nfscl: Add optional support for slots marked bad

This patch adds support for session slots marked bad
to nfsv4_sequencelookup().  An additional boolean
argument indicates if the check for slots marked bad
should be done.

The "cred" argument added to nfscl_reqstart() by
commit 326bcf9394 is now passed into nfsv4_setquence()
so that it can optionally set the boolean argument
for nfsv4_sequencelookup().  When optionally enabled,
nfsv4_setsequence() will do a DestroySession when all
slots are marked bad.

Since the code that marks slots bad is not yet committed,
this patch should not result in a semantics change.

PR: 260011
MFC after:	2 weeks

sys/fs/nfs/nfs_commonkrpc.c

@@ -1121,7 +1121,7 @@ newnfs_request(struct nfsrv_descript *nd, struct nfsmount *nmp,
 				if ((nd->nd_flag & ND_LOOPBADSESS) != 0) {
 					reterr = nfsv4_sequencelookup(nmp, sep,
 					    &slotpos, &maxslot, &slotseq,
-					    sessionid);
+					    sessionid, true);
 					if (reterr == 0) {
 						/* Fill in new session info. */
 						NFSCL_DEBUG(1,

sys/fs/nfs/nfs_commonsubs.c

@@ -323,7 +323,7 @@ static int nfs_bigrequest[NFSV42_NPROCS] = {
 void
 nfscl_reqstart(struct nfsrv_descript *nd, int procnum, struct nfsmount *nmp,
     u_int8_t *nfhp, int fhlen, u_int32_t **opcntpp, struct nfsclsession *sep,
-    int vers, int minorvers, __unused struct ucred *cred)
+    int vers, int minorvers, struct ucred *cred)
 {
 	struct mbuf *mb;
 	u_int32_t *tl;
@@ -416,11 +416,17 @@ nfscl_reqstart(struct nfsrv_descript *nd, int procnum, struct nfsmount *nmp,
 			*tl = txdr_unsigned(NFSV4OP_SEQUENCE);
 			if (sep == NULL) {
 				sep = nfsmnt_mdssession(nmp);
+				/*
+				 * For MDS mount sessions, check for bad
+				 * slots.  If the caller does not want this
+				 * check to be done, the "cred" argument can
+				 * be passed in as NULL.
+				 */
 				nfsv4_setsequence(nmp, nd, sep,
-				    nfs_bigreply[procnum]);
+				    nfs_bigreply[procnum], cred);
 			} else
 				nfsv4_setsequence(nmp, nd, sep,
-				    nfs_bigreply[procnum]);
+				    nfs_bigreply[procnum], NULL);
 		}
 		if (nfsv4_opflag[nfsv4_opmap[procnum].op].needscfh > 0) {
 			NFSM_BUILD(tl, u_int32_t *, NFSX_UNSIGNED);
@@ -4769,14 +4775,23 @@ nfsv4_seqsess_cacherep(uint32_t slotid, struct nfsslot *slots, int repstat,
  */
 void
 nfsv4_setsequence(struct nfsmount *nmp, struct nfsrv_descript *nd,
-    struct nfsclsession *sep, int dont_replycache)
+    struct nfsclsession *sep, int dont_replycache, struct ucred *cred)
 {
 	uint32_t *tl, slotseq = 0;
 	int error, maxslot, slotpos;
 	uint8_t sessionid[NFSX_V4SESSIONID];
 
-	error = nfsv4_sequencelookup(nmp, sep, &slotpos, &maxslot, &slotseq,
-	    sessionid);
+	if (cred != NULL) {
+		error = nfsv4_sequencelookup(nmp, sep, &slotpos, &maxslot,
+		    &slotseq, sessionid, false);
+		if (error == NFSERR_SEQMISORDERED) {
+			/* If all slots are bad, Destroy the session. */
+			nfsrpc_destroysession(nmp, sep, cred, curthread);
+			error = 0;
+		}
+	} else
+		error = nfsv4_sequencelookup(nmp, sep, &slotpos, &maxslot,
+		    &slotseq, sessionid, true);
 	nd->nd_maxreq = sep->nfsess_maxreq;
 	nd->nd_maxresp = sep->nfsess_maxresp;
 
@@ -4813,12 +4828,18 @@ nfsv4_setsequence(struct nfsmount *nmp, struct nfsrv_descript *nd,
 	nd->nd_flag |= ND_HASSEQUENCE;
 }
 
+/*
+ * If fnd_init is true, ignore the badslots.
+ * If fnd_init is false, return NFSERR_SEQMISORDERED if all slots are bad.
+ */
 int
 nfsv4_sequencelookup(struct nfsmount *nmp, struct nfsclsession *sep,
-    int *slotposp, int *maxslotp, uint32_t *slotseqp, uint8_t *sessionid)
+    int *slotposp, int *maxslotp, uint32_t *slotseqp, uint8_t *sessionid,
+    bool fnd_init)
 {
 	int i, maxslot, slotpos;
 	uint64_t bitval;
+	bool fnd_ok;
 
