Re: [PATCH 2/2] NFS: Fix a bogus warning in nfs_generic_pgio

[Weston Andros Adamson <dros@primarydata.com>]

On Oct 13, 2014, at 11:07 AM, Trond Myklebust <trond.myklebust@primarydata.com> wrote:

> It is OK for pageused == pagecount in the loop, as long as we don't add
> another entry to the *pages array. Move the test so that it only triggers
> in that case.
> 
> Reported-by: Steve Dickson <SteveD@redhat.com>
> Fixes: bba5c1887a92 (nfs: disallow duplicate pages in pgio page vectors)
> Cc: Weston Andros Adamson <dros@primarydata.com>
> Cc: stable@vger.kernel.org # 3.16.x
> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
> ---
> fs/nfs/pagelist.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
> index 08085de879ed..ed0db61f8543 100644
> --- a/fs/nfs/pagelist.c
> +++ b/fs/nfs/pagelist.c
> @@ -752,12 +752,11 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
> 		nfs_list_remove_request(req);
> 		nfs_list_add_request(req, &hdr->pages);
> 
> -		if (WARN_ON_ONCE(pageused >= pagecount))
> -			return nfs_pgio_error(desc, hdr);
> -
> 		if (!last_page || last_page != req->wb_page) {
> -			*pages++ = last_page = req->wb_page;
> 			pageused++;
> +			if (pageused > pagecount)
> +				break;
> +			*pages++ = last_page = req->wb_page;

This looks right.  Thanks Trond!

-dros

> 		}
> 	}
> 	if (WARN_ON_ONCE(pageused != pagecount))
> -- 
> 1.9.3
>