From nobody Mon Sep 15 03:55:28 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 457B2C54EBE for ; Mon, 16 Jan 2023 23:15:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232873AbjAPXPG (ORCPT ); Mon, 16 Jan 2023 18:15:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235364AbjAPXOH (ORCPT ); Mon, 16 Jan 2023 18:14:07 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BBDD92FCC4 for ; Mon, 16 Jan 2023 15:10:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673910625; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hzJ1pMyiJ+RsXEy2r6s2nQM3QoHbxUG3+tLaUVatkNA=; b=ASRyUDAJRq87l/k4Ql5X/PSrHccI3pOyleDUJPtuEfELhs8WxQMQAQTHjaXLjj48gAviA8 uMnw9v4n24fKkOEj5oZeAw2BYNYyaEHsybdc/+5vYRLed9+Zz68MnKTzxOrFFooRTFJuNh +qevApJlv1P1P7ELK5p/aCWB70Bsv30= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-578-oNGc_qOmMcuLavBHLMbwog-1; Mon, 16 Jan 2023 18:10:20 -0500 X-MC-Unique: oNGc_qOmMcuLavBHLMbwog-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4A6583806628; Mon, 16 Jan 2023 23:10:20 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id C70FC40C2064; Mon, 16 Jan 2023 23:10:18 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v6 19/34] fuse: Pin pages rather than ref'ing if appropriate From: David Howells To: Al Viro Cc: Miklos Szeredi , Christoph Hellwig , linux-fsdevel@vger.kernel.org, dhowells@redhat.com, Christoph Hellwig , Matthew Wilcox , Jens Axboe , Jan Kara , Jeff Layton , Logan Gunthorpe , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 16 Jan 2023 23:10:18 +0000 Message-ID: <167391061826.2311931.4301280201217181104.stgit@warthog.procyon.org.uk> In-Reply-To: <167391047703.2311931.8115712773222260073.stgit@warthog.procyon.org.uk> References: <167391047703.2311931.8115712773222260073.stgit@warthog.procyon.org.uk> User-Agent: StGit/1.5 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Convert the fuse code to use iov_iter_extract_pages() instead of iov_iter_get_pages(). This will pin pages or leave them unaltered rather than getting a ref on them as appropriate to the iterator. The pages need to be pinned for DIO-read rather than having refs taken on them to prevent VM copy-on-write from malfunctioning during a concurrent fork() (the result of the I/O would otherwise end up only visible to the child process and not the parent). Signed-off-by: David Howells cc: Miklos Szeredi cc: Al Viro cc: Christoph Hellwig cc: linux-fsdevel@vger.kernel.org --- fs/fuse/dev.c | 25 +++++++++++++++++++------ fs/fuse/file.c | 26 ++++++++++++++++++-------- fs/fuse/fuse_i.h | 1 + 3 files changed, 38 insertions(+), 14 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index e3d8443e24a6..107497e68726 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -641,6 +641,7 @@ static int unlock_request(struct fuse_req *req) =20 struct fuse_copy_state { int write; + unsigned int cleanup_mode; /* Page cleanup mode (0/FOLL_GET/PIN) */ struct fuse_req *req; struct iov_iter *iter; struct pipe_buffer *pipebufs; @@ -661,6 +662,11 @@ static void fuse_copy_init(struct fuse_copy_state *cs,= int write, cs->iter =3D iter; } =20 +static void fuse_release_copy_page(struct fuse_copy_state *cs, struct page= *page) +{ + page_put_unpin(page, cs->cleanup_mode); +} + /* Unmap and put previous page of userspace buffer */ static void fuse_copy_finish(struct fuse_copy_state *cs) { @@ -675,7 +681,7 @@ static void fuse_copy_finish(struct fuse_copy_state *cs) flush_dcache_page(cs->pg); set_page_dirty_lock(cs->pg); } - put_page(cs->pg); + fuse_release_copy_page(cs, cs->pg); } cs->pg =3D NULL; } @@ -704,6 +710,7 @@ static int fuse_copy_fill(struct fuse_copy_state *cs) =20 BUG_ON(!cs->nr_segs); cs->currbuf =3D buf; + cs->cleanup_mode =3D FOLL_GET; cs->pg =3D buf->page; cs->offset =3D buf->offset; cs->len =3D buf->len; @@ -722,6 +729,7 @@ static int fuse_copy_fill(struct fuse_copy_state *cs) buf->len =3D 0; =20 cs->currbuf =3D buf; + cs->cleanup_mode =3D FOLL_GET; cs->pg =3D page; cs->offset =3D 0; cs->len =3D PAGE_SIZE; @@ -729,15 +737,18 @@ static