Re: [PATCH 2/2] nfsd4: handle seqid-mutating open errors from xdr decoding

["J. Bruce Fields" <bfields@fieldses.org>]

On Tue, Mar 05, 2013 at 05:17:59PM -0500, J. Bruce Fields wrote:
> From: "J. Bruce Fields" <bfields@redhat.com>
> 
> If a client sets an owner (or group_owner or acl) attribute on open for
> create, and the mapping of that owner to an id fails, then we return
> BAD_OWNER.  But BAD_OWNER is a seqid-mutating error, so we can't
> shortcut the open processing that case: we have to at least look up the
> owner so we can find the seqid to bump.

This seems like an awful hack.

Better might be to move idmapping out of xdr decoding, but that's a
bigger change and I wonder if it would break anything else.

--b.

> 
> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
> ---
>  fs/nfsd/nfs4proc.c |   27 ++++++++++++++++++++++++++-
>  fs/nfsd/nfs4xdr.c  |    1 +
>  fs/nfsd/xdr4.h     |    1 +
>  3 files changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index c7e4e8c..42c498c 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -351,6 +351,10 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  	}
>  	if (status)
>  		goto out;
> +	if (open->op_xdr_error) {
> +		status = open->op_xdr_error;
> +		goto out;
> +	}
>  
>  	status = nfsd4_check_open_attributes(rqstp, cstate, open);
>  	if (status)
> @@ -417,6 +421,24 @@ out:
>  }
>  
>  /*
> + * OPEN is the only seqid-mutating operation whose decoding can fail
> + * with a seqid-mutating error (specifically, decoding of user names in
> + * the attributes).  Therefore we have to do some processing to look up
> + * the stateowner so that we can bump the seqid.
> + */
> +static __be32 nfsd4_open_omfg(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd4_op *op)
> +{
> +	struct nfsd4_open *open = (struct nfsd4_open *)&op->u;
> +
> +	if (!seqid_mutating_err(ntohl(op->status)))
> +		return op->status;
> +	if (nfsd4_has_session(cstate))
> +		return op->status;
> +	open->op_xdr_error = op->status;
> +	return nfsd4_open(rqstp, cstate, open);
> +}
> +
> +/*
>   * filehandle-manipulating ops.
>   */
>  static __be32
> @@ -1244,8 +1266,11 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
>  		 * for example, if there is a miscellaneous XDR error
>  		 * it will be set to nfserr_bad_xdr.
>  		 */
> -		if (op->status)
> +		if (op->status) {
> +			if (op->opnum == OP_OPEN)
> +				op->status = nfsd4_open_omfg(rqstp, cstate, op);
>  			goto encode_op;
> +		}
>  
>  		/* We must be able to encode a successful response to
>  		 * this operation, with enough room left over to encode a
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 0116886..a82df26 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -804,6 +804,7 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
>  	open->op_iattr.ia_valid = 0;
>  	open->op_openowner = NULL;
>  
> +	open->op_xdr_error = 0;
>  	/* seqid, share_access, share_deny, clientid, ownerlen */
>  	READ_BUF(4);
>  	READ32(open->op_seqid);
> diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
> index 546f898..be0a79d 100644
> --- a/fs/nfsd/xdr4.h
> +++ b/fs/nfsd/xdr4.h
> @@ -237,6 +237,7 @@ struct nfsd4_open {
>  	u32		op_share_deny;      /* request */
>  	u32		op_deleg_want;      /* request */
>  	stateid_t	op_stateid;         /* response */
> +	__be32		op_xdr_error;       /* see nfsd4_open_omfg() */
>  	u32		op_recall;          /* recall */
>  	struct nfsd4_change_info  op_cinfo; /* response */
>  	u32		op_rflags;          /* response */
> -- 
> 1.7.9.5
>