Re: [PATCH] ramfs fixes

From: David Gibson (
Date: Mon Jun 19 2000 - 22:20:19 EST

On Mon, Jun 19, 2000 at 11:02:22AM -0300, Rik van Riel wrote:
> On Mon, 19 Jun 2000, David Gibson wrote:
> > The PG_dirty bit is cleared in add_to_swap_cache() and
> > __add_to_page_cache() so this is kind of redundant, but the
> > detach_page hook is good news in general.
> Oww, good that you alert me to this bug. It makes no sense to
> clear the bit there since we may have dirty pages in both the
> filecache and the swapcache...
> (well, it doesn't cause any bugs, but it could add some nasty
> surprises later when we change the code so we can have dirty
> pages in all the caches)

This actually went in somewhat recently, in 2.3.99pre something (where
something is around 4 IIRC). This fixed a bug in ramfs, since
previously the dirty bit was never being cleared.

At the time ramfs was the *only* place using PG_dirty - it looked like
it was just a misleading name for something analagous to BH_protected.

Obviously that's not true any more. What does the PG_dirty bit mean
these days?

David Gibson, Technical Support Engineer, Linuxcare, Inc.
+61 2 6262 8990, 
Linuxcare. Support for the revolution.

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