swap file number

Hi,

I noticed this line in storeSwapOutStart function:
    e->swap_file_number = storeDirMapAllocate();

This means every time we have a new swapoutable copy of a StoreEntry,
it will be swapped out to a different swap file. And I guess the old
swap file of this StoreEntry will be removed by the disk space
maintenance routine. Is that right?

I can imagine that this can avoid some race condition for simultaneous
client requests, but wanna check with Squid vets here to make sure.
Thanks.

-- 
Chengdu