1 files changed, 22 insertions, 16 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 1c6867810cbd..84fadea08705 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -334,35 +334,41 @@ static unsigned long dax_end_pfn(void *entry)
 	for (pfn = dax_to_pfn(entry); \
 			pfn < dax_end_pfn(entry); pfn++)
 
-static inline bool dax_mapping_is_cow(struct address_space *mapping)
+static inline bool dax_page_is_shared(struct page *page)
 {
-	return (unsigned long)mapping == PAGE_MAPPING_DAX_COW;
+	return page->mapping == PAGE_MAPPING_DAX_SHARED;
 }
 
 /*
- * Set the page->mapping with FS_DAX_MAPPING_COW flag, increase the refcount.
+ * Set the page->mapping with PAGE_MAPPING_DAX_SHARED flag, increase the
+ * refcount.
  */
-static inline void dax_mapping_set_cow(struct page *page)
+static inline void dax_page_share_get(struct page *page)
 {
-	if ((uintptr_t)page->mapping != PAGE_MAPPING_DAX_COW) {
+	if (page->mapping != PAGE_MAPPING_DAX_SHARED) {
 		/*
 		 * Reset the index if the page was already mapped
 		 * regularly before.
 		 */
 		if (page->mapping)
-			page->index = 1;
-		page->mapping = (void *)PAGE_MAPPING_DAX_COW;
+			page->share = 1;
+		page->mapping = PAGE_MAPPING_DAX_SHARED;
 	}
-	page->index++;
+	page->share++;
+}
+
+static inline unsigned long dax_page_share_put(struct page *page)
+{
+	return --page->share;
 }
 
 /*
- * When it is called in dax_insert_entry(), the cow flag will indicate that
+ * When it is called in dax_insert_entry(), the shared flag will indicate that
  * whether this entry is shared by multiple files.  If so, set the page->mapping
- * FS_DAX_MAPPING_COW, and use page->index as refcount.
+ * PAGE_MAPPING_DAX_SHARED, and use page->share as refcount.
  */
 static void dax_associate_entry(void *entry, struct address_space *mapping,
-		struct vm_area_struct *vma, unsigned long address, bool cow)
+		struct vm_area_struct *vma, unsigned long address, bool shared)
 {
 	unsigned long size = dax_entry_size(entry), pfn, index;
 	int i = 0;
@@ -374,8 +380,8 @@ static void dax_associate_entry(void *entry, struct address_space *mapping,
 	for_each_mapped_pfn(entry, pfn) {
 		struct page *page = pfn_to_page(pfn);
 
-		if (cow) {
-			dax_mapping_set_cow(page);
+		if (shared) {
+			dax_page_share_get(page);
 		} else {
 			WARN_ON_ONCE(page->mapping);
 			page->mapping = mapping;
@@ -396,9 +402,9 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping,
 		struct page *page = pfn_to_page(pfn);
 
 		WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
-		if (dax_mapping_is_cow(page->mapping)) {
-			/* keep the CoW flag if this page is still shared */
-			if (page->index-- > 0)
+		if (dax_page_is_shared(page)) {
+			/* keep the shared flag if this page is still shared */
+			if (dax_page_share_put(page) > 0)
 				continue;
 		} else
 			WARN_ON_ONCE(page->mapping && page->mapping != mapping);