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freebsd-dev/sys/nfsserver/nfs_srvcache.c
Robert Watson 1ee624b31d The socket code upcalls into the NFS server using the so_upcall 
mechanism so that early processing on mbufs can be performed before
a context switch to the NFS server threads.  Because of this, if
the socket code is running without Giant, the NFS server also needs
to be able to run the upcall code without relying on the presence on
Giant.  This change modifies the NFS server to run using a "giant
code lock" covering operation of the whole subsystem.  Work is in
progress to move to data-based locking as part of the NFSv4 server
changes.

Introduce an NFS server subsystem lock, 'nfsd_mtx', and a set of
macros to operate on the lock:

  NFSD_LOCK_ASSERT()    Assert nfsd_mtx owned by current thread
  NFSD_UNLOCK_ASSERT()  Assert nfsd_mtx not owned by current thread
  NFSD_LOCK_DONTCARE()  Advisory: this function doesn't care
  NFSD_LOCK()           Lock nfsd_mtx
  NFSD_UNLOCK()         Unlock nfsd_mtx

Constify a number of global variables/structures in the NFS server
code, as they are not modified and contain constants only:

  nfsrvv2_procid       nfsrv_nfsv3_procid      nonidempotent
  nfsv2_repstat        nfsv2_type              nfsrv_nfsv3_procid
  nfsrvv2_procid       nfsrv_v2errmap          nfsv3err_null
  nfsv3err_getattr     nfsv3err_setattr        nfsv3err_lookup
  nfsv3err_access      nfsv3err_readlink       nfsv3err_read
  nfsv3err_write       nfsv3err_create         nfsv3err_mkdir
  nfsv3err_symlink     nfsv3err_mknod          nfsv3err_remove
  nfsv3err_rmdir       nfsv3err_rename         nfsv3err_link
  nfsv3err_readdir     nfsv3err_readdirplus    nfsv3err_fsstat
  nfsv3err_fsinfo      nfsv3err_pathconf       nfsv3err_commit
  nfsrv_v3errmap

There are additional structures that should be constified but due
to their being passed into general purpose functions without const
arguments, I have not yet converted.

In general, acquire nfsd_mtx when accessing any of the global NFS
structures, including struct nfssvc_sock, struct nfsd, struct
nfsrv_descript.

Release nfsd_mtx whenever calling into VFS, and acquire Giant for
calls into VFS.  Giant is not required for any part of the
operation of the NFS server with the exception of calls into VFS.
Giant will never by acquired in the upcall code path.  However, it
may operate entirely covered by Giant, or not.  If debug.mpsafenet
is set to 0, the system calls will acquire Giant across all
operations, and the upcall will assert Giant.  As such, by default,
this enables locking and allows us to test assertions, but should not
cause any substantial new amount of code to be run without Giant.
Bugs should manifest in the form of lock assertion failures for now.

This approach is similar (but not identical) to modifications to the
BSD/OS NFS server code snapshot provided by BSDi as part of their
SMPng snapshot.  The strategy is almost the same (single lock over
the NFS server), but differs in the following ways:

- Our NFS client and server code bases don't overlap, which means
  both fewer bugs and easier locking (thanks Peter!).  Also means
  NFSD_*() as opposed to NFS_*().

- We make broad use of assertions, whereas the BSD/OS code does not.

- Made slightly different choices about how to handle macros building
  packets but operating with side effects.

- We acquire Giant only when entering VFS from the NFS server daemon
  threads.

- Serious bugs in BSD/OS implementation corrected -- the snapshot we
  received was clearly a work in progress.

Based on ideas from:	BSDi SMPng Snapshot
Reviewed by:		rick@snowhite.cis.uoguelph.ca
Extensive testing by:	kris
2004-05-24 04:06:14 +00:00

