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nfsd: Fix close handling when vfs.nfsd.enable_locallocks=1

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nfsrv_freeopen() was being called after the mutex
lock was released, making it possible for other
kernel threads to change the lists while nfsrv_freeopen()
took the nfsstateid out of the lists.

This patch moves the code around
"if (nfsrv_freeopen(stp, vp, 1 p) == 0) {"
into nfsrv_freeopen(), so that it can remove the nfsstateid
structure from all lists before unlocking the mutex.
This should avoid any race between CLOSE and other nfsd threads
updating the NFSv4 state.

The patch does not affect semantics when vfs.nfsd.enable_locallocks=0.

PR:	280978
Tested by:	Matthew L. Dailey <matthew.l.dailey@dartmouth.edu>
MFC after:	1 week
This commit is contained in:
Rick Macklem 2024-09-30 15:49:57 -07:00
parent c4564a47c1
commit eb345e05ac
1 changed files with 30 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
sys/fs/nfsserver/nfs_nfsdstate.c
View File

@ -139,7 +139,7 @@ static void nfsrv_dumpaclient(struct nfsclient *clp,
struct nfsd_dumpclients *dumpp);
static void nfsrv_freeopenowner(struct nfsstate *stp, int cansleep,
NFSPROC_T *p);
static int nfsrv_freeopen(struct nfsstate *stp, vnode_t vp, int cansleep,
static void nfsrv_freeopen(struct nfsstate *stp, vnode_t vp, int cansleep,
NFSPROC_T *p);
static void nfsrv_freelockowner(struct nfsstate *stp, vnode_t vp, int cansleep,
NFSPROC_T *p);
@ -1566,7 +1566,7 @@ nfsrv_freeopenowner(struct nfsstate *stp, int cansleep, NFSPROC_T *p)
while (nstp != LIST_END(&stp->ls_open)) {
tstp = nstp;
nstp = LIST_NEXT(nstp, ls_list);
(void) nfsrv_freeopen(tstp, NULL, cansleep, p);
nfsrv_freeopen(tstp, NULL, cansleep, p);
}
if (stp->ls_op)
nfsrvd_derefcache(stp->ls_op);
@ -1581,12 +1581,11 @@ nfsrv_freeopenowner(struct nfsstate *stp, int cansleep, NFSPROC_T *p)
* are no other opens on the file.
* Returns 1 if it free'd the nfslockfile, 0 otherwise.
*/
static int
static void
nfsrv_freeopen(struct nfsstate *stp, vnode_t vp, int cansleep, NFSPROC_T *p)
{
struct nfsstate *nstp, *tstp;
struct nfslockfile *lfp;
int ret;
LIST_REMOVE(stp, ls_hash);
LIST_REMOVE(stp, ls_list);
@ -1595,35 +1594,46 @@ nfsrv_freeopen(struct nfsstate *stp, vnode_t vp, int cansleep, NFSPROC_T *p)
lfp = stp->ls_lfp;
/*
* Now, free all lockowners associated with this open.
* Note that, if vp != NULL, nfsrv_freelockowner() will
* not call nfsrv_freeallnfslocks(), so it needs to be called, below.
*/
LIST_FOREACH_SAFE(tstp, &stp->ls_open, ls_list, nstp)
nfsrv_freelockowner(tstp, vp, cansleep, p);
if (vp != NULL) {
KASSERT(cansleep != 0, ("nfsrv_freeopen: cansleep == 0"));
mtx_assert(NFSSTATEMUTEXPTR, MA_OWNED);
/*
* Only called with vp != NULL for Close when
* vfs.nfsd.enable_locallocks != 0.
* Lock the lfp so that it will not go away and do the
