mm/swap: reduce indentation level

Patch series "mm/swap: remove boilerplate".

This patch (of 5):

Use folio_activate() as an example:

Before this series
------------------
    if (!folio_test_active(folio) && !folio_test_unevictable(folio)) {
      struct folio_batch *fbatch;

      folio_get(folio);
      if (!folio_test_clear_lru(folio)) {
        folio_put(folio);
        return;
      }

      local_lock(&cpu_fbatches.lock);
      fbatch = this_cpu_ptr(&cpu_fbatches.activate);
      folio_batch_add_and_move(fbatch, folio, folio_activate_fn);
      local_unlock(&cpu_fbatches.lock);
    }
  }

After this series
-----------------
  void folio_activate(struct folio *folio)
  {
    if (folio_test_active(folio) || folio_test_unevictable(folio))
      return;

    folio_batch_add_and_move(folio, lru_activate, true);
  }

And this is applied to all 6 folio_batch handlers in mm/swap.c.

bloat-o-meter
-------------
  add/remove: 12/13 grow/shrink: 3/2 up/down: 4653/-4721 (-68)
  ...
  Total: Before=28083019, After=28082951, chg -0.00%

This patch (of 5):

Reduce indentation level by returning directly when there is no cleanup
needed, i.e.,

  if (condition) {    |    if (condition) {
    do_this();        |      do_this();
    return;           |      return;
  } else {            |    }
    do_that();        |
  }                   |    do_that();

and

  if (condition) {    |    if (!condition)
    do_this();        |      return;
    do_that();        |
  }                   |    do_this();
  return;             |    do_that();

Presumably the old style became repetitive as the result of copy and
paste.

Link: https://lkml.kernel.org/r/20240711021317.596178-1-yuzhao@google.com
Link: https://lkml.kernel.org/r/20240711021317.596178-2-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/swap.c b/mm/swap.c
index 9caf6b017cf0abc281e107580b8d9f771a2af29e..952e4aac6eb16c83afa652508c754a22f974ca3d 100644 (file)
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -117,7 +117,9 @@ void __folio_put(struct folio *folio)
        if (unlikely(folio_is_zone_device(folio))) {
                free_zone_device_folio(folio);
                return;
-       } else if (folio_test_hugetlb(folio)) {
+       }
+
+       if (folio_test_hugetlb(folio)) {
                free_huge_folio(folio);
                return;
        }
@@ -228,17 +230,19 @@ static void folio_batch_add_and_move(struct folio_batch *fbatch,
        if (folio_batch_add(fbatch, folio) && !folio_test_large(folio) &&
            !lru_cache_disabled())
                return;
+
        folio_batch_move_lru(fbatch, move_fn);
 }
 
 static void lru_move_tail_fn(struct lruvec *lruvec, struct folio *folio)
 {
-       if (!folio_test_unevictable(folio)) {
-               lruvec_del_folio(lruvec, folio);
-               folio_clear_active(folio);
-               lruvec_add_folio_tail(lruvec, folio);
-               __count_vm_events(PGROTATED, folio_nr_pages(folio));
-       }
+       if (folio_test_unevictable(folio))
+               return;
+
+       lruvec_del_folio(lruvec, folio);
+       folio_clear_active(folio);
+       lruvec_add_folio_tail(lruvec, folio);
+       __count_vm_events(PGROTATED, folio_nr_pages(folio));
 }
 
 /*
@@ -250,22 +254,23 @@ static void lru_move_tail_fn(struct lruvec *lruvec, struct folio *folio)
  */
 void folio_rotate_reclaimable(struct folio *folio)
 {
-       if (!folio_test_locked(folio) && !folio_test_dirty(folio) &&
-           !folio_test_unevictable(folio)) {
-               struct folio_batch *fbatch;
-               unsigned long flags;
+       struct folio_batch *fbatch;
+       unsigned long flags;
 
-               folio_get(folio);
-               if (!folio_test_clear_lru(folio)) {
-                       folio_put(folio);
-                       return;
-               }
+       if (folio_test_locked(folio) || folio_test_dirty(folio) ||
+           folio_test_unevictable(folio))
+               return;
 
