From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
__filemap_get_folio() with FGP_CREAT should allocate at least folio of
filemap's min_order set using folio_set_mapping_orders().
A higher order folio than min_order by definition is a multiple of the
min_order. If an index is aligned to an order higher than a min_order, it
will also be aligned to the min order.
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
---
mm/filemap.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 8962d1255905..b1ce63143df5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1862,6 +1862,10 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
fgf_t fgp_flags, gfp_t gfp)
{
struct folio *folio;
+ int min_order = mapping_min_folio_order(mapping);
+ int nr_of_pages = (1U << min_order);
+
+ index = round_down(index, nr_of_pages);
repeat:
folio = filemap_get_entry(mapping, index);
@@ -1929,8 +1933,14 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
err = -ENOMEM;
if (order == 1)
order = 0;
+ if (order < min_order)
+ order = min_order;
if (order > 0)
alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
+
+ if (min_order)
+ VM_BUG_ON(index & ((1UL << order) - 1));
+
folio = filemap_alloc_folio(alloc_gfp, order);
if (!folio)
continue;
@@ -1944,7 +1954,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
break;
folio_put(folio);
folio = NULL;
- } while (order-- > 0);
+ } while (order-- > min_order);
if (err == -EEXIST)
goto repeat;
--
2.40.1
