On Thu, 2024-02-08 at 08:40 +1100, Dave Chinner wrote: > i_size_write()? Thanks, I will post a v2. > > And why doesn't debugfs_create_file_unsafe() do this already when it > attaches the blob to the inode? Because it doesn't know the size any more. The 'blob' in debugfs_create_blob() is this: struct debugfs_blob_wrapper { void *data; unsigned long size; }; When it passes the blob to debugfs_create_file_unsafe(), that's passed as "void *data", and so debugfs_create_file_unsafe() doesn't know that it's a 'blob' any more.