The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/nfsclient/nfs_nfsiod.c

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    1 /*
    2  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * Rick Macklem at The University of Guelph.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 3. All advertising materials mentioning features or use of this software
   17  *    must display the following acknowledgement:
   18  *      This product includes software developed by the University of
   19  *      California, Berkeley and its contributors.
   20  * 4. Neither the name of the University nor the names of its contributors
   21  *    may be used to endorse or promote products derived from this software
   22  *    without specific prior written permission.
   23  *
   24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  *
   36  *      @(#)nfs_syscalls.c      8.5 (Berkeley) 3/30/95
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD: releng/5.1/sys/nfsclient/nfs_nfsiod.c 111748 2003-03-02 16:54:40Z des $");
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/sysproto.h>
   45 #include <sys/kernel.h>
   46 #include <sys/sysctl.h>
   47 #include <sys/file.h>
   48 #include <sys/filedesc.h>
   49 #include <sys/vnode.h>
   50 #include <sys/malloc.h>
   51 #include <sys/mount.h>
   52 #include <sys/proc.h>
   53 #include <sys/bio.h>
   54 #include <sys/buf.h>
   55 #include <sys/mbuf.h>
   56 #include <sys/socket.h>
   57 #include <sys/socketvar.h>
   58 #include <sys/domain.h>
   59 #include <sys/protosw.h>
   60 #include <sys/namei.h>
   61 #include <sys/unistd.h>
   62 #include <sys/kthread.h>
   63 #include <sys/fcntl.h>
   64 #include <sys/lockf.h>
   65 #include <sys/mutex.h>
   66 
   67 #include <netinet/in.h>
   68 #include <netinet/tcp.h>
   69 #include <nfs/xdr_subs.h>
   70 #include <nfs/rpcv2.h>
   71 #include <nfs/nfsproto.h>
   72 #include <nfsclient/nfs.h>
   73 #include <nfsclient/nfsm_subs.h>
   74 #include <nfsclient/nfsmount.h>
   75 #include <nfsclient/nfsnode.h>
   76 #include <nfsclient/nfs_lock.h>
   77 
   78 static MALLOC_DEFINE(M_NFSSVC, "NFS srvsock", "Nfs server structure");
   79 
   80 static void     nfssvc_iod(void *);
   81 
   82 static int nfs_asyncdaemon[NFS_MAXASYNCDAEMON];
   83 
   84 SYSCTL_DECL(_vfs_nfs);
   85 
   86 /* Maximum number of seconds a nfsiod kthread will sleep before exiting */
   87 static unsigned int nfs_iodmaxidle = 120;
   88 SYSCTL_UINT(_vfs_nfs, OID_AUTO, iodmaxidle, CTLFLAG_RW, &nfs_iodmaxidle, 0, "");
   89 
   90 /* Maximum number of nfsiod kthreads */
   91 static unsigned int nfs_iodmax = 20;
   92 
   93 /* Minimum number of nfsiod kthreads to keep as spares */
   94 static unsigned int nfs_iodmin = 4;
   95 
   96 static int
   97 sysctl_iodmin(SYSCTL_HANDLER_ARGS)
   98 {
   99         int error, i;
  100         int newmin;
  101 
  102         newmin = nfs_iodmin;
  103         error = sysctl_handle_int(oidp, &newmin, 0, req);
  104         if (error || (req->newptr == NULL))
  105                 return (error);
  106         if (newmin > nfs_iodmax)
  107                 return (EINVAL);
  108         nfs_iodmin = newmin;
  109         if (nfs_numasync >= nfs_iodmin)
  110                 return (0);
  111         /*
  112          * If the current number of nfsiod is lower
  113          * than the new minimum, create some more.
  114          */
  115         for (i = nfs_iodmin - nfs_numasync; i > 0; i--)
  116                 nfs_nfsiodnew();
  117         return (0);
  118 }
  119 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmin, CTLTYPE_UINT | CTLFLAG_RW, 0,
  120     sizeof (nfs_iodmin), sysctl_iodmin, "IU", "");
  121 
  122 
  123 static int
  124 sysctl_iodmax(SYSCTL_HANDLER_ARGS)
  125 {
  126         int error, i;
  127         int iod, newmax;
  128 
  129         newmax = nfs_iodmax;
  130         error = sysctl_handle_int(oidp, &newmax, 0, req);
  131         if (error || (req->newptr == NULL))
  132                 return (error);
  133         if (newmax > NFS_MAXASYNCDAEMON)
  134                 return (EINVAL);
  135         nfs_iodmax = newmax;
  136         if (nfs_numasync <= nfs_iodmax)
  137                 return (0);
  138         /*
  139          * If there are some asleep nfsiods that should
  140          * exit, wakeup() them so that they check nfs_iodmax
  141          * and exit.  Those who are active will exit as
  142          * soon as they finish I/O.
