diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 1b1b6ff855aa..4f4b13830b25 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3243,6 +3243,7 @@ static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
 static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
 				   struct inode *dst, u64 dst_loff)
 {
+	const u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
 	int ret;
 
 	/*
@@ -3250,7 +3251,7 @@ static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
 	 * source range to serialize with relocation.
 	 */
 	btrfs_double_extent_lock(src, loff, dst, dst_loff, len);
-	ret = btrfs_clone(src, dst, loff, len, len, dst_loff, 1);
+	ret = btrfs_clone(src, dst, loff, len, ALIGN(len, bs), dst_loff, 1);
 	btrfs_double_extent_unlock(src, loff, dst, dst_loff, len);
 
 	return ret;
diff --git a/fs/read_write.c b/fs/read_write.c
index 5bbf587f5bc1..7458fccc59e1 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1777,10 +1777,9 @@ static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
  * else.  Assume that the offsets have already been checked for block
  * alignment.
  *
- * For deduplication we always scale down to the previous block because we
- * can't meaningfully compare post-EOF contents.
- *
- * For clone we only link a partial EOF block above the destination file's EOF.
+ * For clone we only link a partial EOF block above or at the destination file's
+ * EOF.  For deduplication we accept a partial EOF block only if it ends at the
+ * destination file's EOF (can not link it into the middle of a file).
  *
  * Shorten the request if possible.
  */
@@ -1796,8 +1795,7 @@ static int generic_remap_check_len(struct inode *inode_in,
 	if ((*len & blkmask) == 0)
 		return 0;
 
-	if ((remap_flags & REMAP_FILE_DEDUP) ||
-	    pos_out + *len < i_size_read(inode_out))
+	if (pos_out + *len < i_size_read(inode_out))
 		new_len &= ~blkmask;
 
 	if (new_len == *len)