On Sat, Feb 12, 2011 at 07:15:55PM -0500, Theodore Ts'o wrote:
> If we have accumulated a contiguous region of memory to be written
> out, and the next page can added to this region, don't bother locking
> (and then unlocking the page) before writing out the memory. In the
> unlikely event that the next page was being written back by some other
> CPU, we can also skip waiting that page to finish writeback.
>
> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
> ---
> fs/ext4/inode.c | 27 ++++++++++-----------------
> 1 files changed, 10 insertions(+), 17 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 6dfdc0e..2ac64e3 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2761,6 +2761,16 @@ static int write_cache_pages_da(struct address_space *mapping,
>
> *done_index = page->index + 1;
>
> + /*
> + * If we can't merge this page, and we have
> + * accumulated an contiguous region, write it
> + */
> + if ((mpd->next_page != page->index) &&
> + (mpd->next_page != mpd->first_page)) {
> + mpage_da_map_and_submit(mpd);
> + goto ret_extent_tail;
> + }
> +
> lock_page(page);
>
> /*
> @@ -2784,25 +2794,8 @@ static int write_cache_pages_da(struct address_space *mapping,
>
> BUG_ON(PageWriteback(page));
>
> - /*
> - * Can we merge this page to current extent?
> - */
> if (mpd->next_page != page->index) {
> /*
> - * Nope, we can't. So, we map
> - * non-allocated blocks and start IO
> - * on them
> - */
> - if (mpd->next_page != mpd->first_page) {
> - mpage_da_map_and_submit(mpd);
> - /*
> - * skip rest of the page in the page_vec
> - */
> - unlock_page(page);
> - goto ret_extent_tail;
> - }
> -
> - /*
> * Start next extent of pages and blocks
> */
> mpd->first_page = page->index;
Looks good.
Josef
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