Re: Irritating ext2fs corruption

Jakob Borg (jb@k2.lund.se)
Tue, 4 Aug 1998 02:10:19 +0200


On Mon, Aug 03, 1998 at 06:53:52PM -0400, Theodore Y. Ts'o wrote:
> Date: Tue, 4 Aug 1998 00:22:08 +0200
> From: Stefan Traby <stefan@sime.com>
>
> > No, it's not a cache problem. The reason why you don't get the space
> > back is because some process still has an open file descriptor on the
> > file. The space won't be released until the file descriptor is closed.
>
> Which open file descriptor ? (He wrote that the problem appears even after
> unmount and remount...)
> [No, I've _never_ seen such a problem]

Have you never seen a "deleted inode has zero dtime" message frpm e2fsck+ I get them all the time...

> That's not what he said. He said he didn't want to unmount the
> filesystem, and wasn't unmounting the filesystem.

Yeas that _was_ what I said. I did unmount the filesystem and remount
it. It did not help. Output from fuser and losf indicated the file was
not open by anything.

Reproducing the error is as ease as creating 700 Mb files and deleting
them, keeping track of free space. In no time, the error will occur.

> I interpreted his remarks and description of symptoms as being likely
> caused by some process still having the image open, thus keeping the
> disk space allocated. That process (or possibly loopback mount) is
> probably also not dieing as part of the system shutdown, so the
> filesystem is probably not getting unmounted as part of the shutdown,
> and so you have an unceanly mounted disk where the disk space hasn't
> been reclaimed yet.
>
> It could be something else, but the bug report wasn't terribly clear,
> and this was the best I could come up with. Given that no one else has
> reported anything else like this (and I would get inundated with
> complaints if this was happening in general), I'm for the moment
> ascribing it to a system adminisrtation error as opposed to anything
> else.

To clarify my original report:

I create a file (a CD isofs image to be exact). I use it. I remove
it. I do not get my free space back. I unmount the partition (no
errors here). Check with a 'mount', yes it is unmounted. I mount
it. Still no more free space. Unmount and fsck. "deleted inode has
zero dtime" on one inode, most likely the file in question and
hundreds of screens of scrolling block numbers when fixing summary
information. Mount partition, everything is happy again.

I _can_ reproduce this. I do not think it is new to latest 2.1.11x
kernels. (vaguely remeber seeing this before, will check later tonight
or tomorrow)

-- 
Jakob Borg <jb@k2.lund.se>
[Debian GNU/Linux 2.0 narayan 2.1.112 i586]

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