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page cache: Convert find_get_pages_range to XArray

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The 'end' parameter of the xas_for_each iterator avoids a useless
iteration at the end of the range.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2018-05-16 17:38:56 -04:00
parent f280bf092d
commit fd1b3cee2a
1 changed files with 19 additions and 33 deletions
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52
mm/filemap.c
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@ -1650,64 +1650,50 @@ unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
pgoff_t end, unsigned int nr_pages,
struct page **pages)
{
struct radix_tree_iter iter;
void **slot;
XA_STATE(xas, &mapping->i_pages, *start);
struct page *page;
unsigned ret = 0;
if (unlikely(!nr_pages))
return 0;
rcu_read_lock();
radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, *start) {
struct page *head, *page;
if (iter.index > end)
break;
repeat:
page = radix_tree_deref_slot(slot);
if (unlikely(!page))
xas_for_each(&xas, page, end) {
struct page *head;
if (xas_retry(&xas, page))
continue;
if (radix_tree_exception(page)) {
if (radix_tree_deref_retry(page)) {
slot = radix_tree_iter_retry(&iter);
/* Skip over shadow, swap and DAX entries */
if (xa_is_value(page))
continue;
}
/*
* A shadow entry of a recently evicted page,
* or a swap entry from shmem/tmpfs. Skip
* over it.
*/
continue;
}
head = compound_head(page);
if (!page_cache_get_speculative(head))
goto repeat;
goto retry;
/* The page was split under us? */
if (compound_head(page) != head) {
put_page(head);
goto repeat;
}
if (compound_head(page) != head)
goto put_page;
/* Has the page moved? */
if (unlikely(page != *slot)) {
put_page(head);
goto repeat;
}
if (unlikely(page != xas_reload(&xas)))
goto put_page;
pages[ret] = page;
if (++ret == nr_pages) {
*start = pages[ret - 1]->index + 1;
*start = page->index + 1;
goto out;
}
continue;
put_page:
put_page(head);
retry:
xas_reset(&xas);
}
/*
* We come here when there is no page beyond @end. We take care to not
* overflow the index @start as it confuses some of the callers. This
* breaks the iteration when there is page at index -1 but that is
* breaks the iteration when there is a page at index -1 but that is
* already broken anyway.
*/
if (end == (pgoff_t)-1)