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nfsd: fix session slot handling for failed callbacks 

When the NFSv4.1/4.2 server does a callback to a client
on the back channel, it will use a session slot in the
back channel session. If the back channel has failed,
the callback will fail and, without this patch, the
session slot will not be released.
As more callbacks are attempted, all session slots
can become busy and then the nfsd thread gets stuck
waiting for a back channel session slot.

This patch frees the session slot upon callback
failure to avoid this problem.

Without this patch, the problem can be avoided by leaving
delegations disabled in the NFS server.

MFC after:	2 weeks
This commit is contained in:
Rick Macklem 2021-04-23 15:24:47 -07:00
parent 576b477ba4
commit 4281bfec36
1 changed files with 18 additions and 12 deletions
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30
sys/fs/nfsserver/nfs_nfsdstate.c
View File

@ -166,7 +166,8 @@ static int nfsrv_docallback(struct nfsclient *clp, int procnum,
nfsv4stateid_t *stateidp, int trunc, fhandle_t *fhp, nfsv4stateid_t *stateidp, int trunc, fhandle_t *fhp,
struct nfsvattr *nap, nfsattrbit_t *attrbitp, int laytype, NFSPROC_T *p); struct nfsvattr *nap, nfsattrbit_t *attrbitp, int laytype, NFSPROC_T *p);
static int nfsrv_cbcallargs(struct nfsrv_descript *nd, struct nfsclient *clp, static int nfsrv_cbcallargs(struct nfsrv_descript *nd, struct nfsclient *clp,
uint32_t callback, int op, const char *optag, struct nfsdsession **sepp); uint32_t callback, int op, const char *optag, struct nfsdsession **sepp,
int *slotposp);
static u_int32_t nfsrv_nextclientindex(void); static u_int32_t nfsrv_nextclientindex(void);
static u_int32_t nfsrv_nextstateindex(struct nfsclient *clp); static u_int32_t nfsrv_nextstateindex(struct nfsclient *clp);
static void nfsrv_markstable(struct nfsclient *clp); static void nfsrv_markstable(struct nfsclient *clp);
@ -201,7 +202,7 @@ static void nfsrv_unlocklf(struct nfslockfile *lfp);
static struct nfsdsession *nfsrv_findsession(uint8_t *sessionid); static struct nfsdsession *nfsrv_findsession(uint8_t *sessionid);
static int nfsrv_freesession(struct nfsdsession *sep, uint8_t *sessionid); static int nfsrv_freesession(struct nfsdsession *sep, uint8_t *sessionid);
static int nfsv4_setcbsequence(struct nfsrv_descript *nd, struct nfsclient *clp, static int nfsv4_setcbsequence(struct nfsrv_descript *nd, struct nfsclient *clp,
int dont_replycache, struct nfsdsession **sepp); int dont_replycache, struct nfsdsession **sepp, int *slotposp);
static int nfsv4_getcbsession(struct nfsclient *clp, struct nfsdsession **sepp); static int nfsv4_getcbsession(struct nfsclient *clp, struct nfsdsession **sepp);
static int nfsrv_addlayout(struct nfsrv_descript *nd, struct nfslayout **lypp, static int nfsrv_addlayout(struct nfsrv_descript *nd, struct nfslayout **lypp,
