Re: git: b92b9da33006 - main - nfsd: Allow vfs.nfsd.srvmaxio to be up to 4Mbytes

Hi!

On Friday, May 15, 2026, Rick Macklem <rmacklem@freebsd.org> wrote:

> The branch main has been updated by rmacklem:
>
> URL: https://cgit.FreeBSD.org/src/commit/?id=
> b92b9da3300655c86dcd42ea8a5ba45badd90847
>
> commit b92b9da3300655c86dcd42ea8a5ba45badd90847
> Author:     Rick Macklem <rmacklem@FreeBSD.org>
> AuthorDate: 2026-05-14 22:33:23 +0000
> Commit:     Rick Macklem <rmacklem@FreeBSD.org>
> CommitDate: 2026-05-14 22:33:23 +0000
>
>     nfsd: Allow vfs.nfsd.srvmaxio to be up to 4Mbytes
>
>     Without this patch, the maximum setting for
>     vfs.nfsd.srvmaxio was 1Mbyte.  This patch increases
>     that to 4Mbytes.
>
>     The same as for any setting above 128Kbytes, settings up to
>     4Mbytes require that kern.ipc.maxsockbuf be increased.
>     (A message generated after setting vfs.nfsd.srvmaxio via
>     the /etc/rc.conf variable nfs_server_maxio will indicate
>     the minimum setting, which will be somewhat greater than
>     four times the setting of vfs.nfsd.srvmaxio.)
>
>     Requested by:   Cedric Blancher <cedric.blancher@gmail.com>
>     MFC after:      2 weeks
>     Fixes:  13d3bd165e22 ("subr_uio.c: Remove a KASSERT() for large NFS
> server I/O")


Wouldn't be better to introduce an MFC with tag, rater than abusing the
Fixes tag? This seems to me like a new "feature", rather than a bug. And it
will may be added to releasenotes also.


> ---
>  sys/fs/nfs/nfsproto.h           | 3 +++
>  sys/fs/nfsserver/nfs_nfsdport.c | 5 +++--
>  2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/sys/fs/nfs/nfsproto.h b/sys/fs/nfs/nfsproto.h
> index 6e67c5be3416..1054c85d8e8f 100644
> --- a/sys/fs/nfs/nfsproto.h
> +++ b/sys/fs/nfs/nfsproto.h
> @@ -89,8 +89,11 @@
>   * It used to be called NFS_MAXDATA, but has been renamed to clarify that
>   * it refers to server side only and doesn't conflict with the NFS_MAXDATA
>   * defined in rpcsvc/nfs_prot.h for userland.
> + * NFS_SRVMAXIO is the default setting for vfs.nfsd.srvmaxio
> + * NFS_SRVLIMITIO is the maximum setting allowed for vfs.nfsd.srvmaxio
>   */
>  #define        NFS_SRVMAXIO    (128 * 1024)
> +#define        NFS_SRVLIMITIO  (4 * 1024 * 1024)
>
>  /* Stat numbers for rpc returns (version 2, 3 and 4) */
>  /*
> diff --git a/sys/fs/nfsserver/nfs_nfsdport.c b/sys/fs/nfsserver/nfs_
> nfsdport.c
> index e42d5ca1e0a3..1e6936ed351c 100644
> --- a/sys/fs/nfsserver/nfs_nfsdport.c
> +++ b/sys/fs/nfsserver/nfs_nfsdport.c
> @@ -241,8 +241,9 @@ sysctl_srvmaxio(SYSCTL_HANDLER_ARGS)
>                 printf("nfsd: vfs.nfsd.srvmaxio can only be increased\n");
>                 return (EINVAL);
>         }
> -       if (newsrvmaxio > 1048576) {
> -               printf("nfsd: vfs.nfsd.srvmaxio cannot be > 1Mbyte\n");
> +       if (newsrvmaxio > NFS_SRVLIMITIO) {
> +               printf("nfsd: vfs.nfsd.srvmaxio cannot be > %d\n",
> +                   NFS_SRVLIMITIO);
>                 return (EINVAL);
>         }
>         if ((newsrvmaxio & (newsrvmaxio - 1)) != 0) {
>
>