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("$FreeBSD$");
   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, "nfsclient_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 = 0;
   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         mtx_lock(&nfs_iod_mtx);
  106         if (newmin > nfs_iodmax) {
  107                 error = EINVAL;
  108                 goto out;
  109         }
  110         nfs_iodmin = newmin;
  111         if (nfs_numasync >= nfs_iodmin)
  112                 goto out;
  113         /*
  114          * If the current number of nfsiod is lower
  115          * than the new minimum, create some more.
  116          */
  117         for (i = nfs_iodmin - nfs_numasync; i > 0; i--)
  118                 nfs_nfsiodnew();
  119 out:
  120         mtx_unlock(&nfs_iod_mtx);       
  121         return (0);
  122 }
  123 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmin, CTLTYPE_UINT | CTLFLAG_RW, 0,
  124     sizeof (nfs_iodmin), sysctl_iodmin, "IU", "");
  125 
  126 
  127 static int
  128 sysctl_iodmax(SYSCTL_HANDLER_ARGS)
  129 {
  130         int error, i;
  131         int iod, newmax;
  132 
  133         newmax = nfs_iodmax;
  134         error = sysctl_handle_int(oidp, &newmax, 0, req);
  135         if (error || (req->newptr == NULL))
  136                 return (error);
  137         if (newmax > NFS_MAXASYNCDAEMON)
  138                 return (EINVAL);
  139         mtx_lock(&nfs_iod_mtx);
  140         nfs_iodmax = newmax;
  141         if (nfs_numasync <= nfs_iodmax)
  142                 goto out;
  143         /*
  144          * If there are some asleep nfsiods that should
  145          * exit, wakeup() them so that they check nfs_iodmax
  146          * and exit.  Those who are active will exit as
  147          * soon as they finish I/O.
  148          */
  149         iod = nfs_numasync - 1;
  150         for (i = 0; i < nfs_numasync - nfs_iodmax; i++) {
  151                 if (nfs_iodwant[iod])
  152                         wakeup(&nfs_iodwant[iod]);
  153                 iod--;
  154         }
  155 out:
  156         mtx_unlock(&nfs_iod_mtx);
  157         return (0);
  158 }
  159 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmax, CTLTYPE_UINT | CTLFLAG_RW, 0,
  160     sizeof (nfs_iodmax), sysctl_iodmax, "IU", "");
  161 
  162 int
  163 nfs_nfsiodnew(void)
  164 {
  165         int error, i;
  166         int newiod;
  167 
  168         if (nfs_numasync >= nfs_iodmax)
  169                 return (-1);
  170         newiod = -1;
  171         for (i = 0; i < nfs_iodmax; i++)
  172                 if (nfs_asyncdaemon[i] == 0) {
  173                         nfs_asyncdaemon[i]++;
  174                         newiod = i;
  175                         break;
  176                 }
  177         if (newiod == -1)
  178                 return (-1);
  179         mtx_unlock(&nfs_iod_mtx);
  180         error = kthread_create(nfssvc_iod, nfs_asyncdaemon + i, NULL, RFHIGHPID,
  181             0, "nfsiod %d", newiod);
  182         mtx_lock(&nfs_iod_mtx);
  183         if (error)
  184                 return (-1);
  185         nfs_numasync++;
  186         return (newiod);
  187 }
  188 
  189 static void
  190 nfsiod_setup(void *dummy)
  191 {
  192         int i;
  193         int error;
  194 
  195         TUNABLE_INT_FETCH("vfs.nfs.iodmin", &nfs_iodmin);
  196         mtx_lock(&nfs_iod_mtx);
  197         /* Silently limit the start number of nfsiod's */
  198         if (nfs_iodmin > NFS_MAXASYNCDAEMON)
  199                 nfs_iodmin = NFS_MAXASYNCDAEMON;
  200 
  201         for (i = 0; i < nfs_iodmin; i++) {
  202                 error = nfs_nfsiodnew();
  203                 if (error == -1)
  204                         panic("nfsiod_setup: nfs_nfsiodnew failed");
  205         }
  206         mtx_unlock(&nfs_iod_mtx);
  207 }
  208 SYSINIT(nfsiod, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, nfsiod_setup, NULL);
  209 
  210 static int nfs_defect = 0;
  211 SYSCTL_INT(_vfs_nfs, OID_AUTO, defect, CTLFLAG_RW, &nfs_defect, 0, "");
  212 
  213 /*
  214  * Asynchronous I/O daemons for client nfs.
  215  * They do read-ahead and write-behind operations on the block I/O cache.
