From patchwork Wed Apr 17 05:45:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amir Goldstein X-Patchwork-Id: 10904633 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CDA7E1515 for ; Wed, 17 Apr 2019 05:46:12 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BAF8328699 for ; Wed, 17 Apr 2019 05:46:12 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AF227289FF; Wed, 17 Apr 2019 05:46:12 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0FF7628699 for ; Wed, 17 Apr 2019 05:46:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726597AbfDQFqL (ORCPT ); Wed, 17 Apr 2019 01:46:11 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:37024 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725811AbfDQFqK (ORCPT ); Wed, 17 Apr 2019 01:46:10 -0400 Received: by mail-wr1-f68.google.com with SMTP id w10so30206646wrm.4; Tue, 16 Apr 2019 22:46:08 -0700 (PDT) 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; bh=8+vNdus7e6pYg9OnRGbCjVCBd8LPFBxVz8hY7lWMvBo=; b=ZK2XXyQnC09zgSaVvKYVKu1w7cBjOlt6XloEXtkqs4jJCTF3bjLaKw/6B6KbIXPpKm pnQ0UNfnp73OWusyBTUv+fxsLeppd4dA+dy3hj7+Y/vY1sXINGGqwgJrTUyP0Aj/XWEb uOzemRif+HKdTwGWnIMFOL3RGpTywmP0Rt89KHpsGrGsQSoIZyH2qCjKyCDk6pnTR2x0 90WYfU1Fw9T0Z5Uk7hgEkGIwiUXh2MqtkP7HiwUeg5mGQScnXCbpXTt4MIT9km1dh9/O 9qyM5naMA2rsPFITcFs6OoEl5oMEVtLlrWU+6bwZVY9kNPMNVcYchS1MBhdkWOBwN7az n2XQ== 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; bh=8+vNdus7e6pYg9OnRGbCjVCBd8LPFBxVz8hY7lWMvBo=; b=dh8qQzimqh9p2YH7Q68yzoJw38BL8yOdC2KaagmDa7WAZDS/F6iRjSxcKg2BUpeJbS EAwHqchAD/ofXZ4Yl//wcB/KGf9/q//SEVvlZ2T28o83XrpZL24gv+3MplJC27yXVP06 lmj6SiMg4fLT96BFgbzobBOA6XgM81aw99UWOOU/JDM6xCm+R6wFE6re8rQxU2doSSFf u46Ae9MA6oOGG2L0A06V2sU4XyryCUJ4DrDebPQfX3OXWnSHGveoYEFDiRdducEnjGkW sMysxWB321UN54qiGAV0BlQ6Y7vSNRMneVapAq35/z2MmFoqZfEIthpMhHzI19Ld6/or R4vA== X-Gm-Message-State: APjAAAX7ZuJUlFAJEjlE9KrHXb+RICfktmre6n6RkSs1anyDaFnRxFtS cvsayohKTCh/fLm01rtayH5MlRRi X-Google-Smtp-Source: APXvYqx37nPMf4GZe7ysOs7dqeX9FFHTrnAkvjkd+KX9l72hqbBbfjELGzNgC58FLHwouVZN7QBWww== X-Received: by 2002:adf:e443:: with SMTP id t3mr4041228wrm.257.1555479968232; Tue, 16 Apr 2019 22:46:08 -0700 (PDT) Received: from localhost.localdomain ([5.102.238.208]) by smtp.gmail.com with ESMTPSA id q24sm1247143wmj.26.2019.04.16.22.46.06 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Apr 2019 22:46:07 -0700 (PDT) From: Amir Goldstein To: Andrew Morton Cc: Jan Kara , Dave Chinner , Al Viro , linux-mm@kvack.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v4] fs/sync.c: sync_file_range(2) may use WB_SYNC_ALL writeback Date: Wed, 17 Apr 2019 08:45:59 +0300 Message-Id: <20190417054559.29252-1-amir73il@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190409114922.30095-1-amir73il@gmail.com> References: <20190409114922.30095-1-amir73il@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Commit 23d0127096cb ("fs/sync.c: make sync_file_range(2) use WB_SYNC_NONE writeback") claims that sync_file_range(2) syscall was "created for userspace to be able to issue background writeout and so waiting for in-flight IO is undesirable there" and changes the writeback (back) to WB_SYNC_NONE. This claim is only partially true. It is true for users that use the flag SYNC_FILE_RANGE_WRITE by itself, as does PostgreSQL, the user that was the reason for changing to WB_SYNC_NONE writeback. However, that claim is not true for users that use that flag combination SYNC_FILE_RANGE_{WAIT_BEFORE|WRITE|_WAIT_AFTER}. Those users explicitly requested to wait for in-flight IO as well as to writeback of dirty pages. Re-brand that flag combination as SYNC_FILE_RANGE_WRITE_AND_WAIT and use the helper filemap_write_and_wait_range(), that uses