From: Chuck Lever chuck.lever@oracle.com
[ Upstream commit ae605ee9830840f14566a3b1cde27fa8096dbdd4 ]
Commit 9ed5af268e88 ("SUNRPC: Clean up the handling of page padding in rpc_prepare_reply_pages()") [Dec 2020] affects RPC Replies that have a data payload (i.e., Write chunks).
rpcrdma_prepare_readch(), as its name suggests, sets up Read chunks which are data payloads within RPC Calls. Those payloads are constructed by xdr_write_pages(), which continues to stuff the call buffer's tail kvec with the payload's XDR roundup. Thus removing the tail buffer logic in rpcrdma_prepare_readch() was the wrong thing to do.
Fixes: 586a0787ce35 ("xprtrdma: Clean up rpcrdma_prepare_readch()") Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/sunrpc/xprtrdma/rpc_rdma.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index 21ddd78a8c35..15e0c4e7b24a 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -628,8 +628,9 @@ out_mapping_err: return false; }
-/* The tail iovec might not reside in the same page as the - * head iovec. +/* The tail iovec may include an XDR pad for the page list, + * as well as additional content, and may not reside in the + * same page as the head iovec. */ static bool rpcrdma_prepare_tail_iov(struct rpcrdma_req *req, struct xdr_buf *xdr, @@ -747,19 +748,27 @@ static bool rpcrdma_prepare_readch(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req, struct xdr_buf *xdr) { - struct kvec *tail = &xdr->tail[0]; - if (!rpcrdma_prepare_head_iov(r_xprt, req, xdr->head[0].iov_len)) return false;
- /* If there is a Read chunk, the page list is handled + /* If there is a Read chunk, the page list is being handled * via explicit RDMA, and thus is skipped here. */
- if (tail->iov_len) { - if (!rpcrdma_prepare_tail_iov(req, xdr, - offset_in_page(tail->iov_base), - tail->iov_len)) + /* Do not include the tail if it is only an XDR pad */ + if (xdr->tail[0].iov_len > 3) { + unsigned int page_base, len; + + /* If the content in the page list is an odd length, + * xdr_write_pages() adds a pad at the beginning of + * the tail iovec. Force the tail's non-pad content to + * land at the next XDR position in the Send message. + */ + page_base = offset_in_page(xdr->tail[0].iov_base); + len = xdr->tail[0].iov_len; + page_base += len & 3; + len -= len & 3; + if (!rpcrdma_prepare_tail_iov(req, xdr, page_base, len)) return false; kref_get(&req->rl_kref); }