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/8.0/sys/fs/nfsclient/nfs_clnfsiod.c 191783 2009-05-04 15:23:58Z 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 #include <fs/nfsclient/nfs_lock.h>
   71 
   72 extern struct mtx ncl_iod_mutex;
   73 
   74 int ncl_numasync;
   75 struct proc *ncl_iodwant[NFS_MAXRAHEAD];
   76 struct nfsmount *ncl_iodmount[NFS_MAXRAHEAD];
   77 
   78 static void     nfssvc_iod(void *);
   79 
   80 static int nfs_asyncdaemon[NFS_MAXRAHEAD];
   81 
   82 SYSCTL_DECL(_vfs_newnfs);
   83 
   84 /* Maximum number of seconds a nfsiod kthread will sleep before exiting */
   85 static unsigned int ncl_iodmaxidle = 120;
   86 SYSCTL_UINT(_vfs_newnfs, OID_AUTO, iodmaxidle, CTLFLAG_RW, &ncl_iodmaxidle, 0, "");
   87 
   88 /* Maximum number of nfsiod kthreads */
   89 unsigned int ncl_iodmax = NFS_MAXRAHEAD;
   90 
   91 /* Minimum number of nfsiod kthreads to keep as spares */
   92 static unsigned int nfs_iodmin = 0;
   93 
   94 static int
   95 sysctl_iodmin(SYSCTL_HANDLER_ARGS)
   96 {
   97         int error, i;
   98         int newmin;
   99 
  100         newmin = nfs_iodmin;
  101         error = sysctl_handle_int(oidp, &newmin, 0, req);
  102         if (error || (req->newptr == NULL))
  103                 return (error);
  104         mtx_lock(&ncl_iod_mutex);
  105         if (newmin > ncl_iodmax) {
  106                 error = EINVAL;
  107                 goto out;
  108         }
  109         nfs_iodmin = newmin;
  110         if (ncl_numasync >= nfs_iodmin)
  111                 goto out;
  112         /*
  113          * If the current number of nfsiod is lower
  114          * than the new minimum, create some more.
  115          */
  116         for (i = nfs_iodmin - ncl_numasync; i > 0; i--)
  117                 ncl_nfsiodnew();
  118 out:
  119         mtx_unlock(&ncl_iod_mutex);     
  120         return (0);
  121 }
  122 SYSCTL_PROC(_vfs_newnfs, OID_AUTO, iodmin, CTLTYPE_UINT | CTLFLAG_RW, 0,
  123     sizeof (nfs_iodmin), sysctl_iodmin, "IU", "");
  124 
  125 
  126 static int
  127 sysctl_iodmax(SYSCTL_HANDLER_ARGS)
  128 {
  129         int error, i;
  130         int iod, newmax;
  131 
  132         newmax = ncl_iodmax;
  133         error = sysctl_handle_int(oidp, &newmax, 0, req);
  134         if (error || (req->newptr == NULL))
  135                 return (error);
  136         if (newmax > NFS_MAXRAHEAD)
  137                 return (EINVAL);
  138         mtx_lock(&ncl_iod_mutex);
  139         ncl_iodmax = newmax;
  140         if (ncl_numasync <= ncl_iodmax)
  141                 goto out;
  142         /*
  143          * If there are some asleep nfsiods that should
  144          * exit, wakeup() them so that they check ncl_iodmax
  145          * and exit.  Those who are active will exit as
  146          * soon as they finish I/O.
