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: stable/8/sys/nfsclient/nfs_nfsiod.c 214977 2010-11-08 10:23:39Z kib $");
   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 #include <sys/taskqueue.h>
   63 
   64 #include <netinet/in.h>
   65 #include <netinet/tcp.h>
   66 
   67 #include <nfs/xdr_subs.h>
   68 #include <nfs/nfsproto.h>
   69 #include <nfsclient/nfs.h>
   70 #include <nfsclient/nfsm_subs.h>
   71 #include <nfsclient/nfsmount.h>
   72 #include <nfsclient/nfsnode.h>
   73 #include <nfs/nfs_lock.h>
   74 
   75 static MALLOC_DEFINE(M_NFSSVC, "nfsclient_srvsock", "Nfs server structure");
   76 
   77 static void     nfssvc_iod(void *);
   78 
   79 static int nfs_asyncdaemon[NFS_MAXASYNCDAEMON];
   80 
   81 SYSCTL_DECL(_vfs_nfs);
   82 
   83 /* Maximum number of seconds a nfsiod kthread will sleep before exiting */
   84 static unsigned int nfs_iodmaxidle = 120;
   85 SYSCTL_UINT(_vfs_nfs, OID_AUTO, iodmaxidle, CTLFLAG_RW, &nfs_iodmaxidle, 0,
   86     "Max number of seconds an nfsiod kthread will sleep before exiting");
   87 
   88 /* Maximum number of nfsiod kthreads */
   89 unsigned int nfs_iodmax = 20;
   90 
   91 /* Minimum number of nfsiod kthreads to keep as spares */
   92 static unsigned int nfs_iodmin = 0;
   93 
   94 static int nfs_nfsiodnew_sync(void);
   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         mtx_lock(&nfs_iod_mtx);
  107         if (newmin > nfs_iodmax) {
  108                 error = EINVAL;
  109                 goto out;
  110         }
  111         nfs_iodmin = newmin;
  112         if (nfs_numasync >= nfs_iodmin)
  113                 goto out;
  114         /*
  115          * If the current number of nfsiod is lower
  116          * than the new minimum, create some more.
  117          */
  118         for (i = nfs_iodmin - nfs_numasync; i > 0; i--)
  119                 nfs_nfsiodnew_sync();
  120 out:
  121         mtx_unlock(&nfs_iod_mtx);       
  122         return (0);
  123 }
  124 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmin, CTLTYPE_UINT | CTLFLAG_RW, 0,
  125     sizeof (nfs_iodmin), sysctl_iodmin, "IU",
  126     "Min number of nfsiod kthreads to keep as spares");
  127 
  128 
  129 static int
  130 sysctl_iodmax(SYSCTL_HANDLER_ARGS)
  131 {
  132         int error, i;
  133         int iod, newmax;
  134 
  135         newmax = nfs_iodmax;
  136         error = sysctl_handle_int(oidp, &newmax, 0, req);
  137         if (error || (req->newptr == NULL))
  138                 return (error);
  139         if (newmax > NFS_MAXASYNCDAEMON)
  140                 return (EINVAL);
  141         mtx_lock(&nfs_iod_mtx);
  142         nfs_iodmax = newmax;
  143         if (nfs_numasync <= nfs_iodmax)
  144                 goto out;
  145         /*
  146          * If there are some asleep nfsiods that should
  147          * exit, wakeup() them so that they check nfs_iodmax
  148          * and exit.  Those who are active will exit as
  149          * soon as they finish I/O.