int fuse_copy_fill(struct fuse_copy_state *cs) cs->nr_segs++; } } else { + unsigned int gup_flags =3D cs->write ? FOLL_SOURCE_BUF : FOLL_DEST_BUF; + struct page **pages =3D &cs->pg; size_t off; - err =3D iov_iter_get_pages(cs->iter, &page, PAGE_SIZE, 1, &off, - cs->write ? FOLL_SOURCE_BUF : FOLL_DEST_BUF); + + err =3D iov_iter_extract_pages(cs->iter, &pages, PAGE_SIZE, 1, + gup_flags, &off); if (err < 0) return err; BUG_ON(!err); cs->len =3D err; cs->offset =3D off; - cs->pg =3D page; + cs->cleanup_mode =3D iov_iter_extract_mode(cs->iter, gup_flags); } =20 return lock_request(cs->req); @@ -899,10 +910,12 @@ static int fuse_ref_page(struct fuse_copy_state *cs, = struct page *page, if (cs->nr_segs >=3D cs->pipe->max_usage) return -EIO; =20 - get_page(page); + err =3D try_grab_page(page, cs->cleanup_mode); + if (err < 0) + return err; err =3D unlock_request(cs->req); if (err) { - put_page(page); + fuse_release_copy_page(cs, page); return err; } =20 diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 68c196437306..c317300e757a 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -624,6 +624,11 @@ void fuse_read_args_fill(struct fuse_io_args *ia, stru= ct file *file, loff_t pos, args->out_args[0].size =3D count; } =20 +static void fuse_release_page(struct fuse_args_pages *ap, struct page *pag= e) +{ + page_put_unpin(page, ap->cleanup_mode); +} + static void fuse_release_user_pages(struct fuse_args_pages *ap, bool should_dirty) { @@ -632,7 +637,7 @@ static void fuse_release_user_pages(struct fuse_args_pa= ges *ap, for (i =3D 0; i < ap->num_pages; i++) { if (should_dirty) set_page_dirty_lock(ap->pages[i]); - put_page(ap->pages[i]); + fuse_release_page(ap, ap->pages[i]); } } =20 @@ -920,7 +925,7 @@ static void fuse_readpages_end(struct fuse_mount *fm, s= truct fuse_args *args, else SetPageError(page); unlock_page(page); - put_page(page); + fuse_release_page(ap, page); } if (ia->ff) fuse_file_put(ia->ff, false, false); @@ -1153,7 +1158,7 @@ static ssize_t fuse_send_write_pages(struct fuse_io_a= rgs *ia, } if (ia->write.page_locked && (i =3D=3D ap->num_pages - 1)) unlock_page(page); - put_page(page); + fuse_release_page(ap, page); } =20 return err; @@ -1172,6 +1177,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_a= rgs *ia, =20 ap->args.in_pages =3D true; ap->descs[0].offset =3D offset; + ap->cleanup_mode =3D FOLL_GET; =20 do { size_t tmp; @@ -1200,7 +1206,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_a= rgs *ia, =20 if (!tmp) { unlock_page(page); - put_page(page); + fuse_release_page(ap, page); goto again; } =20 @@ -1393,9 +1399,12 @@ static int fuse_get_user_pages(struct fuse_args_page= s *ap, struct iov_iter *ii, size_t *nbytesp, int write, unsigned int max_pages) { + unsigned int gup_flags =3D write ? FOLL_SOURCE_BUF : FOLL_DEST_BUF; size_t nbytes =3D 0; /* # bytes already packed in req */ ssize_t ret =3D 0; =20 + ap->cleanup_mode =3D iov_iter_extract_mode(ii, gup_flags); + /* Special case for kernel I/O: can copy directly into the buffer */ if (iov_iter_is_kvec(ii)) { unsigned long user_addr =3D fuse_get_user_addr(ii); @@ -1412,12 +1421,13 @@ static int fuse_get_user_pages(struct fuse_args_pag= es *ap, struct iov_iter *ii, } =20 while (nbytes < *nbytesp && ap->num_pages < max_pages) { + struct page **pages =3D &ap->pages[ap->num_pages]; unsigned npages; size_t start; - ret =3D iov_iter_get_pages(ii, &ap->pages[ap->num_pages], - *nbytesp - nbytes, - max_pages - ap->num_pages, - &start, write ? FOLL_SOURCE_BUF : FOLL_DEST_BUF); + ret =3D iov_iter_extract_pages(ii, &pages, + *nbytesp - nbytes, + max_pages - ap->num_pages, + gup_flags, &start); if (ret < 0) break; =20 diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index c673faefdcb9..7b6be1dd7593 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -271,6 +271,7 @@ struct fuse_args_pages { struct page **pages; struct fuse_page_desc *descs; unsigned int num_pages; + unsigned int cleanup_mode; }; =20 #define FUSE_ARGS(args) struct fuse_args args =3D {}