Re: document ext3 requirements

Rob Landley
2009-01-05T03:23:35Z

On Sunday 04 January 2009 13:21:06 Geert Uytterhoeven wrote:
> I think most people get shocked when they discover that mounting something
> read-only may actualy write to the media. This is a bit unexpected (hey, if
> I mount `read-only', I expect that no writes will happen), as it behaved
> differently before the introduction of journalling.

Is this an unreasonable use case:

kill -STOP $(pidof qemu)
mount -o loop,ro hdb.img blah
cp blah/thingy thingy
umount blah
kill -CONT $(pidof qemu)

Currently, if your loopback mount is -t ext3 it'll write to the block device,
and if your mount is -t ext2 it'll refuse to work on an unclean ext3
filesystem, even if it's read only. (But it _will_ work on an unclean ext2
filesystem.)

My theory when I first found out about this was "the filesystem developers
hate me personally".

Rob