If the WL pool runs out of PEBs we schedule a fastmap write
to refill it as soon as possible.
Ensure that only one at a time is scheduled otherwise we might end in
a fastmap write storm because writing the fastmap can schedule another
write if bitflips are detected.
Signed-off-by: NRichard Weinberger <richard@nod.at>
Reviewed-by: NTanya Brokhman <tlinder@codeaurora.org>
Reviewed-by: NGuido Martínez <guido@vanguardiasur.com.ar>