From patchwork Sun Nov 29 00:45:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nadav Amit X-Patchwork-Id: 11938907 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B891CC64E90 for ; Sun, 29 Nov 2020 00:51:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76D3520885 for ; Sun, 29 Nov 2020 00:51:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="lqD/tU0t" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730159AbgK2Auu (ORCPT ); Sat, 28 Nov 2020 19:50:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729806AbgK2Aus (ORCPT ); Sat, 28 Nov 2020 19:50:48 -0500 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92EA6C061A48; Sat, 28 Nov 2020 16:50:05 -0800 (PST) Received: by mail-pf1-x442.google.com with SMTP id w202so7733123pff.10; Sat, 28 Nov 2020 16:50:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=m3T85bPGe5F+Y++Xanv5e+8tOU25N4OYONQwuoq/1Bg=; b=lqD/tU0tDTQCtA7PjLcc+V2DExVFb+xzSTUWJkOWg05/7ncV1krxldnwCAwNQbKtIr kX0ubA1jlwnfeL7wh0sqxAOpWkxq6I/TnUH6ydeF7C+k8P3OHNwR+eD/nKEpa4J7LeCL JWYXvxCkL2N/912drcMK3sw2tRkl5oG4zGYGl+BKn1JjigqIF4L0hzgTzZPkYJA8Ztij Tobt70TN3tvcPduGuqriyeun8JBv3Ug4E5Ly8fsoQJU5ucEGZ4aCTsRsZWsQVyuFQezp x5QPByemKbVvEKcYrYjn8Dds29j1cFTbc+13wyA1fSneWSwsfWrKOdioadcv+plh9kha 1gZg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=m3T85bPGe5F+Y++Xanv5e+8tOU25N4OYONQwuoq/1Bg=; b=is2tYOGv2piW7Q20MNAlsuA+kKsaNZruaPildJX1ClG/sTmDnXG5Xt4YX0armO8PNI Nj9JcC87da/NArJfJ/igajMGcEJzIJcoo8+nnYV8PDqR1B8N7RX+DVz2iOJ0wZHGAXRk 5Ro+e24bVD3GD8lP+1RoO0NgwLtBioUpYSgFHDzVnJFUh86CGfZaZBb1q7kMn2GfoYFY GAA/dJAZt6U5WqnmmgLpmpJaux2wKP3CxIIjrw+61Pui9dupoitaeEgh/SK+Lx27bTSd VsprHiR6VVhGGJvlOzPhINwbdlTIgvxNyLR0DHdMCX7PPAsruGv1giHUchgXVEa8J7z2 I/sg== X-Gm-Message-State: AOAM532eEE4TXOGN7MZYPQZk56wLWnL3L6NZIo0N9joq9I0hnksJqQyP UZxs3yZszJ5N0vWp/QEZ+1lLRPGWLroguQ== X-Google-Smtp-Source: ABdhPJwysR6pHHiIU7NpGqTX7WAlLbdiNThKHFXvrC9AzG3R2hvHHnbX1oMJ/YdkgURbzNUeOoVjCg== X-Received: by 2002:a17:90a:5b10:: with SMTP id o16mr18898825pji.142.1606611004639; Sat, 28 Nov 2020 16:50:04 -0800 (PST) Received: from sc2-haas01-esx0118.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id gg19sm16444871pjb.21.2020.11.28.16.50.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 28 Nov 2020 16:50:03 -0800 (PST) From: Nadav Amit X-Google-Original-From: Nadav Amit To: linux-fsdevel@vger.kernel.org Cc: Nadav Amit , Jens Axboe , Andrea Arcangeli , Peter Xu , Alexander Viro , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 07/13] fs/userfaultfd: support read_iter to use io_uring Date: Sat, 28 Nov 2020 16:45:42 -0800 Message-Id: <20201129004548.1619714-8-namit@vmware.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201129004548.1619714-1-namit@vmware.com> References: <20201129004548.1619714-1-namit@vmware.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Nadav Amit iouring with userfaultfd cannot currently be used fixed buffers since userfaultfd does not provide read_iter(). This is required to allow asynchronous (queued) reads from userfaultfd. To support async-reads of userfaultfd provide read_iter() instead of read(). Cc: Jens Axboe Cc: Andrea Arcangeli Cc: Peter Xu Cc: Alexander Viro Cc: io-uring@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Nadav Amit --- fs/userfaultfd.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index b6a04e526025..6333b4632742 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1195,9 +1195,9 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait, return ret; } -static ssize_t userfaultfd_read(struct file *file, char __user *buf, - size_t count, loff_t *ppos) +static ssize_t userfaultfd_read_iter(struct kiocb *iocb, struct iov_iter *to) { + struct file *file = iocb->ki_filp; struct userfaultfd_ctx *ctx = file->private_data; ssize_t _ret, ret = 0; struct uffd_msg msg; @@ -1207,16 +1207,18 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf, return -EINVAL; for (;;) { - if (count < sizeof(msg)) + if (iov_iter_count(to) < sizeof(msg)) return ret ? ret : -EINVAL; _ret = userfaultfd_ctx_read(ctx, no_wait, &msg); if (_ret < 0) return ret ? ret : _ret; - if (copy_to_user((__u64 __user *) buf, &msg, sizeof(msg))) - return ret ? ret : -EFAULT; + + _ret = copy_to_iter(&msg, sizeof(msg), to); + if (_ret != sizeof(msg)) + return ret ? ret : -EINVAL; + ret += sizeof(msg); - buf += sizeof(msg); - count -= sizeof(msg); + /* * Allow to read more than one fault at time but only * block if waiting for the very first one. @@ -1980,7 +1982,7 @@ static const struct file_operations userfaultfd_fops = { #endif .release = userfaultfd_release, .poll = userfaultfd_poll, - .read = userfaultfd_read, + .read_iter = userfaultfd_read_iter, .unlocked_ioctl = userfaultfd_ioctl, .compat_ioctl = compat_ptr_ioctl, .llseek = noop_llseek,