Re: [PATCH 3/8] watch_queue: Support a text field at the end of the notification

David Howells
2020-12-08T12:58:39Z

Gabriel Krisman Bertazi <krisman@collabora.com> wrote:

> This allow notifications to send text information to userspace without
> having to copy it to a temporary buffer to then copy to the ring. One
> use case to pass text information in notifications is for error
> reporting, where more debug information might be needed, but we don't
> want to explode the number of subtypes of notifications. For instance,
> ext4 can have a single inode error notification subtype, and pass more
> information on the cause of the error in this field.

I'm generally okay with this, but you really need to note that if you make use
of this for a subtype, you don't get to add more fields for that subtype
unless there's an offset to it.

Speaking of that, you need to update:

Documentation/watch_queue.rst

since you're changing the API.

The "Watch Sources" section will also need altering to indicate that
superblock events are now a thing.

David