From: Daniel Borkmann [ 

On 02/25/2015 04:41 PM, David Laight wrote:
...

quoted

Why not cache the 'number of items before we need to expand' value
after each expansion, setting it to 'infinite' when expansion is disabled.
Then the above check is a simple comparison.
You probably don't even need an atomic_read() - provided something is
double checked once the first test determines that an expansion is needed.

Did you read my cover letter? ;)

I probably didn't infer the relevant references :-)

Actually even if some code wanted other rules, provided they
are based on comparing the 'number of items' to a preset limit
the limit could be set during expansion/contraction.

	David