From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: [PATCH] [2/2] Optimize touch_time too Date: Mon, 6 Jul 2009 21:24:47 +0200 (CEST) Message-ID: <20090706192447.9D0531D024A@basil.firstfloor.org> References: <20090706924.495556466@firstfloor.org> To: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Return-path: Received: from one.firstfloor.org ([213.235.205.2]:38300 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754010AbZGFTYq (ORCPT ); Mon, 6 Jul 2009 15:24:46 -0400 In-Reply-To: <20090706924.495556466@firstfloor.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Do a similar optimization as earlier for touch_atime. Getting the lock in mnt_get_write is relatively costly, so try all avenues to avoid it first. This patch is careful to still only update inode fields inside the lock region. This didn't show up in benchmarks, but it's easy enough to do. Signed-off-by: Andi Kleen --- fs/inode.c | 43 +++++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 20 deletions(-) Index: linux-2.6.31-rc1-ak/fs/inode.c =================================================================== --- linux-2.6.31-rc1-ak.orig/fs/inode.c +++ linux-2.6.31-rc1-ak/fs/inode.c @@ -1431,34 +1431,37 @@ void file_update_time(struct file *file) { struct inode *inode = file->f_path.dentry->d_inode; struct timespec now; - int sync_it = 0; - int err; + enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0; + /* First try to exhause all avenues to not sync */ if (IS_NOCMTIME(inode)) return; - err = mnt_want_write_file(file); - if (err) - return; - now = current_fs_time(inode->i_sb); - if (!timespec_equal(&inode->i_mtime, &now)) { - inode->i_mtime = now; - sync_it = 1; - } + if (!timespec_equal(&inode->i_mtime, &now)) + sync_it = S_MTIME; - if (!timespec_equal(&inode->i_ctime, &now)) { - inode->i_ctime = now; - sync_it = 1; - } + if (!timespec_equal(&inode->i_ctime, &now)) + sync_it |= S_CTIME; - if (IS_I_VERSION(inode)) { - inode_inc_iversion(inode); - sync_it = 1; - } + if (IS_I_VERSION(inode)) + sync_it |= S_VERSION; + + if (!sync_it) + return; + + /* Finally allowed to write? Takes lock. */ + if (!mnt_want_write_file(file)) + return; - if (sync_it) - mark_inode_dirty_sync(inode); + /* Only change inode inside the lock region */ + if (sync_it & S_VERSION) + inode_inc_iversion(inode); + if (sync_it & S_CTIME) + inode->i_ctime = now; + if (sync_it & S_MTIME) + inode->i_mtime = now; + mark_inode_dirty_sync(inode); mnt_drop_write(file->f_path.mnt); } EXPORT_SYMBOL(file_update_time);