1 files changed, 32 insertions, 3 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index c543d965e288..676b02fae589 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1565,6 +1565,36 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
 }
 #endif
 
+/**
+ * generic_copy_file_range - copy data between two files
+ * @file_in:	file structure to read from
+ * @pos_in:	file offset to read from
+ * @file_out:	file structure to write data to
+ * @pos_out:	file offset to write data to
+ * @len:	amount of data to copy
+ * @flags:	copy flags
+ *
+ * This is a generic filesystem helper to copy data from one file to another.
+ * It has no constraints on the source or destination file owners - the files
+ * can belong to different superblocks and different filesystem types. Short
+ * copies are allowed.
+ *
+ * This should be called from the @file_out filesystem, as per the
+ * ->copy_file_range() method.
+ *
+ * Returns the number of bytes copied or a negative error indicating the
+ * failure.
+ */
+
+ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				size_t len, unsigned int flags)
+{
+	return do_splice_direct(file_in, &pos_in, file_out, &pos_out,
+				len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
+}
+EXPORT_SYMBOL(generic_copy_file_range);
+
 /*
  * copy_file_range() differs from regular file read and write in that it
  * specifically allows return partial success.  When it does so is up to
@@ -1632,9 +1662,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 			goto done;
 	}
 
-	ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
-			len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
-
+	ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
+				      flags);
 done:
 	if (ret > 0) {
 		fsnotify_access(file_in);