wic/filemap: Fall back to standard copy when no way to get the block map

For some filesystems, such as aufs which may be used by docker container,
don't support either the SEEK_DATA/HOLE or FIEMAP to get the block
map. So add a FileNobmap class to fall back to standard copy when there
is no way to get the block map.

[Yocto #12988]

Signed-off-by: Kevin Hao <kexin.hao@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 27 insertions, 1 deletions

diff --git a/scripts/lib/wic/filemap.py b/scripts/lib/wic/filemap.py
index f8c6e09d017..4d9da281720 100644
--- a/scripts/lib/wic/filemap.py
+++ b/scripts/lib/wic/filemap.py
@@ -469,6 +469,29 @@ class FilemapFiemap(_FilemapBase):
                         % (first_prev, last_prev))
         yield (first_prev, last_prev)
 
+class FilemapNobmap(_FilemapBase):
+    """
+    This class is used when both the 'SEEK_DATA/HOLE' and FIEMAP are not
+    supported by the filesystem or kernel.
+    """
+
+    def __init__(self, image, log=None):
+        """Refer the '_FilemapBase' class for the documentation."""
+
+        # Call the base class constructor first
+        _FilemapBase.__init__(self, image, log)
+        self._log.debug("FilemapNobmap: initializing")
+
+    def block_is_mapped(self, block):
+        """Refer the '_FilemapBase' class for the documentation."""
+        return True
+
+    def get_mapped_ranges(self, start, count):
+        """Refer the '_FilemapBase' class for the documentation."""
+        self._log.debug("FilemapNobmap: get_mapped_ranges(%d,  %d(%d))"
+                        % (start, count, start + count - 1))
+        yield (start, start + count -1)
+
 def filemap(image, log=None):
     """
     Create and return an instance of a Filemap class - 'FilemapFiemap' or
@@ -482,7 +505,10 @@ def filemap(image, log=None):
     try:
         return FilemapFiemap(image, log)
     except ErrorNotSupp:
-        return FilemapSeek(image, log)
+        try:
+            return FilemapSeek(image, log)
+        except ErrorNotSupp:
+            return FilemapNobmap(image, log)
 
 def sparse_copy(src_fname, dst_fname, skip=0, seek=0,
                 length=0, api=None):