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  * 4. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  *      @(#)nfs_syscalls.c      8.5 (Berkeley) 3/30/95
   33  */
   34 
   35 #include <sys/cdefs.h>
   36 __FBSDID("$FreeBSD: src/sys/nfsclient/nfs_nfsiod.c,v 1.81.2.1 2005/01/31 23:26:46 imp Exp $");
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/sysproto.h>
   41 #include <sys/kernel.h>
   42 #include <sys/sysctl.h>
   43 #include <sys/file.h>
   44 #include <sys/filedesc.h>
   45 #include <sys/vnode.h>
   46 #include <sys/malloc.h>
   47 #include <sys/mount.h>
   48 #include <sys/proc.h>
   49 #include <sys/bio.h>
   50 #include <sys/buf.h>
   51 #include <sys/mbuf.h>
   52 #include <sys/socket.h>
   53 #include <sys/socketvar.h>
   54 #include <sys/domain.h>
   55 #include <sys/protosw.h>
   56 #include <sys/namei.h>
   57 #include <sys/unistd.h>
   58 #include <sys/kthread.h>
   59 #include <sys/fcntl.h>
   60 #include <sys/lockf.h>
   61 #include <sys/mutex.h>
   62 
   63 #include <netinet/in.h>
   64 #include <netinet/tcp.h>
   65 
   66 #include <rpc/rpcclnt.h>
   67 
   68 #include <nfs/xdr_subs.h>
   69 #include <nfs/rpcv2.h>
   70 #include <nfs/nfsproto.h>
   71 #include <nfsclient/nfs.h>
   72 #include <nfsclient/nfsm_subs.h>
   73 #include <nfsclient/nfsmount.h>
   74 #include <nfsclient/nfsnode.h>
   75 #include <nfsclient/nfs_lock.h>
   76 
   77 static MALLOC_DEFINE(M_NFSSVC, "NFS srvsock", "Nfs server structure");
   78 
   79 static void     nfssvc_iod(void *);
   80 
   81 static int nfs_asyncdaemon[NFS_MAXASYNCDAEMON];
   82 
   83 SYSCTL_DECL(_vfs_nfs);
   84 
   85 /* Maximum number of seconds a nfsiod kthread will sleep before exiting */
   86 static unsigned int nfs_iodmaxidle = 120;
   87 SYSCTL_UINT(_vfs_nfs, OID_AUTO, iodmaxidle, CTLFLAG_RW, &nfs_iodmaxidle, 0, "");
   88 
   89 /* Maximum number of nfsiod kthreads */
   90 unsigned int nfs_iodmax = 20;
   91 
   92 /* Minimum number of nfsiod kthreads to keep as spares */
   93 static unsigned int nfs_iodmin = 4;
   94 
   95 static int
   96 sysctl_iodmin(SYSCTL_HANDLER_ARGS)
   97 {
   98         int error, i;
   99         int newmin;
  100 
  101         newmin = nfs_iodmin;
  102         error = sysctl_handle_int(oidp, &newmin, 0, req);
  103         if (error || (req->newptr == NULL))
  104                 return (error);
  105         if (newmin > nfs_iodmax)
  106                 return (EINVAL);
  107         nfs_iodmin = newmin;
  108         if (nfs_numasync >= nfs_iodmin)
  109                 return (0);
  110         /*
  111          * If the current number of nfsiod is lower
  112          * than the new minimum, create some more.
  113          */
  114         for (i = nfs_iodmin - nfs_numasync; i > 0; i--)
  115                 nfs_nfsiodnew();
  116         return (0);
  117 }
  118 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmin, CTLTYPE_UINT | CTLFLAG_RW, 0,
  119     sizeof (nfs_iodmin), sysctl_iodmin, "IU", "");
  120 
  121 
  122 static int
  123 sysctl_iodmax(SYSCTL_HANDLER_ARGS)
  124 {
  125         int error, i;
  126         int iod, newmax;
  127 
  128         newmax = nfs_iodmax;
  129         error = sysctl_handle_int(oidp, &newmax, 0, req);
  130         if (error || (req->newptr == NULL))
  131                 return (error);
  132         if (newmax > NFS_MAXASYNCDAEMON)
  133                 return (EINVAL);
  134         nfs_iodmax = newmax;
  135         if (nfs_numasync <= nfs_iodmax)
  136                 return (0);
  137         /*
  138          * If there are some asleep nfsiods that should
  139          * exit, wakeup() them so that they check nfs_iodmax
  140          * and exit.  Those who are active will exit as
  141          * soon as they finish I/O.
