fs: Add support for resizing FAT filesystem

blivet/formats/fs.py

@@ -1012,10 +1012,14 @@ class FATFS(FS):
     _uuidfs = fsuuid.FATFSUUID()
     _supported = True
     _formattable = True
+    _resizable = True
+    _resize_support = FSResize.OFFLINE_GROW | FSResize.OFFLINE_SHRINK
     _max_size = Size("1 TiB")
     _packages = ["dosfstools"]
     _fsck_class = fsck.DosFSCK
     _info_class = fsinfo.FATFSInfo
+    _minsize_class = fsminsize.FATFSMinSize
+    _resize_class = fsresize.FATFSResize
     _size_info_class = fssize.FATFSSize
     _mkfs_class = fsmkfs.FATFSMkfs
     _mount_class = fsmount.FATFSMount

blivet/tasks/availability.py

@@ -553,6 +553,7 @@ class FSOperation():
 BLOCKDEV_EXT_RESIZE = blockdev_fs_plugin_operation(BlockDevFSMethod(FSOperation.RESIZE, blockdev.fs.can_resize, "ext2"))
 BLOCKDEV_XFS_RESIZE = blockdev_fs_plugin_operation(BlockDevFSMethod(FSOperation.RESIZE, blockdev.fs.can_resize, "xfs"))
 BLOCKDEV_NTFS_RESIZE = blockdev_fs_plugin_operation(BlockDevFSMethod(FSOperation.RESIZE, blockdev.fs.can_resize, "ntfs"))
+BLOCKDEV_VFAT_RESIZE = blockdev_fs_plugin_operation(BlockDevFSMethod(FSOperation.RESIZE, blockdev.fs.can_resize, "vfat"))
 
 BLOCKDEV_EXT_INFO = blockdev_fs_plugin_operation(BlockDevFSMethod(FSOperation.INFO, blockdev.fs.can_get_size, "ext2"))
 BLOCKDEV_XFS_INFO = blockdev_fs_plugin_operation(BlockDevFSMethod(FSOperation.INFO, blockdev.fs.can_get_size, "xfs"))

blivet/tasks/fsminsize.py

@@ -80,5 +80,23 @@ def do_task(self):  # pylint: disable=arguments-differ
         return min_size
 
 
+class FATFSMinSize(FSMinSize):
+    ext = availability.BLOCKDEV_VFAT_INFO
+
+    def do_task(self):  # pylint: disable=arguments-differ
+        error_msgs = self.availability_errors
+        if error_msgs:
+            raise FSError("\n".join(error_msgs))
+
+        try:
+            info = BlockDev.fs.vfat_get_info(self.fs.device)
+        except BlockDev.FSError as e:
+            raise FSError("failed to get fs min size: %s" % e)
+        min_size = Size((info.free_cluster_count - info.free_cluster_count) * info.cluster_size)
+        # resizing below 32 MiB would require changing from VFAT/FAT32 to FAT16 which is not
+        # currently supported by libparted which libblockdev uses for FAT resize
+        return max(min_size, Size("32 MiB"))
+
+
 class UnimplementedFSMinSize(fstask.UnimplementedFSTask):
     pass

blivet/tasks/fsresize.py

@@ -47,6 +47,10 @@ class FSResize(task.BasicApplication, FSResizeTask):
 
     # IMPLEMENTATION methods
 
+    @property
+    def fs_type(self):
+        return self.fs.type
+
     def do_task(self):  # pylint: disable=arguments-differ
         """ Resize the device.
 
@@ -57,7 +61,7 @@ def do_task(self):  # pylint: disable=arguments-differ
             raise FSError("\n".join(error_msgs))
 
         try:
-            BlockDev.fs.resize(self.fs.device, self.fs.target_size.convert_to(B), self.fs.type)
+            BlockDev.fs.resize(self.fs.device, self.fs.target_size.convert_to(B), self.fs_type)
         except BlockDev.FSError as e:
             raise FSError(str(e))
 
@@ -77,6 +81,16 @@ class XFSResize(FSResize):
     unit = B
 
 
+class FATFSResize(FSResize):
+    ext = availability.BLOCKDEV_VFAT_RESIZE
+    unit = B
+
+    @property
+    def fs_type(self):
+        # we don't want 'efi' to be used for EFIFS
+        return "vfat"
+
+
 class TmpFSResize(FSResize):
     ext = availability.BLOCKDEV_FS_PLUGIN
     unit = MiB

tests/storage_tests/formats_test/fstesting.py

@@ -278,7 +278,7 @@ def test_shrink(self):
         an_fs.target_size = TARGET_SIZE
         self.assertIsNone(an_fs.do_resize())
 
-        TARGET_SIZE = TARGET_SIZE / 2
+        TARGET_SIZE = TARGET_SIZE - Size("10 MiB")
         self.assertTrue(TARGET_SIZE > an_fs.min_size)
         an_fs.target_size = TARGET_SIZE
         self.assertEqual(an_fs.target_size, TARGET_SIZE)