Received-SPF: pass (google.com: domain of linux-nfs+bounces-3842-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Message-ID: <9bfbc01c4cb0d3713a160a5d00e8cc360ee6bb60.camel@kernel.org>
Subject: Re: [PATCH] nfs: fix nfs_swap_rw for large-folio swap
From: Jeff Layton <jlayton@kernel.org>
To: Christoph Hellwig <hch@lst.de>, Trond Myklebust <trondmy@kernel.org>, 
	Anna Schumaker
	 <anna@kernel.org>
Cc: Steve French <sfrench@samba.org>, Andrew Morton
 <akpm@linux-foundation.org>,  linux-nfs@vger.kernel.org,
 linux-cifs@vger.kernel.org, linux-mm@kvack.org
Date: Fri, 14 Jun 2024 13:52:06 -0400
In-Reply-To: <20240614100329.1203579-2-hch@lst.de>
References: <20240614100329.1203579-1-hch@lst.de>
	 <20240614100329.1203579-2-hch@lst.de>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
User-Agent: Evolution 3.50.4 (3.50.4-1.fc39) 
Precedence: bulk
MIME-Version: 1.0

On Fri, 2024-06-14 at 12:03 +0200, Christoph Hellwig wrote:
> As of Linux 6.10-rc the MM can swap out larger than page size chunks.
> NFS has all code ready to handle this, but has a VM_BUG_ON that
> triggers when this happens.=C2=A0 Simply remove the VM_BUG_ON to fix this
> use case.
>=20
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> =C2=A0fs/nfs/direct.c | 2 --
> =C2=A01 file changed, 2 deletions(-)
>=20
> diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
> index bb2f583eb28bf1..90079ca134dd3c 100644
> --- a/fs/nfs/direct.c
> +++ b/fs/nfs/direct.c
> @@ -141,8 +141,6 @@ int nfs_swap_rw(struct kiocb *iocb, struct
> iov_iter *iter)
> =C2=A0{
> =C2=A0	ssize_t ret;
> =C2=A0
> -	VM_BUG_ON(iov_iter_count(iter) !=3D PAGE_SIZE);
> -
> =C2=A0	if (iov_iter_rw(iter) =3D=3D READ)
> =C2=A0		ret =3D nfs_file_direct_read(iocb, iter, true);
> =C2=A0	else


This definitely seems wrong in a large folio world.

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