forced fsck (again?)

[Theodore Tso]

On Fri, Jan 25, 2008 at 01:55:57AM -0700, Andreas Dilger wrote:
> > 		nice logsave -as "${tmpfile}" fsck.${fstype} -p -C 0 "$dev" &&
> > 			nice logsave -as "${tmpfile}" fsck.${fstype} -fy -C 0 "$dev"
> 
> Hmm, I'm not sure I understand what it is you want to do?  The fsck should
> be run as 'e2fsck -fn "$dev"' (since we already know this is ext2|ext3).
> Using "-C 0" isn't useful because we don't want progress in the output log,

This was my fault.  It means that when you run this from a tty, you
get to see the progress bar.  The -s flag to logsave will strip out
the progress information.  (I added logsave -s precisely for this
purpose.  :-)

> and "-p" without "-f" will just check the superblock.  

That's needed e2fsck -p will clean up the orphaned inode list, so that
the subsequent e2fsck -fy will return 0 if the filesystem is clean.
Without the the fsck -p, then e2fsck -fy will return 1 (because it
modified the filesystem) which we can't distinguish from the case
where the filesystem had errors.

> We don't want to be
> fixing anything (since this should be a read-only snapshot) so "-fy" is 
> also not so great.

This is a tradeoff.  e2fsck -fy requires that the snapshot have more
space (although if you run off, it's not that horrible; the snapshot
will just go invalid).  The advantage of "-fy" is that you get more
information about any errors in the filesystem, where as "-fn" may not
report as useful information.

> > # do everything needed to check and reset dates and counters on /dev/$1/$2.
> > function check_fs() {
> > 	local tmpfile=`mktemp -t e2fsck.log.XXXXXXXXXX`
> > 	trap "rm $tmpfile ; trap - RETURN" RETURN
> 
> For the log file it probably makes sense to keep this around with a
> timestamp if there is a failure.  That means it is fine to generate a
> random filename temporarily, but it should be renamed to something
> meaningful (e.g. /var/log/lvfsck.$dev.$(date +%Y%m%d) or similar).

The idea is if there is a failure we'll e-mail to the administrator;
after that, there's no real need to keep it around.

      	    	       	    	    	 - Ted