* master: timeout AllocateVolume/DeleteVolume and defer growRequest cleanup
The volume-grow goroutine clears the layout's growRequest flag only after
ms.DoAutomaticVolumeGrow returns, and AllocateVolume / DeleteVolume were
calling the volume-server RPC with context.Background(). A volume server
that hung mid-call (heavy I/O, stuck lock, dead peer behind a stable VIP)
would park the goroutine forever, leaving growRequest=true and silently
blocking every subsequent automatic grow for that layout — Assign retries
then drained their 30s budget with "context deadline exceeded" until the
operator restarted the master.
Bound both RPCs with a 5-minute deadline (creating/removing a volume is
sub-second normally, generous for contended disks) and move the flag
clear + filter delete into defers so a panic in DoAutomaticVolumeGrow
doesn't strand the layout either.
* allocate_volume: shorten timeout to 1m for faster recovery
Volume create/delete is sub-second under normal conditions; 1 minute is
generous even on a contended disk and clears the growRequest flag well
before too many client Assigns drain their own retry budget.
* trim comments
29eec2f111