[PATCH 04/30] mm: introduce and use vma_end_pgoff()

[Lorenzo Stoakes]

We already have vma_last_pgoff() which retrieves the last page offset
within a VMA.

However, code often wishes to span a page offset range, which requires the
exclusive end of this range.

So provide this in vma_end_pgoff() and update vma_last_pgoff() to use this
function.

No functional change intended.

Signed-off-by: Lorenzo Stoakes <ljs@xxxxxxxxxx>
---
 include/linux/mm.h | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2f00c75e66bd..e7ee315d5ba2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4298,6 +4298,23 @@ static inline pgoff_t vma_start_pgoff(const struct vm_area_struct *vma)
 	return vma->vm_pgoff;
 }
 
+/**
+ * vma_end_pgoff() - Get the page offset of the exclusive end of @vma
+ * @vma: The VMA whose end page offset is required.
+ *
+ * This returns the exclusive end page offset of @vma, which is useful for
+ * expressing page offset ranges.
+ *
+ * See the description of vma_start_pgoff() for a description of VMA page
+ * offsets.
+ *
+ * Returns: The exclusive end page offset of @vma.
+ */
+static inline pgoff_t vma_end_pgoff(const struct vm_area_struct *vma)
+{
+	return vma_start_pgoff(vma) + vma_pages(vma);
+}
+
 /**
  * vma_last_pgoff() - Get the page offset of the last page in @vma
  * @vma: The VMA whose last page offset is required.
@@ -4311,7 +4328,7 @@ static inline pgoff_t vma_start_pgoff(const struct vm_area_struct *vma)
  */
 static inline pgoff_t vma_last_pgoff(const struct vm_area_struct *vma)
 {
-	return vma_start_pgoff(vma) + vma_pages(vma) - 1;
+	return vma_end_pgoff(vma) - 1;
 }
 
 static inline unsigned long vma_desc_size(const struct vm_area_desc *desc)
-- 
2.54.0