On 01/05/2010 02:23 PM, Chuck Lever wrote:
>>
>> Author: Steve Dickson <steved@xxxxxxxxxx>
>> Date: Tue Jan 5 13:29:07 2010 -0500
>>
>> showmount: Try the highest mount version then fall back to lower ones
>>
>> Showmount should try the highest mount version first then fall
>> back to the lower ones when the server returns a RPC_PROGVERSMISMATCH
>> error. The idea being not using the lower mount versions will begin
>> the process of moving away from NFSv2 support.
>>
>> Signed-off-by: Steve Dickson <steved@xxxxxxxxxx>
>>
>> diff --git a/utils/showmount/showmount.c b/utils/showmount/showmount.c
>> index 418e8b9..17224a6 100644
>> --- a/utils/showmount/showmount.c
>> +++ b/utils/showmount/showmount.c
>> @@ -85,22 +85,29 @@ static const char *nfs_sm_pgmtbl[] = {
>> NULL,
>> };
>>
>> +static const int mount_vers[] = {
>
> RPC version numbers are rpcvers_t, not int.
True..
>
> The array above this one is called "nfs_sm_pgmtbl"... to be consistent
> with existing code you should name this one "nfs_sm_verstbl".
>
>> + MOUNTVERS_NFSV3,
>> + MOUNTVERS_POSIX,
>> + MOUNTVERS,
>> +};
>> +static const int max_vers = (sizeof(mount_vers)/sizeof(mount_vers[0]));
>
> Array indices are unsigned.
Sure...
>
> Calling this "max_vers" suggests it's actually a version number, and not
> an index into the version array; that's confusing.
Its pretty simple code.. don't see this confusion.... but..
It changed to mount_vers_tbl
>
> The array above this one has a NULL entry as it's final element. To be
> consistent with existing code, you should copy that logic for this array
> instead of using a separate "max_vers" variable.
Having the NULL messes up the sizeof calculations
>
>> +
>> /*
>> * Generate an RPC client handle connected to the mountd service
>> * at @hostname, or die trying.
>> *
>> * Supports both AF_INET and AF_INET6 server addresses.
>> */
>> -static CLIENT *nfs_get_mount_client(const char *hostname)
>> +static CLIENT *nfs_get_mount_client(const char *hostname, int vers)
>
> RPC version numbers are rpcvers_t, not int. At the very least,
> clnt_create(3t) takes an unsigned version number argument.
>
>> {
>> rpcprog_t program = nfs_getrpcbyname(MOUNTPROG, nfs_sm_pgmtbl);
>> CLIENT *client;
>>
>> - client = clnt_create(hostname, program, MOUNTVERS, "tcp");
>> + client = clnt_create(hostname, program, vers, "tcp");
>> if (client)
>> return client;
>>
>> - client = clnt_create(hostname, program, MOUNTVERS, "udp");
>> + client = clnt_create(hostname, program, vers, "udp");
>> if (client)
>> return client;
>>
>> @@ -122,7 +129,7 @@ int main(int argc, char **argv)
>> mountlist list;
>> int i;
>> int n;
>> - int maxlen;
>> + int maxlen, vers=0;
>
> Array indices are unsigned integers.
>
> Calling this "vers" suggests it's actually a version number, and not an
> index into the version array; that's confusing.
and an index call 'j' or 'i' is descriptive?? vers is clear enough imho...
>
>> char **dumpv;
>>
>> program_name = argv[0];
>> @@ -185,7 +192,8 @@ int main(int argc, char **argv)
>> break;
>> }
>>
>> - mclient = nfs_get_mount_client(hostname);
>> +again:
>> + mclient = nfs_get_mount_client(hostname, mount_vers[vers]);
>> mclient->cl_auth = authunix_create_default();
>> total_timeout.tv_sec = TOTAL_TIMEOUT;
>> total_timeout.tv_usec = 0;
>> @@ -197,6 +205,10 @@ int main(int argc, char **argv)
>> (xdrproc_t) xdr_void, NULL,
>> (xdrproc_t) xdr_exports, (caddr_t) &exportlist,
>> total_timeout);
>> + if (clnt_stat == RPC_PROGVERSMISMATCH) {
>> + if (++vers < max_vers)
>> + goto again;
>> + }
>
> clnt_create(3t) should tell you if the requested version number is
> working; libtirpc's version does a NULLPROC call, for example. It would
> be simpler to move this check into nfs_get_mount_client(), then you
> wouldn't need the retry loop here.
clnt_create() does not fail.. the clnt_call() does..
>
> But nfs_get_mount_client() already doesn't care why the clnt_create(3t)
> call fails, it just retries the creation with different parameters if it
> didn't succeed. Do we really care enough to retry _only_ if the
> specific RPC version isn't available? We use the same procedure number
> with the same arguments and the same results for all three protocol
> versions, yes?
Let not make a mountain out of mole hill... the goal of this patch is stop using the lower mount protocol version so server can only support v3 and v4... nothing
more...
steved.
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