 	/* Find an unused slot. */
 	slotpos = -1;
@@ -4832,14 +4853,18 @@ nfsv4_sequencelookup(struct nfsmount *nmp, struct nfsclsession *sep,
 			mtx_unlock(&sep->nfsess_mtx);
 			return (NFSERR_BADSESSION);
 		}
+		fnd_ok = fnd_init;
 		bitval = 1;
 		for (i = 0; i < sep->nfsess_foreslots; i++) {
-			if ((bitval & sep->nfsess_slots) == 0) {
-				slotpos = i;
-				sep->nfsess_slots |= bitval;
-				sep->nfsess_slotseq[i]++;
-				*slotseqp = sep->nfsess_slotseq[i];
-				break;
+			if ((bitval & sep->nfsess_badslots) == 0 || fnd_init) {
+				fnd_ok = true;
+				if ((bitval & sep->nfsess_slots) == 0) {
+					slotpos = i;
+					sep->nfsess_slots |= bitval;
+					sep->nfsess_slotseq[i]++;
+					*slotseqp = sep->nfsess_slotseq[i];
+					break;
+				}
 			}
 			bitval <<= 1;
 		}
@@ -4854,10 +4879,19 @@ nfsv4_sequencelookup(struct nfsmount *nmp, struct nfsclsession *sep,
 				return (ESTALE);
 			}
 			/* Wake up once/sec, to check for a forced dismount. */
-			(void)mtx_sleep(&sep->nfsess_slots, &sep->nfsess_mtx,
-			    PZERO, "nfsclseq", hz);
+			if (fnd_ok)
+				mtx_sleep(&sep->nfsess_slots, &sep->nfsess_mtx,
+				    PZERO, "nfsclseq", hz);
 		}
-	} while (slotpos == -1);
+	} while (slotpos == -1 && fnd_ok);
+	/*
+	 * If all slots are bad, just return slot 0 and NFSERR_SEQMISORDERED.
+	 * The caller will do a DestroySession, so that the session's use
+	 * will get a NFSERR_BADSESSION reply from the server.
+	 */
+	if (!fnd_ok)
+		slotpos = 0;
+
 	/* Now, find the highest slot in use. (nfsc_slots is 64bits) */
 	bitval = 1;
 	for (i = 0; i < 64; i++) {
@@ -4869,6 +4903,9 @@ nfsv4_sequencelookup(struct nfsmount *nmp, struct nfsclsession *sep,
 	mtx_unlock(&sep->nfsess_mtx);
 	*slotposp = slotpos;
 	*maxslotp = maxslot;
+
+	if (!fnd_ok)
+		return (NFSERR_SEQMISORDERED);
 	return (0);
 }
 

sys/fs/nfs/nfs_var.h

@@ -358,9 +358,9 @@ int nfsv4_seqsession(uint32_t, uint32_t, uint32_t, struct nfsslot *,
     struct mbuf **, uint16_t);
 void nfsv4_seqsess_cacherep(uint32_t, struct nfsslot *, int, struct mbuf **);
 void nfsv4_setsequence(struct nfsmount *, struct nfsrv_descript *,
-    struct nfsclsession *, int);
+    struct nfsclsession *, int, struct ucred *);
 int nfsv4_sequencelookup(struct nfsmount *, struct nfsclsession *, int *,
-    int *, uint32_t *, uint8_t *);
+    int *, uint32_t *, uint8_t *, bool);
 void nfsv4_freeslot(struct nfsclsession *, int, bool);
 struct ucred *nfsrv_getgrpscred(struct ucred *);
 struct nfsdevice *nfsv4_findmirror(struct nfsmount *);

sys/fs/nfs/nfsclstate.h

@@ -67,6 +67,7 @@ struct nfsclsession {
 	SVCXPRT		*nfsess_xprt;		/* For backchannel callback */
 	uint32_t	nfsess_slotseq[64];	/* Max for 64bit nm_slots */
 	uint64_t	nfsess_slots;
+	uint64_t	nfsess_badslots;	/* Slots possibly broken */
 	uint32_t	nfsess_sequenceid;
 	uint32_t	nfsess_maxcache;	/* Max size for cached reply. */
 	uint32_t	nfsess_maxreq;		/* Max request size. */

sys/fs/nfsserver/nfs_nfsdstate.c

@@ -6637,8 +6637,8 @@ nfsv4_setcbsequence(struct nfsrv_descript *nd, struct nfsclient *clp,
 	if (error != 0)
 		return (error);
 	sep = *sepp;
-	(void)nfsv4_sequencelookup(NULL, &sep->sess_cbsess, slotposp, &maxslot,
-	    &slotseq, sessionid);
+	nfsv4_sequencelookup(NULL, &sep->sess_cbsess, slotposp, &maxslot,
+	    &slotseq, sessionid, true);
 	KASSERT(maxslot >= 0, ("nfsv4_setcbsequence neg maxslot"));
 
 	/* Build the Sequence arguments. */