Re: MSDOSFS woes

On Sat, Aug 02, 2003 at 05:00:45PM +0100, Bruce Cran wrote:
> On Sat, Aug 02, 2003 at 06:08:50PM +0300, Ruslan Ermilov wrote:
> > Gang, :-)
> > 
> > While working with Marcel on a bootable CD-ROM for IA64 issue,
> > I've stumbled upon the following problem.  I needed to increase
> > the size of the EFI partition (which is an MS-DOS file system)
> > to 64M, and that made two of my machines stuck solidly -- a lot
> > of process are waiting on the "wdrain" event.
> > 
> > The issue is not IA64 specific, both machines in question are
> > i386.  The following script makes my machines unhappy:
> > 
> > EFISZ=131072
> > dd if=/dev/zero of=$BASE/$EFIPART count=$EFISZ
> > md=`mdconfig -a -t vnode -f $BASE/$EFIPART`
> > newfs_msdos -F 12 -S 512 -h 4 -o 0 -s $EFISZ -u 16 $md
> > mount -t msdosfs /dev/$md /mnt
> > dd if=/dev/zero of=/mnt/foo
> > 
> > Changing to the -F 16 does not take any (good) effect.
> > Anyone is interested in narrowing it down?
> > 
> 
> I've also seen this happening on my Athlon XP system running -CURRENT.  I 
> presumed it was the deadlock in vnode-backed md disks.  It seems that when
> a lot of disk activity occurs on the md partition, the process stops - 
> this is on a 30GB image containing UFS2 partitions /dev/md0s1[a,d,e].
> Attempting to reboot results in the message 'processes would not die - ps
> axl advised', I had to reset the computer because nothing more happened.
> 
Yes, the same here.

And I have just been able to reproduce this with only a 16MB MS-DOS file
system on a vnode backed md(4) device.


Cheers,
-- 
Ruslan Ermilov		Sysadmin and DBA,
ru_at_sunbay.com		Sunbay Software Ltd,
ru_at_FreeBSD.org		FreeBSD committer