From mboxrd@z Thu Jan 1 00:00:00 1970 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 6911DC433E6 for ; Tue, 26 Jan 2021 05:25:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 40E4C206F7 for ; Tue, 26 Jan 2021 05:25:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732040AbhAZFZ1 (ORCPT ); Tue, 26 Jan 2021 00:25:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730253AbhAYPmb (ORCPT ); Mon, 25 Jan 2021 10:42:31 -0500 Received: from mail-wr1-x429.google.com (mail-wr1-x429.google.com [IPv6:2a00:1450:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6410BC061BD1 for ; Mon, 25 Jan 2021 07:31:13 -0800 (PST) Received: by mail-wr1-x429.google.com with SMTP id a9so13051856wrt.5 for ; Mon, 25 Jan 2021 07:31:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=czRDsr9ZveGlA8Lh9Z/2Mcsvya5PJVoy03eWuT8s21A=; b=Nc7odzg9UfBt9Cztyn7oJXUuGuEaPINkh4HcF8tCwL6QydMJTw2bmDU18RP2eOhhfw ePgjf3pmTG4MpLsKkntdB/KkguZ5V8AEK3F/hVhEzxkD+9MYckgjKpbPyGGTXU50PV4c E93p427a15/+JjVI3J5lppYDaKZhg9X2eJ9b3wqC2WIMcsUopruusKcBT3rzagEZ/8dd JF14cHgqdQMwp3QCnGmkWzRC/tVyfIdi3pd5yycPwcnWNwOASenr21U2u8o8+Q729+hf zGYb22YwmOOafGvfRwM882pHOVBY6+XER5CMGcBz75hLYQ8BhB5FKmyOTFzH8iuHgQi7 4dpg== 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=czRDsr9ZveGlA8Lh9Z/2Mcsvya5PJVoy03eWuT8s21A=; b=tZk5bVaV+GDYTKO6yP48RUCXzCi/xJ3n3oBYP2OL9KbvDqFQs4JxggH6rF5uZEPNWc pWQAzs0FAtDRIz2axUxn5EUnrm7Hb7PesMknnnyK/tmoQBWmGYEVXK/ilwH35k+iPgxT rNQqWOUPKQvpu+NB58anWpcwql/vFUimWG46NK7el/Mg86B2H/2CWasmrVDb6DBG3U7L qwPvfbh66jT08qbbZZOCy5VImlJ2iljZQG96GrGUcuro8u8WdQO7rozQnl6RGmroVyFa pwj5bUly/65swfBxAHlAbM4QM4uwjyLjvTFsGfPsAGsGtXDT8QW7GYSN3ETdvUaNmEby iUPQ== X-Gm-Message-State: AOAM5316W5c40+Jd0Mm5ro/pgTxWidJHxKtzL171kPHyJQfKT+C48EbZ Y2DocgHDD+ZqKmlbrHF4ml/jWw== X-Google-Smtp-Source: ABdhPJxRalGgtsXNqfUpShWnl29ttfx4tBQRgzfNHdPdlZQBfdjgX6kBkwceyp+jLPxO4iLmohi6HQ== X-Received: by 2002:adf:b78d:: with SMTP id s13mr1611637wre.344.1611588672186; Mon, 25 Jan 2021 07:31:12 -0800 (PST) Received: from balsini.lon.corp.google.com ([2a00:79e0:d:210:4cd4:5994:40fe:253d]) by smtp.gmail.com with ESMTPSA id o14sm22611965wri.48.2021.01.25.07.31.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 07:31:11 -0800 (PST) From: Alessio Balsini To: Miklos Szeredi Cc: Akilesh Kailash , Amir Goldstein , Antonio SJ Musumeci , David Anderson , Giuseppe Scrivano , Jann Horn , Jens Axboe , Martijn Coenen , Palmer Dabbelt , Paul Lawrence , Peng Tao , Stefano Duo , Zimuzo Ezeozue , wuyan , fuse-devel@lists.sourceforge.net, kernel-team@android.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH RESEND V12 5/8] fuse: Introduce synchronous read and write for passthrough Date: Mon, 25 Jan 2021 15:30:54 +0000 Message-Id: <20210125153057.3623715-6-balsini@android.com> X-Mailer: git-send-email 2.30.0.280.ga3ce27912f-goog In-Reply-To: <20210125153057.3623715-1-balsini@android.com> References: <20210125153057.3623715-1-balsini@android.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org All the read and write operations performed on fuse_files which have the passthrough feature enabled are forwarded to the associated lower file system file via VFS. Sending the request directly to the lower file system avoids the userspace round-trip that, because of possible context switches and additional operations might reduce the overall performance, especially in those cases where caching doesn't help, for example in reads at random offsets. Verifying if a fuse_file has a lower file system file associated with can be done by checking the validity of its passthrough_filp pointer. This pointer is not NULL only if passthrough has been successfully enabled via the appropriate ioctl(). When a read/write operation is requested for a FUSE file with passthrough enabled, a new equivalent VFS request is generated, which instead targets the lower file