Re: [PATCH 1/3] ceph: handle InodeStat v8 versioned field in reply parsing

[Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>]

On Thu, 2025-11-27 at 13:46 +0000, Alex Markuze wrote:
> Add forward-compatible handling for the new versioned field introduced
> in InodeStat v8. This patch only skips the field without using it,
> preparing for future protocol extensions.
> 
> The v8 encoding adds a versioned sub-structure that needs to be properly
> decoded and skipped to maintain compatibility with newer MDS versions.
> 
> Signed-off-by: Alex Markuze <amarkuze@redhat.com>
> ---
>  fs/ceph/mds_client.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 1740047aef0f..32561fc701e5 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -231,6 +231,18 @@ static int parse_reply_info_in(void **p, void *end,
>  						      info->fscrypt_file_len, bad);
>  			}
>  		}
> +
> +		/* struct_v 8 added a versioned field - skip it */
> +		if (struct_v >= 8) {
> +			u8 v8_struct_v, v8_struct_compat;
> +			u32 v8_struct_len;
> +

Probably, we need to have warning here that, currently, this protocol is not
supported yet.

Thanks,
Slava.

> +			ceph_decode_8_safe(p, end, v8_struct_v, bad);
> +			ceph_decode_8_safe(p, end, v8_struct_compat, bad);
> +			ceph_decode_32_safe(p, end, v8_struct_len, bad);
> +			ceph_decode_skip_n(p, end, v8_struct_len, bad);
> +		}
> +
>  		*p = end;
>  	} else {
>  		/* legacy (unversioned) struct */