mm: swap: zswap: maybe_preload & refactoring
zswap_get_swap_cache_page and read_swap_cache_async have pretty much the
same code with only significant difference in return value and usage of
swap_readpage.
I a helper __read_swap_cache_async() with the common code. Behavior
change: now zswap_get_swap_cache_page will use radix_tree_maybe_preload
instead radix_tree_preload. Looks like, this wasn't changed only by the
reason of code duplication.
Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/zswap.c b/mm/zswap.c
index 2d5727b..09208c7 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -446,75 +446,14 @@
static int zswap_get_swap_cache_page(swp_entry_t entry,
struct page **retpage)
{
- struct page *found_page, *new_page = NULL;
- struct address_space *swapper_space = swap_address_space(entry);
- int err;
+ bool page_was_allocated;
- *retpage = NULL;
- do {
- /*
- * First check the swap cache. Since this is normally
- * called after lookup_swap_cache() failed, re-calling
- * that would confuse statistics.
- */
- found_page = find_get_page(swapper_space, entry.val);
- if (found_page)
- break;
-
- /*
- * Get a new page to read into from swap.
- */
- if (!new_page) {
- new_page = alloc_page(GFP_KERNEL);
- if (!new_page)
- break; /* Out of memory */
- }
-
- /*
- * call radix_tree_preload() while we can wait.
- */
- err = radix_tree_preload(GFP_KERNEL);
- if (err)
- break;
-
- /*
- * Swap entry may have been freed since our caller observed it.
- */
- err = swapcache_prepare(entry);
- if (err == -EEXIST) { /* seems racy */
- radix_tree_preload_end();
- continue;
- }
- if (err) { /* swp entry is obsolete ? */
- radix_tree_preload_end();
- break;
- }
-
- /* May fail (-ENOMEM) if radix-tree node allocation failed. */
- __set_page_locked(new_page);
- SetPageSwapBacked(new_page);
- err = __add_to_swap_cache(new_page, entry);
- if (likely(!err)) {
- radix_tree_preload_end();
- lru_cache_add_anon(new_page);
- *retpage = new_page;
- return ZSWAP_SWAPCACHE_NEW;
- }
- radix_tree_preload_end();
- ClearPageSwapBacked(new_page);
- __clear_page_locked(new_page);
- /*
- * add_to_swap_cache() doesn't return -EEXIST, so we can safely
- * clear SWAP_HAS_CACHE flag.
- */
- swapcache_free(entry);
- } while (err != -ENOMEM);
-
- if (new_page)
- page_cache_release(new_page);
- if (!found_page)
+ *retpage = __read_swap_cache_async(entry, GFP_KERNEL,
+ NULL, 0, &page_was_allocated);
+ if (page_was_allocated)
+ return ZSWAP_SWAPCACHE_NEW;
+ if (!*retpage)
return ZSWAP_SWAPCACHE_FAIL;
- *retpage = found_page;
return ZSWAP_SWAPCACHE_EXIST;
}