system file. The VFS layer performs additional checks that allow for safer operations but may cause the operation to fail if the process accessing the FUSE file system does not have access to the lower file system. This change only implements synchronous requests in passthrough, returning an error in the case of asynchronous operations, yet covering the majority of the use cases. Signed-off-by: Alessio Balsini --- fs/fuse/file.c | 8 ++++-- fs/fuse/fuse_i.h | 2 ++ fs/fuse/passthrough.c | 57 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 65 insertions(+), 2 deletions(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 953f3034c375..cddada1e8bd9 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1581,7 +1581,9 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to) if (FUSE_IS_DAX(inode)) return fuse_dax_read_iter(iocb, to); - if (!(ff->open_flags & FOPEN_DIRECT_IO)) + if (ff->passthrough.filp) + return fuse_passthrough_read_iter(iocb, to); + else if (!(ff->open_flags & FOPEN_DIRECT_IO)) return fuse_cache_read_iter(iocb, to); else return fuse_direct_read_iter(iocb, to); @@ -1599,7 +1601,9 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from) if (FUSE_IS_DAX(inode)) return fuse_dax_write_iter(iocb, from); - if (!(ff->open_flags & FOPEN_DIRECT_IO)) + if (ff->passthrough.filp) + return fuse_passthrough_write_iter(iocb, from); + else if (!(ff->open_flags & FOPEN_DIRECT_IO)) return fuse_cache_write_iter(iocb, from); else return fuse_direct_write_iter(iocb, from); diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 8d39f5304a11..c4730d893324 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1239,5 +1239,7 @@ int fuse_passthrough_open(struct fuse_dev *fud, int fuse_passthrough_setup(struct fuse_conn *fc, struct fuse_file *ff, struct fuse_open_out *openarg); void fuse_passthrough_release(struct fuse_passthrough *passthrough); +ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *to); +ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, struct iov_iter *from); #endif /* _FS_FUSE_I_H */ diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c index cf993e83803e..d949ca07a83b 100644 --- a/fs/fuse/passthrough.c +++ b/fs/fuse/passthrough.c @@ -4,6 +4,63 @@ #include #include +#include + +#define PASSTHROUGH_IOCB_MASK \ + (IOCB_APPEND | IOCB_DSYNC | IOCB_HIPRI | IOCB_NOWAIT | IOCB_SYNC) + +static void fuse_copyattr(struct file *dst_file, struct file *src_file) +{ + struct inode *dst = file_inode(dst_file); + struct inode *src = file_inode(src_file); + + i_size_write(dst, i_size_read(src)); +} + +ssize_t fuse_passthrough_read_iter(struct kiocb *iocb_fuse, + struct iov_iter *iter) +{ + ssize_t ret; + struct file *fuse_filp = iocb_fuse->ki_filp; + struct fuse_file *ff = fuse_filp->private_data; + struct file *passthrough_filp = ff->passthrough.filp; + + if (!iov_iter_count(iter)) + return 0; + + ret = vfs_iter_read(passthrough_filp, iter, &iocb_fuse->ki_pos, + iocb_to_rw_flags(iocb_fuse->ki_flags, + PASSTHROUGH_IOCB_MASK)); + + return ret; +} + +ssize_t fuse_passthrough_write_iter(struct kiocb *iocb_fuse, + struct iov_iter *iter) +{ + ssize_t ret; + struct file *fuse_filp = iocb_fuse->ki_filp; + struct fuse_file *ff = fuse_filp->private_data; + struct inode *fuse_inode = file_inode(fuse_filp); + struct file *passthrough_filp = ff->passthrough.filp; + + if (!iov_iter_count(iter)) + return 0; + + inode_lock(fuse_inode); + + file_start_write(passthrough_filp); + ret = vfs_iter_write(passthrough_filp, iter, &iocb_fuse->ki_pos, + iocb_to_rw_flags(iocb_fuse->ki_flags, + PASSTHROUGH_IOCB_MASK)); + file_end_write(passthrough_filp); + if (ret > 0) + fuse_copyattr(fuse_filp, passthrough_filp); + + inode_unlock(fuse_inode); + + return ret; +} int fuse_passthrough_open(struct fuse_dev *fud, struct fuse_passthrough_out *pto) -- 2.30.0.280.ga3ce27912f-goog