memcg: convert mem_cgroup_swap_full() to take a folio

All callers now have a folio, so convert the function to take a folio. 
Saves a couple of calls to compound_head().

Link: https://lkml.kernel.org/r/20220902194653.1739778-48-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/swap.h

@@ -692,7 +692,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_p
 }
 
 extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
-extern bool mem_cgroup_swap_full(struct page *page);
+extern bool mem_cgroup_swap_full(struct folio *folio);
 #else
 static inline void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
 {
@@ -714,7 +714,7 @@ static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 	return get_nr_swap_pages();
 }
 
-static inline bool mem_cgroup_swap_full(struct page *page)
+static inline bool mem_cgroup_swap_full(struct folio *folio)
 {
 	return vm_swap_full();
 }

mm/memcontrol.c

@@ -7406,18 +7406,18 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 	return nr_swap_pages;
 }
 
-bool mem_cgroup_swap_full(struct page *page)
+bool mem_cgroup_swap_full(struct folio *folio)
 {
 	struct mem_cgroup *memcg;
 
-	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
 
 	if (vm_swap_full())
 		return true;
 	if (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
 		return false;
 
-	memcg = page_memcg(page);
+	memcg = folio_memcg(folio);
 	if (!memcg)
 		return false;
 

mm/memory.c

@@ -3647,7 +3647,7 @@ static inline bool should_try_to_free_swap(struct folio *folio,
 {
 	if (!folio_test_swapcache(folio))
 		return false;
-	if (mem_cgroup_swap_full(&folio->page) || (vma->vm_flags & VM_LOCKED) ||
+	if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) ||
 	    folio_test_mlocked(folio))
 		return true;
 	/*

mm/swapfile.c

@@ -148,7 +148,7 @@ static int __try_to_reclaim_swap(struct swap_info_struct *si,
 	if (folio_trylock(folio)) {
 		if ((flags & TTRS_ANYWAY) ||
 		    ((flags & TTRS_UNMAPPED) && !folio_mapped(folio)) ||
-		    ((flags & TTRS_FULL) && mem_cgroup_swap_full(&folio->page)))
+		    ((flags & TTRS_FULL) && mem_cgroup_swap_full(folio)))
 			ret = folio_free_swap(folio);
 		folio_unlock(folio);
 	}

mm/vmscan.c

@@ -2047,8 +2047,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
 activate_locked:
 		/* Not a candidate for swapping, so reclaim swap space. */
 		if (folio_test_swapcache(folio) &&
-		    (mem_cgroup_swap_full(&folio->page) ||
-		     folio_test_mlocked(folio)))
+		    (mem_cgroup_swap_full(folio) || folio_test_mlocked(folio)))
 			folio_free_swap(folio);
 		VM_BUG_ON_FOLIO(folio_test_active(folio), folio);
 		if (!folio_test_mlocked(folio)) {