Re: [PATCH v4 1/6] fs: enhance and rename shutdown() callback to remove_bdev()

[Christoph Hellwig <hch@infradead.org>]

On Tue, Jul 08, 2025 at 09:55:14AM +0200, Christian Brauner wrote:
> I think letting filesystems implement their own holder ops should be
> avoided if we can. Christoph may chime in here.

Ccing helps for that..

>
> I have no appettite for
> exporting stuff like get_bdev_super() unless absolutely necessary. We
> tried to move all that handling into the VFS to eliminate a slew of
> deadlocks we detected and fixed. I have no appetite to repeat that
> cycle.

Exactly.

> The shutdown method is implemented only by block-based filesystems and
> arguably shutdown was always a misnomer because it assumed that the
> filesystem needs to actually shut down when it is called. IOW, we made
> it so that it is a call to action but that doesn't have to be the case.
> Calling it ->remove_bdev() is imo the correct thing because it gives
> block based filesystem the ability to handle device events how they see
> fit.
> 
> Once we will have non-block based filesystems that need a method to
> always shut down the filesystem itself we might have to revisit this
> design anyway but no one had that use-case yet.

I'm not sure what non-block file systems would need it for except
maybe for a generic IOC_SHUTDOWN implementation, but that would have
a different signature anyway as it needs to pass flags that don't
fit here.  So that would be a separate method.