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" <tytso@mit.edu>

1 files changed, 24 insertions, 18 deletions

diff --git a/e2fsck/super.c b/e2fsck/super.c
index c946664b..951f6dbb 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