Function write_primary_superblock() has two ways to flush
superblock, byte-by-byte as default. It may use
io_channel_write_byte() many times. If some errors occur
during these funcs, the superblock may become inconsistent
and produce checksum error.

Try write_primary_superblock() with whole-block way again
when it failed on byte-by-byte way.
---
 lib/ext2fs/closefs.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/lib/ext2fs/closefs.c b/lib/ext2fs/closefs.c
index 69cbdd8c..1fc27fb5 100644
--- a/lib/ext2fs/closefs.c
+++ b/lib/ext2fs/closefs.c

@@ -223,10 +223,8 @@ static errcode_t write_primary_superblock(ext2_filsys fs,
 		retval = io_channel_write_byte(fs->io,
 			       SUPERBLOCK_OFFSET + (2 * write_idx), size,
 					       new_super + write_idx);
-		if (retval == EXT2_ET_UNIMPLEMENTED)
-			goto fallback;
 		if (retval)
-			return retval;
+			goto fallback;
 	}
 	memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
 	return 0;