mm: filemap: use xa_get_order() to get the swap entry order

In the following patches, shmem will support the swap out of large folios,
which means the shmem mappings may contain large order swap entries, so
using xa_get_order() to get the folio order of the shmem swap entry to
update the '*start' correctly.

Link: https://lkml.kernel.org/r/6876d55145c1cc80e79df7884aa3a62e397b101d.1723434324.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index fcfec2a78a309df56f8cf18a21f14c713c5d240d..5985382adb6adb5fe00a3ff337eb2722ca04a860 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2055,6 +2055,8 @@ unsigned find_get_entries(struct address_space *mapping, pgoff_t *start,
                folio = fbatch->folios[idx];
                if (!xa_is_value(folio))
                        nr = folio_nr_pages(folio);
+               else
+                       nr = 1 << xa_get_order(&mapping->i_pages, indices[idx]);
                *start = indices[idx] + nr;
        }
        return folio_batch_count(fbatch);
@@ -2119,6 +2121,8 @@ put:
                folio = fbatch->folios[idx];
                if (!xa_is_value(folio))
                        nr = folio_nr_pages(folio);
+               else
+                       nr = 1 << xa_get_order(&mapping->i_pages, indices[idx]);
                *start = indices[idx] + nr;
        }
        return folio_batch_count(fbatch);