[PATCH v2 04/33] 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.

Also update the VMA userland tests to reflect the change.

No functional change intended.

Reviewed-by: Gregory Price <gourry@xxxxxxxxxx>
Reviewed-by: Pedro Falcato <pfalcato@xxxxxxx>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>
Signed-off-by: Lorenzo Stoakes <ljs@xxxxxxxxxx>
---
 include/linux/mm.h              | 19 ++++++++++++++++++-
 tools/testing/vma/include/dup.h |  5 +++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index abac72785277..c56ca22d406c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4331,6 +4331,23 @@ 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.
@@ -4344,7 +4361,7 @@ 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)
diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h
index 668650067c7c..535747d7fee4 100644
--- a/tools/testing/vma/include/dup.h
+++ b/tools/testing/vma/include/dup.h
@@ -1306,6 +1306,11 @@ static inline pgoff_t vma_start_pgoff(const struct vm_area_struct *vma)
 	return vma->vm_pgoff;
 }
 
+static inline pgoff_t vma_end_pgoff(const struct vm_area_struct *vma)
+{
+	return vma_start_pgoff(vma) + vma_pages(vma);
+}
+
 static inline int vfs_mmap_prepare(struct file *file, struct vm_area_desc *desc)
 {
 	return file->f_op->mmap_prepare(desc);

-- 
2.55.0