Re: [PATCH] thinko in mm/filemap.c (242p1)

[Marcelo Tosatti <marcelo@conectiva.com.br>]

On Tue, 6 Feb 2001, Rasmus Andersen wrote:

> On Tue, Feb 06, 2001 at 10:51:05AM -0200, Rik van Riel wrote:
> > On Tue, 6 Feb 2001, Rasmus Andersen wrote:
> [...]
> > 
> > I guess the writeout_one_page schedules the dirty pages for IO
> > and puts them on the list of locked pages. The last call then
> > waits on those same pages until they've been flushed to disk.
> > 
> > Your change would wait on the pages but never submit them for
> > IO (again, a guess, I haven't looked at the code in too much
> > detail).
> 
> The total function (generic_buffer_fdatasync) (with my patch):
> 
>         /* writeout dirty buffers on pages from both clean and dirty lists */
>         retval = do_buffer_fdatasync(&inode->i_mapping->dirty_pages, start_idx, 
> end_idx, writeout_one_page);
>         retval |= do_buffer_fdatasync(&inode->i_mapping->clean_pages, start_idx,
>  end_idx, writeout_one_page);
>         retval |= do_buffer_fdatasync(&inode->i_mapping->locked_pages, start_idx
> , end_idx, writeout_one_page);
> 
>         /* now wait for locked buffers on pages from both clean and dirty lists 
> */
>         retval |= do_buffer_fdatasync(&inode->i_mapping->dirty_pages, start_idx,
>  end_idx, waitfor_one_page);
>         retval |= do_buffer_fdatasync(&inode->i_mapping->clean_pages, start_idx,
>  end_idx, waitfor_one_page);
>         retval |= do_buffer_fdatasync(&inode->i_mapping->locked_pages, start_idx
> , end_idx, waitfor_one_page);
> 
> 
> So we start the writeout in the three first lines and wait for them in
> the last three. Without my patch we write dirty_pages out again in the
> second run.

Pages written in the first run will be moved to the locked list. 

No big deal, but its not a critical bug right now.



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