freebsd-dev/sys/nfsclient/nfs_node.c
Matthew Dillon 885d36ce36 nfs_nget() does no locking whatsoever when looking up a vnode. If the
vget() sleeps we have to retry the operation to avoid racing against
a deletion.

MFC maybe: submitted to re's
2001-12-27 19:40:34 +00:00

445 lines
11 KiB
C

/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Rick Macklem at The University of Guelph.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)nfs_node.c 8.6 (Berkeley) 5/22/95
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fnv_hash.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>
#include <vm/vm_zone.h>
#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfsclient/nfs.h>
#include <nfsclient/nfsnode.h>
#include <nfsclient/nfsmount.h>
static vm_zone_t nfsnode_zone;
static LIST_HEAD(nfsnodehashhead, nfsnode) *nfsnodehashtbl;
static u_long nfsnodehash;
static int nfs_node_hash_lock;
#define TRUE 1
#define FALSE 0
SYSCTL_DECL(_debug_hashstat);
/*
* Grab an atomic snapshot of the nfsnode hash chain lengths
*/
static int
sysctl_debug_hashstat_rawnfsnode(SYSCTL_HANDLER_ARGS)
{
int error;
struct nfsnodehashhead *nnpp;
struct nfsnode *nnp;
int n_nfsnode;
int count;
n_nfsnode = nfsnodehash + 1; /* nfsnodehash = max index, not count */
if (!req->oldptr)
return SYSCTL_OUT(req, 0, n_nfsnode * sizeof(int));
/* Scan hash tables for applicable entries */
for (nnpp = nfsnodehashtbl; n_nfsnode > 0; n_nfsnode--, nnpp++) {
count = 0;
LIST_FOREACH(nnp, nnpp, n_hash) {
count++;
}
error = SYSCTL_OUT(req, (caddr_t)&count, sizeof(count));
if (error)
return (error);
}
return (0);
}
SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnfsnode, CTLTYPE_INT|CTLFLAG_RD, 0, 0,
sysctl_debug_hashstat_rawnfsnode, "S,int", "nfsnode chain lengths");
static int
sysctl_debug_hashstat_nfsnode(SYSCTL_HANDLER_ARGS)
{
int error;
struct nfsnodehashhead *nnpp;
struct nfsnode *nnp;
int n_nfsnode;
int count, maxlength, used, pct;
if (!req->oldptr)
return SYSCTL_OUT(req, 0, 4 * sizeof(int));
n_nfsnode = nfsnodehash + 1; /* nfsnodehash = max index, not count */
used = 0;
maxlength = 0;
/* Scan hash tables for applicable entries */
for (nnpp = nfsnodehashtbl; n_nfsnode > 0; n_nfsnode--, nnpp++) {
count = 0;
LIST_FOREACH(nnp, nnpp, n_hash) {
count++;
}
if (count)
used++;
if (maxlength < count)
maxlength = count;
}
n_nfsnode = nfsnodehash + 1;
pct = (used * 100 * 100) / n_nfsnode;
error = SYSCTL_OUT(req, (caddr_t)&n_nfsnode, sizeof(n_nfsnode));
if (error)
return (error);
error = SYSCTL_OUT(req, (caddr_t)&used, sizeof(used));
if (error)
return (error);
error = SYSCTL_OUT(req, (caddr_t)&maxlength, sizeof(maxlength));
if (error)
return (error);
error = SYSCTL_OUT(req, (caddr_t)&pct, sizeof(pct));
if (error)
return (error);
return (0);
}
SYSCTL_PROC(_debug_hashstat, OID_AUTO, nfsnode, CTLTYPE_INT|CTLFLAG_RD,
0, 0, sysctl_debug_hashstat_nfsnode, "I", "nfsnode chain lengths");
/*
* Initialize hash links for nfsnodes
* and build nfsnode free list.
*/
void
nfs_nhinit(void)
{
nfsnode_zone = zinit("NFSNODE", sizeof(struct nfsnode), 0, 0, 1);
nfsnodehashtbl = hashinit(desiredvnodes, M_NFSHASH, &nfsnodehash);
}
/*
* Look up a vnode/nfsnode by file handle.
* Callers must check for mount points!!
* In all cases, a pointer to a
* nfsnode structure is returned.
