Re: [RFC][PATCH 2/3][cr][v2]: Checkpoint/restart file leases

[Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>]

Oren Laadan [orenl@cs.columbia.edu] wrote:
| 
| 
| >  		h->fl_type = lock->fl_type;
| > +		h->fl_type_prev = lock->fl_type_prev;
| >  		h->fl_flags = lock->fl_flags;
| > +		if (h->fl_type & F_INPROGRESS && 
| > +					(lock->fl_break_time > jiffies))
| > +			h->fl_rem_lease = (lock->fl_break_time - jiffies) / HZ;
| 
| Hmmm -- we have a ctx->ktime_begin marking the start of the checkpoint.
| It is used for relative-time calculations, for example, the expiry of
| restart-blocks and timeouts.  I suggest that we use it here too to be
| consistent.

Well, I started off using ktime_begin but discussed this with John Stultz
(CC'd here) who pointed out that mixing different domains of time is likely
to cause errors. ktime is an absolute time and fl_break_time uses jiffies -
a relative time. 

I think use of ktime_begin for restart_blocks is fine (since they use
ktime_t) but using ktime_t for file leases and converting between jiffies
and nanoseconds could be a problem, unless we convert fl_break_time to
seconds.

IOW, can we leave the above computation of ->fl_rem_lease for now ?

Sukadev