Re: [PATCH v1 3/4] NFSD: Refactor the generic write vector fill helper

[Bruce Fields <bfields@fieldses.org>]

On Mon, Nov 19, 2018 at 02:58:17PM -0500, Chuck Lever wrote:
> Should I send you a patch?

I'm applying the following.

--b.

commit fc4ee8d8a5f7
Author: J. Bruce Fields <bfields@redhat.com>
Date:   Thu Nov 15 11:21:40 2018 -0500

    nfsd4: zero-length WRITE should succeed
    
    Zero-length writes are legal; from 5661 section 18.32.3: "If the count
    is zero, the WRITE will succeed and return a count of zero subject to
    permissions checking".
    
    This check is unnecessary and is causing zero-length reads to return
    EINVAL.
    
    Cc: stable@vger.kernel.org
    Fixes: 3fd9557aec91 "NFSD: Refactor the generic write vector fill helper"
    Cc: Chuck Lever <chuck.lever@oracle.com>
    Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index d505990dac7c..c364acbb6aba 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1016,8 +1016,6 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 
 	nvecs = svc_fill_write_vector(rqstp, write->wr_pagelist,
 				      &write->wr_head, write->wr_buflen);
-	if (!nvecs)
-		return nfserr_io;
 	WARN_ON_ONCE(nvecs > ARRAY_SIZE(rqstp->rq_vec));
 
 	status = nfsd_vfs_write(rqstp, &cstate->current_fh, filp,