Re: writepage

["Raghu R. Arur" <rra2002@cs.columbia.edu>]

 Yes a page that is in swap cache and on which a rw_swap_page() is done, 
will have both buffers and mapping NON_NULL..

On Mon, 1 Mar 2004, Anand Eswaran wrote:

> 
> Sorry I meant for a given page , during the next pass, when the
> page->buffers is NON_NULL and is released, by definition the page cannot
> have a null mapping because it would have been added in the swapcache
> previous pass. Is that true?
> 
> Thanks,
> ----
> Anand.
> 
> On Mon, 1 Mar 2004, Anand Eswaran wrote:
> 
> > In that case, it seems to me that during the next pass of the launder
> > loop, the loop by definition cannot have a (page->mapping) value of NULL
> > because it has been added to the swapcache in the previous pass.
> >
> > Is that true?
> > -----
> > Anand.
> >
> >
> >
> > On Mon, 1 Mar 2004, Raghu R. Arur wrote:
> >
> > >
> > >  The page is added to the swap cache by add_to_swap_cache and not by
> > > writepage.
> > >
> > >  writepage() (swap_writepage() in this case) prepares the page to write to
> > > the swap disk by creating buffers and submits the page to the disk. So
> > > page->buffers will be NON_NULL.
> > >
> > > Raghu.
> > >
> > > On Mon, 1 Mar 2004, Anand Eswaran wrote:
> > >
> > > > Hi :
> > > >
> > > >   I have quick question reg Linux 2.4.18, Ive tried to understand the code
> > > > but am pretty confused:
> > > >
> > > >   In the typical malloc execution-path,  the page is added to swap and it's
> > > > pte_chain is unmapped  after which the writepage() is executed.  However I
> > > > notice that *after* the writepage(), the page->buffers is NON_NULL.
> > > >
> > > >   Is this supposed to happen? I thought the writepage function flushed the
> > > > page to swap, so why are there residual buffers?
> > > >
> > > > Thanks,
> > > > ----
> > > > Anand.
> > > >
> > > > --
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> > >
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