Re: Worse yet Re: Whoops! Re: [PATCH] Another semi-critical one... (was Re: towards 0.91 )

[Yoshinori K. Okuji]

At Wed, 07 Nov 2001 11:08:00 -0800,
address@hidden wrote:
> Personally, I am *very* wary of reading the journal on a filesystem
> mounted for writing, because by definition it changes very fast.  You'd
> be getting inconsistency errors all over the place when the journal
> has something in it that isn't in the main filesystem on-disk structures
> yet.

I agree. So, a way to solve that problem would be that GRUB disallows
the user to write data to any filesystem, if it is mounted with write
enabled by the OS. What do you think? This may be just annoying for
experts, though.

> #1:  I think we add a "--mapdump" feature that spits out a simple
> file listing all the blockmaps.  Then we run the final stage of
> the GRUB shell in "grub-install" something like 3 times with short
> delays and compare the results to see if they are all identical (you
> don't even need a terribly nice format, just something you can run a
> binary compare on).  If not, then a simple retry mechanism after a
> delay, and if a few delays don't cause it to settle down, you give up.

Since we have the command "blocklist", this is easy.

> #2:  Add at least some support for journals, so that you can at least
> recognize when it's not empty and maybe just error out in a way that
> "grub-install" can then print out "journal not flushed, delaying...",
> puts in a wait, then tries again.  Obviously any such behavior where
> it errors out would only be in the GRUB shell, not the bootloader
> version.

This is a Good Thing to have, but I think this should be transparent
for the user and shouldn't be "grub-install"-specific, i.e., the mount
function for a journal filesystem should do this automatically only in
the grub shell.

Okuji