  216  * Returns if we hit the timeout defined by the iodmaxidle sysctl.
  217  */
  218 static void
  219 nfssvc_iod(void *instance)
  220 {
  221         struct buf *bp;
  222         struct nfsmount *nmp;
  223         int myiod, timo;
  224         int error = 0;
  225 
  226         mtx_lock(&nfs_iod_mtx);
  227         myiod = (int *)instance - nfs_asyncdaemon;
  228         /*
  229          * Main loop
  230          */
  231         for (;;) {
  232             while (((nmp = nfs_iodmount[myiod]) == NULL)
  233                    || !TAILQ_FIRST(&nmp->nm_bufq)) {
  234                 if (myiod >= nfs_iodmax)
  235                         goto finish;
  236                 if (nmp)
  237                         nmp->nm_bufqiods--;
  238                 nfs_iodwant[myiod] = curthread->td_proc;
  239                 nfs_iodmount[myiod] = NULL;
  240                 /*
  241                  * Always keep at least nfs_iodmin kthreads.
  242                  */
  243                 timo = (myiod < nfs_iodmin) ? 0 : nfs_iodmaxidle * hz;
  244                 error = msleep(&nfs_iodwant[myiod], &nfs_iod_mtx, PWAIT | PCATCH,
  245                     "-", timo);
  246                 if (error) {
  247                         nmp = nfs_iodmount[myiod];
  248                         /*
  249                          * Rechecking the nm_bufq closes a rare race where the 
  250                          * nfsiod is woken up at the exact time the idle timeout
  251                          * fires
  252                          */
  253                         if (nmp && TAILQ_FIRST(&nmp->nm_bufq))
  254                                 error = 0;
  255                         break;
  256                 }
  257             }
  258             if (error)
  259                     break;
  260             while ((bp = TAILQ_FIRST(&nmp->nm_bufq)) != NULL) {
  261                 int giant_locked = 0;
  262                     
  263                 /* Take one off the front of the list */
  264                 TAILQ_REMOVE(&nmp->nm_bufq, bp, b_freelist);
  265                 nmp->nm_bufqlen--;
  266                 if (nmp->nm_bufqwant && nmp->nm_bufqlen <= nfs_numasync) {
  267                     nmp->nm_bufqwant = 0;
  268                     wakeup(&nmp->nm_bufq);
  269                 }
  270                 mtx_unlock(&nfs_iod_mtx);
  271                 if (NFS_ISV4(bp->b_vp)) {
  272                         giant_locked = 1;
  273                         mtx_lock(&Giant);
  274                 }
  275                 if (bp->b_flags & B_DIRECT) {
  276                         KASSERT((bp->b_iocmd == BIO_WRITE), ("nfscvs_iod: BIO_WRITE not set"));
  277                         (void)nfs_doio_directwrite(bp);
  278                 } else {
  279                         if (bp->b_iocmd == BIO_READ)
  280                                 (void) nfs_doio(bp->b_vp, bp, bp->b_rcred, NULL);
  281                         else
  282                                 (void) nfs_doio(bp->b_vp, bp, bp->b_wcred, NULL);
  283                 }
  284                 if (giant_locked)
  285                         mtx_unlock(&Giant);
  286                 mtx_lock(&nfs_iod_mtx);
  287                 /*
  288                  * If there are more than one iod on this mount, then defect
  289                  * so that the iods can be shared out fairly between the mounts
  290                  */
  291                 if (nfs_defect && nmp->nm_bufqiods > 1) {
  292                     NFS_DPF(ASYNCIO,
  293                             ("nfssvc_iod: iod %d defecting from mount %p\n",
  294                              myiod, nmp));
  295                     nfs_iodmount[myiod] = NULL;
  296                     nmp->nm_bufqiods--;
  297                     break;
  298                 }
  299             }
  300         }
  301 finish:
  302         nfs_asyncdaemon[myiod] = 0;
  303         if (nmp)
  304             nmp->nm_bufqiods--;
  305         nfs_iodwant[myiod] = NULL;
  306         nfs_iodmount[myiod] = NULL;
  307         /* Someone may be waiting for the last nfsiod to terminate. */
  308         if (--nfs_numasync == 0)
  309                 wakeup(&nfs_numasync);
  310         mtx_unlock(&nfs_iod_mtx);
  311         if ((error == 0) || (error == EWOULDBLOCK))
  312                 kthread_exit(0);
  313         /* Abnormal termination */
  314         kthread_exit(1);
  315 }

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