On Tue, Jul 15, 2014 at 10:11:34AM -0400, Chuck Lever wrote: > See RFC 5666 section 3.7: clients don't have to send zero XDR > padding. > > BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=246 > Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> > --- > Hi Bruce- > > This is an alternative solution to changing the sanity check in the > XDR WRITE decoder. It adjusts the incoming xdr_buf to include a zero > pad just after the transport has received each RPC request. > > Thoughts? That looks pretty simple. So if this works then I think I'd be happier doing this than worrying about other spots like the drc code where we might have missed an assumption. > net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 30 ++++++++++++++++++++++++++++++ > 1 files changed, 30 insertions(+), 0 deletions(-) > > diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c > index 8f92a61..9a3465d 100644 > --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c > +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c > @@ -43,6 +43,7 @@ > #include <linux/sunrpc/debug.h> > #include <linux/sunrpc/rpc_rdma.h> > #include <linux/spinlock.h> > +#include <linux/highmem.h> > #include <asm/unaligned.h> > #include <rdma/ib_verbs.h> > #include <rdma/rdma_cm.h> > @@ -435,6 +436,34 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt, > return ret; > } > > +/* > + * To avoid a separate RDMA READ just for a handful of zero bytes, > + * RFC 5666 section 3.7 allows the client to omit the XDR zero pad > + * in chunk lists. > + */ > +static void > +rdma_fix_xdr_pad(struct xdr_buf *buf) > +{ > + unsigned int page_len = buf->page_len; > + unsigned int size = (XDR_QUADLEN(page_len) << 2) - page_len; > + unsigned int offset, pg_no; > + char *p; > + > + if (size == 0) > + return; > + > + offset = page_len & ~PAGE_MASK; > + pg_no = page_len >> PAGE_SHIFT; > + > + p = kmap_atomic(buf->pages[pg_no]); > + memset(p + offset, 0, size); > + kunmap_atomic(p); If these are pages alloc'd by svc_recv() with alloc_page(GFP_KERNEL) then the kmap/kunmap shouldn't be necessary. --b. > + > + buf->page_len += size; > + buf->buflen += size; > + buf->len += size; > +} > + > static int rdma_read_complete(struct svc_rqst *rqstp, > struct svc_rdma_op_ctxt *head) > { > @@ -449,6 +478,7 @@ static int rdma_read_complete(struct svc_rqst *rqstp, > rqstp->rq_pages[page_no] = head->pages[page_no]; > } > /* Point rq_arg.pages past header */ > + rdma_fix_xdr_pad(&head->arg); > rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count]; > rqstp->rq_arg.page_len = head->arg.page_len; > rqstp->rq_arg.page_base = head->arg.page_base; > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
