Re: nfs invalidates lose pte dirty bits

[Trond Myklebust]

On Fri, 2005-12-23 at 16:17 +0100, Andrea Arcangeli wrote:
> > However if the user is doing mmap writes while the file is in the
> > process of being modified on the server, then they are doing something
> > wrong anyway. The small race between nfs_sync_mapping() and
> > invalidate_inode_pages2() is the least of their problems.
> 
> I'm talking about spurious revalidates, I don't think the testcase I'm
> dealing with is really needing an invalidate, it's a spurious one
> (perhaps triggered by flock), but I'm lucky it's single threaded so
> current fix will work for them.

We should perhaps think of setting up an
"unmap_write_dirty_and_invalidate" helper in order to deal with this
sort of race. As long as we have to first unmap all the pages, then
write the dirty ones, then invalidate them, we will be open to races.

Cheers,
  Trond

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