On Fri 10-07-09 11:33:25, Nick Piggin wrote:
> After the previous patchset, this is my progress on the page_mkwrite
> thing... These patches are RFC only and have some bugs.
> --
> invalidate should not be required in the writeout path. The truncate
> sequence will first reduce i_size, then clean and discard any existing
> pagecache (and no new dirty pagecache can be added because i_size was
> reduced and i_mutex is being held), then filesystem data structures
> are updated.
>
> Filesystem needs to be able to handle writeout at any point before
> the last step, and once the 2nd step completes, there should be no
> unfreeable dirty buffers anyway (truncate performs the do_invalidatepage).
>
> Having filesystem changes depend on reading i_size without holding
> i_mutex is confusing at least. There is still a case in writepage
> paths in buffer.c uses i_size (testing which block to write out), but
> this is a small improvement.
This looks good.
Acked-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/buffer.c | 20 ++------------------
> 1 file changed, 2 insertions(+), 18 deletions(-)
>
> Index: linux-2.6/fs/buffer.c
> ===================================================================
> --- linux-2.6.orig/fs/buffer.c
> +++ linux-2.6/fs/buffer.c
> @@ -2663,18 +2663,8 @@ int nobh_writepage(struct page *page, ge
> /* Is the page fully outside i_size? (truncate in progress) */
> offset = i_size & (PAGE_CACHE_SIZE-1);
> if (page->index >= end_index+1 || !offset) {
> - /*
> - * The page may have dirty, unmapped buffers. For example,
> - * they may have been added in ext3_writepage(). Make them
> - * freeable here, so the page does not leak.
> - */
> -#if 0
> - /* Not really sure about this - do we need this ? */
> - if (page->mapping->a_ops->invalidatepage)
> - page->mapping->a_ops->invalidatepage(page, offset);
> -#endif
> unlock_page(page);
> - return 0; /* don't care */
> + return 0;
> }
>
> /*
> @@ -2867,14 +2857,8 @@ int block_write_full_page_endio(struct p
> /* Is the page fully outside i_size? (truncate in progress) */
> offset = i_size & (PAGE_CACHE_SIZE-1);
> if (page->index >= end_index+1 || !offset) {
> - /*
> - * The page may have dirty, unmapped buffers. For example,
> - * they may have been added in ext3_writepage(). Make them
> - * freeable here, so the page does not leak.
> - */
> - do_invalidatepage(page, 0);
> unlock_page(page);
> - return 0; /* don't care */
> + return 0;
> }
>
> /*
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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