On Apr 23, 2012, at 5:27 PM, Myklebust, Trond wrote:
> On Mon, 2012-04-23 at 16:55 -0400, Chuck Lever wrote:
>> Currently the Linux NFS client waits to perform a SETCLIENTID until
>> just before an application wants to open a file. Quite a bit of
>> activity can occur before any state is needed.
>>
>> If the client cares about server trunking, however, no NFSv4
>> operations can proceed until the client determines who it is talking
>> to. Thus server IP trunking detection must be done when the client
>> first encounters an unfamiliar server IP address.
>>
>> The nfs_get_client() function walks the nfs_client_list and matches on
>> server IP address. The outcome of that walk tells us immediately if
>> we have an unfamiliar server IP address. It invokes an init_client()
>> method in this case.
>>
>> Thus, nfs4_init_client() can establish a fresh client ID, and perform
>> trunking detection with it. The exact process for detecting trunking
>> is different for NFSv4.0 and NFSv4.1, so a minorversion-specific
>> init_client callout is introduced.
>>
>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>> ---
>>
>> fs/nfs/client.c | 223 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>> fs/nfs/internal.h | 6 +
>> fs/nfs/nfs4_fs.h | 7 ++
>> fs/nfs/nfs4proc.c | 2
>> fs/nfs/nfs4state.c | 131 ++++++++++++++++++++++++++++++-
>> 5 files changed, 367 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
>> index 920abbc..7330673 100644
>> --- a/fs/nfs/client.c
>> +++ b/fs/nfs/client.c
>> @@ -566,7 +566,8 @@ nfs_get_client(const struct nfs_client_initdata *cl_init,
>> return nfs_found_client(cl_init, clp);
>> }
>> if (new) {
>> - list_add(&new->cl_share_link, &nn->nfs_client_list);
>> + list_add_tail(&new->cl_share_link,
>> + &nn->nfs_client_list);
>> spin_unlock(&nn->nfs_client_lock);
>> new->cl_flags = cl_init->init_flags;
>> return cl_init->rpc_ops->init_client(new,
>> @@ -584,6 +585,210 @@ nfs_get_client(const struct nfs_client_initdata *cl_init,
>> return new;
>> }
>>
>> +#ifdef CONFIG_NFS_V4
>> +/*
>> + * Returns true if the client IDs match
>> + */
>> +static bool
>> +nfs4_match_clientids(struct nfs_client *a, struct nfs_client *b)
>> +{
>> + if (a->cl_clientid != b->cl_clientid) {
>> + dprintk("NFS: --> %s client ID %llx does not match %llx\n",
>> + __func__, a->cl_clientid, b->cl_clientid);
>> + return false;
>> + }
>> + dprintk("NFS: --> %s client ID %llx matches %llx\n",
>> + __func__, a->cl_clientid, b->cl_clientid);
>> + return true;
>> +}
>> +
>> +/**
>> + * nfs40_walk_client_list - Find server that recognizes a client ID
>> + *
>> + * @new: nfs_client with client ID to test
>> + * @result: OUT: found nfs_client, or new
>> + * @cred: credential to use for trunking test
>> + *
>> + * Returns NFS4_OK, a negative errno, or a negative NFS4ERR status.
>> + * If NFS4_OK is returned, an nfs_client pointer is planted in "result."
>> + *
>> + * NB: nfs40_walk_client_list() relies on the new nfs_client being
>> + * the last nfs_client on the list.
>> + */
>> +int nfs40_walk_client_list(struct nfs_client *new,
>> + struct nfs_client **result,
>> + struct rpc_cred *cred)
>> +{
>> + struct nfs_net *nn = net_generic(new->cl_net, nfs_net_id);
>> + struct nfs_client *pos, *prev = NULL;
>> + struct nfs4_setclientid_res clid = {
>> + .clientid = new->cl_clientid,
>> + .confirm = new->cl_confirm,
>> + };
>> + int status;
>> +
>> + dprintk("NFS: --> %s nfs_client = %p\n", __func__, new);
>> +
>> + spin_lock(&nn->nfs_client_lock);
>> +
>> + list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
>> + if (pos->cl_cons_state < 0)
>> + continue;
>> +
>> + if (pos->rpc_ops != new->rpc_ops)
>> + continue;
>> +
>> + if (pos->cl_proto != new->cl_proto)
>> + continue;
>> +
>> + if (pos->cl_minorversion != new->cl_minorversion)
>> + continue;
>> +
>> + dprintk("NFS: --> %s comparing %llx and %llx\n", __func__,
>> + new->cl_clientid, pos->cl_clientid);
>> + if (pos->cl_clientid != new->cl_clientid)
>> + continue;
>> +
>> + atomic_inc(&pos->cl_count);
>> + dprintk("%s nfs_client = %p ({%d})\n",
>> + __func__, pos, atomic_read(&pos->cl_count));
>> + spin_unlock(&nn->nfs_client_lock);
>> +
>> + dprintk("NFS: --> %s confirming %llx\n",
>> + __func__, new->cl_clientid);
>> +
>> + if (prev)
>> + nfs_put_client(prev);
>> +
>> + status = nfs4_proc_setclientid_confirm(pos, &clid, cred);
>
> How are you protecting against NFS4CLNT_PURGE_STATE?
My design is that the clid_init_mutex is held by nfs4_reclaim_lease() and while we are in this code. Whether that made it out of my head and into the source code is another question.
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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