  150          */
  151         iod = nfs_numasync - 1;
  152         for (i = 0; i < nfs_numasync - nfs_iodmax; i++) {
  153                 if (nfs_iodwant[iod] == NFSIOD_AVAILABLE)
  154                         wakeup(&nfs_iodwant[iod]);
  155                 iod--;
  156         }
  157 out:
  158         mtx_unlock(&nfs_iod_mtx);
  159         return (0);
  160 }
  161 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmax, CTLTYPE_UINT | CTLFLAG_RW, 0,
  162     sizeof (nfs_iodmax), sysctl_iodmax, "IU",
  163     "Max number of nfsiod kthreads");
  164 
  165 static int
  166 nfs_nfsiodnew_sync(void)
  167 {
  168         int error, i;
  169 
  170         mtx_assert(&nfs_iod_mtx, MA_OWNED);
  171         for (i = 0; i < nfs_iodmax; i++) {
  172                 if (nfs_asyncdaemon[i] == 0) {
  173                         nfs_asyncdaemon[i] = 1;
  174                         break;
  175                 }
  176         }
  177         if (i == nfs_iodmax)
  178                 return (0);
  179         mtx_unlock(&nfs_iod_mtx);
  180         error = kproc_create(nfssvc_iod, nfs_asyncdaemon + i, NULL,
  181             RFHIGHPID, 0, "nfsiod %d", i);
  182         mtx_lock(&nfs_iod_mtx);
  183         if (error == 0) {
  184                 nfs_numasync++;
  185                 nfs_iodwant[i] = NFSIOD_AVAILABLE;
  186         } else
  187                 nfs_asyncdaemon[i] = 0;
  188         return (error);
  189 }
  190 
  191 void
  192 nfs_nfsiodnew_tq(__unused void *arg, int pending)
  193 {
  194 
  195         mtx_lock(&nfs_iod_mtx);
  196         while (pending > 0) {
  197                 pending--;
  198                 nfs_nfsiodnew_sync();
  199         }
  200         mtx_unlock(&nfs_iod_mtx);
  201 }
  202 
  203 void
  204 nfs_nfsiodnew(void)
  205 {
  206 
  207         mtx_assert(&nfs_iod_mtx, MA_OWNED);
  208         taskqueue_enqueue(taskqueue_thread, &nfs_nfsiodnew_task);
  209 }
  210 
  211 static void
  212 nfsiod_setup(void *dummy)
  213 {
  214         int error;
  215 
  216         TUNABLE_INT_FETCH("vfs.nfs.iodmin", &nfs_iodmin);
  217         mtx_lock(&nfs_iod_mtx);
  218         /* Silently limit the start number of nfsiod's */
  219         if (nfs_iodmin > NFS_MAXASYNCDAEMON)
  220                 nfs_iodmin = NFS_MAXASYNCDAEMON;
  221 
  222         while (nfs_numasync < nfs_iodmin) {
  223                 error = nfs_nfsiodnew_sync();
  224                 if (error == -1)
  225                         panic("nfsiod_setup: nfs_nfsiodnew failed");
  226         }
  227         mtx_unlock(&nfs_iod_mtx);
  228 }
  229 SYSINIT(nfsiod, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, nfsiod_setup, NULL);
  230 
  231 static int nfs_defect = 0;
  232 SYSCTL_INT(_vfs_nfs, OID_AUTO, defect, CTLFLAG_RW, &nfs_defect, 0,
  233     "Allow nfsiods to migrate serving different mounts");
  234 
  235 /*
  236  * Asynchronous I/O daemons for client nfs.
  237  * They do read-ahead and write-behind operations on the block I/O cache.
  238  * Returns if we hit the timeout defined by the iodmaxidle sysctl.
  239  */
  240 static void
  241 nfssvc_iod(void *instance)
  242 {
  243         struct buf *bp;
  244         struct nfsmount *nmp;
  245         int myiod, timo;
  246         int error = 0;
  247 
  248         mtx_lock(&nfs_iod_mtx);
  249         myiod = (int *)instance - nfs_asyncdaemon;
  250         /*
  251          * Main loop
  252          */
  253         for (;;) {
  254             while (((nmp = nfs_iodmount[myiod]) == NULL)
  255                    || !TAILQ_FIRST(&nmp->nm_bufq)) {
  256                 if (myiod >= nfs_iodmax)
  257                         goto finish;
  258                 if (nmp)
  259                         nmp->nm_bufqiods--;
  260                 if (nfs_iodwant[myiod] == NFSIOD_NOT_AVAILABLE)
  261                         nfs_iodwant[myiod] = NFSIOD_AVAILABLE;
  262                 nfs_iodmount[myiod] = NULL;
  263                 /*
  264                  * Always keep at least nfs_iodmin kthreads.
