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

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? ;)