From: Theodore Tso Subject: Re: [PATCH] e2fsck: Always fix last mount/write/check time with -p Date: Fri, 16 Oct 2009 21:03:30 -0400 Message-ID: <20091017010330.GA8081@mit.edu> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Scott James Remnant Return-path: Received: from THUNK.ORG ([69.25.196.29]:51424 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751087AbZJQGGh (ORCPT ); Sat, 17 Oct 2009 02:06:37 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, Oct 12, 2009 at 04:10:31PM +0100, Scott James Remnant wrote: > - Installing onto a system with an externally synchronised hardware > clock, where the hardware clock is (without the user's knowledge > and beyond the capabilities of the Installer to detect) being set > to local time. > > Again, each time NTP will fix the problem, but after each reboot > the mount time will again be in the future. > > (This is a common case when using virtualisation, where the hardware > clock is in fact being emulated based off something's system clock.) I'm pretty sure this is caused by a buggy or misconfigured virtualization manager. The host OS knows the correct time, and the guest OS's (emulated) RTC hardware clock should be set the host OS's system time, which should be correct. In fact qemu and kvm have an option which controls this: -localtime Set the real time clock to local time (the default is to UTC time). This option is needed to have correct date in MS-DOS or Windows. Qemu's default is correct for Linux, so I'm guessing either the user copied a configuration for Windows, or the virtualization manager was set up by default for running Windows as a guest OS. In any case, I accept that in some cases it's not possible for the distribution to do the right thing. I do want to leave the possibility for a "strict mode", in the hopes that one day we can do a better job. So here's what I ultimately checked into e2fsprogs. - Ted >From ba5131f6d48eded504e84c2a8ffc8131df8a512e Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Fri, 16 Oct 2009 20:46:45 -0400 Subject: [PATCH] e2fsck: Accept superblock times to be fudged by up to 24 hours by default Unfortunately, due to Windows' unfortunate design decision to configure the hardware clock to tick localtime, instead of the more proper and less error-prone UTC time, many users end up in the situation where the system clock is incorrectly set at the time when e2fsck is run. Historically this was usually due to some distributions having buggy init scripts and/or installers that didn't correctly detect this case and take appropriate countermeasures. However, it's still possible, despite the best efforts of init script and installer authors to not be able to detect this misconfiguration, usually due to a buggy or misconfigured virtualization manager or the installer not having access to a network time server during the installation process. So by default, we allow the superblock times to be fudged by up to 24 hours. This can be disabled by setting options.accept_time_fudge to the boolean value of false in e2fsck.conf. The old options.buggy_init_scripts is left for backwards compatibility. Since we are now accepting the 24 hour time fudge by default, there is no longer a need to install an Ubuntu-specific e2fsck.conf file, so we can remove it. Signed-off-by: "Theodore Ts'o" --- debian/rules | 6 ------ e2fsck/e2fsck.conf.5.in | 36 ++++++++++++++++++++++-------------- e2fsck/e2fsck.conf.ubuntu | 2 -- e2fsck/problem.c | 4 ++-- e2fsck/super.c | 42 ++++++++++++++++++++++++------------------ 5 files changed, 48 insertions(+), 42 deletions(-) delete mode 100644 e2fsck/e2fsck.conf.ubuntu diff --git a/debian/rules b/debian/rules index f62e86f..f658bd1 100755 --- a/debian/rules +++ b/debian/rules @@ -445,12 +445,6 @@ endif $(INSTALL) -p -m 0644 debugfs/debug_cmds.ct \ ${debdir}/ss-dev/usr/share/doc/libss${SS_SOVERSION}/examples - if test -f /etc/lsb-release && \ - grep -q DISTRIB_ID=Ubuntu /etc/lsb-release; then \ - $(INSTALL) -p -m 0644 e2fsck/e2fsck.conf.ubuntu \ - ${debdir}/e2fsprogs/etc/e2fsck.conf; \ - fi - dh_installinfo -pcomerr-dev ${stdbuilddir}/lib/et/com_err.info dh_installinfo -pe2fslibs-dev ${stdbuilddir}/doc/libext2fs.info diff --git a/e2fsck/e2fsck.conf.5.in b/e2fsck/e2fsck.conf.5.in index 6638a39..a5021bd 100644 --- a/e2fsck/e2fsck.conf.5.in +++ b/e2fsck/e2fsck.conf.5.in @@ -87,19 +87,27 @@ interrupts e2fsck using ^C, and the filesystem is not explicitly flagged as containing errors, e2fsck will exit with an exit status of 0 instead of 32. This setting defaults to false. .TP -.I buggy_init_scripts -Some buggy distributions (such as Ubuntu) have init scripts and/or -installers which fail to correctly set the system clock before running -e2fsck and/or formatting the filesystem initially. Normally this -happens because the hardware clock is ticking localtime, instead of the -more proper and less error-prone UTC time. So while the kernel is -booting, the system time (which in Linux systems always ticks in UTC -time) is set from the hardware clock, but since the hardware clock is -ticking localtime, the system time is incorrect. Unfortunately, some -buggy distributions do not correct this before running e2fsck. If this -option is set to a boolean value of true, we attempt to work around this -situation by allowing the superblock last write time, last mount time, -and