Re: Getting FS access events

From: Alexander Viro (viro@math.psu.edu)
Date: Tue May 15 2001 - 05:44:08 EST


On Tue, 15 May 2001, Daniel Phillips wrote:

> That's because you left out his invalidate:
>
> * create an instance in pagecache
> * start reading into buffer cache (doesn't invalidate, right?)
> * start writing using pagecache (invalidate buffer copy)

Bzzert. You have a race here. Let's make it explicit:

start writing
put write request in queue
block on that
                                        start reading into buffer cache
                                        put read request into queue
                                        read from media
write to media

And no, we can't invalidate from IO completion hook.

> * lose the page
> * try to read it (via pagecache)
>
> Everthing ok.

Nope.

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