path: root/net/sunrpc
diff options
authorChuck Lever <chuck.lever@oracle.com>2019-02-11 11:25:25 -0500
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2019-02-14 10:13:49 -0500
commit02ef04e432babf8fc703104212314e54112ecd2d (patch)
tree4386362756ae73c0fbe207be07fe5bda86037295 /net/sunrpc
parentSUNRPC: Introduce rpc_prepare_reply_pages() (diff)
NFS: Account for XDR pad of buf->pages
Certain NFS results (eg. READLINK) might expect a data payload that is not an exact multiple of 4 bytes. In this case, XDR encoding is required to pad that payload so its length on the wire is a multiple of 4 bytes. The constants that define the maximum size of each NFS result do not appear to account for this extra word. In each case where the data payload is to be received into pages: - 1 word is added to the size of the receive buffer allocated by call_allocate - rpc_inline_rcv_pages subtracts 1 word from @hdrsize so that the extra buffer space falls into the rcv_buf's tail iovec - If buf->pagelen is word-aligned, an XDR pad is not needed and is thus removed from the tail Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net/sunrpc')
2 files changed, 7 insertions, 1 deletions
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index f780605fffe0..4ea38b029e2f 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1177,7 +1177,11 @@ void rpc_prepare_reply_pages(struct rpc_rqst *req, struct page **pages,
unsigned int base, unsigned int len,
unsigned int hdrsize)
- hdrsize += RPC_REPHDRSIZE + req->rq_cred->cr_auth->au_rslack;
+ /* Subtract one to force an extra word of buffer space for the
+ * payload's XDR pad to fall into the rcv_buf's tail iovec.
+ */
+ hdrsize += RPC_REPHDRSIZE + req->rq_cred->cr_auth->au_rslack - 1;
xdr_inline_pages(&req->rq_rcv_buf, hdrsize << 2, pages, base, len);
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 7cca51560442..aa8177ddcbda 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -189,6 +189,8 @@ xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
tail->iov_base = buf + offset;
tail->iov_len = buflen - offset;
+ if ((xdr->page_len & 3) == 0)
+ tail->iov_len -= sizeof(__be32);
xdr->buflen += len;