last check time to be in the future by up to 24 hours. +.I accept_time_fudge +Unfortunately, due to Windows' unfortunate design decision +to configure the hardware clock to tick localtime, instead +of the more proper and less error-prone UTC time, many +users end up in the situation where the system clock is +incorrectly set at the time when e2fsck is run. +.IP +Historically this was usually due to some distributions +having buggy init scripts and/or installers that didn't +correctly detect this case and take appropriate +countermeasures. However, it's still possible, despite the +best efforts of init script and installer authors to not be +able to detect this misconfiguration, usually due to a +buggy or misconfigured virtualization manager or the +installer not having access to a network time server +during the installation process. So by default, we allow +the superblock times to be fudged by up to 24 hours. +This can be disabled by setting +.I accept_time_fudge +to the +boolean value of false. This setting defaults to true. .TP .I clear_test_fs_flag This boolean relation controls whether or not @@ -111,7 +119,7 @@ defaults to true. .I defer_check_on_battery This boolean relation controls whether or not the interval between filesystem checks (either based on time or number of mounts) should -be doubled if the system is running on battery. It defaults to +be doubled if the system is running on battery. This setting defaults to true. .TP .I indexed_dir_slack_percentage diff --git a/e2fsck/e2fsck.conf.ubuntu b/e2fsck/e2fsck.conf.ubuntu deleted file mode 100644 index 49d6d19..0000000 --- a/e2fsck/e2fsck.conf.ubuntu +++ /dev/null @@ -1,2 +0,0 @@ -[options] - buggy_init_scripts = 1 diff --git a/e2fsck/problem.c b/e2fsck/problem.c index 540ac91..a713f1b 100644 --- a/e2fsck/problem.c +++ b/e2fsck/problem.c @@ -388,13 +388,13 @@ static struct e2fsck_problem problem_table[] = { /* Last mount time is in the future (fudged) */ { PR_0_FUTURE_SB_LAST_MOUNT_FUDGED, N_("@S last mount time is in the future.\n\t(by less than a day, " - "probably due to buggy init scripts) "), + "probably due to the hardware clock being incorrectly set) "), PROMPT_FIX, PR_PREEN_OK | PR_NO_OK }, /* Last write time is in the future (fudged) */ { PR_0_FUTURE_SB_LAST_WRITE_FUDGED, N_("@S last write time is in the future.\n\t(by less than a day, " - "probably due to buggy init scripts). "), + "probably due to the hardware clock being incorrectly set). "), PROMPT_FIX, PR_PREEN_OK | PR_NO_OK }, /* Block group checksum (latch question) is invalid. */ diff --git a/e2fsck/super.c b/e2fsck/super.c index c946664..951f6db 100644 --- a/e2fsck/super.c +++ b/e2fsck/super.c @@ -463,7 +463,7 @@ void check_super_block(e2fsck_t ctx) int inodes_per_block; int ipg_max; int inode_size; - int buggy_init_scripts; + int accept_time_fudge; dgrp_t i; blk_t should_be; struct problem_context pctx; @@ -795,25 +795,31 @@ void check_super_block(e2fsck_t ctx) } /* - * Some buggy distributions (such as Ubuntu) have init scripts - * and/or installers which fail to correctly set the system - * clock before running e2fsck and/or formatting the - * filesystem initially. Normally this happens because the - * hardware clock is ticking localtime, instead of the more - * proper and less error-prone UTC time. So while the kernel - * is booting, the system time (which in Linux systems always - * ticks in UTC time) is set from the hardware clock, but - * since the hardware clock is ticking localtime, the system - * time is incorrect. Unfortunately, some buggy distributions - * do not correct this before running e2fsck. If this option - * is set to a boolean value of true, we attempt to work - * around this situation by allowing the superblock last write - * time, last mount time, and last check time to be in the - * future by up to 24 hours. + * Unfortunately, due to Windows' unfortunate design decision + * to configure the hardware clock to tick localtime, instead + * of the more proper and less error-prone UTC time, many + * users end up in the situation where the system clock is + * incorrectly set at the time when e2fsck is run. + * + * Historically this was usually due to some distributions + * having buggy init scripts and/or installers that didn't + * correctly detect this case and take appropriate + * countermeasures. However, it's still possible, despite the + * best efforts of init script and installer authors to not be + * able to detect this misconfiguration, usually due to a + * buggy or misconfigured virtualization manager or the + * installer not having access to a network time server during + * the installation process. So by default, we allow the + * superblock times to be fudged by up to 24 hours. This can + * be disabled by setting options.accept_time_fudge to the + * boolean value of false in e2fsck.conf. We also support + * options.buggy_init_scripts for backwards compatibility. */ + profile_get_boolean(ctx->profile, "options", "accept_time_fudge", + 0, 1, &accept_time_fudge); profile_get_boolean(ctx->profile, "options", "buggy_init_scripts", - 0, 0, &buggy_init_scripts); - ctx->time_fudge = buggy_init_scripts ? 86400 : 0; + 0, accept_time_fudge, &accept_time_fudge); + ctx->time_fudge = accept_time_fudge ? 86400 : 0; /* * Check to see if the superblock last mount time or last -- 1.6.5.104.g2567b.dirty