nfsv4stateid_t *stateidp, char *layp, int *layoutlenp, NFSPROC_T *p); nfsv4stateid_t *stateidp, char *layp, int *layoutlenp, NFSPROC_T *p);
@ -4434,7 +4435,7 @@ nfsrv_docallback(struct nfsclient *clp, int procnum, nfsv4stateid_t *stateidp,
u_int32_t *tl; u_int32_t *tl;
struct nfsrv_descript *nd; struct nfsrv_descript *nd;
struct ucred *cred; struct ucred *cred;
int error = 0; int error = 0, slotpos;
u_int32_t callback; u_int32_t callback;
struct nfsdsession *sep = NULL; struct nfsdsession *sep = NULL;
uint64_t tval; uint64_t tval;
@ -4492,7 +4493,7 @@ nfsrv_docallback(struct nfsclient *clp, int procnum, nfsv4stateid_t *stateidp,
if (procnum == NFSV4OP_CBGETATTR) { if (procnum == NFSV4OP_CBGETATTR) {
nd->nd_procnum = NFSV4PROC_CBCOMPOUND; nd->nd_procnum = NFSV4PROC_CBCOMPOUND;
error = nfsrv_cbcallargs(nd, clp, callback, NFSV4OP_CBGETATTR, error = nfsrv_cbcallargs(nd, clp, callback, NFSV4OP_CBGETATTR,
"CB Getattr", &sep); "CB Getattr", &sep, &slotpos);
if (error != 0) { if (error != 0) {
m_freem(nd->nd_mreq); m_freem(nd->nd_mreq);
goto errout; goto errout;
@ -4502,7 +4503,7 @@ nfsrv_docallback(struct nfsclient *clp, int procnum, nfsv4stateid_t *stateidp,
} else if (procnum == NFSV4OP_CBRECALL) { } else if (procnum == NFSV4OP_CBRECALL) {
nd->nd_procnum = NFSV4PROC_CBCOMPOUND; nd->nd_procnum = NFSV4PROC_CBCOMPOUND;
error = nfsrv_cbcallargs(nd, clp, callback, NFSV4OP_CBRECALL, error = nfsrv_cbcallargs(nd, clp, callback, NFSV4OP_CBRECALL,
"CB Recall", &sep); "CB Recall", &sep, &slotpos);
if (error != 0) { if (error != 0) {
m_freem(nd->nd_mreq); m_freem(nd->nd_mreq);
goto errout; goto errout;
@ -4521,7 +4522,7 @@ nfsrv_docallback(struct nfsclient *clp, int procnum, nfsv4stateid_t *stateidp,
NFSD_DEBUG(4, "docallback layout recall\n"); NFSD_DEBUG(4, "docallback layout recall\n");
nd->nd_procnum = NFSV4PROC_CBCOMPOUND; nd->nd_procnum = NFSV4PROC_CBCOMPOUND;
error = nfsrv_cbcallargs(nd, clp, callback, error = nfsrv_cbcallargs(nd, clp, callback,
NFSV4OP_CBLAYOUTRECALL, "CB Reclayout", &sep); NFSV4OP_CBLAYOUTRECALL, "CB Reclayout", &sep, &slotpos);
NFSD_DEBUG(4, "aft cbcallargs=%d\n", error); NFSD_DEBUG(4, "aft cbcallargs=%d\n", error);
if (error != 0) { if (error != 0) {
m_freem(nd->nd_mreq); m_freem(nd->nd_mreq);
@ -4570,6 +4571,8 @@ nfsrv_docallback(struct nfsclient *clp, int procnum, nfsv4stateid_t *stateidp,
if (clp->lc_req.nr_client == NULL) { if (clp->lc_req.nr_client == NULL) {
if ((clp->lc_flags & LCL_NFSV41) != 0) { if ((clp->lc_flags & LCL_NFSV41) != 0) {
error = ECONNREFUSED; error = ECONNREFUSED;
if (procnum != NFSV4PROC_CBNULL)
nfsv4_freeslot(&sep->sess_cbsess, slotpos);
nfsrv_freesession(sep, NULL); nfsrv_freesession(sep, NULL);
} else if (nd->nd_procnum == NFSV4PROC_CBNULL) } else if (nd->nd_procnum == NFSV4PROC_CBNULL)
error = newnfs_connect(NULL, &clp->lc_req, cred, error = newnfs_connect(NULL, &clp->lc_req, cred,
@ -4601,6 +4604,8 @@ nfsrv_docallback(struct nfsclient *clp, int procnum, nfsv4stateid_t *stateidp,
error = ECONNREFUSED; error = ECONNREFUSED;
