mm/swap: convert __read_swap_cache_async() to use a folio

Remove a few hidden (and one visible) calls to compound_head().

Link: https://lkml.kernel.org/r/20220902194653.1739778-12-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/swap_state.c b/mm/swap_state.c
index 41afa6d..b1e181f 100644 (file)
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -411,7 +411,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
                        bool *new_page_allocated)
 {
        struct swap_info_struct *si;
-       struct page *page;
+       struct folio *folio;
        void *shadow = NULL;
 
        *new_page_allocated = false;
@@ -426,11 +426,11 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
                si = get_swap_device(entry);
                if (!si)
                        return NULL;
-               page = find_get_page(swap_address_space(entry),
-                                    swp_offset(entry));
+               folio = filemap_get_folio(swap_address_space(entry),
+                                               swp_offset(entry));
                put_swap_device(si);
-               if (page)
-                       return page;
+               if (folio)
+                       return folio_file_page(folio, swp_offset(entry));
 
                /*
                 * Just skip read ahead for unused swap slot.
@@ -448,8 +448,8 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
                 * before marking swap_map SWAP_HAS_CACHE, when -EEXIST will
                 * cause any racers to loop around until we add it to cache.
                 */
-               page = alloc_page_vma(gfp_mask, vma, addr);
-               if (!page)
+               folio = vma_alloc_folio(gfp_mask, 0, vma, addr, false);
+               if (!folio)
                        return NULL;
 
                /*
@@ -459,7 +459,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
                if (!err)
                        break;
 
-               put_page(page);
+               folio_put(folio);
                if (err != -EEXIST)
                        return NULL;
 
@@ -477,30 +477,30 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
         * The swap entry is ours to swap in. Prepare the new page.
         */
 
-       __SetPageLocked(page);
-       __SetPageSwapBacked(page);
+       __folio_set_locked(folio);
+       __folio_set_swapbacked(folio);
 
-       if (mem_cgroup_swapin_charge_page(page, NULL, gfp_mask, entry))
+       if (mem_cgroup_swapin_charge_page(&folio->page, NULL, gfp_mask, entry))
                goto fail_unlock;
 
        /* May fail (-ENOMEM) if XArray node allocation failed. */
-       if (add_to_swap_cache(page, entry, gfp_mask & GFP_RECLAIM_MASK, &shadow))
+       if (add_to_swap_cache(&folio->page, entry, gfp_mask & GFP_RECLAIM_MASK, &shadow))
                goto fail_unlock;
 
        mem_cgroup_swapin_uncharge_swap(entry);
 
        if (shadow)
-               workingset_refault(page_folio(page), shadow);
+               workingset_refault(folio, shadow);
 
-       /* Caller will initiate read into locked page */
-       lru_cache_add(page);
+       /* Caller will initiate read into locked folio */
+       folio_add_lru(folio);
        *new_page_allocated = true;
-       return page;
+       return &folio->page;
 
 fail_unlock:
-       put_swap_page(page, entry);
-       unlock_page(page);
-       put_page(page);
+       put_swap_page(&folio->page, entry);
+       folio_unlock(folio);
+       folio_put(folio);
        return NULL;
 }