Re: [PATCH] SMP race in ext2 - metadata corruption.

[Andrea Arcangeli]

On Thu, Apr 26, 2001 at 11:49:14AM -0700, Linus Torvalds wrote:
> 
> On Thu, Apr 26, 2001 at 11:45:47AM -0400, Alexander Viro wrote:
> >
> >	Ext2 does getblk+wait_on_buffer for new metadata blocks before
> > filling them with zeroes. While that is enough for single-processor,
> > on SMP we have the following race:
> > 
> > getblk gives us unlocked, non-uptodate bh
> > wait_on_buffer() does nothing
> > 					read from device locks it and starts IO
> 
> I see the race, but I don't see how you can actually trigger it.
> 
> Exactly _who_ does the "read from device" part? Somebody doing a

/sbin/dump

> the wait-on-buffer is not strictly necessary: it's probably there to make

maybe not but I need to check some more bit to be sure.

Andrea