On Dec 13, 2019, at 11:40 AM, Arnd Bergmann arnd@arndb.de wrote:
On Fri, Dec 13, 2019 at 5:26 PM Chuck Lever chuck.lever@oracle.com wrote:
On Dec 13, 2019, at 9:10 AM, Arnd Bergmann arnd@arndb.de wrote:
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index 24534db87e86..508d7c6c00b5 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -823,7 +823,12 @@ static const struct rpc_program cb_program = { static int max_cb_time(struct net *net) { struct nfsd_net *nn = net_generic(net, nfsd_net_id);
return max(nn->nfsd4_lease/10, (time_t)1) * HZ;
/* nfsd4_lease is set to at most one hour */if (WARN_ON_ONCE(nn->nfsd4_lease > 3600))return 360 * HZ;Why is the WARN_ON_ONCE added here? Is it really necessary?
This is to ensure the kernel doesn't change to a larger limit that requires a 64-bit division on a 32-bit architecture.
With the old code, dividing by 10 was always fast as nn->nfsd4_lease was the size of an integer register. Now it is 64 bit wide, and I check that truncating it to 32 bit again is safe.
OK. That comment should state this reason rather than just repeating what the code does. ;-)
(Otherwise these all LGTM).
Thanks for taking a look.
Arnd
-- Chuck Lever