Messages in this thread |  | | Date | Tue, 15 May 2001 02:57:03 -0400 (EDT) | From | Alexander Viro <> | Subject | Re: Getting FS access events |
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On Tue, 15 May 2001, Richard Gooch wrote:
> > What happens if you create a buffer cache entry? Does that > > invalidate the page cache one? Or do you just allow invalidates one > > way, and not the other? And why= > > I just figured on one way invalidates, because that seems cheap and > easy and has some benefits. Invalidating the other way is costly, so > don't bother, even if there were some benefits.
Cute. * create an instance in pagecache * start reading into buffer cache (doesn't invalidate, right?) * start writing using pagecache * lose the page * try to read it (via pagecache) Woops - just found a copy in buffer cache, let's pick data from it. Pity that said data is obsolete...
> So what happens if I dd from the block device and also from a file on > the mounted FS, where that file overlaps the bnums I dd'ed? Do we get > two copies in the page cache? One for the block device access, and one > for the file access?
Yes.
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