diff mbox

[18/21] fs: nfs: Make nfs boot time y2038 safe

Message ID 1465448705-25055-19-git-send-email-deepa.kernel@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Deepa Dinamani June 9, 2016, 5:05 a.m. UTC
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.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Anna Schumaker <anna.schumaker@netapp.com>
Cc: linux-nfs@vger.kernel.org
---
 fs/nfs/client.c | 2 +-
 fs/nfs/netns.h  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Comments

Trond Myklebust June 9, 2016, 7:23 p.m. UTC | #1
On 6/9/16, 01:05, "Deepa Dinamani" <deepa.kernel@gmail.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
Deepa Dinamani June 9, 2016, 9:10 p.m. UTC | #2
>>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?

timespec64 is the same as timespec already on 64 bit machines.
But, yes, we can use ktime_t here.

Did you mean the internal storage value or the wire boo_time used for verifier?
In case you don't want to change the wire value, then we will have a division
operation, every time the verifier needs to be sent.

-Deepa

-Deepa
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Schumaker, Anna June 10, 2016, 1:12 p.m. UTC | #3
On 06/09/2016 05:10 PM, Deepa Dinamani 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?
> 
> timespec64 is the same as timespec already on 64 bit machines.
> But, yes, we can use ktime_t here.
> 
> Did you mean the internal storage value or the wire boo_time used for verifier?
> In case you don't want to change the wire value, then we will have a division
> operation, every time the verifier needs to be sent.

The verifier is mostly used during mounting, so we don't send too many of them.  I don't think we need to worry about adding an extra division operation here, they're pretty cheap compared to making RPC calls! :)

Anna

> 
> -Deepa
> 
> -Deepa
> 

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Trond Myklebust June 10, 2016, 2:02 p.m. UTC | #4
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diff mbox

Patch

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 0c96528..406972e 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1080,7 +1080,7 @@  void nfs_clients_init(struct net *net)
 	idr_init(&nn->cb_ident_idr);
 #endif
 	spin_lock_init(&nn->nfs_client_lock);
-	nn->boot_time = CURRENT_TIME;
+	ktime_get_real_ts64(&nn->boot_time);
 }
 
 #ifdef CONFIG_PROC_FS
diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h
index f0e06e4..48d6b95 100644
--- a/fs/nfs/netns.h
+++ b/fs/nfs/netns.h
@@ -29,7 +29,7 @@  struct nfs_net {
 	int cb_users[NFS4_MAX_MINOR_VERSION + 1];
 #endif
 	spinlock_t nfs_client_lock;
-	struct timespec boot_time;
+	struct timespec64 boot_time;
 #ifdef CONFIG_PROC_FS
 	struct proc_dir_entry *proc_nfsfs;
 #endif