*/
int
nfs_nget(struct mount *mntp, nfsfh_t *fhp, int fhsize, struct nfsnode **npp)
{
struct thread *td = curthread; /* XXX */
struct nfsnode *np, *np2;
struct nfsnodehashhead *nhpp;
struct vnode *vp;
struct vnode *nvp;
int error;
int rsflags;
struct nfsmount *nmp;
/*
* Calculate nfs mount point and figure out whether the rslock should
* be interruptable or not.
*/
nmp = VFSTONFS(mntp);
if (nmp->nm_flag & NFSMNT_INT)
rsflags = PCATCH;
else
rsflags = 0;
retry:
nhpp = NFSNOHASH(fnv_32_buf(fhp->fh_bytes, fhsize, FNV1_32_INIT));
loop:
LIST_FOREACH(np, nhpp, n_hash) {
if (mntp != NFSTOV(np)->v_mount || np->n_fhsize != fhsize ||
bcmp((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize))
continue;
vp = NFSTOV(np);
/*
* np or vp may become invalid if vget() blocks, so loop
*/
if (vget(vp, LK_EXCLUSIVE|LK_SLEEPFAIL, td))
goto loop;
*npp = np;
return(0);
}
/*
* Obtain a lock to prevent a race condition if the getnewvnode()
* or MALLOC() below happens to block.
*/
if (nfs_node_hash_lock) {
while (nfs_node_hash_lock) {
nfs_node_hash_lock = -1;
tsleep(&nfs_node_hash_lock, PVM, "nfsngt", 0);
}
goto loop;
}
nfs_node_hash_lock = 1;
/*
* Allocate before getnewvnode since doing so afterward
* might cause a bogus v_data pointer to get dereferenced
* elsewhere if zalloc should block.
*/
np = zalloc(nfsnode_zone);
error = getnewvnode(VT_NFS, mntp, nfsv2_vnodeop_p, &nvp);
if (error) {
if (nfs_node_hash_lock < 0)
wakeup(&nfs_node_hash_lock);
nfs_node_hash_lock = 0;
*npp = 0;
zfree(nfsnode_zone, np);
return (error);
}
vp = nvp;
bzero((caddr_t)np, sizeof *np);
vp->v_data = np;
np->n_vnode = vp;
/*
* Insert the nfsnode in the hash queue for its new file handle
*/
LIST_FOREACH(np2, nhpp, n_hash) {
if (mntp != NFSTOV(np2)->v_mount || np2->n_fhsize != fhsize ||
bcmp((caddr_t)fhp, (caddr_t)np2->n_fhp, fhsize))
continue;
vrele(vp);
if (nfs_node_hash_lock < 0)
wakeup(&nfs_node_hash_lock);
nfs_node_hash_lock = 0;
zfree(nfsnode_zone, np);
goto retry;
}
LIST_INSERT_HEAD(nhpp, np, n_hash);
if (fhsize > NFS_SMALLFH) {
MALLOC(np->n_fhp, nfsfh_t *, fhsize, M_NFSBIGFH, M_WAITOK);
} else
np->n_fhp = &np->n_fh;
bcopy((caddr_t)fhp, (caddr_t)np->n_fhp, fhsize);
np->n_fhsize = fhsize;
lockinit(&np->n_rslock, PVFS | rsflags, "nfrslk", 0, LK_NOPAUSE);
lockinit(&vp->v_lock, PVFS, "nfsnlk", 0, LK_NOPAUSE);
*npp = np;
if (nfs_node_hash_lock < 0)
wakeup(&nfs_node_hash_lock);
nfs_node_hash_lock = 0;
/*
* Lock the new nfsnode.
*/
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
return (0);
}
int
nfs_inactive(struct vop_inactive_args *ap)
{
struct nfsnode *np;
struct sillyrename *sp;
struct thread *td = curthread; /* XXX */
np = VTONFS(ap->a_vp);
if (prtactive && ap->a_vp->v_usecount != 0)
vprint("nfs_inactive: pushing active", ap->a_vp);
if (ap->a_vp->v_type != VDIR) {
sp = np->n_sillyrename;
np->n_sillyrename = (struct sillyrename *)0;
} else
sp = (struct sillyrename *)0;
if (sp) {
/*
* We need a reference to keep the vnode from being
* recycled by getnewvnode while we do the I/O
* associated with discarding the buffers unless we
* are being forcibly unmounted in which case we already
* have our own reference.
