[PATCH v10 6/9] mm: move pgoff_address() to vma_pgoff_address()

[Shiyang Ruan]

Since it is not a DAX-specific function, move it into mm and rename it
to be a generic helper.

Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/dax.c           | 12 +-----------
 include/linux/mm.h | 13 +++++++++++++
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 964512107c23..250794a5b789 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -834,16 +834,6 @@ static void *dax_insert_entry(struct xa_state *xas,
 	return entry;
 }
 
-static inline
-unsigned long pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
-{
-	unsigned long address;
-
-	address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
-	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
-	return address;
-}
-
 /* Walk all mappings of a given index of a file and writeprotect them */
 static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index,
 		unsigned long pfn)
@@ -863,7 +853,7 @@ static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index,
 		if (!(vma->vm_flags & VM_SHARED))
 			continue;
 
-		address = pgoff_address(index, vma);
+		address = vma_pgoff_address(vma, index);
 
 		/*
 		 * follow_invalidate_pte() will use the range to call
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e1a84b1e6787..9b1d56c5c224 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2816,6 +2816,19 @@ static inline unsigned long vma_pages(struct vm_area_struct *vma)
 	return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 }
 
+/*
+ * Get user virtual address at the specific offset within a vma.
+ */
+static inline unsigned long vma_pgoff_address(struct vm_area_struct *vma,
+					      pgoff_t pgoff)
+{
+	unsigned long address;
+
+	address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
+	return address;
+}
+
 /* Look up the first VMA which exactly match the interval vm_start ... vm_end */
 static inline struct vm_area_struct *find_exact_vma(struct mm_struct *mm,
 				unsigned long vm_start, unsigned long vm_end)
-- 
2.34.1