mm: use folio more widely in __split_huge_page

We already have a folio; use it instead of the head page where reasonable.
Saves a couple of calls to compound_head() and elimimnates a few
references to page->mapping.

Link: https://lkml.kernel.org/r/20240228164326.1355045-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index fd745bcc97ff1dbfc3778d698a560412d2393a70..a81a09236c16171b2c2d18adee0a8c67c4362e1d 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2919,7 +2919,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
                if (head[i].index >= end) {
                        struct folio *tail = page_folio(head + i);
 
-                       if (shmem_mapping(head->mapping))
+                       if (shmem_mapping(folio->mapping))
                                nr_dropped++;
                        else if (folio_test_clear_dirty(tail))
                                folio_account_cleaned(tail,
@@ -2927,7 +2927,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
                        __filemap_remove_folio(tail, NULL);
                        folio_put(tail);
                } else if (!PageAnon(page)) {
-                       __xa_store(&head->mapping->i_pages, head[i].index,
+                       __xa_store(&folio->mapping->i_pages, head[i].index,
                                        head + i, 0);
                } else if (swap_cache) {
                        __xa_store(&swap_cache->i_pages, offset + i,
@@ -2948,23 +2948,23 @@ static void __split_huge_page(struct page *page, struct list_head *list,
        split_page_owner(head, order, new_order);
 
        /* See comment in __split_huge_page_tail() */
-       if (PageAnon(head)) {
+       if (folio_test_anon(folio)) {
                /* Additional pin to swap cache */
-               if (PageSwapCache(head)) {
-                       page_ref_add(head, 1 + new_nr);
+               if (folio_test_swapcache(folio)) {
+                       folio_ref_add(folio, 1 + new_nr);
                        xa_unlock(&swap_cache->i_pages);
                } else {
-                       page_ref_inc(head);
+                       folio_ref_inc(folio);
                }
        } else {
                /* Additional pin to page cache */
-               page_ref_add(head, 1 + new_nr);
-               xa_unlock(&head->mapping->i_pages);
+               folio_ref_add(folio, 1 + new_nr);
+               xa_unlock(&folio->mapping->i_pages);
        }
        local_irq_enable();
 
        if (nr_dropped)
-               shmem_uncharge(head->mapping->host, nr_dropped);
+               shmem_uncharge(folio->mapping->host, nr_dropped);
        remap_page(folio, nr);
 
        if (folio_test_swapcache(folio))
@@ -2980,9 +2980,10 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 
        for (i = 0; i < nr; i += new_nr) {
                struct page *subpage = head + i;
+               struct folio *new_folio = page_folio(subpage);
                if (subpage == page)
                        continue;
-               unlock_page(subpage);
+               folio_unlock(new_folio);
 
                /*
                 * Subpages may be freed if there wasn't any mapping