make_ext4fs: fix dentry padding when dentry size is 4088 or 4092

When the total dentry size is N * 4096 - 4 or N * 4096 - 8, there is
not enough room in the block to insert an extra padding dentry.
Instead, switch to always padding the previous dentry out to the end
of the block, which matches what the kernel does when creating new
directory entries.

Also fix dentry_size to return the size of all the dentries
without the padding, the len + 8 padding is incorrect, and the
DIV_ROUND_UP will round up to the correct number of blocks.

Change-Id: If11f90e4ee172c135a0eae2a50b8be213e2dd0dc

1 files changed, 2 insertions, 10 deletions

diff --git a/ext4_utils/contents.c b/ext4_utils/contents.c
index 8d20eb2f..63006808 100644
--- a/ext4_utils/contents.c
+++ b/ext4_utils/contents.c
@@ -44,11 +44,6 @@ static u32 dentry_size(u32 entries, struct dentry *dentries)
 		len += dentry_len;
 	}
 
-	/* include size of the dentry used to pad until the end of the block */
-	if (len % info.block_size + 8 > info.block_size)
-		len += info.block_size - (len % info.block_size);
-	len += 8;
-
 	return len;
 }
 
@@ -160,11 +155,8 @@ u32 make_directory(u32 dir_inode_num, u32 entries, struct dentry *dentries,
 		}
 	}
 
-	dentry = (struct ext4_dir_entry_2 *)(data + offset);
-	dentry->inode = 0;
-	dentry->rec_len = len - offset;
-	dentry->name_len = 0;
-	dentry->file_type = EXT4_FT_UNKNOWN;
+	/* pad the last dentry out to the end of the block */
+	dentry->rec_len += len - offset;
 
 	return inode_num;
 }