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

[Andrea Arcangeli]

On Thu, Apr 26, 2001 at 07:25:23PM -0400, Alexander Viro wrote:
> 
> 
> On Thu, 26 Apr 2001, Andrea Arcangeli wrote:
> 
> > > How about adding
> > >   if (!buffer_uptodate(bh)) {
> > >           printk(KERN_ERR "IO error or racy use of wait_on_buffer()");
> > >           show_task(current);
> > >   }
> > > in the end of wait_on_buffer() for a while?
> > 
> > At the _top_ of wait_on_buffer would be better then at the end.
> 
> In that case ll_rw_block() + wait_on_buffer() (absolutely legitimate
> combination) will scream at you.

--- 2.4.4pre7/include/linux/locks.h     Thu Apr 26 05:22:11 2001
+++ 2.4.4pre7aa1/include/linux/locks.h  Fri Apr 27 01:52:31 2001
@@ -18,6 +18,11 @@
 {
        if (test_bit(BH_Lock, &bh->b_state))
                __wait_on_buffer(bh);
+       else if (!buffer_uptodate(bh)) {
+               __label__ here; 
+       here:
+               printk(KERN_ERR "IO error or racy use of wait_on_buffer() from %p\n", 
+&&here);
+       }
 }
 
 extern inline void lock_buffer(struct buffer_head * bh)

Andrea
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