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Date: Mon, 12 Oct 2009 16:41:12 -0700
From: Andreas Dilger <adilger@....com>
To: Eric Sandeen <sandeen@...hat.com>
Cc: Scott James Remnant <scott@...ntu.com>, linux-ext4@...r.kernel.org,
Theodore Tso <tytso@....edu>
Subject: Re: [PATCH] e2fsck: Always fix last mount/write/check time with -p
On 12-Oct-09, at 08:44, Eric Sandeen wrote:
> Scott James Remnant wrote:
>> After much debugging, we've come to the conclusion that the problems
>> with a last mount, write and check time in the future by up to 24
>> hours are not caused by buggy init scripts. In fact, in every
>> report,
>> the "now" time was always correct and it was the last mount/write/
>> check
>> time that was wrong.
>> Investigation has led us to the following common scenarios:
>> - Overwriting a system that previously had Windows installed, and
>> thus a localtime ticking hardware clock. The installer may not
>> even be aware that the hardware clock is in localtime, and the
>> user fails to notice that the clock is wrong while they are
>> installing.
>
> This has recently started showing up on Fedora as well, and I agree
> that the 24h "grace period" seems like the best approach. Ted, if
> you bless this I'd like to pull it into Fedora too. I might even go
> so far as to say a times outside 24h don't necessarily warrant a
> full fs check either, but I'm not hung up on that. :)
>
> Minor nitpick, a
>
> #define 24H_IN_SECONDS 86400
>
> might be nicer than having the sorta-magic number sprinkled around
> (though I see that was just inherited from the current code)
I hit this same problem recently, just due to the h/w clock being in
local
time (windows machine) instead of UTC...
>> ---
>> debian/rules | 6 ------
>> e2fsck/e2fsck.conf.5.in | 14 --------------
>> e2fsck/e2fsck.conf.ubuntu | 2 --
>> e2fsck/e2fsck.h | 1 -
>> e2fsck/problem.c | 4 ++--
>> e2fsck/super.c | 39 ++++++++++++++
>> +------------------------
>> e2fsck/unix.c | 2 +-
>> 7 files changed, 18 insertions(+), 50 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..daa4e9f 100644
>> --- a/e2fsck/e2fsck.conf.5.in
>> +++ b/e2fsck/e2fsck.conf.5.in
>> @@ -87,20 +87,6 @@ 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.
>> -.TP
>> .I clear_test_fs_flag
>> This boolean relation controls whether or not .BR e2fsck (8)
>> 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/e2fsck.h b/e2fsck/e2fsck.h
>> index ff73444..a5a811f 100644
>> --- a/e2fsck/e2fsck.h
>> +++ b/e2fsck/e2fsck.h
>> @@ -339,7 +339,6 @@ struct e2fsck_struct {
>> /* misc fields */
>> time_t now;
>> - time_t time_fudge; /* For working around buggy init scripts */
>> int ext_attr_ver;
>> profile_t profile;
>> int blocks_per_page;
>> diff --git a/e2fsck/problem.c b/e2fsck/problem.c
>> index 540ac91..7e3cafb 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 bad system clock last boot) "),
>> 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 bad system clock last boot). "),
>> 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 097c87a..3fa0441 100644
>> --- a/e2fsck/super.c
>> +++ b/e2fsck/super.c
>> @@ -465,7 +465,6 @@ void check_super_block(e2fsck_t ctx)
>> int inodes_per_block;
>> int ipg_max;
>> int inode_size;
>> - int buggy_init_scripts;
>> dgrp_t i;
>> blk_t should_be;
>> struct problem_context pctx;
>> @@ -801,34 +800,26 @@ 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.
>> - */
>> - profile_get_boolean(ctx->profile, "options", "buggy_init_scripts",
>> - 0, 0, &buggy_init_scripts);
>> - ctx->time_fudge = buggy_init_scripts ? 86400 : 0;
>> -
>> - /*
>> * Check to see if the superblock last mount time or last
>> * write time is in the future.
>> + *
>> + * Unfortunately it's remarkably easy for users to get
>> + * themselves into a problem where they've mounted the
>> + * filesystem at least once before the hardware clock has
>> + * been corrected by NTP (especially when overwriting or
>> + * dual booting with Windows). Sadly these are the very
>> + * users who have no idea what to do when presented with a
>> + * root shell and invited to fix their filesystem.
>> + *
>> + * Work around this situation by always allowing the
>> + * superblock last write time, last mount time, and last
>> + * check time to be in the future by up to 24 hours (when
>> + * fsck called with -a/-p).
>> */
>> if (fs->super->s_mtime > (__u32) ctx->now) {
>> pctx.num = fs->super->s_mtime;
>> problem = PR_0_FUTURE_SB_LAST_MOUNT;
>> - if (fs->super->s_mtime <= (__u32) ctx->now + ctx->time_fudge)
>> + if (fs->super->s_mtime <= (__u32) ctx->now + 86400)
>> problem = PR_0_FUTURE_SB_LAST_MOUNT_FUDGED;
>> if (fix_problem(ctx, problem, &pctx)) {
>> fs->super->s_mtime = ctx->now;
>> @@ -838,7 +829,7 @@ void check_super_block(e2fsck_t ctx)
>> if (fs->super->s_wtime > (__u32) ctx->now) {
>> pctx.num = fs->super->s_wtime;
>> problem = PR_0_FUTURE_SB_LAST_WRITE;
>> - if (fs->super->s_wtime <= (__u32) ctx->now + ctx->time_fudge)
>> + if (fs->super->s_wtime <= (__u32) ctx->now + 86400)
>> problem = PR_0_FUTURE_SB_LAST_WRITE_FUDGED;
>> if (fix_problem(ctx, problem, &pctx)) {
>> fs->super->s_wtime = ctx->now;
>> diff --git a/e2fsck/unix.c b/e2fsck/unix.c
>> index e629602..fe7093b 100644
>> --- a/e2fsck/unix.c
>> +++ b/e2fsck/unix.c
>> @@ -304,7 +304,7 @@ static void check_if_skip(e2fsck_t ctx)
>> lastcheck = fs->super->s_lastcheck;
>> if (lastcheck > ctx->now)
>> - lastcheck -= ctx->time_fudge;
>> + lastcheck -= 86400; /* see comment in super.c */
>> if ((fs->super->s_state & EXT2_ERROR_FS) ||
>> !ext2fs_test_valid(fs))
>> reason = _(" contains a file system with errors");
>
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Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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