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/*
* 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.
* 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_srvcache.c 8.3 (Berkeley) 3/30/95
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* Reference: Chet Juszczak, "Improving the Performance and Correctness
* of an NFS Server", in Proc. Winter 1989 USENIX Conference,
* pages 53-63. San Diego, February 1989.
*/
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/socket.h>
#include <sys/socketvar.h> /* for sodupsockaddr */
#include <netinet/in.h>
#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfsserver/nfs.h>
#include <nfsserver/nfsrvcache.h>
static long numnfsrvcache;
static long desirednfsrvcache = NFSRVCACHESIZ;
#define NFSRCHASH(xid) \
(&nfsrvhashtbl[((xid) + ((xid) >> 24)) & nfsrvhash])
static LIST_HEAD(nfsrvhash, nfsrvcache) *nfsrvhashtbl;
static TAILQ_HEAD(nfsrvlru, nfsrvcache) nfsrvlruhead;
static u_long nfsrvhash;
#define TRUE 1
#define FALSE 0
#define NETFAMILY(rp) \
(((rp)->rc_flag & RC_NAM) ? (rp)->rc_nam->sa_family : AF_INET)
/*
* Static array that defines which nfs rpc's are nonidempotent
*/
static const int nonidempotent[NFS_NPROCS] = {
FALSE,
FALSE,
TRUE,
FALSE,
FALSE,
FALSE,
FALSE,
TRUE,
TRUE,
TRUE,
TRUE,
TRUE,
TRUE,
TRUE,
TRUE,
TRUE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
};
/* True iff the rpc reply is an nfs status ONLY! */
static const int nfsv2_repstat[NFS_NPROCS] = {
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
TRUE,
TRUE,
TRUE,
TRUE,
FALSE,
TRUE,
FALSE,
FALSE,
};
/*
* Initialize the server request cache list
*/
void
nfsrv_initcache(void)
{
nfsrvhashtbl = hashinit(desirednfsrvcache, M_NFSD, &nfsrvhash);
TAILQ_INIT(&nfsrvlruhead);
}
/*
* Look for the request in the cache
* If found then
* return action and optionally reply
* else
* insert it in the cache
*
* The rules are as follows:
* - if in progress, return DROP request
* - if completed within DELAY of the current time, return DROP it
* - if completed a longer time ago return REPLY if the reply was cached or
* return DOIT
* Update/add new request at end of lru list
*/
int
nfsrv_getcache(struct nfsrv_descript *nd, struct mbuf **repp)
{
struct nfsrvcache *rp;
struct mbuf *mb;
struct sockaddr_in *saddr;
caddr_t bpos;
int ret;
NFSD_LOCK_ASSERT();
/*
* Don't cache recent requests for reliable transport protocols.
* (Maybe we should for the case of a reconnect, but..)
*/
if (!nd->nd_nam2)
return (RC_DOIT);
loop:
LIST_FOREACH(rp, NFSRCHASH(nd->nd_retxid), rc_hash) {
if (nd->nd_retxid == rp->rc_xid && nd->nd_procnum == rp->rc_proc &&
netaddr_match(NETFAMILY(rp), &rp->rc_haddr, nd->nd_nam)) {
NFS_DPF(RC, ("H%03x", rp->rc_xid & 0xfff));
if ((rp->rc_flag & RC_LOCKED) != 0) {
rp->rc_flag |= RC_WANTED;
(void) msleep(rp, &nfsd_mtx, PZERO-1,
"nfsrc", 0);
goto loop;
}
rp->rc_flag |= RC_LOCKED;
/* If not at end of LRU chain, move it there */
if (TAILQ_NEXT(rp, rc_lru)) {
TAILQ_REMOVE(&nfsrvlruhead, rp, rc_lru);
TAILQ_INSERT_TAIL(&nfsrvlruhead, rp, rc_lru);
}
if (rp->rc_state == RC_UNUSED)
panic("nfsrv cache");
if (rp->rc_state == RC_INPROG) {
nfsrvstats.srvcache_inproghits++;
ret = RC_DROPIT;
} else if (rp->rc_flag & RC_REPSTATUS) {
nfsrvstats.srvcache_nonidemdonehits++;
*repp = nfs_rephead(0, nd, rp->rc_status,
&mb, &bpos);
ret = RC_REPLY;
} else if (rp->rc_flag & RC_REPMBUF) {
nfsrvstats.srvcache_nonidemdonehits++;
NFSD_UNLOCK();
*repp = m_copym(rp->rc_reply, 0, M_COPYALL,
M_TRYWAIT);
NFSD_LOCK();
ret = RC_REPLY;
} else {