*/
if (ap->a_vp->v_usecount > 0)
(void) nfs_vinvalbuf(ap->a_vp, 0, sp->s_cred, td, 1);
else if (vget(ap->a_vp, 0, td))
panic("nfs_inactive: lost vnode");
else {
(void) nfs_vinvalbuf(ap->a_vp, 0, sp->s_cred, td, 1);
vrele(ap->a_vp);
}
/*
* Remove the silly file that was rename'd earlier
*/
nfs_removeit(sp);
crfree(sp->s_cred);
vrele(sp->s_dvp);
FREE((caddr_t)sp, M_NFSREQ);
}
np->n_flag &= (NMODIFIED | NFLUSHINPROG | NFLUSHWANT);
VOP_UNLOCK(ap->a_vp, 0, ap->a_td);
return (0);
}
/*
* Reclaim an nfsnode so that it can be used for other purposes.
*/
int
nfs_reclaim(struct vop_reclaim_args *ap)
{
struct vnode *vp = ap->a_vp;
struct nfsnode *np = VTONFS(vp);
struct nfsdmap *dp, *dp2;
if (prtactive && vp->v_usecount != 0)
vprint("nfs_reclaim: pushing active", vp);
if (np->n_hash.le_prev != NULL) /* XXX beware */
LIST_REMOVE(np, n_hash);
/*
* Free up any directory cookie structures and
* large file handle structures that might be associated with
* this nfs node.
*/
if (vp->v_type == VDIR) {
dp = LIST_FIRST(&np->n_cookies);
while (dp) {
dp2 = dp;
dp = LIST_NEXT(dp, ndm_list);
FREE((caddr_t)dp2, M_NFSDIROFF);
}
}
if (np->n_fhsize > NFS_SMALLFH) {
FREE((caddr_t)np->n_fhp, M_NFSBIGFH);
}
lockdestroy(&np->n_rslock);
cache_purge(vp);
zfree(nfsnode_zone, vp->v_data);
vp->v_data = (void *)0;
return (0);
}
#if 0
/*
* Lock an nfsnode
*/
int
nfs_lock(struct vop_lock_args *ap)
{
struct vnode *vp = ap->a_vp;
/*
* Ugh, another place where interruptible mounts will get hung.
* If you make this sleep interruptible, then you have to fix all
* the VOP_LOCK() calls to expect interruptibility.
*/
while (vp->v_flag & VXLOCK) {
vp->v_flag |= VXWANT;
(void) tsleep((caddr_t)vp, PINOD, "nfslck", 0);
}
if (vp->v_tag == VT_NON)
return (ENOENT);
#if 0
/*
* Only lock regular files. If a server crashed while we were
* holding a directory lock, we could easily end up sleeping
* until the server rebooted while holding a lock on the root.
* Locks are only needed for protecting critical sections in
* VMIO at the moment.
* New vnodes will have type VNON but they should be locked
* since they may become VREG. This is checked in loadattrcache
* and unwanted locks are released there.
*/
if (vp->v_type == VREG || vp->v_type == VNON) {
while (np->n_flag & NLOCKED) {
np->n_flag |= NWANTED;
(void) tsleep((caddr_t) np, PINOD, "nfslck2", 0);
/*
* If the vnode has transmuted into a VDIR while we
* were asleep, then skip the lock.
*/
if (vp->v_type != VREG && vp->v_type != VNON)
return (0);
}
np->n_flag |= NLOCKED;
}
#endif
return (0);
}
/*
* Unlock an nfsnode
*/
int
nfs_unlock(struct vop_unlock_args *ap)
{
#if 0
struct vnode* vp = ap->a_vp;
struct nfsnode* np = VTONFS(vp);
if (vp->v_type == VREG || vp->v_type == VNON) {
if (!(np->n_flag & NLOCKED))
panic("nfs_unlock: nfsnode not locked");
np->n_flag &= ~NLOCKED;
if (np->n_flag & NWANTED) {
np->n_flag &= ~NWANTED;
wakeup((caddr_t) np);
}
}
#endif
return (0);
}
/*
* Check for a locked nfsnode
*/
int
nfs_islocked(struct vop_islocked_args *ap)
{
return VTONFS(ap->a_vp)->n_flag & NLOCKED ? 1 : 0;
}
#endif