mm: migrate: split folio_migrate_mapping()

The folio refcount check is moved out for both !mapping and mapping folio,
also update comment from page to folio for folio_migrate_mapping().

No functional change intended.

Link: https://lkml.kernel.org/r/20240626085328.608006-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 9a1c5b4a3f9958fa40dbbd524146e4fabc17dd8b..13b03226924227356d5e92b6e07fda6409fd0c5d 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -393,28 +393,23 @@ static int folio_expected_refs(struct address_space *mapping,
 }
 
 /*
- * Replace the page in the mapping.
+ * Replace the folio in the mapping.
  *
  * The number of remaining references must be:
- * 1 for anonymous pages without a mapping
- * 2 for pages with a mapping
- * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
+ * 1 for anonymous folios without a mapping
+ * 2 for folios with a mapping
+ * 3 for folios with a mapping and PagePrivate/PagePrivate2 set.
  */
-int folio_migrate_mapping(struct address_space *mapping,
-               struct folio *newfolio, struct folio *folio, int extra_count)
+static int __folio_migrate_mapping(struct address_space *mapping,
+               struct folio *newfolio, struct folio *folio, int expected_count)
 {
        XA_STATE(xas, &mapping->i_pages, folio_index(folio));
        struct zone *oldzone, *newzone;
        int dirty;
-       int expected_count = folio_expected_refs(mapping, folio) + extra_count;
        long nr = folio_nr_pages(folio);
        long entries, i;
 
        if (!mapping) {
-               /* Anonymous page without mapping */
-               if (folio_ref_count(folio) != expected_count)
-                       return -EAGAIN;
-
                /* Take off deferred split queue while frozen and memcg set */
                if (folio_test_large(folio) &&
                    folio_test_large_rmappable(folio)) {
@@ -465,7 +460,7 @@ int folio_migrate_mapping(struct address_space *mapping,
                entries = 1;
        }
 
-       /* Move dirty while page refs frozen and newpage not yet exposed */
+       /* Move dirty while folio refs frozen and newfolio not yet exposed */
        dirty = folio_test_dirty(folio);
        if (dirty) {
                folio_clear_dirty(folio);
@@ -479,7 +474,7 @@ int folio_migrate_mapping(struct address_space *mapping,
        }
 
        /*
-        * Drop cache reference from old page by unfreezing
+        * Drop cache reference from old folio by unfreezing
         * to one less reference.
         * We know this isn't the last reference.
         */
@@ -490,11 +485,11 @@ int folio_migrate_mapping(struct address_space *mapping,
 
        /*
         * If moved to a different zone then also account
-        * the page for that zone. Other VM counters will be
+        * the folio for that zone. Other VM counters will be
         * taken care of when we establish references to the
-        * new page and drop references to the old page.
+        * new folio and drop references to the old folio.
         *
-        * Note that anonymous pages are accounted for
+        * Note that anonymous folios are accounted for
         * via NR_FILE_PAGES and NR_ANON_MAPPED if they
         * are mapped to swap space.
         */
@@ -534,6 +529,17 @@ int folio_migrate_mapping(struct address_space *mapping,
 
        return MIGRATEPAGE_SUCCESS;
 }
+
+int folio_migrate_mapping(struct address_space *mapping,
+               struct folio *newfolio, struct folio *folio, int extra_count)
+{
+       int expected_count = folio_expected_refs(mapping, folio) + extra_count;
+
+       if (folio_ref_count(folio) != expected_count)
+               return -EAGAIN;
+
+       return __folio_migrate_mapping(mapping, newfolio, folio, expected_count);
+}
 EXPORT_SYMBOL(folio_migrate_mapping);
 
 /*