  143          */
  144         iod = nfs_numasync - 1;
  145         for (i = 0; i < nfs_numasync - nfs_iodmax; i++) {
  146                 if (nfs_iodwant[iod])
  147                         wakeup(&nfs_iodwant[iod]);
  148                 iod--;
  149         }
  150         return (0);
  151 }
  152 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmax, CTLTYPE_UINT | CTLFLAG_RW, 0,
  153     sizeof (nfs_iodmax), sysctl_iodmax, "IU", "");
  154 
  155 int
  156 nfs_nfsiodnew(void)
  157 {
  158         int error, i;
  159         int newiod;
  160 
  161         if (nfs_numasync >= nfs_iodmax)
  162                 return (-1);
  163         newiod = -1;
  164         for (i = 0; i < nfs_iodmax; i++)
  165                 if (nfs_asyncdaemon[i] == 0) {
  166                         nfs_asyncdaemon[i]++;
  167                         newiod = i;
  168                         break;
  169                 }
  170         if (newiod == -1)
  171                 return (-1);
  172         error = kthread_create(nfssvc_iod, nfs_asyncdaemon + i, NULL, RFHIGHPID,
  173             0, "nfsiod %d", newiod);
  174         if (error)
  175                 return (-1);
  176         nfs_numasync++;
  177         return (newiod);
  178 }
  179 
  180 static void
  181 nfsiod_setup(void *dummy)
  182 {
  183         int i;
  184         int error;
  185 
  186         TUNABLE_INT_FETCH("vfs.nfs.iodmin", &nfs_iodmin);
  187         /* Silently limit the start number of nfsiod's */
  188         if (nfs_iodmin > NFS_MAXASYNCDAEMON)
  189                 nfs_iodmin = NFS_MAXASYNCDAEMON;
  190 
  191         for (i = 0; i < nfs_iodmin; i++) {
  192                 error = nfs_nfsiodnew();
  193                 if (error == -1)
  194                         panic("nfsiod_setup: nfs_nfsiodnew failed");
  195         }
  196 }
  197 SYSINIT(nfsiod, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, nfsiod_setup, NULL);
  198 
  199 static int nfs_defect = 0;
  200 SYSCTL_INT(_vfs_nfs, OID_AUTO, defect, CTLFLAG_RW, &nfs_defect, 0, "");
  201 
  202 int
  203 nfsclnt(struct thread *td, struct nfsclnt_args *uap)
  204 {
  205         struct lockd_ans la;
  206         int error;
  207 
  208         if ((uap->flag & NFSCLNT_LOCKDANS) != 0) {
  209                 error = copyin(uap->argp, &la, sizeof(la));
  210                 return (error != 0 ? error : nfslockdans(td, &la));
  211         }
  212         return EINVAL;
  213 }
  214 
  215 /*
  216  * Asynchronous I/O daemons for client nfs.
  217  * They do read-ahead and write-behind operations on the block I/O cache.
  218  * Returns if we hit the timeout defined by the iodmaxidle sysctl.
  219  */
  220 static void
  221 nfssvc_iod(void *instance)
  222 {
  223         struct buf *bp;
  224         struct nfsmount *nmp;
  225         int myiod, timo;
  226         int error = 0;
  227 
  228         mtx_lock(&Giant);
  229         myiod = (int *)instance - nfs_asyncdaemon;
  230         /*
  231          * Main loop
  232          */
  233         for (;;) {
  234             while (((nmp = nfs_iodmount[myiod]) == NULL
  235                    || !TAILQ_FIRST(&nmp->nm_bufq))
  236                    && error == 0) {
  237                 if (myiod >= nfs_iodmax)
  238                         goto finish;
  239                 if (nmp)
  240                         nmp->nm_bufqiods--;
  241                 nfs_iodwant[myiod] = curthread->td_proc;
  242                 nfs_iodmount[myiod] = NULL;
  243                 /*
  244                  * Always keep at least nfs_iodmin kthreads.
  245                  */
  246                 timo = (myiod < nfs_iodmin) ? 0 : nfs_iodmaxidle * hz;
  247                 error = tsleep(&nfs_iodwant[myiod], PWAIT | PCATCH,
  248                     "nfsidl", timo);
  249             }
  250             if (error)
  251                     break;
  252             while ((bp = TAILQ_FIRST(&nmp->nm_bufq)) != NULL) {
  253                 /* Take one off the front of the list */
  254                 TAILQ_REMOVE(&nmp->nm_bufq, bp, b_freelist);
  255                 nmp->nm_bufqlen--;
  256                 if (nmp->nm_bufqwant && nmp->nm_bufqlen <= nfs_numasync) {
  257                     nmp->nm_bufqwant = 0;
  258                     wakeup(&nmp->nm_bufq);
  259                 }
  260                 if (bp->b_iocmd == BIO_READ)
  261                     (void) nfs_doio(bp, bp->b_rcred, NULL);
  262                 else
  263                     (void) nfs_doio(bp, bp->b_wcred, NULL);
  264                 /*
  265                  * If there are more than one iod on this mount, then defect
  266                  * so that the iods can be shared out fairly between the mounts
  267                  */
  268                 if (nfs_defect && nmp->nm_bufqiods > 1) {
  269                     NFS_DPF(ASYNCIO,
  270                             ("nfssvc_iod: iod %d defecting from mount %p\n",
  271                              myiod, nmp));
  272                     nfs_iodmount[myiod] = NULL;
  273                     nmp->nm_bufqiods--;
  274                     break;
  275                 }
  276             }
  277         }
  278 finish:
  279         nfs_asyncdaemon[myiod] = 0;
  280         if (nmp)
  281             nmp->nm_bufqiods--;
  282         nfs_iodwant[myiod] = NULL;
  283         nfs_iodmount[myiod] = NULL;
  284         nfs_numasync--;
  285         if ((error == 0) || (error == EWOULDBLOCK))
  286                 kthread_exit(0);
  287         /* Abnormal termination */
  288         kthread_exit(1);
  289 }

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