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/fs/nfsclient/nfs_clnfsiod.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  *      from nfs_syscalls.c     8.5 (Berkeley) 3/30/95
   33  */
   34 
   35 #include <sys/cdefs.h>
   36 __FBSDID("$FreeBSD: releng/8.2/sys/fs/nfsclient/nfs_clnfsiod.c 210985 2010-08-07 01:05:02Z rmacklem $");
   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 <fs/nfs/nfsport.h>
   67 #include <fs/nfsclient/nfsmount.h>
   68 #include <fs/nfsclient/nfs.h>
   69 #include <fs/nfsclient/nfsnode.h>
   70 
   71 extern struct mtx ncl_iod_mutex;
   72 
   73 int ncl_numasync;
   74 enum nfsiod_state ncl_iodwant[NFS_MAXRAHEAD];
   75 struct nfsmount *ncl_iodmount[NFS_MAXRAHEAD];
   76 
   77 static void     nfssvc_iod(void *);
   78 
   79 static int nfs_asyncdaemon[NFS_MAXRAHEAD];
   80 
   81 SYSCTL_DECL(_vfs_newnfs);
   82 
   83 /* Maximum number of seconds a nfsiod kthread will sleep before exiting */
   84 static unsigned int ncl_iodmaxidle = 120;
   85 SYSCTL_UINT(_vfs_newnfs, OID_AUTO, iodmaxidle, CTLFLAG_RW, &ncl_iodmaxidle, 0, "");
   86 
   87 /* Maximum number of nfsiod kthreads */
   88 unsigned int ncl_iodmax = NFS_MAXRAHEAD;
   89 
   90 /* Minimum number of nfsiod kthreads to keep as spares */
   91 static unsigned int nfs_iodmin = 0;
   92 
   93 static int
   94 sysctl_iodmin(SYSCTL_HANDLER_ARGS)
   95 {
   96         int error, i;
   97         int newmin;
   98 
   99         newmin = nfs_iodmin;
  100         error = sysctl_handle_int(oidp, &newmin, 0, req);
  101         if (error || (req->newptr == NULL))
  102                 return (error);
  103         mtx_lock(&ncl_iod_mutex);
  104         if (newmin > ncl_iodmax) {
  105                 error = EINVAL;
  106                 goto out;
  107         }
  108         nfs_iodmin = newmin;
  109         if (ncl_numasync >= nfs_iodmin)
  110                 goto out;
  111         /*
  112          * If the current number of nfsiod is lower
  113          * than the new minimum, create some more.
  114          */
  115         for (i = nfs_iodmin - ncl_numasync; i > 0; i--)
  116                 ncl_nfsiodnew(0);
  117 out:
  118         mtx_unlock(&ncl_iod_mutex);     
  119         return (0);
  120 }
  121 SYSCTL_PROC(_vfs_newnfs, OID_AUTO, iodmin, CTLTYPE_UINT | CTLFLAG_RW, 0,
  122     sizeof (nfs_iodmin), sysctl_iodmin, "IU", "");
  123 
  124 
  125 static int
  126 sysctl_iodmax(SYSCTL_HANDLER_ARGS)
  127 {
  128         int error, i;
  129         int iod, newmax;
  130 
  131         newmax = ncl_iodmax;
  132         error = sysctl_handle_int(oidp, &newmax, 0, req);
  133         if (error || (req->newptr == NULL))
  134                 return (error);
  135         if (newmax > NFS_MAXRAHEAD)
  136                 return (EINVAL);
  137         mtx_lock(&ncl_iod_mutex);
  138         ncl_iodmax = newmax;
  139         if (ncl_numasync <= ncl_iodmax)
  140                 goto out;
  141         /*
  142          * If there are some asleep nfsiods that should
  143          * exit, wakeup() them so that they check ncl_iodmax
  144          * and exit.  Those who are active will exit as
  145          * soon as they finish I/O.