-               local_lock_irqsave(&lru_rotate.lock, flags);
-               fbatch = this_cpu_ptr(&lru_rotate.fbatch);
-               folio_batch_add_and_move(fbatch, folio, lru_move_tail_fn);
-               local_unlock_irqrestore(&lru_rotate.lock, flags);
+       folio_get(folio);
+       if (!folio_test_clear_lru(folio)) {
+               folio_put(folio);
+               return;
        }
+
+       local_lock_irqsave(&lru_rotate.lock, flags);
+       fbatch = this_cpu_ptr(&lru_rotate.fbatch);
+       folio_batch_add_and_move(fbatch, folio, lru_move_tail_fn);
+       local_unlock_irqrestore(&lru_rotate.lock, flags);
 }
 
 void lru_note_cost(struct lruvec *lruvec, bool file,
@@ -328,18 +333,19 @@ void lru_note_cost_refault(struct folio *folio)
 
 static void folio_activate_fn(struct lruvec *lruvec, struct folio *folio)
 {
-       if (!folio_test_active(folio) && !folio_test_unevictable(folio)) {
-               long nr_pages = folio_nr_pages(folio);
+       long nr_pages = folio_nr_pages(folio);
 
-               lruvec_del_folio(lruvec, folio);
-               folio_set_active(folio);
-               lruvec_add_folio(lruvec, folio);
-               trace_mm_lru_activate(folio);
+       if (folio_test_active(folio) || folio_test_unevictable(folio))
+               return;
 
-               __count_vm_events(PGACTIVATE, nr_pages);
-               __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE,
-                                    nr_pages);
-       }
+
+       lruvec_del_folio(lruvec, folio);
+       folio_set_active(folio);
+       lruvec_add_folio(lruvec, folio);
+       trace_mm_lru_activate(folio);
+
+       __count_vm_events(PGACTIVATE, nr_pages);
+       __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE, nr_pages);
 }
 
 #ifdef CONFIG_SMP
@@ -353,20 +359,21 @@ static void folio_activate_drain(int cpu)
 
 void folio_activate(struct folio *folio)
 {
-       if (!folio_test_active(folio) && !folio_test_unevictable(folio)) {
-               struct folio_batch *fbatch;
+       struct folio_batch *fbatch;
 
-               folio_get(folio);
-               if (!folio_test_clear_lru(folio)) {
-                       folio_put(folio);
-                       return;
-               }
+       if (folio_test_active(folio) || folio_test_unevictable(folio))
+               return;
 
-               local_lock(&cpu_fbatches.lock);
-               fbatch = this_cpu_ptr(&cpu_fbatches.activate);
-               folio_batch_add_and_move(fbatch, folio, folio_activate_fn);
-               local_unlock(&cpu_fbatches.lock);
+       folio_get(folio);
+       if (!folio_test_clear_lru(folio)) {
+               folio_put(folio);
+               return;
        }
+
+       local_lock(&cpu_fbatches.lock);
+       fbatch = this_cpu_ptr(&cpu_fbatches.activate);
+       folio_batch_add_and_move(fbatch, folio, folio_activate_fn);
+       local_unlock(&cpu_fbatches.lock);
 }
 
 #else
@@ -378,12 +385,13 @@ void folio_activate(struct folio *folio)
 {
        struct lruvec *lruvec;
 
-       if (folio_test_clear_lru(folio)) {
-               lruvec = folio_lruvec_lock_irq(folio);
-               folio_activate_fn(lruvec, folio);
-               unlock_page_lruvec_irq(lruvec);
-               folio_set_lru(folio);
-       }
+       if (!folio_test_clear_lru(folio))
+               return;
+
+       lruvec = folio_lruvec_lock_irq(folio);
+       folio_activate_fn(lruvec, folio);
+       unlock_page_lruvec_irq(lruvec);
+       folio_set_lru(folio);
 }
 #endif
 
@@ -610,41 +618,41 @@ static void lru_deactivate_file_fn(struct lruvec *lruvec, struct folio *folio)
 
 static void lru_deactivate_fn(struct lruvec *lruvec, struct folio *folio)
 {
-       if (!folio_test_unevictable(folio) && (folio_test_active(folio) || lru_gen_enabled())) {
-               long nr_pages = folio_nr_pages(folio);
+       long nr_pages = folio_nr_pages(folio);
 
-               lruvec_del_folio(lruvec, folio);
-               folio_clear_active(folio);
-               folio_clear_referenced(folio);
-               lruvec_add_folio(lruvec, folio);
+       if (folio_test_unevictable(folio) || !(folio_test_active(folio) || lru_gen_enabled()))
+               return;
 