WB_SYNC_ALL writeback, to perform the full range sync request. Link: http://lkml.kernel.org/r/20190409114922.30095-1-amir73il@gmail.com Fixes: 23d0127096cb ("fs/sync.c: make sync_file_range(2) use WB_SYNC_NONE") Signed-off-by: Amir Goldstein Acked-by: Jan Kara Cc: Dave Chinner Cc: Al Viro --- Andrew, V2 of this patch is on your mmtotm queue. However, I had already sent out V3 with a braino fix and Dave Chinner just added more review comments which I had addressed in this version. Thanks, Amir. Changes since v3: - Remove unneeded change to VALID_FLAGS (Dave) - Call file_fdatawait_range() before writeback (Dave) Changes since v2: - Return after filemap_write_and_wait_range() Changes since v1: - Remove non-guaranties of the API from commit message - Added ACK by Jan fs/sync.c | 20 +++++++++++++++----- include/uapi/linux/fs.h | 3 +++ 2 files changed, 18 insertions(+), 5 deletions(-) diff --git a/fs/sync.c b/fs/sync.c index b54e0541ad89..1836328f1ae8 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -235,9 +235,9 @@ SYSCALL_DEFINE1(fdatasync, unsigned int, fd) } /* - * sys_sync_file_range() permits finely controlled syncing over a segment of + * ksys_sync_file_range() permits finely controlled syncing over a segment of * a file in the range offset .. (offset+nbytes-1) inclusive. If nbytes is - * zero then sys_sync_file_range() will operate from offset out to EOF. + * zero then ksys_sync_file_range() will operate from offset out to EOF. * * The flag bits are: * @@ -254,7 +254,7 @@ SYSCALL_DEFINE1(fdatasync, unsigned int, fd) * Useful combinations of the flag bits are: * * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages - * in the range which were dirty on entry to sys_sync_file_range() are placed + * in the range which were dirty on entry to ksys_sync_file_range() are placed * under writeout. This is a start-write-for-data-integrity operation. * * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which @@ -266,10 +266,13 @@ SYSCALL_DEFINE1(fdatasync, unsigned int, fd) * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait * for that operation to complete and to return the result. * - * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER: + * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER + * (a.k.a. SYNC_FILE_RANGE_WRITE_AND_WAIT): * a traditional sync() operation. This is a write-for-data-integrity operation * which will ensure that all pages in the range which were dirty on entry to - * sys_sync_file_range() are committed to disk. + * ksys_sync_file_range() are written to disk. It should be noted that disk + * caches are not flushed by this call, so there are no guarantees here that the + * data will be available on disk after a crash. * * * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any @@ -344,6 +347,13 @@ int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, goto out_put; } + if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == + SYNC_FILE_RANGE_WRITE_AND_WAIT) { + /* Unlike SYNC_FILE_RANGE_WRITE alone, uses WB_SYNC_ALL */ + ret = filemap_write_and_wait_range(mapping, offset, endbyte); + goto out_put; + } + if (flags & SYNC_FILE_RANGE_WRITE) { ret = __filemap_fdatawrite_range(mapping, offset, endbyte, WB_SYNC_NONE); diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 121e82ce296b..59c71fa8c553 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -320,6 +320,9 @@ struct fscrypt_key { #define SYNC_FILE_RANGE_WAIT_BEFORE 1 #define SYNC_FILE_RANGE_WRITE 2 #define SYNC_FILE_RANGE_WAIT_AFTER 4 +#define SYNC_FILE_RANGE_WRITE_AND_WAIT (SYNC_FILE_RANGE_WRITE | \ + SYNC_FILE_RANGE_WAIT_BEFORE | \ + SYNC_FILE_RANGE_WAIT_AFTER) /* * Flags for preadv2/pwritev2: