Re: [PATCH] ramfs fixes

Re: [PATCH] ramfs fixes

[Rik van Riel]

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)

regards,

Rik
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Re: [PATCH] ramfs fixes

[David Gibson]

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?

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Re: [PATCH] ramfs fixes

[Juan J. Quintela]

>>>>> "david" == David Gibson <dgibson@linuxcare.com> writes:

Hi

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

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

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

It means that the page is Dirty??? :)))))
Seriosly, now we can have dirty swap cache pages and soon dirty page
cache pages, coming from mmaped files, not only pages from Ramfs have
that bit set.

Later, Juan.

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