Re: [PATCH 0/3 V3] libxfs: better cache allocation error handling

[Christoph Hellwig <hch@infradead.org>]

On Fri, Sep 25, 2026 at 02:41:42PM -0500, Eric Sandeen wrote:
> OK, 3rd try.
> 
> This is to handle an underlying problem that an actual ENOMEM cache
> node allocation failure is indistinguishable from "current cache full"
> and so ENOMEM may send us into a pointless cache-expansion loop which
> ultimately overflows the cache size variable, rather than just reporting
> the bad news up the chain to callers.
> 
> Darrick suggested "I think I'd almost rather we change cache_node_allocate
> to return int and the cache node as an outparam since we do that elsewhere"
> 
> on the last review cycle, and so I've done that here, I agree that it
> is cleaner.

Sorry for chiming in so late, but wouldn't it make more sense to keep
returning the node, and have a bool for what to if it is NULL?
The 0/1/-errno pattern already requires a lot of attention in the kernel,
but in userland where we have errno and -1 returns that are usually not
specifically checked it feels like even more trouble waiting to happen.

That being said, the changes themselves do look correct, so this should
not be a strong objection.