[ext2resize] Re: Deadlock help

[Robert W. <rj...@du...>]

[ Andreas: just for context - I was getting an oops while doing I/O on a
filesystem that was being resized. ]

> Is this ext3?  Probably you have someone doing a journal_start()
> while holding the superblock lock.  That's the wrong order.

That was it.  The resize code does a lock_super/unlock_super around the
two resize entry points in ioctl.c and calls journal_start/journal_stop
in several places while doing the resize.  This was causing the oops
while doing I/O and resizing simultaneously.

Since I don't know when the superblock actually really needs to be
locked, I err'd on the side of caution and put an
unlock_super/lock_super around each call to journal_start and
journal_stop.  This seemed to make the problem go away but it's a lot of
locking/unlocking to be going on.

Is it really necessary for the resize code to hold onto the superblock
locks for such a long length of time?  Would it be possible to minimize
the amount of locking needed here?

I can create a new patch with the fix, but if there's a better way of
doing this, I'd like to wait...

Regards,
 Robert.=20

--=20
Robert Walsh
Amalgamated Durables, Inc.  -  "We don't make the things you buy."
Email: rj...@du...