e2fsprogs: turn off enforced fsck intervals by default

The forced fsck often comes at unexpected and inopportune moments,
and even enterprise customers are often caught by surprise when
this happens.  Because a filesystem with an error condition will
be marked as requiring fsck anyway, I submit that the time-based
and mount-based checks are not particularly useful, and that
administrators can schedule fscks on their own time, or tune2fs
the enforced intervals if they so choose.  This patch disables the
intervals by default, and I've added a new mkfs.conf option to
turn on the old behavior of random, unexpected, time-consuming
fscks at boot time.  ;)

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

3 files changed, 36 insertions, 6 deletions

diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index b994e1e1..87d3c262 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -2168,13 +2168,31 @@ int main (int argc, char *argv[])
 	uuid_generate((unsigned char *) fs->super->s_hash_seed);
 
 	/*
-	 * Add "jitter" to the superblock's check interval so that we
-	 * don't check all the filesystems at the same time.  We use a
-	 * kludgy hack of using the UUID to derive a random jitter value.
+	 * Periodic checks can be enabled/disabled via config file.
+	 * Note we override the kernel include file's idea of what the default
+	 * check interval (never) should be.  It's a good idea to check at
+	 * least *occasionally*, specially since servers will never rarely get
+	 * to reboot, since Linux is so robust these days.  :-)
+	 *
+	 * 180 days (six months) seems like a good value.
 	 */
-	for (i = 0, val = 0 ; i < sizeof(fs->super->s_uuid); i++)
-		val += fs->super->s_uuid[i];
-	fs->super->s_max_mnt_count += val % EXT2_DFL_MAX_MNT_COUNT;
+#ifdef EXT2_DFL_CHECKINTERVAL
+#undef EXT2_DFL_CHECKINTERVAL
+#endif
+#define EXT2_DFL_CHECKINTERVAL (86400L * 180L)
+
+	if (get_bool_from_profile(fs_types, "enable_periodic_fsck", 0)) {
+		fs->super->s_checkinterval = EXT2_DFL_CHECKINTERVAL;
+		fs->super->s_max_mnt_count = EXT2_DFL_MAX_MNT_COUNT;
+		/*
+		 * Add "jitter" to the superblock's check interval so that we
+		 * don't check all the filesystems at the same time.  We use a
+		 * kludgy hack of using the UUID to derive a random jitter value
+		 */
+		for (i = 0, val = 0 ; i < sizeof(fs->super->s_uuid); i++)
+			val += fs->super->s_uuid[i];
+		fs->super->s_max_mnt_count += val % EXT2_DFL_MAX_MNT_COUNT;
+	}
 
 	/*
 	 * Override the creator OS, if applicable
diff --git a/misc/mke2fs.conf b/misc/mke2fs.conf
index 52fe58ed..868821d3 100644
--- a/misc/mke2fs.conf
+++ b/misc/mke2fs.conf
@@ -1,5 +1,6 @@
 [defaults]
 	base_features = sparse_super,filetype,resize_inode,dir_index,ext_attr
+	enable_periodic_fsck = 0
 	blocksize = 4096
 	inode_size = 256
 	inode_ratio = 16384
diff --git a/misc/mke2fs.conf.5.in b/misc/mke2fs.conf.5.in
index dfc06958..cb643eb7 100644
--- a/misc/mke2fs.conf.5.in
+++ b/misc/mke2fs.conf.5.in
@@ -107,6 +107,17 @@ command-line option
 to 
 .BR mke2fs (8).
 .TP
+.I enable_periodic_fsck
+This relation specifies whether periodic filesystem checks should be
+enforced at boot time.  If enabled, checks will be forced every
+180 days, or after a random number of mounts.  These values may
+be changed later via the
+.B -i
+and
+.B -c
+command-line options to
+.BR tune2fs (8).
+.TP
 .I force_undo
 This relation, if set to a boolean value of true, forces
 .B mke2fs