Re: Question on set_page_dirty()

[Ingo Oeser <ingo.oeser@informatik.tu-chemnitz.de>]

Hi,

On Wed, Dec 11, 2002 at 09:01:02AM +0100, Jan Hudec wrote:
> > What is the meaning of this dirty queue, what is the effect of linking
> > a page onto that queue, and when should the set_page_dirty() function
> > be used rather than the
> > SetPageDirty() macro?
> 
> If you use the SetPageDirty macro, then the page is marked dirty, but
> kernel can't find it when it should clean it. Thus it eventualy won't
> flush the data (it won't call writepage on it).

set_page_dirty() can be used in all cases, IMHO, since it:
   - will not sleep
   - will not call the set_page_dirty() method, if page has been dirty
     before (test_and_set_XXX is atomic an guarantees to trigger
     once only)
   - will not do anything besides settingt the PG_Dirty bit,
     if the page contains no mapping, or does not contain a
     set_page_dirty_method

So if set_page_dirty() exists on a certain kernel you want to
support, it should be used in all cases. Accounting code can also
be hooked into this, if it is used properly.

Regards

Ingo Oeser
-- 
Science is what we can tell a computer. Art is everything else. --- D.E.Knuth
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