Use as_any to downcast inodes for updating in ext4

[arihant2math]

Solves the problem of input inodes not being updated by ext4 functions with as_any. Since inodes on the same filesystem are equivalent we can guarantee that the downcast will not fail (if it does, the cross device error will be caught first)

I'll probably do the same to FileOps later.

[hexagonal-sun]

Is there a way we could provide a default implementation for this so all the trait implementations don't have to provide a boilerplate impl?

[arihant2math]

For weird trait-bounding reasons that fails to compile. I could make it a proc macro, but that feels a little redundant.

[hexagonal-sun]

I'm a bit unsure exactly what this is trying to solve. Could you expand further?

[arihant2math]

I'm a bit unsure exactly what this is trying to solve. Could you expand further?

I'm trying to mutate the inputs to various inode methods.

For example: link takes inode: Arc<dyn Inode> as a parameter, however I can't modify it without downcasting. I would prefer to keep it up to date because there probably would possible data loss if nlinks is out of date and the inode is accidentally deleted.

[hexagonal-sun]

LGTM