  146          */
  147         iod = ncl_numasync - 1;
  148         for (i = 0; i < ncl_numasync - ncl_iodmax; i++) {
  149                 if (ncl_iodwant[iod] == NFSIOD_AVAILABLE)
  150                         wakeup(&ncl_iodwant[iod]);
  151                 iod--;
  152         }
  153 out:
  154         mtx_unlock(&ncl_iod_mutex);
  155         return (0);
  156 }
  157 SYSCTL_PROC(_vfs_newnfs, OID_AUTO, iodmax, CTLTYPE_UINT | CTLFLAG_RW, 0,
  158     sizeof (ncl_iodmax), sysctl_iodmax, "IU", "");
  159 
  160 int
  161 ncl_nfsiodnew(int set_iodwant)
  162 {
  163         int error, i;
  164         int newiod;
  165 
  166         if (ncl_numasync >= ncl_iodmax)
  167                 return (-1);
  168         newiod = -1;
  169         for (i = 0; i < ncl_iodmax; i++)
  170                 if (nfs_asyncdaemon[i] == 0) {
  171                         nfs_asyncdaemon[i]++;
  172                         newiod = i;
  173                         break;
  174                 }
  175         if (newiod == -1)
  176                 return (-1);
  177         if (set_iodwant > 0)
  178                 ncl_iodwant[i] = NFSIOD_CREATED_FOR_NFS_ASYNCIO;
  179         mtx_unlock(&ncl_iod_mutex);
  180         error = kproc_create(nfssvc_iod, nfs_asyncdaemon + i, NULL, RFHIGHPID,
  181             0, "nfsiod %d", newiod);
  182         mtx_lock(&ncl_iod_mutex);
  183         if (error) {
  184                 if (set_iodwant > 0)
  185                         ncl_iodwant[i] = NFSIOD_NOT_AVAILABLE;
  186                 return (-1);
  187         }
  188         ncl_numasync++;
  189         return (newiod);
  190 }
  191 
  192 static void
  193 nfsiod_setup(void *dummy)
  194 {
  195         int i;
  196         int error;
  197 
  198         TUNABLE_INT_FETCH("vfs.newnfs.iodmin", &nfs_iodmin);
  199         nfscl_init();
  200         mtx_lock(&ncl_iod_mutex);
  201         /* Silently limit the start number of nfsiod's */
  202         if (nfs_iodmin > NFS_MAXRAHEAD)
  203                 nfs_iodmin = NFS_MAXRAHEAD;
  204 
  205         for (i = 0; i < nfs_iodmin; i++) {
  206                 error = ncl_nfsiodnew(0);
  207                 if (error == -1)
  208                         panic("newnfsiod_setup: ncl_nfsiodnew failed");
  209         }
  210         mtx_unlock(&ncl_iod_mutex);
  211 }
  212 SYSINIT(newnfsiod, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, nfsiod_setup, NULL);
  213 
  214 static int nfs_defect = 0;
  215 SYSCTL_INT(_vfs_newnfs, OID_AUTO, defect, CTLFLAG_RW, &nfs_defect, 0, "");
  216 
  217 /*
  218  * Asynchronous I/O daemons for client nfs.
  219  * They do read-ahead and write-behind operations on the block I/O cache.
  220  * Returns if we hit the timeout defined by the iodmaxidle sysctl.
  221  */
  222 static void
  223 nfssvc_iod(void *instance)
  224 {
  225         struct buf *bp;
  226         struct nfsmount *nmp;
  227         int myiod, timo;
  228         int error = 0;
  229 
  230         mtx_lock(&ncl_iod_mutex);
  231         myiod = (int *)instance - nfs_asyncdaemon;
  232         /*
  233          * Main loop
  234          */
  235         for (;;) {
  236             while (((nmp = ncl_iodmount[myiod]) == NULL)
  237                    || !TAILQ_FIRST(&nmp->nm_bufq)) {
  238                 if (myiod >= ncl_iodmax)
  239                         goto finish;
  240                 if (nmp)
  241                         nmp->nm_bufqiods--;
  242                 if (ncl_iodwant[myiod] == NFSIOD_NOT_AVAILABLE)
  243                         ncl_iodwant[myiod] = NFSIOD_AVAILABLE;
  244                 ncl_iodmount[myiod] = NULL;
  245                 /*
  246                  * Always keep at least nfs_iodmin kthreads.
  247                  */
  248                 timo = (myiod < nfs_iodmin) ? 0 : ncl_iodmaxidle * hz;
  249                 error = msleep(&ncl_iodwant[myiod], &ncl_iod_mutex, PWAIT | PCATCH,
  250                     "-", timo);
  251                 if (error) {
  252                         nmp = ncl_iodmount[myiod];
  253                         /*
  254                          * Rechecking the nm_bufq closes a rare race where the 
  255                          * nfsiod is woken up at the exact time the idle timeout
  256                          * fires
  257                          */
  258                         if (nmp && TAILQ_FIRST(&nmp->nm_bufq))
  259                                 error = 0;
  260                         break;
  261                 }
  262             }
  263             if (error)
  264                     break;
  265             while ((bp = TAILQ_FIRST(&nmp->nm_bufq)) != NULL) {
  266                     
  267                 /* Take one off the front of the list */
  268                 TAILQ_REMOVE(&nmp->nm_bufq, bp, b_freelist);
  269                 nmp->nm_bufqlen--;
  270                 if (nmp->nm_bufqwant && nmp->nm_bufqlen <= ncl_numasync) {
  271                     nmp->nm_bufqwant = 0;
  272                     wakeup(&nmp->nm_bufq);
  273                 }
  274                 mtx_unlock(&ncl_iod_mutex);
  275                 if (bp->b_flags & B_DIRECT) {
  276                         KASSERT((bp->b_iocmd == BIO_WRITE), ("nfscvs_iod: BIO_WRITE not set"));
  277                         (void)ncl_doio_directwrite(bp);
  278                 } else {
  279                         if (bp->b_iocmd == BIO_READ)
  280                                 (void) ncl_doio(bp->b_vp, bp, bp->b_rcred,
  281                                     NULL, 0);
  282                         else
  283                                 (void) ncl_doio(bp->b_vp, bp, bp->b_wcred,
  284                                     NULL, 0);
  285                 }
  286                 mtx_lock(&ncl_iod_mutex);
  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                     ncl_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         ncl_iodwant[myiod] = NFSIOD_NOT_AVAILABLE;
  306         ncl_iodmount[myiod] = NULL;
  307         /* Someone may be waiting for the last nfsiod to terminate. */
  308         if (--ncl_numasync == 0)
  309                 wakeup(&ncl_numasync);
  310         mtx_unlock(&ncl_iod_mutex);
  311         if ((error == 0) || (error == EWOULDBLOCK))
  312                 kproc_exit(0);
  313         /* Abnormal termination */
  314         kproc_exit(1);
  315 }

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