster <bfoster@redhat.com>]

On Wed, Sep 30, 2020 at 04:35:32PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> Nathan popped up on #xfs and pointed out that we fail to handle
> finobt btree blocks in xlog_recover_get_buf_lsn(). This means they
> always fall through the entire magic number matching code to "recover
> immediately". Whilst most of the time this is the correct behaviour,
> occasionally it will be incorrect and could potentially overwrite
> more recent metadata because we don't check the LSN in the on disk
> metadata at all.
> 
> This bug has been present since the finobt was first introduced, and
> is a potential cause of the occasional xfs_iget_check_free_state()
> failures we see that indicate that the inode btree state does not
> match the on disk inode state.
> 
> Fixes: aafc3c246529 ("xfs: support the XFS_BTNUM_FINOBT free inode btree type")
> Reported-by: Nathan Scott <nathans@redhat.com>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---

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

>  fs/xfs/xfs_buf_item_recover.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/xfs/xfs_buf_item_recover.c b/fs/xfs/xfs_buf_item_recover.c
> index 24c7a8d11e1a..d44e8b4a3391 100644
> --- a/fs/xfs/xfs_buf_item_recover.c
> +++ b/fs/xfs/xfs_buf_item_recover.c
> @@ -719,6 +719,8 @@ xlog_recover_get_buf_lsn(
>  	case XFS_ABTC_MAGIC:
>  	case XFS_RMAP_CRC_MAGIC:
>  	case XFS_REFC_CRC_MAGIC:
> +	case XFS_FIBT_CRC_MAGIC:
> +	case XFS_FIBT_MAGIC:
>  	case XFS_IBT_CRC_MAGIC:
>  	case XFS_IBT_MAGIC: {
>  		struct xfs_btree_block *btb = blk;
> -- 
> 2.28.0
>