1 files changed, 47 insertions, 5 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 3e457a16c7d1..2ababb89918d 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -781,6 +781,33 @@ out:
 	return ret;
 }
 
+static int __dax_clear_dirty_range(struct address_space *mapping,
+		pgoff_t start, pgoff_t end)
+{
+	XA_STATE(xas, &mapping->i_pages, start);
+	unsigned int scanned = 0;
+	void *entry;
+
+	xas_lock_irq(&xas);
+	xas_for_each(&xas, entry, end) {
+		entry = get_unlocked_entry(&xas, 0);
+		xas_clear_mark(&xas, PAGECACHE_TAG_DIRTY);
+		xas_clear_mark(&xas, PAGECACHE_TAG_TOWRITE);
+		put_unlocked_entry(&xas, entry, WAKE_NEXT);
+
+		if (++scanned % XA_CHECK_SCHED)
+			continue;
+
+		xas_pause(&xas);
+		xas_unlock_irq(&xas);
+		cond_resched();
+		xas_lock_irq(&xas);
+	}
+	xas_unlock_irq(&xas);
+
+	return 0;
+}
+
 /*
  * Delete DAX entry at @index from @mapping.  Wait for it
  * to be unlocked before deleting it.
@@ -1258,15 +1285,20 @@ static s64 dax_unshare_iter(struct iomap_iter *iter)
 	/* don't bother with blocks that are not shared to start with */
 	if (!(iomap->flags & IOMAP_F_SHARED))
 		return length;
-	/* don't bother with holes or unwritten extents */
-	if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
-		return length;
 
 	id = dax_read_lock();
 	ret = dax_iomap_direct_access(iomap, pos, length, &daddr, NULL);
 	if (ret < 0)
 		goto out_unlock;
 
+	/* zero the distance if srcmap is HOLE or UNWRITTEN */
+	if (srcmap->flags & IOMAP_F_SHARED || srcmap->type == IOMAP_UNWRITTEN) {
+		memset(daddr, 0, length);
+		dax_flush(iomap->dax_dev, daddr, length);
+		ret = length;
+		goto out_unlock;
+	}
+
 	ret = dax_iomap_direct_access(srcmap, pos, length, &saddr, NULL);
 	if (ret < 0)
 		goto out_unlock;
@@ -1435,6 +1467,16 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
 	 * written by write(2) is visible in mmap.
 	 */
 	if (iomap->flags & IOMAP_F_NEW || cow) {
+		/*
+		 * Filesystem allows CoW on non-shared extents. The src extents
+		 * may have been mmapped with dirty mark before. To be able to
+		 * invalidate its dax entries, we need to clear the dirty mark
+		 * in advance.
+		 */
+		if (cow)
+			__dax_clear_dirty_range(iomi->inode->i_mapping,
+						pos >> PAGE_SHIFT,
+						(end - 1) >> PAGE_SHIFT);
 		invalidate_inode_pages2_range(iomi->inode->i_mapping,
 					      pos >> PAGE_SHIFT,
 					      (end - 1) >> PAGE_SHIFT);
@@ -2022,8 +2064,8 @@ int dax_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
 
 	while ((ret = iomap_iter(&src_iter, ops)) > 0 &&
 	       (ret = iomap_iter(&dst_iter, ops)) > 0) {
-		compared = dax_range_compare_iter(&src_iter, &dst_iter, len,
-						  same);
+		compared = dax_range_compare_iter(&src_iter, &dst_iter,
+				min(src_iter.len, dst_iter.len), same);
 		if (compared < 0)
 			return ret;
 		src_iter.processed = dst_iter.processed = compared;