Re: [PATCH 06/18] fsinfo: Add a uniquifier ID to struct mount [ver #21]

[Miklos Szeredi]

On Wed, Aug 5, 2020 at 4:14 PM David Howells <dhowells@xxxxxxxxxx> wrote:

> However, looking up that identifier requires some sort of structure for doing
> this and it's kind of worst case for the IDR tree as the keys are gradually
> going to spread out, causing it to eat more memory.  It may be a tradeoff
> worth making, and the memory consumption might not be that bad - or we could
> use some other data structure such as an rbtree.

idr_alloc_cyclic() seems to be a good template for doing the lower
32bit allocation, and we can add code to increment the high 32bit on
wraparound.

Lots of code uses idr_alloc_cyclic() so I guess it shouldn't be too
bad in terms of memory use or performance.

Thanks,
Miklos