include ext4

Theodore Tso tytso at mit.edu
Wed Sep 24 12:49:26 UTC 2008


On Tue, Sep 23, 2008 at 08:04:34PM -0700, Jason Newton wrote:
> Just to clarify, intrepid is currently based on 2.6.27, though what  
> subrelease/rc I don't know.

What -rc release is it currently on?  A lot of fixes went in during
the 2.6.27-rc series, so that's actually rather important. 

> It is using e2fsprogs 1.41.0 though but  
> perhaps intrepid will be willing to adopt 1.41.1 before everything is  
> frozen if 1.41.2 is out by then.

The biggest and most important patch pending for 1.41.2 isn't actually
an ext4-specific bug.  I didn't notice right away, unfortunately, but
ever since a little while before 1.41.0 was released, "e2fsck -b
32768" and "e2fsck -b 8193" was broken; you have to type "e2fsck -b
32768 -B 4096" and "e2fsck -b 8193 -B 1024", because the automatic
block size detection was broken (unfortunately, e2fsck's own error
messages for very badly corrupted filesystems, as well as many
recovery FAQ's/HOWTO's tell people to use e2fsck -b 32768 or e2fsck -b
8193, depending on your filesystem block size; fortunately in many of
those cases where it's safe e2fsck will now automatically retry with
the right block size, but there are still a few cases where people
have to manually type the magic command line options.)

I hadn't bothered hurrying with the rollout because there were a few
other changes I was trying to batch into 1.41.2, and the prepping for
the Kernel Summit and Plumber's Conference sucked up all available
time.  Still, if I had known there was a hope of getting something
into Intrepid (I thought you were already in a hard freeze), I might
have rushed 1.41.2 out the door.

> I just think Intrepid should  
> have the ability to be able to read and write to a ext4 filesystem  
> without jumping through a bunch of hoops since it seems its got the  
> right environment for it right now.

Thanks for the context; yes, if Intrepid is not going to add support
for installing on ext4, that lowers the stakes tremendously.  This
means we're now talking about users who know how to run a partitioner
and run mkfs by hand, which means they have a pretty fair amount of
clue.

> @Ted:
> So does the 2.6.27 based kernel make Intrepid a plausible environment  
> for general, non-mission-critical ext4 usage?

Post 2.6.27-rc5 (released August 28), yes.  There were a chunk-load of
bug fixes which didn't land into mainline until August 22nd, right
after 2.6.27-rc4 was released, and which didn't get pushed out in an
-rc release until -rc5.  Between -rc2 and -rc5, things should mostly
work OK as long as you disable delayed allocation.

						- Ted

P.S.  You can see what is in e2fsprogs 1.41.1 here:

	http://e2fsprogs.sourceforge.net/e2fsprogs-release.html#1.41.1




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