From patchwork Fri Apr 19 07:29:38 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amir Goldstein X-Patchwork-Id: 10909353 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 F2B56922 for ; Fri, 19 Apr 2019 18:28:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E8F6C28C6D for ; Fri, 19 Apr 2019 18:28:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DCE7C28DB3; Fri, 19 Apr 2019 18:28:48 +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=unavailable 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 66E3428C6D for ; Fri, 19 Apr 2019 18:28:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726180AbfDSS2r (ORCPT ); Fri, 19 Apr 2019 14:28:47 -0400 Received: from mail-wm1-f68.google.com ([209.85.128.68]:52886 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726088AbfDSS2q (ORCPT ); Fri, 19 Apr 2019 14:28:46 -0400 Received: by mail-wm1-f68.google.com with SMTP id a184so7023853wma.2; Fri, 19 Apr 2019 11:28:45 -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=JUrL+t/sGkk+Nd+0JlZtFUe7lRgqB2NCcYxNia/KE+Q=; b=rotvELedYkfsMEDZw4+zMLSEYZrkCQewj8XNhvPQou+5xQKTeUyv8KrZyggorJjGET r1bPrfPqlprXmHjt4LF97AXqE53KYsdrIivOj/iUxhAEJNoFXwb1FZyMnM6MKwYqjz+6 +Jb/qqEqizgyeYOki11WGYIZ26MT+o1hZ9kxndi66xVXSd0O0luLLecSu6Y/Fzk1Pkwr bfvsIVJkm5WbktC8x5Rbd9azkPzVsjBl6UA94mBhq4ECHJrWqy/sIeqRL5FjOgf4P9Sx ne2S82CNtSBXvBagWsq6ifC3WE6CmnwFySpL6b/8RKkrJcxXHqwGuKjYprV7jr4nHqMa nuGA== 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=JUrL+t/sGkk+Nd+0JlZtFUe7lRgqB2NCcYxNia/KE+Q=; b=Lvq7jSbaih4tbb9otdBYyEgksfY6I9FrkJ7Hjw2+PwqIz2dYqdfuoVFXB1t64c+PjL 6gUNj7ue3UQBFzCGao+IodH7ZtEfLOKF5m28MmvuU15ZyX9cfVst6LsM+sUuPgmyfVQj YzfqQuMHj+DeHHgePd17iUNGii6LlUe6HuNQinALS1HC2ScNAY50/Q4ZtUjJfx0CrKOu 4tu4NGCiIOdGBYkc5uwGD+1yAhXUmNwMo6cEk5c821eOWNFwpBERCoUOBwADzTABs64H A3h95qVKgJWGrz48o+y1dm3tJASmSp/ce1uwzsIZqcnXPeqo0LnjNH+9goLJOpYqX+qK hCiw== X-Gm-Message-State: APjAAAWspHAC9mePHHm39pC2/zIJUlps9nVmasup6VFy1EUcj1inh2cy sQqqPPDKT0WtYXnMJkciaIf+GDxg X-Google-Smtp-Source: APXvYqzOWHpn1wSg+lT9K1wFIQIDgkcFXYdMOItJU3yOIH6AH4oCYQEiO3Wcw3VfodNnpv1E78czBA== X-Received: by 2002:a1c:9dc8:: with SMTP id g191mr1608551wme.132.1555658985835; Fri, 19 Apr 2019 00:29:45 -0700 (PDT) Received: from localhost.localdomain ([5.102.238.208]) by smtp.gmail.com with ESMTPSA id z18sm5481865wrr.90.2019.04.19.00.29.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Apr 2019 00:29:45 -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 v5] fs/sync.c: sync_file_range(2) may use WB_SYNC_ALL writeback Date: Fri, 19 Apr 2019 10:29:38 +0300 Message-Id: <20190419072938.31320-1-amir73il@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190419000225.GF1454@dread.disaster.area> References: <20190419000225.GF1454@dread.disaster.area> 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 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, One more version addressing another comment by Dave Chinner. Thanks, Amir. Changes since v4: - Don't use filemap_write_and_wait_range() helper (Dave) 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 | 21 +++++++++++++++------ include/uapi/linux/fs.h | 3 +++ 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/fs/sync.c b/fs/sync.c index b54e0541ad89..9e8cd90e890f 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 @@ -345,8 +348,14 @@ int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes, } if (flags & SYNC_FILE_RANGE_WRITE) { + int sync_mode = WB_SYNC_NONE; + + if ((flags & SYNC_FILE_RANGE_WRITE_AND_WAIT) == + SYNC_FILE_RANGE_WRITE_AND_WAIT) + sync_mode = WB_SYNC_ALL; + ret = __filemap_fdatawrite_range(mapping, offset, endbyte, - WB_SYNC_NONE); + sync_mode); if (ret < 0) goto out_put; } 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: