Re: [PATCH v4 11/14] NFSD: Remove NFSD_BUFSIZE

[Jeff Layton <jlayton@kernel.org>]

On Mon, 2025-04-28 at 15:36 -0400, cel@kernel.org wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> Clean up: The documenting comment for NFSD_BUFSIZE is quite stale.
> NFSD_BUFSIZE is used only for NFSv4 Reply these days; never for
> NFSv2 or v3, and never for RPC Calls. Even so, the byte count
> estimate does not include the size of the NFSv4 COMPOUND Reply
> HEADER or the RPC auth flavor.
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  fs/nfsd/nfs4proc.c  |  2 +-
>  fs/nfsd/nfs4state.c |  2 +-
>  fs/nfsd/nfs4xdr.c   |  2 +-
>  fs/nfsd/nfsd.h      | 13 -------------
>  4 files changed, 3 insertions(+), 16 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index b397246dae7b..59451b405b5c 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -3832,7 +3832,7 @@ static const struct svc_procedure nfsd_procedures4[2] = {
>  		.pc_ressize = sizeof(struct nfsd4_compoundres),
>  		.pc_release = nfsd4_release_compoundargs,
>  		.pc_cachetype = RC_NOCACHE,
> -		.pc_xdrressize = NFSD_BUFSIZE/4,
> +		.pc_xdrressize = 3+NFSSVC_MAXBLKSIZE/4,
>  		.pc_name = "COMPOUND",
>  	},
>  };
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 59a693f22452..8adcee9dc4d3 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4402,7 +4402,7 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  				    nfserr_rep_too_big;
>  	if (xdr_restrict_buflen(xdr, buflen - rqstp->rq_auth_slack))
>  		goto out_put_session;
> -	svc_reserve(rqstp, buflen);
> +	svc_reserve_auth(rqstp, buflen);
>  
>  	status = nfs_ok;
>  	/* Success! accept new slot seqid */
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 44e7fb34f433..ac1bc2431f27 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -2564,7 +2564,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
>  	/* Sessions make the DRC unnecessary: */
>  	if (argp->minorversion)
>  		cachethis = false;
> -	svc_reserve(argp->rqstp, max_reply + readbytes);
> +	svc_reserve_auth(argp->rqstp, max_reply + readbytes);
>  	argp->rqstp->rq_cachetype = cachethis ? RC_REPLBUFF : RC_NOCACHE;
>  
>  	argp->splice_ok = nfsd_read_splice_ok(argp->rqstp);
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index e2997f0ffbc5..91d144655351 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -50,19 +50,6 @@ bool nfsd_support_version(int vers);
>  /* NFSv2 is limited by the protocol specification, see RFC 1094 */
>  #define NFSSVC_MAXBLKSIZE_V2    (8*1024)
>  
> -
> -/*
> - * Largest number of bytes we need to allocate for an NFS
> - * call or reply.  Used to control buffer sizes.  We use
> - * the length of v3 WRITE, READDIR and READDIR replies
> - * which are an RPC header, up to 26 XDR units of reply
> - * data, and some page data.
> - *
> - * Note that accuracy here doesn't matter too much as the
> - * size is rounded up to a page size when allocating space.
> - */
> -#define NFSD_BUFSIZE            ((RPC_MAX_HEADER_WITH_AUTH+26)*XDR_UNIT + NFSSVC_MAXBLKSIZE)
> -
>  struct readdir_cd {
>  	__be32			err;	/* 0, nfserr, or nfserr_eof */
>  };

Reviewed-by: Jeff Layton <jlayton@kernel.org>