-               __count_vm_events(PGDEACTIVATE, nr_pages);
-               __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
-                                    nr_pages);
-       }
+       lruvec_del_folio(lruvec, folio);
+       folio_clear_active(folio);
+       folio_clear_referenced(folio);
+       lruvec_add_folio(lruvec, folio);
+
+       __count_vm_events(PGDEACTIVATE, nr_pages);
+       __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_pages);
 }
 
 static void lru_lazyfree_fn(struct lruvec *lruvec, struct folio *folio)
 {
-       if (folio_test_anon(folio) && folio_test_swapbacked(folio) &&
-           !folio_test_swapcache(folio) && !folio_test_unevictable(folio)) {
-               long nr_pages = folio_nr_pages(folio);
+       long nr_pages = folio_nr_pages(folio);
 
-               lruvec_del_folio(lruvec, folio);
-               folio_clear_active(folio);
-               folio_clear_referenced(folio);
-               /*
-                * Lazyfree folios are clean anonymous folios.  They have
-                * the swapbacked flag cleared, to distinguish them from normal
-                * anonymous folios
-                */
-               folio_clear_swapbacked(folio);
-               lruvec_add_folio(lruvec, folio);
+       if (!folio_test_anon(folio) || !folio_test_swapbacked(folio) ||
+           folio_test_swapcache(folio) || folio_test_unevictable(folio))
+               return;
 
-               __count_vm_events(PGLAZYFREE, nr_pages);
-               __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE,
-                                    nr_pages);
-       }
+       lruvec_del_folio(lruvec, folio);
+       folio_clear_active(folio);
+       folio_clear_referenced(folio);
+       /*
+        * Lazyfree folios are clean anonymous folios.  They have
+        * the swapbacked flag cleared, to distinguish them from normal
+        * anonymous folios
+        */
+       folio_clear_swapbacked(folio);
+       lruvec_add_folio(lruvec, folio);
+
+       __count_vm_events(PGLAZYFREE, nr_pages);
+       __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE, nr_pages);
 }
 
 /*
@@ -726,21 +734,21 @@ void deactivate_file_folio(struct folio *folio)
  */
 void folio_deactivate(struct folio *folio)
 {
-       if (!folio_test_unevictable(folio) && (folio_test_active(folio) ||
-           lru_gen_enabled())) {
-               struct folio_batch *fbatch;
-
-               folio_get(folio);
-               if (!folio_test_clear_lru(folio)) {
-                       folio_put(folio);
-                       return;
-               }
+       struct folio_batch *fbatch;
+
+       if (folio_test_unevictable(folio) || !(folio_test_active(folio) || lru_gen_enabled()))
+               return;
 
-               local_lock(&cpu_fbatches.lock);
-               fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate);
-               folio_batch_add_and_move(fbatch, folio, lru_deactivate_fn);
-               local_unlock(&cpu_fbatches.lock);
+       folio_get(folio);
+       if (!folio_test_clear_lru(folio)) {
+               folio_put(folio);
+               return;
        }
+
+       local_lock(&cpu_fbatches.lock);
+       fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate);
+       folio_batch_add_and_move(fbatch, folio, lru_deactivate_fn);
+       local_unlock(&cpu_fbatches.lock);
 }
 
 /**
@@ -752,21 +760,22 @@ void folio_deactivate(struct folio *folio)
  */
 void folio_mark_lazyfree(struct folio *folio)
 {
-       if (folio_test_anon(folio) && folio_test_swapbacked(folio) &&
-           !folio_test_swapcache(folio) && !folio_test_unevictable(folio)) {
-               struct folio_batch *fbatch;
-
-               folio_get(folio);
-               if (!folio_test_clear_lru(folio)) {
-                       folio_put(folio);
-                       return;
-               }
+       struct folio_batch *fbatch;
 
-               local_lock(&cpu_fbatches.lock);
-               fbatch = this_cpu_ptr(&cpu_fbatches.lru_lazyfree);
-               folio_batch_add_and_move(fbatch, folio, lru_lazyfree_fn);
-               local_unlock(&cpu_fbatches.lock);
+       if (!folio_test_anon(folio) || !folio_test_swapbacked(folio) ||
+           folio_test_swapcache(folio) || folio_test_unevictable(folio))
+               return;
+
+       folio_get(folio);
+       if (!folio_test_clear_lru(folio)) {
+               folio_put(folio);
+               return;
        }
+
+       local_lock(&cpu_fbatches.lock);
+       fbatch = this_cpu_ptr(&cpu_fbatches.lru_lazyfree);
+       folio_batch_add_and_move(fbatch, folio, lru_lazyfree_fn);
+       local_unlock(&cpu_fbatches.lock);
 }
 
 void lru_add_drain(void)