  265                  */
  266                 timo = (myiod < nfs_iodmin) ? 0 : nfs_iodmaxidle * hz;
  267                 error = msleep(&nfs_iodwant[myiod], &nfs_iod_mtx, PWAIT | PCATCH,
  268                     "-", timo);
  269                 if (error) {
  270                         nmp = nfs_iodmount[myiod];
  271                         /*
  272                          * Rechecking the nm_bufq closes a rare race where the 
  273                          * nfsiod is woken up at the exact time the idle timeout
  274                          * fires
  275                          */
  276                         if (nmp && TAILQ_FIRST(&nmp->nm_bufq))
  277                                 error = 0;
  278                         break;
  279                 }
  280             }
  281             if (error)
  282                     break;
  283             while ((bp = TAILQ_FIRST(&nmp->nm_bufq)) != NULL) {
  284                 int giant_locked = 0;
  285                     
  286                 /* Take one off the front of the list */
  287                 TAILQ_REMOVE(&nmp->nm_bufq, bp, b_freelist);
  288                 nmp->nm_bufqlen--;
  289                 if (nmp->nm_bufqwant && nmp->nm_bufqlen <= nfs_numasync) {
  290                     nmp->nm_bufqwant = 0;
  291                     wakeup(&nmp->nm_bufq);
  292                 }
  293                 mtx_unlock(&nfs_iod_mtx);
  294                 if (NFS_ISV4(bp->b_vp)) {
  295                         giant_locked = 1;
  296                         mtx_lock(&Giant);
  297                 }
  298                 if (bp->b_flags & B_DIRECT) {
  299                         KASSERT((bp->b_iocmd == BIO_WRITE), ("nfscvs_iod: BIO_WRITE not set"));
  300                         (void)nfs_doio_directwrite(bp);
  301                 } else {
  302                         if (bp->b_iocmd == BIO_READ)
  303                                 (void) nfs_doio(bp->b_vp, bp, bp->b_rcred, NULL);
  304                         else
  305                                 (void) nfs_doio(bp->b_vp, bp, bp->b_wcred, NULL);
  306                 }
  307                 if (giant_locked)
  308                         mtx_unlock(&Giant);
  309                 mtx_lock(&nfs_iod_mtx);
  310                 /*
  311                  * If there are more than one iod on this mount, then defect
  312                  * so that the iods can be shared out fairly between the mounts
  313                  */
  314                 if (nfs_defect && nmp->nm_bufqiods > 1) {
  315                     NFS_DPF(ASYNCIO,
  316                             ("nfssvc_iod: iod %d defecting from mount %p\n",
  317                              myiod, nmp));
  318                     nfs_iodmount[myiod] = NULL;
  319                     nmp->nm_bufqiods--;
  320                     break;
  321                 }
  322             }
  323         }
  324 finish:
  325         nfs_asyncdaemon[myiod] = 0;
  326         if (nmp)
  327             nmp->nm_bufqiods--;
  328         nfs_iodwant[myiod] = NFSIOD_NOT_AVAILABLE;
  329         nfs_iodmount[myiod] = NULL;
  330         /* Someone may be waiting for the last nfsiod to terminate. */
  331         if (--nfs_numasync == 0)
  332                 wakeup(&nfs_numasync);
  333         mtx_unlock(&nfs_iod_mtx);
  334         if ((error == 0) || (error == EWOULDBLOCK))
  335                 kproc_exit(0);
  336         /* Abnormal termination */
  337         kproc_exit(1);
  338 }

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