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Fix the handling of NFSv4.1 sessions for "soft" mounts.

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When a "soft" mount is used for NFSv4.1, an RPC that fails without completing
will leave a slot in the NFSv4.1 session in an indeterminate state.
As such, all that can be done is free up the slot while making is no longer
usable.
A "soft" NFSv4.1 mount is not recommended in general, since it will leave
Open/Lock state in an indeterminate state. An exception is a pNFS mount of
a DS, since there are no Opens/Locks done for them except file creates
where loss of the Open state does not matter.
The patch also makes connections to DSs soft, so that they will fail when
a DS is non-functional or network partitioned, allowing the pNFS MDS to disable
the DS for a mirrored configuration.
This patch should not affect normal "hard" NFSv4.1 mounts.

MFC after:	2 weeks
This commit is contained in:
Rick Macklem 2018-06-22 21:37:20 +00:00
parent 2e35b8fe24
commit ba6cce3aea
1 changed files with 64 additions and 16 deletions
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80
sys/fs/nfs/nfs_commonkrpc.c
View File

@ -157,6 +157,9 @@ static int nfsv2_procid[NFS_V3NPROCS] = {
/*
* Initialize sockets and congestion for a new NFS connection.
* We do not free the sockaddr if error.
* Which arguments are set to NULL indicate what kind of call it is.
* cred == NULL --> a call to connect to a pNFS DS
* nmp == NULL --> indicates an upcall to userland or a NFSv4.0 callback
*/
int
newnfs_connect(struct nfsmount *nmp, struct nfssockreq *nrp,
@ -293,24 +296,38 @@ newnfs_connect(struct nfsmount *nmp, struct nfssockreq *nrp,
retries = nmp->nm_retry;
} else
retries = INT_MAX;
/* cred == NULL for DS connects. */
if (NFSHASNFSV4N(nmp) && cred != NULL) {
/*
* Make sure the nfscbd_pool doesn't get destroyed
* while doing this.
*/
NFSD_LOCK();
if (nfs_numnfscbd > 0) {
nfs_numnfscbd++;
NFSD_UNLOCK();
xprt = svc_vc_create_backchannel(nfscbd_pool);
CLNT_CONTROL(client, CLSET_BACKCHANNEL, xprt);
if (NFSHASNFSV4N(nmp)) {
if (cred != NULL) {
/*
* Make sure the nfscbd_pool doesn't get
* destroyed while doing this.
*/
NFSD_LOCK();
nfs_numnfscbd--;
if (nfs_numnfscbd == 0)
wakeup(&nfs_numnfscbd);
if (nfs_numnfscbd > 0) {
nfs_numnfscbd++;
NFSD_UNLOCK();
xprt = svc_vc_create_backchannel(
nfscbd_pool);
CLNT_CONTROL(client, CLSET_BACKCHANNEL,
xprt);
NFSD_LOCK();
nfs_numnfscbd--;
if (nfs_numnfscbd == 0)
wakeup(&nfs_numnfscbd);
}
NFSD_UNLOCK();
} else {
/*
* cred == NULL for a DS connect.
* For connects to a DS, set a retry limit
* so that failed DSs will be detected.
* This is ok for NFSv4.1, since a DS does
* not maintain open/lock state and is the
* only case where using a "soft" mount is
* recommended for NFSv4.
*/
retries = 2;
}
NFSD_UNLOCK();
}
} else {
/*
@ -762,6 +779,7 @@ tryagain:
else
stat = CLNT_CALL_MBUF(nrp->nr_client, &ext, procnum,
nd->nd_mreq, &nd->nd_mrep, timo);
NFSCL_DEBUG(2, "clnt call=%d\n", stat);
if (rep != NULL) {
/*
@ -789,6 +807,36 @@ tryagain:
error = EPROTONOSUPPORT;
} else if (stat == RPC_INTR) {
error = EINTR;
} else if (stat == RPC_CANTSEND || stat == RPC_CANTRECV ||
stat == RPC_SYSTEMERROR) {
/* Check for a session slot that needs to be free'd. */
if ((nd->nd_flag & (ND_NFSV41 | ND_HASSLOTID)) ==
(ND_NFSV41 | ND_HASSLOTID) && nmp != NULL &&
nd->nd_procnum != NFSPROC_NULL) {
/*
* This should only occur when either the MDS or
* a client has an RPC against a DS fail.
* This happens because these cases use "soft"
* connections that can time out and fail.
* The slot used for this RPC is now in a
* non-deterministic state, but if the slot isn't
* free'd, threads can get stuck waiting for a slot.
*/
if (sep == NULL)
sep = nfsmnt_mdssession(nmp);
/*
* Bump the sequence# out of range, so that reuse of
* this slot will result in an NFSERR_SEQMISORDERED
* error and not a bogus cached RPC reply.
*/
mtx_lock(&sep->nfsess_mtx);
sep->nfsess_slotseq[nd->nd_slotid] += 10;
mtx_unlock(&sep->nfsess_mtx);
/* And free the slot. */
nfsv4_freeslot(sep, nd->nd_slotid);
}
NFSINCRGLOBAL(nfsstatsv1.rpcinvalid);
error = ENXIO;
} else {
NFSINCRGLOBAL(nfsstatsv1.rpcinvalid);
error = EACCES;