On Thu, Feb 4, 2016 at 9:30 AM, Arnd Bergmann arnd@arndb.de wrote:
On Thursday 04 February 2016 10:00:19 Yan, Zheng wrote:
On Feb 4, 2016, at 05:27, Arnd Bergmann arnd@arndb.de wrote:
{ struct ceph_timespec ts; ceph_encode_timespec(&ts, &req->r_stamp); ceph_encode_copy(&p, &ts, sizeof(ts)); }
Ok, that does make the behavior consistent on all architectures, but leads to a different question:
struct ceph_timespec { __le32 tv_sec; __le32 tv_nsec; } __attribute__ ((packed));
How do you define ceph_timespec, is tv_sec supposed to be signed or unsigned?
It seems that you treat it as signed, meaning you interpret times from the server as being in the [1902..2038] range, rather than the [1970..2106] range:
static inline void ceph_decode_timespec(struct timespec *ts, const struct ceph_timespec *tv) { ts->tv_sec = (__kernel_time_t)le32_to_cpu(tv->tv_sec); ts->tv_nsec = (long)le32_to_cpu(tv->tv_nsec); }
Is that intentional and documented? If yes, what is your plan to deal with y2038 support?
tv_sec is used as a time_t, so signed. The problem is that ceph_timespec is not only passed over the wire, but is also stored on disk, part of quite a few other data structures. The plan is to eventually switch to a 64-bit tv_sec and tv_nsec, bump the version on all the structures that contain it and add a cluster-wide feature bit to deal with older clients. We've recently had a discussion about this, so it may even happen in a not so distant future, but no promises ;)
Thanks,
Ilya