From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [patch 11/12] vfs: optimize touch_time() too Date: Thu, 06 Aug 2009 16:10:17 -0700 Message-ID: <200908062310.n76NAH21012990@imap1.linux-foundation.org> Cc: linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, andi@firstfloor.org, ak@linux.intel.com, haveblue@us.ibm.com, hch@infradead.org, vaurora@redhat.com To: viro@zeniv.linux.org.uk Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:59345 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932223AbZHFXTX (ORCPT ); Thu, 6 Aug 2009 19:19:23 -0400 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: From: Andi Kleen 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. [akpm@linux-foundation.org: fix typo in comment] Signed-off-by: Andi Kleen Cc: Christoph Hellwig Cc: Valerie Aurora Cc: Al Viro Cc: Dave Hansen Signed-off-by: Andrew Morton --- fs/inode.c | 43 +++++++++++++++++++++++-------------------- 1 file changed, 23 insertions(+), 20 deletions(-) diff -puN fs/inode.c~vfs-optimize-touch_time-too fs/inode.c --- a/fs/inode.c~vfs-optimize-touch_time-too +++ a/fs/inode.c @@ -1448,34 +1448,37 @@ 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 exhaust 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); _