Re: Checking page_count(page) in invalidate_complete_page

[Chuck Lever <chuck.lever@oracle.com>]

Nick Piggin wrote:
> Andrew Morton wrote:
> Also, you can't guarantee anything much about its refcount even then
> (because it could be on a private reclaim list or pagevec somewhere).
> 
>> We could retry the invalidation a few times, but that stinks.
>>
>> I think invalidate_inode_pages2() is sufficiently different from (ie:
>> stronger than) invalidate_inode_pages() to justify the addition of a new
>> invalidate_complete_page2(), which skips the page refcount check.
>>
> 
> Yes, I think that would be possible using the lock_page in do_no_page 
> trick.
> That would also enable you to invalidate pages that have direct IO going
> into them, and other weird and wonderful get_user_pages happenings.
> 
> I haven't thrown away those patches, and I am looking for a justification
> for them because they make the code look nicer ;)
> 
> For 2.6.18.stable, Andrew's idea of checking the return value and retry
> might be the only option.

I think allowing callers of invalidate_inode_pages2() to get the 
previous behavior is reasonable here.  There are only 2 of them: v9fs 
and the NFS client.

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