Of course I started fiddling with the aim of throwing together something that could do that, but found a problem.
I ran fsck with -n on my root partition, it said there was an inode problem, so I touched /forcefsck and rebooted to run a full fsck. After rebooting I ran fsck -n again to see what it would tell me, unfortunately I now had more problems than I had the first time, lots of:
Free blocks count wrong for group #10 (19891, counted=19838).
and
Free inodes count wrong for group #10 (16186, counted=16187).
type errors. I also did the same with a different disk, and got the same issue. So it seems that ext3 always has inode and block count issues, making my suggestion of running a full fsck when errors are found with a read only one, unworkable.
Of course I started fiddling with the aim of throwing together something that could do that, but found a problem.
I ran fsck with -n on my root partition, it said there was an inode problem, so I touched /forcefsck and rebooted to run a full fsck. After rebooting I ran fsck -n again to see what it would tell me, unfortunately I now had more problems than I had the first time, lots of:
Free blocks count wrong for group #10 (19891, counted=19838).
and
Free inodes count wrong for group #10 (16186, counted=16187).
type errors. I also did the same with a different disk, and got the same issue. So it seems that ext3 always has inode and block count issues, making my suggestion of running a full fsck when errors are found with a read only one, unworkable.