  142          */
  143         iod = nfs_numasync - 1;
  144         for (i = 0; i < nfs_numasync - nfs_iodmax; i++) {
  145                 if (nfs_iodwant[iod])
  146                         wakeup(&nfs_iodwant[iod]);
  147                 iod--;
  148         }
  149         return (0);
  150 }
  151 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmax, CTLTYPE_UINT | CTLFLAG_RW, 0,
  152     sizeof (nfs_iodmax), sysctl_iodmax, "IU", "");
  153 
  154 int
  155 nfs_nfsiodnew(void)
  156 {
  157         int error, i;
  158         int newiod;
  159 
  160         if (nfs_numasync >= nfs_iodmax)
  161                 return (-1);
  162         newiod = -1;
  163         for (i = 0; i < nfs_iodmax; i++)
  164                 if (nfs_asyncdaemon[i] == 0) {
  165                         nfs_asyncdaemon[i]++;
  166                         newiod = i;
  167                         break;
  168                 }
  169         if (newiod == -1)
  170                 return (-1);
  171         error = kthread_create(nfssvc_iod, nfs_asyncdaemon + i, NULL, RFHIGHPID,
  172             0, "nfsiod %d", newiod);
  173         if (error)
  174                 return (-1);
  175         nfs_numasync++;
  176         return (newiod);
  177 }
  178 
  179 static void
  180 nfsiod_setup(void *dummy)
  181 {
  182         int i;
  183         int error;
  184 
  185         TUNABLE_INT_FETCH("vfs.nfs.iodmin", &nfs_iodmin);
  186         /* Silently limit the start number of nfsiod's */
  187         if (nfs_iodmin > NFS_MAXASYNCDAEMON)
  188                 nfs_iodmin = NFS_MAXASYNCDAEMON;
  189 
  190         for (i = 0; i < nfs_iodmin; i++) {
  191                 error = nfs_nfsiodnew();
  192                 if (error == -1)
  193                         panic("nfsiod_setup: nfs_nfsiodnew failed");
  194         }
  195 }
  196 SYSINIT(nfsiod, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, nfsiod_setup, NULL);
  197 
  198 static int nfs_defect = 0;
  199 SYSCTL_INT(_vfs_nfs, OID_AUTO, defect, CTLFLAG_RW, &nfs_defect, 0, "");
  200 
  201 int
  202 nfsclnt(struct thread *td, struct nfsclnt_args *uap)
  203 {
  204         struct lockd_ans la;
  205         int error;
  206 
  207         if ((uap->flag & NFSCLNT_LOCKDANS) != 0) {
  208                 error = copyin(uap->argp, &la, sizeof(la));
  209                 return (error != 0 ? error : nfslockdans(td, &la));
  210         }
  211         return EINVAL;
  212 }
  213 
  214 /*
  215  * Asynchronous I/O daemons for client nfs.
  216  * They do read-ahead and write-behind operations on the block I/O cache.
  217  * Returns if we hit the timeout defined by the iodmaxidle sysctl.
  218  */
  219 static void
  220 nfssvc_iod(void *instance)
  221 {
  222         struct buf *bp;
  223         struct nfsmount *nmp;
  224         int myiod, timo;
  225         int error = 0;
  226 
  227         mtx_lock(&Giant);
  228         myiod = (int *)instance - nfs_asyncdaemon;
  229         /*
  230          * Main loop
  231          */
  232         for (;;) {
  233             while (((nmp = nfs_iodmount[myiod]) == NULL
  234                    || !TAILQ_FIRST(&nmp->nm_bufq))
  235                    && error == 0) {
  236                 if (myiod >= nfs_iodmax)
  237                         goto finish;
  238                 if (nmp)
  239                         nmp->nm_bufqiods--;
  240                 nfs_iodwant[myiod] = curthread->td_proc;
  241                 nfs_iodmount[myiod] = NULL;
  242                 /*
  243                  * Always keep at least nfs_iodmin kthreads.
  244                  */
  245                 timo = (myiod < nfs_iodmin) ? 0 : nfs_iodmaxidle * hz;
  246                 error = tsleep(&nfs_iodwant[myiod], PWAIT | PCATCH,
  247                     "-", timo);
  248             }
  249             if (error)
  250                     break;
  251             while ((bp = TAILQ_FIRST(&nmp->nm_bufq)) != NULL) {
  252                 /* Take one off the front of the list */
  253                 TAILQ_REMOVE(&nmp->nm_bufq, bp, b_freelist);
  254                 nmp->nm_bufqlen--;
  255                 if (nmp->nm_bufqwant && nmp->nm_bufqlen <= nfs_numasync) {
  256                     nmp->nm_bufqwant = 0;
  257                     wakeup(&nmp->nm_bufq);
  258                 }
  259                 if (bp->b_iocmd == BIO_READ)
  260                     (void) nfs_doio(bp, bp->b_rcred, NULL);
  261                 else
  262                     (void) nfs_doio(bp, bp->b_wcred, NULL);
  263                 /*
  264                  * If there are more than one iod on this mount, then defect
  265                  * so that the iods can be shared out fairly between the mounts
  266                  */
  267                 if (nfs_defect && nmp->nm_bufqiods > 1) {
  268                     NFS_DPF(ASYNCIO,
  269                             ("nfssvc_iod: iod %d defecting from mount %p\n",
  270                              myiod, nmp));
  271                     nfs_iodmount[myiod] = NULL;
  272                     nmp->nm_bufqiods--;
  273                     break;
  274                 }
  275             }
  276         }
  277 finish:
  278         nfs_asyncdaemon[myiod] = 0;
  279         if (nmp)
  280             nmp->nm_bufqiods--;
  281         nfs_iodwant[myiod] = NULL;
  282         nfs_iodmount[myiod] = NULL;
  283         /* Someone may be waiting for the last nfsiod to terminate. */
  284         if (--nfs_numasync == 0)
  285                 wakeup(&nfs_numasync);
  286         if ((error == 0) || (error == EWOULDBLOCK))
  287                 kthread_exit(0);
  288         /* Abnormal termination */
  289         kthread_exit(1);
  290 }

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