Re: Bug in swapfs (2.4.0-ac9)

Christoph Rohland (cr@sap.com)
16 Jan 2001 09:50:09 +0100


Hi Gregor,

On Mon, 15 Jan 2001, Gregor Jasny wrote:
> I think I've found a bug in swapfs:
>
> fstab:
> swapfs /dev/shm swapfs defaults 0 0
> swapfs /tmp swapfs defaults 0 0
>
> When I hit <enter> on a tar.gz file in Midnight Commander nothing
> happens. If I do a umonut /tmp and hit <enter> again it works as It
> should (I see the archived files). Nearly the same Problem with the
> Acrobat Reader pluin for Netscape. It shows only a blank page when
> /tmp is swapfs.

Yep, Alan introduced a maxbytes field to the superblock which is not
set in swapfs. So the vfs will always fail with EFBIG.
I will send out a patch soon.

> I've noticed that it's possible to mount /tmp more than once. mount
> shows then
> [snip]
> swapfs on /dev/shm type swapfs (rw)
> swapfs on /tmp type swapfs (rw)
> swapfs on /tmp type swapfs (rw)
> swapfs on /tmp type swapfs (rw)
> swapfs on /tmp type swapfs (rw)

The vfs allows multiple mount with 2.4, and for swapfs you always get
a fresh instance with its own resource limits. Think anout chroot with
its own swapfs instance. AFAIK the new util-linux will give you some
checking.

> The permissions for /tmp are rwxrwxrwt, and even -omode=777,exec
> didn't help.

Your bootup script sets the mode after mounting? The mode parameter is
functional for me and the default is 777. 1777 has to be done in user
space.

Greetings
Christoph

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