nfsrvstats.srvcache_idemdonehits++;
rp->rc_state = RC_INPROG;
ret = RC_DOIT;
}
rp->rc_flag &= ~RC_LOCKED;
if (rp->rc_flag & RC_WANTED) {
rp->rc_flag &= ~RC_WANTED;
wakeup(rp);
}
return (ret);
}
}
nfsrvstats.srvcache_misses++;
NFS_DPF(RC, ("M%03x", nd->nd_retxid & 0xfff));
if (numnfsrvcache < desirednfsrvcache) {
NFSD_UNLOCK();
rp = (struct nfsrvcache *)malloc((u_long)sizeof *rp,
M_NFSD, M_WAITOK | M_ZERO);
NFSD_LOCK();
numnfsrvcache++;
rp->rc_flag = RC_LOCKED;
} else {
rp = TAILQ_FIRST(&nfsrvlruhead);
while ((rp->rc_flag & RC_LOCKED) != 0) {
rp->rc_flag |= RC_WANTED;
(void) msleep(rp, &nfsd_mtx, PZERO-1, "nfsrc", 0);
rp = TAILQ_FIRST(&nfsrvlruhead);
}
rp->rc_flag |= RC_LOCKED;
LIST_REMOVE(rp, rc_hash);
TAILQ_REMOVE(&nfsrvlruhead, rp, rc_lru);
if (rp->rc_flag & RC_REPMBUF)
m_freem(rp->rc_reply);
if (rp->rc_flag & RC_NAM)
FREE(rp->rc_nam, M_SONAME);
rp->rc_flag &= (RC_LOCKED | RC_WANTED);
}
TAILQ_INSERT_TAIL(&nfsrvlruhead, rp, rc_lru);
rp->rc_state = RC_INPROG;
rp->rc_xid = nd->nd_retxid;
saddr = (struct sockaddr_in *)nd->nd_nam;
switch (saddr->sin_family) {
case AF_INET:
rp->rc_flag |= RC_INETADDR;
rp->rc_inetaddr = saddr->sin_addr.s_addr;
break;
/* case AF_INET6: */
/* case AF_ISO: */
default:
rp->rc_flag |= RC_NAM;
rp->rc_nam = sodupsockaddr(nd->nd_nam, M_WAITOK);
break;
};
rp->rc_proc = nd->nd_procnum;
LIST_INSERT_HEAD(NFSRCHASH(nd->nd_retxid), rp, rc_hash);
rp->rc_flag &= ~RC_LOCKED;
if (rp->rc_flag & RC_WANTED) {
rp->rc_flag &= ~RC_WANTED;
wakeup(rp);
}
return (RC_DOIT);
}
/*
* Update a request cache entry after the rpc has been done
*/
void
nfsrv_updatecache(struct nfsrv_descript *nd, int repvalid, struct mbuf *repmbuf)
{
struct nfsrvcache *rp;
NFSD_LOCK_ASSERT();
if (!nd->nd_nam2)
return;
loop:
LIST_FOREACH(rp, NFSRCHASH(nd->nd_retxid), rc_hash) {
if (nd->nd_retxid == rp->rc_xid && nd->nd_procnum == rp->rc_proc &&
netaddr_match(NETFAMILY(rp), &rp->rc_haddr, nd->nd_nam)) {
NFS_DPF(RC, ("U%03x", rp->rc_xid & 0xfff));
if ((rp->rc_flag & RC_LOCKED) != 0) {
rp->rc_flag |= RC_WANTED;
(void) msleep(rp, &nfsd_mtx, PZERO-1,
"nfsrc", 0);
goto loop;
}
rp->rc_flag |= RC_LOCKED;
if (rp->rc_state == RC_DONE) {
/*
* This can occur if the cache is too small.
* Retransmits of the same request aren't
* dropped so we may see the operation
* complete more then once.
*/
if (rp->rc_flag & RC_REPMBUF) {
m_freem(rp->rc_reply);
rp->rc_flag &= ~RC_REPMBUF;
}
}
rp->rc_state = RC_DONE;
/*
* If we have a valid reply update status and save
* the reply for non-idempotent rpc's.
*/
if (repvalid && nonidempotent[nd->nd_procnum]) {
if ((nd->nd_flag & ND_NFSV3) == 0 &&
nfsv2_repstat[
nfsrvv2_procid[nd->nd_procnum]]) {
rp->rc_status = nd->nd_repstat;
rp->rc_flag |= RC_REPSTATUS;
} else {
NFSD_UNLOCK();
rp->rc_reply = m_copym(repmbuf,
0, M_COPYALL, M_TRYWAIT);
NFSD_LOCK();
rp->rc_flag |= RC_REPMBUF;
}
}
rp->rc_flag &= ~RC_LOCKED;
if (rp->rc_flag & RC_WANTED) {
rp->rc_flag &= ~RC_WANTED;
wakeup(rp);
}
return;
}
}
NFS_DPF(RC, ("L%03x", nd->nd_retxid & 0xfff));
}
/*
* Clean out the cache. Called when the last nfsd terminates.
*/
void
nfsrv_cleancache(void)
{
struct nfsrvcache *rp, *nextrp;
NFSD_LOCK_ASSERT();
for (rp = TAILQ_FIRST(&nfsrvlruhead); rp != 0; rp = nextrp) {
nextrp = TAILQ_NEXT(rp, rc_lru);
LIST_REMOVE(rp, rc_hash);
TAILQ_REMOVE(&nfsrvlruhead, rp, rc_lru);
if (rp->rc_flag & RC_REPMBUF)
m_freem(rp->rc_reply);
if (rp->rc_flag & RC_NAM)
free(rp->rc_nam, M_SONAME);
free(rp, M_NFSD);
}
numnfsrvcache = 0;
}
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