From: Daniel Gomez <da.gomez@xxxxxxxxxxx>
Add large folio support for shmem write and fallocate paths matching the
same high order preference mechanism used in the iomap buffered IO path
as used in __filemap_get_folio().
Add shmem_mapping_size_order() to get a hint for the order of the folio
based on the file size which takes care of the mapping requirements.
If the top level huge page (controlled by '/sys/kernel/mm/transparent_hugepage/shmem_enabled')
is enabled, we just allow PMD sized THP to keep interface backward
compatibility.
Co-developed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Gomez <da.gomez@xxxxxxxxxxx>
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
mm/shmem.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 48 insertions(+), 3 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 0613421e09e7..6dece90ff421 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1672,6 +1672,36 @@ bool shmem_hpage_pmd_enabled(void)
return false;
}
+/**
+ * shmem_mapping_size_order - Get maximum folio order for the given file size.
+ * @mapping: Target address_space.
+ * @index: The page index.
+ * @size: The suggested size of the folio to create.
+ *
+ * This returns a high order for folios (when supported) based on the file size
+ * which the mapping currently allows at the given index. The index is relevant
+ * due to alignment considerations the mapping might have. The returned order
+ * may be less than the size passed.
+ *
+ * Like __filemap_get_folio order calculation.
+ *
+ * Return: The order.
+ */
+static inline unsigned int
+shmem_mapping_size_order(struct address_space *mapping, pgoff_t index, size_t size)
+{
+ unsigned int order = get_order(max_t(size_t, size, PAGE_SIZE));
+
+ if (!mapping_large_folio_support(mapping))
+ return 0;
+
+ /* If we're not aligned, allocate a smaller folio */
+ if (index & ((1UL << order) - 1))
+ order = __ffs(index);
+
+ return min_t(size_t, order, MAX_PAGECACHE_ORDER);
+}
+
unsigned long shmem_allowable_huge_orders(struct inode *inode,
struct vm_area_struct *vma, pgoff_t index,
loff_t write_end, bool shmem_huge_force)
@@ -1694,11 +1724,26 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode,
global_huge = shmem_huge_global_enabled(inode, index, write_end,
shmem_huge_force, vma, vm_flags);
if (!vma || !vma_is_anon_shmem(vma)) {
+ size_t len;
+
+ /*
+ * For tmpfs, if top level huge page is enabled, we just allow
+ * PMD sized THP to keep interface backward compatibility.
+ */
+ if (global_huge)
+ return BIT(HPAGE_PMD_ORDER);
+
+ if (!write_end)
+ return 0;
+
/*
- * For tmpfs, we now only support PMD sized THP if huge page
- * is enabled, otherwise fallback to order 0.
+ * Otherwise, get a highest order hint based on the size of
+ * write and fallocate paths, then will try each allowable
+ * huge orders.
*/
- return global_huge ? BIT(HPAGE_PMD_ORDER) : 0;
+ len = write_end - (index << PAGE_SHIFT);
+ order = shmem_mapping_size_order(inode->i_mapping, index, len);
+ return order > 0 ? BIT(order + 1) - 1 : 0;
}
/*
--
2.39.3
