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SubjectRe: [patch] mm: shmem: use new radix tree iterator
On Fri, 1 Feb 2013, Johannes Weiner wrote:

> In shmem_find_get_pages_and_swap, use the faster radix tree iterator
> construct from 78c1d78 "radix-tree: introduce bit-optimized iterator".
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Yes, that looks fine, and is testing out fine, thanks.
Acked-by: Hugh Dickins <hughd@google.com>

> ---
> mm/shmem.c | 25 ++++++++++++-------------
> 1 file changed, 12 insertions(+), 13 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index a368a1c..c5dc8ae 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -336,19 +336,19 @@ static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
> pgoff_t start, unsigned int nr_pages,
> struct page **pages, pgoff_t *indices)
> {
> - unsigned int i;
> - unsigned int ret;
> - unsigned int nr_found;
> + void **slot;
> + unsigned int ret = 0;
> + struct radix_tree_iter iter;
> +
> + if (!nr_pages)
> + return 0;
>
> rcu_read_lock();
> restart:
> - nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
> - (void ***)pages, indices, start, nr_pages);
> - ret = 0;
> - for (i = 0; i < nr_found; i++) {
> + radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
> struct page *page;
> repeat:
> - page = radix_tree_deref_slot((void **)pages[i]);
> + page = radix_tree_deref_slot(slot);
> if (unlikely(!page))
> continue;
> if (radix_tree_exception(page)) {
> @@ -365,17 +365,16 @@ static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
> goto repeat;
>
> /* Has the page moved? */
> - if (unlikely(page != *((void **)pages[i]))) {
> + if (unlikely(page != *slot)) {
> page_cache_release(page);
> goto repeat;
> }
> export:
> - indices[ret] = indices[i];
> + indices[ret] = iter.index;
> pages[ret] = page;
> - ret++;
> + if (++ret == nr_pages)
> + break;
> }
> - if (unlikely(!ret && nr_found))
> - goto restart;
> rcu_read_unlock();
> return ret;
> }
> --
> 1.7.11.7


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