Re: [patch] 'virtual => physical page mappingcache',vcache-2.5.38-B8

[Andrew Morton]

Alan Cox wrote:
> 
> On Fri, 2002-09-27 at 19:35, Andrew Morton wrote:
> > O_DIRECT writes operate under i_sem, which provides exclusion
> > from trucate.  Do you know something which I don't??
> 
> So it does, hidden away in generic_file_write rather than the lower
> layers.

Well that's sort of the same level at which truncate takes it.
It's a pretty big lock.

> Interesting. So now I have a new question to resolve, which is
> why doing O_DIRECT and truncate together corrupted my disk when I tried
> it trying to break stuff

Interesting indeed.  Possibly invalidate_inode_pages2() accidentally
left some dirty buffers detached from the mapping.  Hard to see how
it could do that.

What kernel were you testing?