From: Trond Myklebust trond.myklebust@hammerspace.com
commit 6622e3a73112fc336c1c2c582428fb5ef18e456a upstream.
When we're reusing the backchannel requests instead of freeing them, then we should reinitialise any values of the send/receive xdr_bufs so that they reflect the available space.
Fixes: 0d2a970d0ae5 ("SUNRPC: Fix a backchannel race") Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sunrpc/backchannel_rqst.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
--- a/net/sunrpc/backchannel_rqst.c +++ b/net/sunrpc/backchannel_rqst.c @@ -69,6 +69,17 @@ static void xprt_free_allocation(struct kfree(req); }
+static void xprt_bc_reinit_xdr_buf(struct xdr_buf *buf) +{ + buf->head[0].iov_len = PAGE_SIZE; + buf->tail[0].iov_len = 0; + buf->pages = NULL; + buf->page_len = 0; + buf->flags = 0; + buf->len = 0; + buf->buflen = PAGE_SIZE; +} + static int xprt_alloc_xdr_buf(struct xdr_buf *buf, gfp_t gfp_flags) { struct page *page; @@ -291,6 +302,9 @@ void xprt_free_bc_rqst(struct rpc_rqst * */ spin_lock_bh(&xprt->bc_pa_lock); if (xprt_need_to_requeue(xprt)) { + xprt_bc_reinit_xdr_buf(&req->rq_snd_buf); + xprt_bc_reinit_xdr_buf(&req->rq_rcv_buf); + req->rq_rcv_buf.len = PAGE_SIZE; list_add_tail(&req->rq_bc_pa_list, &xprt->bc_pa_list); xprt->bc_alloc_count++; req = NULL;