} }
NFSD_DEBUG(4, "aft newnfs_request=%d\n", error); NFSD_DEBUG(4, "aft newnfs_request=%d\n", error);
if (error != 0 && procnum != NFSV4PROC_CBNULL)
nfsv4_freeslot(&sep->sess_cbsess, slotpos);
nfsrv_freesession(sep, NULL); nfsrv_freesession(sep, NULL);
} else } else
error = newnfs_request(nd, NULL, clp, &clp->lc_req, error = newnfs_request(nd, NULL, clp, &clp->lc_req,
@ -4663,7 +4668,8 @@ errout:
*/ */
static int static int
nfsrv_cbcallargs(struct nfsrv_descript *nd, struct nfsclient *clp, nfsrv_cbcallargs(struct nfsrv_descript *nd, struct nfsclient *clp,
uint32_t callback, int op, const char *optag, struct nfsdsession **sepp) uint32_t callback, int op, const char *optag, struct nfsdsession **sepp,
int *slotposp)
{ {
uint32_t *tl; uint32_t *tl;
int error, len; int error, len;
@ -4679,7 +4685,7 @@ nfsrv_cbcallargs(struct nfsrv_descript *nd, struct nfsclient *clp,
*tl++ = txdr_unsigned(callback); *tl++ = txdr_unsigned(callback);
*tl++ = txdr_unsigned(2); *tl++ = txdr_unsigned(2);
*tl = txdr_unsigned(NFSV4OP_CBSEQUENCE); *tl = txdr_unsigned(NFSV4OP_CBSEQUENCE);
error = nfsv4_setcbsequence(nd, clp, 1, sepp); error = nfsv4_setcbsequence(nd, clp, 1, sepp, slotposp);
if (error != 0) if (error != 0)
return (error); return (error);
NFSM_BUILD(tl, u_int32_t *, NFSX_UNSIGNED); NFSM_BUILD(tl, u_int32_t *, NFSX_UNSIGNED);
@ -6599,11 +6605,11 @@ nfsrv_teststateid(struct nfsrv_descript *nd, nfsv4stateid_t *stateidp,
*/ */
static int static int
nfsv4_setcbsequence(struct nfsrv_descript *nd, struct nfsclient *clp, nfsv4_setcbsequence(struct nfsrv_descript *nd, struct nfsclient *clp,
int dont_replycache, struct nfsdsession **sepp) int dont_replycache, struct nfsdsession **sepp, int *slotposp)
{ {
struct nfsdsession *sep; struct nfsdsession *sep;
uint32_t *tl, slotseq = 0; uint32_t *tl, slotseq = 0;
int maxslot, slotpos; int maxslot;
uint8_t sessionid[NFSX_V4SESSIONID]; uint8_t sessionid[NFSX_V4SESSIONID];
int error; int error;
@ -6611,7 +6617,7 @@ nfsv4_setcbsequence(struct nfsrv_descript *nd, struct nfsclient *clp,
if (error != 0) if (error != 0)
return (error); return (error);
sep = *sepp; sep = *sepp;
(void)nfsv4_sequencelookup(NULL, &sep->sess_cbsess, &slotpos, &maxslot, (void)nfsv4_sequencelookup(NULL, &sep->sess_cbsess, slotposp, &maxslot,
&slotseq, sessionid); &slotseq, sessionid);
KASSERT(maxslot >= 0, ("nfsv4_setcbsequence neg maxslot")); KASSERT(maxslot >= 0, ("nfsv4_setcbsequence neg maxslot"));
@ -6621,7 +6627,7 @@ nfsv4_setcbsequence(struct nfsrv_descript *nd, struct nfsclient *clp,
tl += NFSX_V4SESSIONID / NFSX_UNSIGNED; tl += NFSX_V4SESSIONID / NFSX_UNSIGNED;
nd->nd_slotseq = tl; nd->nd_slotseq = tl;
*tl++ = txdr_unsigned(slotseq); *tl++ = txdr_unsigned(slotseq);
*tl++ = txdr_unsigned(slotpos); *tl++ = txdr_unsigned(*slotposp);
*tl++ = txdr_unsigned(maxslot); *tl++ = txdr_unsigned(maxslot);
if (dont_replycache == 0) if (dont_replycache == 0)
*tl++ = newnfs_true; *tl++ = newnfs_true;