migrate: convert unmap_and_move_huge_page() to use folios

Saves several calls to compound_head() and removes a couple of uses of
page->lru.

Link: https://lkml.kernel.org/r/20220902194653.1739778-52-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/migrate.c

@@ -1263,7 +1263,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	if (!hugepage_migration_supported(page_hstate(hpage)))
 		return -ENOSYS;
 
-	if (page_count(hpage) == 1) {
+	if (folio_ref_count(src) == 1) {
 		/* page was freed from under us. So we are done. */
 		putback_active_hugepage(hpage);
 		return MIGRATEPAGE_SUCCESS;
@@ -1274,7 +1274,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 		return -ENOMEM;
 	dst = page_folio(new_hpage);
 
-	if (!trylock_page(hpage)) {
+	if (!folio_trylock(src)) {
 		if (!force)
 			goto out;
 		switch (mode) {
@@ -1284,29 +1284,29 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 		default:
 			goto out;
 		}
-		lock_page(hpage);
+		folio_lock(src);
 	}
 
 	/*
 	 * Check for pages which are in the process of being freed.  Without
-	 * page_mapping() set, hugetlbfs specific move page routine will not
+	 * folio_mapping() set, hugetlbfs specific move page routine will not
 	 * be called and we could leak usage counts for subpools.
 	 */
-	if (hugetlb_page_subpool(hpage) && !page_mapping(hpage)) {
+	if (hugetlb_page_subpool(hpage) && !folio_mapping(src)) {
 		rc = -EBUSY;
 		goto out_unlock;
 	}
 
-	if (PageAnon(hpage))
-		anon_vma = page_get_anon_vma(hpage);
+	if (folio_test_anon(src))
+		anon_vma = page_get_anon_vma(&src->page);
 
-	if (unlikely(!trylock_page(new_hpage)))
+	if (unlikely(!folio_trylock(dst)))
 		goto put_anon;
 
-	if (page_mapped(hpage)) {
+	if (folio_mapped(src)) {
 		enum ttu_flags ttu = 0;
 
-		if (!PageAnon(hpage)) {
+		if (!folio_test_anon(src)) {
 			/*
 			 * In shared mappings, try_to_unmap could potentially
 			 * call huge_pmd_unshare.  Because of this, take
@@ -1327,7 +1327,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 			i_mmap_unlock_write(mapping);
 	}
 
-	if (!page_mapped(hpage))
+	if (!folio_mapped(src))
 		rc = move_to_new_folio(dst, src, mode);
 
 	if (page_was_mapped)
@@ -1335,7 +1335,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 			rc == MIGRATEPAGE_SUCCESS ? dst : src, false);
 
 unlock_put_anon:
-	unlock_page(new_hpage);
+	folio_unlock(dst);
 
 put_anon:
 	if (anon_vma)
@@ -1347,12 +1347,12 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	}
 
 out_unlock:
-	unlock_page(hpage);
+	folio_unlock(src);
 out:
 	if (rc == MIGRATEPAGE_SUCCESS)
 		putback_active_hugepage(hpage);
 	else if (rc != -EAGAIN)
-		list_move_tail(&hpage->lru, ret);
+		list_move_tail(&src->lru, ret);
 
 	/*
 	 * If migration was not successful and there's a freeing callback, use