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

[Rasmus Andersen <rasmus@jaquet.dk>]

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.

Regards,
   Rasmus
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