linux-kernel - Re: [PATCH] nfsd: allow nfsv3 readdir request to be larger.

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Date:   Fri, 8 Mar 2019 14:29:47 -0500
From:   "J. Bruce Fields" <bfields@...ldses.org>
To:     NeilBrown <neilb@...e.com>
Cc:     Jeff Layton <jlayton@...nel.org>, linux-nfs@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfsd: allow nfsv3 readdir request to be larger.

Thanks!  Applied.

On Thu, Mar 07, 2019 at 09:49:46AM +1100, NeilBrown wrote:
> 
> nfsd currently reports the NFSv4 dtpref FSINFO parameter

(Just changed NFSv4 here to NFSv3.)--b.

> to be PAGE_SIZE, so NFS clients will typically ask for one
> page of directory entries at a time.  This is needlessly restrictive
> as nfsd can handle larger replies easily.
> 
> Also, a READDIR request (but not a READDIRPLUS request) has the count
> size clipped to PAGE_SIE, again unnecessary.
> 
> This patch lifts these limits so that larger readdir requests can be
> used.
> 
> Signed-off-by: NeilBrown <neilb@...e.com>
> ---
>  fs/nfsd/nfs3proc.c | 2 +-
>  fs/nfsd/nfs3xdr.c  | 4 +++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
> index c9cf46e0c040..8f933e84cec1 100644
> --- a/fs/nfsd/nfs3proc.c
> +++ b/fs/nfsd/nfs3proc.c
> @@ -588,7 +588,7 @@ nfsd3_proc_fsinfo(struct svc_rqst *rqstp)
>  	resp->f_wtmax  = max_blocksize;
>  	resp->f_wtpref = max_blocksize;
>  	resp->f_wtmult = PAGE_SIZE;
> -	resp->f_dtpref = PAGE_SIZE;
> +	resp->f_dtpref = max_blocksize;
>  	resp->f_maxfilesize = ~(u32) 0;
>  	resp->f_properties = NFS3_FSF_DEFAULT;
>  
> diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
> index 83919116d5cb..93fea246f676 100644
> --- a/fs/nfsd/nfs3xdr.c
> +++ b/fs/nfsd/nfs3xdr.c
> @@ -573,6 +573,8 @@ int
>  nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p)
>  {
>  	struct nfsd3_readdirargs *args = rqstp->rq_argp;
> +	u32 max_blocksize = svc_max_payload(rqstp);
> +
>  	p = decode_fh(p, &args->fh);
>  	if (!p)
>  		return 0;
> @@ -580,7 +582,7 @@ nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p)
>  	args->verf   = p; p += 2;
>  	args->dircount = ~0;
>  	args->count  = ntohl(*p++);
> -	args->count  = min_t(u32, args->count, PAGE_SIZE);
> +	args->count  = min_t(u32, args->count, max_blocksize);
>  	args->buffer = page_address(*(rqstp->rq_next_page++));
>  
>  	return xdr_argsize_check(rqstp, p);
> -- 
> 2.14.0.rc0.dirty
>