/* $NetBSD: nfs_clnfsiod.c,v 1.2 2016/12/13 22:17:33 pgoyette Exp $ */
/*-
* 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.
*
* from nfs_syscalls.c 8.5 (Berkeley) 3/30/95
*/
int ncl_numasync;
enum nfsiod_state ncl_iodwant[NFS_MAXASYNCDAEMON];
struct nfsmount *ncl_iodmount[NFS_MAXASYNCDAEMON];
static void nfssvc_iod(void *);
static int nfs_asyncdaemon[NFS_MAXASYNCDAEMON];
SYSCTL_DECL(_vfs_nfs);
/* Maximum number of seconds a nfsiod kthread will sleep before exiting */
static unsigned int nfs_iodmaxidle = 120;
SYSCTL_UINT(_vfs_nfs, OID_AUTO, iodmaxidle, CTLFLAG_RW, &nfs_iodmaxidle, 0,
"Max number of seconds an nfsiod kthread will sleep before exiting");
/* Maximum number of nfsiod kthreads */
unsigned int ncl_iodmax = 20;
/* Minimum number of nfsiod kthreads to keep as spares */
static unsigned int nfs_iodmin = 0;
static int nfs_nfsiodnew_sync(void);
static int
sysctl_iodmin(SYSCTL_HANDLER_ARGS)
{
int error, i;
int newmin;
newmin = nfs_iodmin;
error = sysctl_handle_int(oidp, &newmin, 0, req);
if (error || (req->newptr == NULL))
return (error);
mtx_lock(&ncl_iod_mutex);
if (newmin > ncl_iodmax) {
error = EINVAL;
goto out;
}
nfs_iodmin = newmin;
if (ncl_numasync >= nfs_iodmin)
goto out;
/*
* If the current number of nfsiod is lower
* than the new minimum, create some more.
*/
for (i = nfs_iodmin - ncl_numasync; i > 0; i--)
nfs_nfsiodnew_sync();
out:
mtx_unlock(&ncl_iod_mutex);
return (0);
}
SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmin, CTLTYPE_UINT | CTLFLAG_RW, 0,
sizeof (nfs_iodmin), sysctl_iodmin, "IU",
"Min number of nfsiod kthreads to keep as spares");
static int
sysctl_iodmax(SYSCTL_HANDLER_ARGS)
{
int error, i;
int iod, newmax;
newmax = ncl_iodmax;
error = sysctl_handle_int(oidp, &newmax, 0, req);
if (error || (req->newptr == NULL))
return (error);
if (newmax > NFS_MAXASYNCDAEMON)
return (EINVAL);
mtx_lock(&ncl_iod_mutex);
ncl_iodmax = newmax;
if (ncl_numasync <= ncl_iodmax)
goto out;
/*
* If there are some asleep nfsiods that should
* exit, wakeup() them so that they check ncl_iodmax
* and exit. Those who are active will exit as
* soon as they finish I/O.
*/
iod = ncl_numasync - 1;
for (i = 0; i < ncl_numasync - ncl_iodmax; i++) {
if (ncl_iodwant[iod] == NFSIOD_AVAILABLE)
wakeup(&ncl_iodwant[iod]);
iod--;
}
out:
mtx_unlock(&ncl_iod_mutex);
return (0);
}
SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmax, CTLTYPE_UINT | CTLFLAG_RW, 0,
sizeof (ncl_iodmax), sysctl_iodmax, "IU",
"Max number of nfsiod kthreads");
static int
nfs_nfsiodnew_sync(void)
{
int error, i;
mtx_assert(&ncl_iod_mutex, MA_OWNED);
for (i = 0; i < ncl_iodmax; i++) {
if (nfs_asyncdaemon[i] == 0) {
nfs_asyncdaemon[i] = 1;
break;
}
}
if (i == ncl_iodmax)
return (0);
mtx_unlock(&ncl_iod_mutex);
error = kproc_create(nfssvc_iod, nfs_asyncdaemon + i, NULL,
RFHIGHPID, 0, "newnfs %d", i);
mtx_lock(&ncl_iod_mutex);
if (error == 0) {
ncl_numasync++;
ncl_iodwant[i] = NFSIOD_AVAILABLE;
} else
nfs_asyncdaemon[i] = 0;
return (error);
}
void
ncl_nfsiodnew_tq(__unused void *arg, int pending)
{
static void
nfsiod_setup(void *dummy)
{
int error;
TUNABLE_INT_FETCH("vfs.nfs.iodmin", &nfs_iodmin);
nfscl_init();
mtx_lock(&ncl_iod_mutex);
/* Silently limit the start number of nfsiod's */
if (nfs_iodmin > NFS_MAXASYNCDAEMON)
nfs_iodmin = NFS_MAXASYNCDAEMON;
static int nfs_defect = 0;
SYSCTL_INT(_vfs_nfs, OID_AUTO, defect, CTLFLAG_RW, &nfs_defect, 0,
"Allow nfsiods to migrate serving different mounts");
/*
* Asynchronous I/O daemons for client nfs.
