linux-kernel - Re: [PATCH 18/21] fs: nfs: Make nfs boot time y2038 safe

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Message-ID: <89EF59F9-52D2-4F37-A7A8-52BD0FF7E98E@primarydata.com>
Date:	Thu, 9 Jun 2016 19:23:49 +0000
From:	Trond Myklebust <trondmy@...marydata.com>
To:	Deepa Dinamani <deepa.kernel@...il.com>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	Arnd Bergmann <arnd@...db.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Al Viro" <viro@...iv.linux.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"y2038@...ts.linaro.org" <y2038@...ts.linaro.org>,
	Anna Schumaker <anna.schumaker@...app.com>,
	"linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>
Subject: Re: [PATCH 18/21] fs: nfs: Make nfs boot time y2038 safe



On 6/9/16, 01:05, "Deepa Dinamani" <deepa.kernel@...il.com> wrote:

>boot_time is represented as a struct timespec.
>struct timespec and CURRENT_TIME are not y2038 safe.
>Overall, the plan is to use timespec64 for all internal
>kernel representation of timestamps.
>CURRENT_TIME will also be removed.
>Use struct timespec64 to represent boot_time.
>And, ktime_get_real_ts64() for the boot_time value.
>
>boot_time is used to construct the nfs client boot verifier.
>This will now wrap in 2106 instead of 2038 on 32-bit systems.
>The server only relies on the value being persistent until
>reboot so the wrapping should be fine.

We really do not give a damn about wraparound here, since the boot time is only ever compared for an exact match, and the odds of two reboots occurring exactly 2^32 * 10^9 nanoseconds apart are cosmically small...

If struct timespec is going away, can we just convert this into a ktime_t?

Trond