From owner-svn-src-head@FreeBSD.ORG Wed Apr 1 08:25:41 2015 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 9C9B8E01; Wed, 1 Apr 2015 08:25:41 +0000 (UTC) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 6D564672; Wed, 1 Apr 2015 08:25:41 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.9/8.14.9) with ESMTP id t318Pf7K038333; Wed, 1 Apr 2015 08:25:41 GMT (envelope-from kib@FreeBSD.org) Received: (from kib@localhost) by svn.freebsd.org (8.14.9/8.14.9/Submit) id t318PfCB038332; Wed, 1 Apr 2015 08:25:41 GMT (envelope-from kib@FreeBSD.org) Message-Id: <201504010825.t318PfCB038332@svn.freebsd.org> X-Authentication-Warning: svn.freebsd.org: kib set sender to kib@FreeBSD.org using -f From: Konstantin Belousov Date: Wed, 1 Apr 2015 08:25:41 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r280949 - head/sys/fs/devfs X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 01 Apr 2015 08:25:41 -0000 Author: kib Date: Wed Apr 1 08:25:40 2015 New Revision: 280949 URL: https://svnweb.freebsd.org/changeset/base/280949 Log: Refine r280308. Do not completely disable timestamping of devfs nodes on reads or writes, the time marks are used to display idle time by w(1) [1]. Instead, use vfs.devfs.dotimes as the selector of default precision vs. using time_second. The later gives seconds precision, which is good enough for the purpose. Note that timestamp updates are unlocked and the updates itself, as well as the check in devfs_timestamp, are non-atomic. Noted by: truckman [1] Reviewed by: bde Sponsored by: The FreeBSD Foundation MFC after: 1 week Modified: head/sys/fs/devfs/devfs_vnops.c Modified: head/sys/fs/devfs/devfs_vnops.c ============================================================================== --- head/sys/fs/devfs/devfs_vnops.c Wed Apr 1 06:44:39 2015 (r280948) +++ head/sys/fs/devfs/devfs_vnops.c Wed Apr 1 08:25:40 2015 (r280949) @@ -84,7 +84,27 @@ SYSCTL_DECL(_vfs_devfs); static int devfs_dotimes; SYSCTL_INT(_vfs_devfs, OID_AUTO, dotimes, CTLFLAG_RW, - &devfs_dotimes, 0, "Update timestamps on DEVFS"); + &devfs_dotimes, 0, "Update timestamps on DEVFS with default precision"); + +/* + * Update devfs node timestamp. Note that updates are unlocked and + * stat(2) could see partially updated times. + */ +static void +devfs_timestamp(struct timespec *tsp) +{ + time_t ts; + + if (devfs_dotimes) { + vfs_timestamp(tsp); + } else { + ts = time_second; + if (tsp->tv_sec != ts) { + tsp->tv_sec = ts; + tsp->tv_nsec = 0; + } + } +} static int devfs_fp_check(struct file *fp, struct cdev **devp, struct cdevsw **dswp, @@ -1228,9 +1248,8 @@ devfs_read_f(struct file *fp, struct uio foffset_lock_uio(fp, uio, flags | FOF_NOLOCK); error = dsw->d_read(dev, uio, ioflag); - if (devfs_dotimes && - (uio->uio_resid != resid || (error == 0 && resid != 0))) - vfs_timestamp(&dev->si_atime); + if (uio->uio_resid != resid || (error == 0 && resid != 0)) + devfs_timestamp(&dev->si_atime); td->td_fpop = fpop; dev_relthread(dev, ref); @@ -1708,9 +1727,8 @@ devfs_write_f(struct file *fp, struct ui resid = uio->uio_resid; error = dsw->d_write(dev, uio, ioflag); - if (devfs_dotimes && - (uio->uio_resid != resid || (error == 0 && resid != 0))) { - vfs_timestamp(&dev->si_ctime); + if (uio->uio_resid != resid || (error == 0 && resid != 0)) { + devfs_timestamp(&dev->si_ctime); dev->si_mtime = dev->si_ctime; } td->td_fpop = fpop;