Re: [patch 3/3] mm: make read_cache_page synchronous

[Nick Piggin <nickpiggin@yahoo.com.au>]

Andrew Morton wrote:
> On Tue,  6 Feb 2007 09:02:33 +0100 (CET) Nick Piggin <npiggin@suse.de> wrote:
> 
> 
>>Ensure pages are uptodate after returning from read_cache_page, which allows
>>us to cut out most of the filesystem-internal PageUptodate_NoLock calls.
> 
> 
> Normally it's good to rename functions when we change their behaviour, but
> I guess any missed (or out-of-tree) filesystems will just end up doing a
> pointless wait_on_page_locked() and will continue to work OK, yes?

Yeah.

> 
> 
>>I didn't have a great look down the call chains, but this appears to fixes 7
>>possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in ecryptfs,
>>1 in jffs2, and a possible cleared data overwritten with readpage in block2mtd.
>>All depending on whether the filler is async and/or can return with a !uptodate
>>page.
>>
>>Also, a memory leak in sys_swapon().
> 
> 
> Separate patch?

Well its fixed by virtue of read_cache_page now correctly dropping the page
refcount if it finds the page !uptodate, rather than any special logic I
added.

I can do another patch though. No problem, I'll be resending the series after
this round of feedback.

-- 
SUSE Labs, Novell Inc.
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