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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08F82C433FE for ; Tue, 17 May 2022 13:41:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348181AbiEQNln (ORCPT ); Tue, 17 May 2022 09:41:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346978AbiEQNk5 (ORCPT ); Tue, 17 May 2022 09:40:57 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0603DA1B2; Tue, 17 May 2022 06:40:56 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 97EF46151C; Tue, 17 May 2022 13:40:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0C7FC34113; Tue, 17 May 2022 13:40:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652794855; bh=DtXyuYsoVHp4WKCWrjxULv0/73a7Urgp+edL/JG+Lck=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Rkqm0KO5f/hKnhFTEmPFWLA2L1VS5S3viQFX/ROdgk8v6vbyT+SZrLav6CqMz/Tif 0F/zjJx2agc3078IjxhCQlMu+TKtoUse2hukZj1zr41ICc3206eF+TWjzp8a6kFbue JC3Kv8W0xU/JFu3t05MGhmeZFvaZVBqf5SBW2aftP1+Q19t//llBp9g20IYYs2aqI9 mUsiU+3wX0pPCJnGx6PZzQ27f+aAQXHWC1K1Vx22MIiKVn1xcsHoMDnmtksDCTG9HL 0NwE0qYSezpPwz/Yx1VubMbgovRDEnGttZxVHOD4/lWCi/JsPMH0oeP7vH5njZQWCf pgzA6zO1Pje/A== Date: Tue, 17 May 2022 15:40:49 +0200 From: Christian Brauner To: Stefan Roesch Cc: io-uring@vger.kernel.org, kernel-team@fb.com, linux-mm@kvack.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, david@fromorbit.com, jack@suse.cz Subject: Re: [RFC PATCH v2 07/16] fs: split off need_file_update_time and do_file_update_time Message-ID: <20220517134049.tfxbsbdscalblsmv@wittgenstein> References: <20220516164718.2419891-1-shr@fb.com> <20220516164718.2419891-8-shr@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220516164718.2419891-8-shr@fb.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, May 16, 2022 at 09:47:09AM -0700, Stefan Roesch wrote: > This splits off the functions need_file_update_time() and > do_file_update_time() from the function file_update_time(). > > This is required to support async buffered writes. > No intended functional changes in this patch. > > Signed-off-by: Stefan Roesch > --- > fs/inode.c | 71 ++++++++++++++++++++++++++++++++++++------------------ > 1 file changed, 47 insertions(+), 24 deletions(-) > > diff --git a/fs/inode.c b/fs/inode.c > index a6d70a1983f8..1d0b02763e98 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -2054,35 +2054,22 @@ int file_remove_privs(struct file *file) > } > EXPORT_SYMBOL(file_remove_privs); > > -/** > - * file_update_time - update mtime and ctime time > - * @file: file accessed > - * > - * Update the mtime and ctime members of an inode and mark the inode > - * for writeback. Note that this function is meant exclusively for > - * usage in the file write path of filesystems, and filesystems may > - * choose to explicitly ignore update via this function with the > - * S_NOCMTIME inode flag, e.g. for network filesystem where these > - * timestamps are handled by the server. This can return an error for > - * file systems who need to allocate space in order to update an inode. > - */ > - > -int file_update_time(struct file *file) > +static int need_file_update_time(struct inode *inode, struct file *file, > + struct timespec64 *now) I think file_need_update_time() is easier to understand. > { > - struct inode *inode = file_inode(file); > - struct timespec64 now; > int sync_it = 0; > - int ret; > + > + if (unlikely(file->f_mode & FMODE_NOCMTIME)) > + return 0; Moving this into this generic helper and using the generic helper directly in file_update_atime() leads to a change in behavior for file_update_time() callers. Currently they'd get time settings updated even if FMODE_NOCMTIME is set but with this change they'd not get it updated anymore if FMODE_NOCMTIME is set. Am I reading this right? Is this a bugfix? And if so it should be split into a separate commit... > > /* First try to exhaust all avenues to not sync */ > if (IS_NOCMTIME(inode)) > return 0; > > - now = current_time(inode); > - if (!timespec64_equal(&inode->i_mtime, &now)) > + if (!timespec64_equal(&inode->i_mtime, now)) > sync_it = S_MTIME; > > - if (!timespec64_equal(&inode->i_ctime, &now)) > + if (!timespec64_equal(&inode->i_ctime, now)) > sync_it |= S_CTIME; > > if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode)) > @@ -2091,15 +2078,49 @@ int file_update_time(struct file *file) > if (!sync_it) > return 0; > > + return sync_it; > +} > + > +static int do_file_update_time(struct inode *inode, struct file *file, > + struct timespec64 *now, int sync_mode) > +{ > + int ret; > + > /* Finally allowed to write? Takes lock. */ > if (__mnt_want_write_file(file)) > return 0; > > - ret = inode_update_time(inode, &now, sync_it); > + ret = inode_update_time(inode, now, sync_mode); > __mnt_drop_write_file(file); > > return ret; > } Maybe static int __file_update_time(struct inode *inode, struct file *file, struct timespec64 *now, int sync_mode) { int ret = 0; /* try to update time settings */ if (!__mnt_want_write_file(file)) { ret = inode_update_time(inode, now, sync_mode); __mnt_drop_write_file(file); } return ret; } reads a little easier and the old comment is a bit confusing imho. I'd just say we keep it short. > + > +/** > + * file_update_time - update mtime and ctime time > + * @file: file accessed > + * > + * Update the mtime and ctime members of an inode and mark the inode > + * for writeback. Note that this function is meant exclusively for > + * usage in the file write path of filesystems, and filesystems may > + * choose to explicitly ignore update via this function with the > + * S_NOCMTIME inode flag, e.g. for network filesystem where these > + * timestamps are handled by the server. This can return an error for > + * file systems who need to allocate space in order to update an inode. > + */ > + > +int file_update_time(struct file *file) My same lame complaint as before to make this kernel-doc. :) /** * file_update_time - update mtime and ctime time * @file: file accessed * * Update the mtime and ctime members of an inode and mark the inode or * writeback. Note that this function is meant exclusively for sage in * the file write path of filesystems, and filesystems may hoose to * explicitly ignore update via this function with the _NOCMTIME inode * flag, e.g. for network filesystem where these imestamps are handled * by the server. This can return an error for ile systems who need to * allocate space in order to update an inode. * * Return: 0 on success, negative errno on failure. */ int file_update_time(struct file *file) > +{ > + int err; > + struct inode *inode = file_inode(file); > + struct timespec64 now = current_time(inode); > + > + err = need_file_update_time(inode, file, &now); > + if (err < 0) > + return err; I may misread this but shouldn't this be err <= 0, i.e., if it returns 0 then we don't need to update time? > + > + return do_file_update_time(inode, file, &now, err); > +} > EXPORT_SYMBOL(file_update_time); > > /* Caller must hold the file's inode lock */ > @@ -2108,6 +2129,7 @@ int file_modified(struct file *file) > int ret; > struct dentry *dentry = file_dentry(file); > struct inode *inode = file_inode(file); > + struct timespec64 now = current_time(inode); > > /* > * Clear the security bits if the process is not being run by root. > @@ -2122,10 +2144,11 @@ int file_modified(struct file *file) > return ret; > } > > - if (unlikely(file->f_mode & FMODE_NOCMTIME)) > - return 0; > + ret = need_file_update_time(inode, file, &now); > + if (ret <= 0) > + return ret; > > - return file_update_time(file); > + return do_file_update_time(inode, file, &now, ret); > } > EXPORT_SYMBOL(file_modified); > > -- > 2.30.2 >