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Date:   Tue, 6 Jul 2021 20:10:56 -0400
From:   "J. Bruce Fields" <bfields@fieldses.org>
To:     Dai Ngo <dai.ngo@oracle.com>
Cc:     olga.kornievskaia@gmail.com, linux-nfs@vger.kernel.org,
        trondmy@hammerspace.com, chuck.lever@oracle.com
Subject: Re: [PATCH v7 2/2] NFSv4.2: remove restriction of copy size for
 inter-server copy.
Message-ID: <20210707001056.GA26847@fieldses.org>
References: <20210521190938.24820-1-dai.ngo@oracle.com>
 <20210521190938.24820-3-dai.ngo@oracle.com>
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Whoops, I overlooked that this is client side, so it needs to go through
Trond or Anna, not me.

Also note:

On Fri, May 21, 2021 at 03:09:38PM -0400, Dai Ngo wrote:
> This patch, relying on the delayed unmount feature, removes this
> restriction since the mount and unmount overhead is now not applicable
> for every inter-server copy.

There's no guarantee that the same kernel version is running on client
and server, or even that the server is a Linux server.

If there's reason to expect that the lower overhead should be more
typical of servers in general, then say that....

--b.

> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfs/nfs4file.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> index 441a2fa073c8..b5821ed46994 100644
> --- a/fs/nfs/nfs4file.c
> +++ b/fs/nfs/nfs4file.c
> @@ -158,13 +158,11 @@ static ssize_t __nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
>  		sync = true;
>  retry:
>  	if (!nfs42_files_from_same_server(file_in, file_out)) {
> -		/* for inter copy, if copy size if smaller than 12 RPC
> -		 * payloads, fallback to traditional copy. There are
> -		 * 14 RPCs during an NFSv4.x mount between source/dest
> -		 * servers.
> +		/*
> +		 * for inter copy, if copy size is too small
> +		 * then fallback to generic copy.
>  		 */
> -		if (sync ||
> -			count <= 14 * NFS_SERVER(file_inode(file_in))->rsize)
> +		if (sync)
>  			return -EOPNOTSUPP;
>  		cn_resp = kzalloc(sizeof(struct nfs42_copy_notify_res),
>  				GFP_NOFS);
> -- 
> 2.9.5