Re: [PATCH v3] ceph: fail the request if the peer MDS doesn't support getvxattr op

["Luís Henriques" <lhenriques@suse.de>]

On Mon, Aug 08, 2022 at 03:08:23PM +0800, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
> 
> Just fail the request instead sending the request out, or the peer
> MDS will crash.
> 
> URL: https://tracker.ceph.com/issues/56529
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
>  fs/ceph/inode.c      |  1 +
>  fs/ceph/mds_client.c | 11 +++++++++++
>  fs/ceph/mds_client.h |  6 +++++-
>  3 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index 79ff197c7cc5..cfa0b550eef2 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -2607,6 +2607,7 @@ int ceph_do_getvxattr(struct inode *inode, const char *name, void *value,
>  		goto out;
>  	}
>  
> +	req->r_feature_needed = CEPHFS_FEATURE_OP_GETVXATTR;
>  	req->r_path2 = kstrdup(name, GFP_NOFS);
>  	if (!req->r_path2) {
>  		err = -ENOMEM;
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index 598012ddc401..3e22783109ad 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -2501,6 +2501,7 @@ ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
>  	INIT_LIST_HEAD(&req->r_unsafe_dir_item);
>  	INIT_LIST_HEAD(&req->r_unsafe_target_item);
>  	req->r_fmode = -1;
> +	req->r_feature_needed = -1;
>  	kref_init(&req->r_kref);
>  	RB_CLEAR_NODE(&req->r_node);
>  	INIT_LIST_HEAD(&req->r_wait);
> @@ -3255,6 +3256,16 @@ static void __do_request(struct ceph_mds_client *mdsc,
>  
>  	dout("do_request mds%d session %p state %s\n", mds, session,
>  	     ceph_session_state_name(session->s_state));
> +
> +	/*
> +	 * The old ceph will crash the MDSs when see unknown OPs
> +	 */
> +	if (req->r_feature_needed > 0 &&
> +	    !test_bit(req->r_feature_needed, &session->s_features)) {
> +		err = -ENODATA;
> +		goto out_session;
> +	}

This patch looks good to me.  The only thing I would have preferred would
be to have ->r_feature_needed defined as an unsigned and initialised to
zero (instead of -1).  But that's me, so feel free to ignore this nit.

Cheers,
--
Luís

> +
>  	if (session->s_state != CEPH_MDS_SESSION_OPEN &&
>  	    session->s_state != CEPH_MDS_SESSION_HUNG) {
>  		/*
> diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
> index e15ee2858fef..728b7d72bf76 100644
> --- a/fs/ceph/mds_client.h
> +++ b/fs/ceph/mds_client.h
> @@ -31,8 +31,9 @@ enum ceph_feature_type {
>  	CEPHFS_FEATURE_METRIC_COLLECT,
>  	CEPHFS_FEATURE_ALTERNATE_NAME,
>  	CEPHFS_FEATURE_NOTIFY_SESSION_STATE,
> +	CEPHFS_FEATURE_OP_GETVXATTR,
>  
> -	CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_NOTIFY_SESSION_STATE,
> +	CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_OP_GETVXATTR,
>  };
>  
>  #define CEPHFS_FEATURES_CLIENT_SUPPORTED {	\
> @@ -45,6 +46,7 @@ enum ceph_feature_type {
>  	CEPHFS_FEATURE_METRIC_COLLECT,		\
>  	CEPHFS_FEATURE_ALTERNATE_NAME,		\
>  	CEPHFS_FEATURE_NOTIFY_SESSION_STATE,	\
> +	CEPHFS_FEATURE_OP_GETVXATTR,		\
>  }
>  
>  /*
> @@ -352,6 +354,8 @@ struct ceph_mds_request {
>  	long long	  r_dir_ordered_cnt;
>  	int		  r_readdir_cache_idx;
>  
> +	int		  r_feature_needed;
> +
>  	struct ceph_cap_reservation r_caps_reservation;
>  };
>  
> -- 
> 2.36.0.rc1
>