NFSv4.1/flexfiles: Fix a protocol error in layoutreturn

According to the flexfiles protocol, the layoutreturn should specify an
array of errors in the following format:

struct ff_ioerr4 {
	offset4        ffie_offset;
	length4        ffie_length;
	stateid4       ffie_stateid;
	device_error4  ffie_errors<>;
};

This patch fixes up the code to ensure that our ffie_errors is indeed
encoded as an array (albeit with only a single entry).

Reported-by: Tom Haynes <thomas.haynes@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
index f13e1969eedd..b28fa4cbea52 100644
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -500,16 +500,19 @@ int ff_layout_encode_ds_ioerr(struct nfs4_flexfile_layout *flo,
                                            range->offset, range->length))
                         continue;
                 /* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
-                 * + deviceid(NFS4_DEVICEID4_SIZE) + status(4) + opnum(4)
+                 * + array length + deviceid(NFS4_DEVICEID4_SIZE)
+                 * + status(4) + opnum(4)
                  */
                 p = xdr_reserve_space(xdr,
-                                24 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
+                                28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
                 if (unlikely(!p))
                         return -ENOBUFS;
                 p = xdr_encode_hyper(p, err->offset);
                 p = xdr_encode_hyper(p, err->length);
                 p = xdr_encode_opaque_fixed(p, &err->stateid,
                                             NFS4_STATEID_SIZE);
+                /* Encode 1 error */
+                *p++ = cpu_to_be32(1);
                 p = xdr_encode_opaque_fixed(p, &err->deviceid,
                                             NFS4_DEVICEID4_SIZE);
                 *p++ = cpu_to_be32(err->status);