Re: [PATCH] palo: fix IPL overlap with ext2/ext3 resize_inode

[Helge Deller <deller@gmx.de>]

On 03.07.19 07:22, James Bottomley wrote:
> palo is producing corrupt filesystems because ext2 can't cope with any
> of the resize_inode, which is traditionally placed at blocks 3-258,
> being in the badblocks list.  If this happens, mke2fs silently
> produces a corrupt filesystem image and the palo partition will
> eventually trigger a filesystem error.  The fix is to force palo to
> specify -O^resize_inode to mke2fs which prevents ext2/3 from
> allocating a resize_inode (and thus prevents the filesystem from being
> resized).
>
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> ---
>   palo/palo.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/palo/palo.c b/palo/palo.c
> index 68b85cf..e088993 100644
> --- a/palo/palo.c
> +++ b/palo/palo.c
> @@ -443,7 +443,11 @@ do_cdrom(int media, int kernel32, int kernel64,
>   #define EXT2_HOLE	((MAXBLSIZE + 1) / EXT2_BLOCKSIZE)
>
>   /* offset in bytes before start of hole,  ext2 doesn't allow holes at
> - * to cover the first four blocks of the filesystem */
> + * to cover the first four blocks of the filesystem
> + *
> + * Note: modern ext2/3 has a resize_inode covering blocks 3-258 so you
> + * must either always include the -O^resize_inode when creating the
> + * filesystem or define EXT2_OFFSET to (259*EXT2_BLOCKSIZE)*/
>   #define EXT2_OFFSET	(4*EXT2_BLOCKSIZE)
>
>   int
> @@ -502,7 +506,7 @@ do_formatted(int init, int media, const char *medianame, int partition,
>   	    }
>   	}
>
> -	sprintf(cmd, "mke2fs %s -b %d -l %s %s", do_format == 3 ? "-j" : "",
> +	sprintf(cmd, "mke2fs %s -O^resize_inode -b %d -l %s %s", do_format == 3 ? "-j" : "",

What happens if we face an "old" mke2fs binary which doesn't know about this feature and thus fails?
I wonder if it makes sense to add a fallback path?

Helge