* nfsrv_freeallnfslocks() call that was not done by
* nfsrv_freelockowner().
*/
nfsrv_locklf(lfp);
NFSUNLOCKSTATE();
NFSVOPUNLOCK(vp);
nfsrv_freeallnfslocks(stp, vp, cansleep, p);
NFSVOPLOCK(vp, LK_EXCLUSIVE | LK_RETRY);
NFSLOCKSTATE();
nfsrv_unlocklf(lfp);
}
/*
* The nfslockfile is freed here if there are no locks
* associated with the open.
* If there are locks associated with the open, the
* nfslockfile structure can be freed via nfsrv_freelockowner().
* Acquire the state mutex to avoid races with calls to
* nfsrv_getlockfile().
*/
if (cansleep != 0)
NFSLOCKSTATE();
if (lfp != NULL && LIST_EMPTY(&lfp->lf_open) &&
LIST_EMPTY(&lfp->lf_deleg) && LIST_EMPTY(&lfp->lf_lock) &&
LIST_EMPTY(&lfp->lf_locallock) && LIST_EMPTY(&lfp->lf_rollback) &&
lfp->lf_usecount == 0 &&
(cansleep != 0 || nfsv4_testlock(&lfp->lf_locallock_lck) == 0)) {
nfsv4_testlock(&lfp->lf_locallock_lck) == 0)
nfsrv_freenfslockfile(lfp);
ret = 1;
} else
ret = 0;
if (cansleep != 0)
NFSUNLOCKSTATE();
free(stp, M_NFSDSTATE);
NFSD_VNET(nfsstatsv1_p)->srvopens--;
nfsrv_openpluslock--;
return (ret);
}
/*
@ -1636,7 +1646,8 @@ nfsrv_freelockowner(struct nfsstate *stp, vnode_t vp, int cansleep,
LIST_REMOVE(stp, ls_hash);
LIST_REMOVE(stp, ls_list);
nfsrv_freeallnfslocks(stp, vp, cansleep, p);
if (vp == NULL)
nfsrv_freeallnfslocks(stp, vp, cansleep, p);
if (stp->ls_op)
nfsrvd_derefcache(stp->ls_op);
free(stp, M_NFSDSTATE);
@ -3431,7 +3442,6 @@ nfsrv_openupdate(vnode_t vp, struct nfsstate *new_stp, nfsquad_t clientid,
{
struct nfsstate *stp;
struct nfsclient *clp;
struct nfslockfile *lfp;
u_int32_t bits;
int error = 0, gotstate = 0, len = 0;
u_char *clidp = NULL;
@ -3526,9 +3536,7 @@ nfsrv_openupdate(vnode_t vp, struct nfsstate *new_stp, nfsquad_t clientid,
NFSBCOPY(clp->lc_id, clidp, len);
gotstate = 1;
}
NFSUNLOCKSTATE();
} else if (new_stp->ls_flags & NFSLCK_CLOSE) {
lfp = stp->ls_lfp;
if (retwriteaccessp != NULL) {
if ((stp->ls_flags & NFSLCK_WRITEACCESS) != 0)
*retwriteaccessp = 1;
@ -3536,20 +3544,10 @@ nfsrv_openupdate(vnode_t vp, struct nfsstate *new_stp, nfsquad_t clientid,
*retwriteaccessp = 0;
}
if (nfsrv_dolocallocks != 0 && !LIST_EMPTY(&stp->ls_open)) {
/* Get the lf lock */
nfsrv_locklf(lfp);
NFSUNLOCKSTATE();
ASSERT_VOP_ELOCKED(vp, "nfsrv_openupdate");
NFSVOPUNLOCK(vp);
if (nfsrv_freeopen(stp, vp, 1, p) == 0) {
NFSLOCKSTATE();
nfsrv_unlocklf(lfp);
NFSUNLOCKSTATE();
}
NFSVOPLOCK(vp, LK_EXCLUSIVE | LK_RETRY);
nfsrv_freeopen(stp, vp, 1, p);
} else {
(void) nfsrv_freeopen(stp, NULL, 0, p);
NFSUNLOCKSTATE();
nfsrv_freeopen(stp, NULL, 0, p);
}
} else {
/*
@ -3567,8 +3565,8 @@ nfsrv_openupdate(vnode_t vp, struct nfsstate *new_stp, nfsquad_t clientid,
if ((nd->nd_flag & ND_NFSV41) != 0 &&
stp->ls_stateid.seqid == 0)
stp->ls_stateid.seqid = 1;
NFSUNLOCKSTATE();
}
NFSUNLOCKSTATE();
/*
* If the client just confirmed its first open, write a timestamp