* They do read-ahead and write-behind operations on the block I/O cache.
* Returns if we hit the timeout defined by the iodmaxidle sysctl.
*/
static void
nfssvc_iod(void *instance)
{
struct buf *bp;
struct nfsmount *nmp;
int myiod, timo;
int error = 0;
mtx_lock(&ncl_iod_mutex);
myiod = (int *)instance - nfs_asyncdaemon;
/*
* Main loop
*/
for (;;) {
while (((nmp = ncl_iodmount[myiod]) == NULL)
|| !TAILQ_FIRST(&nmp->nm_bufq)) {
if (myiod >= ncl_iodmax)
goto finish;
if (nmp)
nmp->nm_bufqiods--;
if (ncl_iodwant[myiod] == NFSIOD_NOT_AVAILABLE)
ncl_iodwant[myiod] = NFSIOD_AVAILABLE;
ncl_iodmount[myiod] = NULL;
/*
* Always keep at least nfs_iodmin kthreads.
*/
timo = (myiod < nfs_iodmin) ? 0 : nfs_iodmaxidle * hz;
error = msleep(&ncl_iodwant[myiod], &ncl_iod_mutex, PWAIT | PCATCH,
"-", timo);
if (error) {
nmp = ncl_iodmount[myiod];
/*
* Rechecking the nm_bufq closes a rare race where the
* nfsiod is woken up at the exact time the idle timeout
* fires
*/
if (nmp && TAILQ_FIRST(&nmp->nm_bufq))
error = 0;
break;
}
}
if (error)
break;
while ((bp = TAILQ_FIRST(&nmp->nm_bufq)) != NULL) {
/* Take one off the front of the list */
TAILQ_REMOVE(&nmp->nm_bufq, bp, b_freelist);
nmp->nm_bufqlen--;
if (nmp->nm_bufqwant && nmp->nm_bufqlen <= ncl_numasync) {
nmp->nm_bufqwant = 0;
wakeup(&nmp->nm_bufq);
}
mtx_unlock(&ncl_iod_mutex);
if (bp->b_flags & B_DIRECT) {
KASSERT((bp->b_iocmd == BIO_WRITE), ("nfscvs_iod: BIO_WRITE not set"));
(void)ncl_doio_directwrite(bp);
} else {
if (bp->b_iocmd == BIO_READ)
(void) ncl_doio(bp->b_vp, bp, bp->b_rcred,
NULL, 0);
else
(void) ncl_doio(bp->b_vp, bp, bp->b_wcred,
NULL, 0);
}
mtx_lock(&ncl_iod_mutex);
/*
* Make sure the nmp hasn't been dismounted as soon as
* ncl_doio() completes for the last buffer.
*/
nmp = ncl_iodmount[myiod];
if (nmp == NULL)
break;
/*
* If there are more than one iod on this mount, then defect
* so that the iods can be shared out fairly between the mounts
*/
if (nfs_defect && nmp->nm_bufqiods > 1) {
NFS_DPF(ASYNCIO,
("nfssvc_iod: iod %d defecting from mount %p\n",
myiod, nmp));
ncl_iodmount[myiod] = NULL;
nmp->nm_bufqiods--;
break;
}
}
}
finish:
nfs_asyncdaemon[myiod] = 0;
if (nmp)
nmp->nm_bufqiods--;
ncl_iodwant[myiod] = NFSIOD_NOT_AVAILABLE;
ncl_iodmount[myiod] = NULL;
/* Someone may be waiting for the last nfsiod to terminate. */
if (--ncl_numasync == 0)
wakeup(&ncl_numasync);
mtx_unlock(&ncl_iod_mutex);
if ((error == 0) || (error == EWOULDBLOCK))
kproc_exit(0);
/* Abnormal termination */
kproc_exit(1);
}
