Re: [PATCH] NFS: Allow very small rsize & wsize again

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2022-11-30 at 15:30 -0500, Anna Schumaker wrote:
> From: Anna Schumaker <Anna.Schumaker@Netapp.com>
> 
> 940261a19508 introduced nfs_io_size() to clamp the iosize to a multiple
> of PAGE_SIZE. This had the unintended side effect of no longer allowing
> iosizes less than a page, which could be useful in some situations.
> 
> UDP already has an exception that causes it to fall back on the
> power-of-two style sizes instead. This patch adds an additional
> exception for very small iosizes.
> 
> Reported-by: Jeff Layton <jlayton@kernel.org>
> Fixes: 940261a19508 ("NFS: Allow setting rsize / wsize to a multiple of PAGE_SIZE")
> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> ---
>  fs/nfs/internal.h | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> index 647fc3f547cb..ae7d4a8c728c 100644
> --- a/fs/nfs/internal.h
> +++ b/fs/nfs/internal.h
> @@ -739,12 +739,10 @@ unsigned long nfs_io_size(unsigned long iosize, enum xprt_transports proto)
>  		iosize = NFS_DEF_FILE_IO_SIZE;
>  	else if (iosize >= NFS_MAX_FILE_IO_SIZE)
>  		iosize = NFS_MAX_FILE_IO_SIZE;
> -	else
> -		iosize = iosize & PAGE_MASK;
>  
> -	if (proto == XPRT_TRANSPORT_UDP)
> +	if (proto == XPRT_TRANSPORT_UDP || iosize < PAGE_SIZE)
>  		return nfs_block_bits(iosize, NULL);
> -	return iosize;
> +	return iosize & PAGE_MASK;
>  }
>  
>  /*

Looks good. Thanks, Anna.

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