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

Jeff Layton
2025-04-28T21:03:58Z

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>