[PATCH 5/6] mm: shmem: factor out the within_size logic into a new helper

[Baolin Wang]

Factor out the within_size logic into a new helper to remove duplicate
code.

Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
 mm/shmem.c | 53 +++++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index c243d814f2b0..671f63063fd4 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -590,6 +590,28 @@ shmem_mapping_size_orders(struct address_space *mapping, pgoff_t index, loff_t w
 	return order > 0 ? BIT(order + 1) - 1 : 0;
 }
 
+static unsigned int shmem_get_orders_within_size(struct inode *inode,
+		unsigned long within_size_orders, pgoff_t index,
+		loff_t write_end)
+{
+	pgoff_t aligned_index;
+	unsigned long order;
+	loff_t i_size;
+
+	order = highest_order(within_size_orders);
+	while (within_size_orders) {
+		aligned_index = round_up(index + 1, 1 << order);
+		i_size = max(write_end, i_size_read(inode));
+		i_size = round_up(i_size, PAGE_SIZE);
+		if (i_size >> PAGE_SHIFT >= aligned_index)
+			return within_size_orders;
+
+		order = next_order(&within_size_orders, order);
+	}
+
+	return 0;
+}
+
 static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
 					      loff_t write_end, bool shmem_huge_force,
 					      struct vm_area_struct *vma,
@@ -598,9 +620,6 @@ static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index
 	unsigned int maybe_pmd_order = HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER ?
 		0 : BIT(HPAGE_PMD_ORDER);
 	unsigned long within_size_orders;
-	unsigned int order;
-	pgoff_t aligned_index;
-	loff_t i_size;
 
 	if (!S_ISREG(inode->i_mode))
 		return 0;
@@ -634,16 +653,11 @@ static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index
 			within_size_orders = shmem_mapping_size_orders(inode->i_mapping,
 								       index, write_end);
 
-		order = highest_order(within_size_orders);
-		while (within_size_orders) {
-			aligned_index = round_up(index + 1, 1 << order);
-			i_size = max(write_end, i_size_read(inode));
-			i_size = round_up(i_size, PAGE_SIZE);
-			if (i_size >> PAGE_SHIFT >= aligned_index)
-				return within_size_orders;
+		within_size_orders = shmem_get_orders_within_size(inode, within_size_orders,
+								  index, write_end);
+		if (within_size_orders > 0)
+			return within_size_orders;
 
-			order = next_order(&within_size_orders, order);
-		}
 		fallthrough;
 	case SHMEM_HUGE_ADVISE:
 		if (vm_flags & VM_HUGEPAGE)
@@ -1756,10 +1770,7 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode,
 	unsigned long mask = READ_ONCE(huge_shmem_orders_always);
 	unsigned long within_size_orders = READ_ONCE(huge_shmem_orders_within_size);
 	unsigned long vm_flags = vma ? vma->vm_flags : 0;
-	pgoff_t aligned_index;
 	unsigned int global_orders;
-	loff_t i_size;
-	int order;
 
 	if (thp_disabled_by_hw() || (vma && vma_thp_disabled(vma, vm_flags)))
 		return 0;
@@ -1785,17 +1796,7 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode,
 		return READ_ONCE(huge_shmem_orders_inherit);
 
 	/* Allow mTHP that will be fully within i_size. */
-	order = highest_order(within_size_orders);
-	while (within_size_orders) {
-		aligned_index = round_up(index + 1, 1 << order);
-		i_size = round_up(i_size_read(inode), PAGE_SIZE);
-		if (i_size >> PAGE_SHIFT >= aligned_index) {
-			mask |= within_size_orders;
-			break;
-		}
-
-		order = next_order(&within_size_orders, order);
-	}
+	mask |= shmem_get_orders_within_size(inode, within_size_orders, index, 0);
 
 	if (vm_flags & VM_HUGEPAGE)
 		mask |= READ_ONCE(huge_shmem_orders_madvise);
-- 
2.39.3