  147          */
  148         iod = ncl_numasync - 1;
  149         for (i = 0; i < ncl_numasync - ncl_iodmax; i++) {
  150                 if (ncl_iodwant[iod])
  151                         wakeup(&ncl_iodwant[iod]);
  152                 iod--;
  153         }
  154 out:
  155         mtx_unlock(&ncl_iod_mutex);
  156         return (0);
  157 }
  158 SYSCTL_PROC(_vfs_newnfs, OID_AUTO, iodmax, CTLTYPE_UINT | CTLFLAG_RW, 0,
  159     sizeof (ncl_iodmax), sysctl_iodmax, "IU", "");
  160 
  161 int
  162 ncl_nfsiodnew(void)
  163 {
  164         int error, i;
  165         int newiod;
  166 
  167         if (ncl_numasync >= ncl_iodmax)
  168                 return (-1);
  169         newiod = -1;
  170         for (i = 0; i < ncl_iodmax; i++)
  171                 if (nfs_asyncdaemon[i] == 0) {
  172                         nfs_asyncdaemon[i]++;
  173                         newiod = i;
  174                         break;
  175                 }
  176         if (newiod == -1)
  177                 return (-1);
  178         mtx_unlock(&ncl_iod_mutex);
  179         error = kproc_create(nfssvc_iod, nfs_asyncdaemon + i, NULL, RFHIGHPID,
  180             0, "nfsiod %d", newiod);
  181         mtx_lock(&ncl_iod_mutex);
  182         if (error)
  183                 return (-1);
  184         ncl_numasync++;
  185         return (newiod);
  186 }
  187 
  188 static void
  189 nfsiod_setup(void *dummy)
  190 {
  191         int i;
  192         int error;
  193 
  194         TUNABLE_INT_FETCH("vfs.newnfs.iodmin", &nfs_iodmin);
  195         nfscl_init();
  196         mtx_lock(&ncl_iod_mutex);
  197         /* Silently limit the start number of nfsiod's */
  198         if (nfs_iodmin > NFS_MAXRAHEAD)
  199                 nfs_iodmin = NFS_MAXRAHEAD;
  200 
  201         for (i = 0; i < nfs_iodmin; i++) {
  202                 error = ncl_nfsiodnew();
  203                 if (error == -1)
  204                         panic("newnfsiod_setup: ncl_nfsiodnew failed");
  205         }
  206         mtx_unlock(&ncl_iod_mutex);
  207 }
  208 SYSINIT(newnfsiod, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, nfsiod_setup, NULL);
  209 
  210 static int nfs_defect = 0;
  211 SYSCTL_INT(_vfs_newnfs, 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(&ncl_iod_mutex);
  227         myiod = (int *)instance - nfs_asyncdaemon;
  228         /*
  229          * Main loop
  230          */
  231         for (;;) {
  232             while (((nmp = ncl_iodmount[myiod]) == NULL)
  233                    || !TAILQ_FIRST(&nmp->nm_bufq)) {
  234                 if (myiod >= ncl_iodmax)
  235                         goto finish;
  236                 if (nmp)
  237                         nmp->nm_bufqiods--;
  238                 ncl_iodwant[myiod] = curthread->td_proc;
  239                 ncl_iodmount[myiod] = NULL;
  240                 /*
  241                  * Always keep at least nfs_iodmin kthreads.
  242                  */
  243                 timo = (myiod < nfs_iodmin) ? 0 : ncl_iodmaxidle * hz;
  244                 error = msleep(&ncl_iodwant[myiod], &ncl_iod_mutex, PWAIT | PCATCH,
  245                     "-", timo);
  246                 if (error) {
  247                         nmp = ncl_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                     
  262                 /* Take one off the front of the list */
  263                 TAILQ_REMOVE(&nmp->nm_bufq, bp, b_freelist);
  264                 nmp->nm_bufqlen--;
  265                 if (nmp->nm_bufqwant && nmp->nm_bufqlen <= ncl_numasync) {
  266                     nmp->nm_bufqwant = 0;
  267                     wakeup(&nmp->nm_bufq);
  268                 }
  269                 mtx_unlock(&ncl_iod_mutex);
  270                 if (bp->b_flags & B_DIRECT) {
  271                         KASSERT((bp->b_iocmd == BIO_WRITE), ("nfscvs_iod: BIO_WRITE not set"));
  272                         (void)ncl_doio_directwrite(bp);
  273                 } else {
  274                         if (bp->b_iocmd == BIO_READ)
  275                                 (void) ncl_doio(bp->b_vp, bp, bp->b_rcred, NULL);
  276                         else
  277                                 (void) ncl_doio(bp->b_vp, bp, bp->b_wcred, NULL);
  278                 }
  279                 mtx_lock(&ncl_iod_mutex);
  280                 /*
  281                  * If there are more than one iod on this mount, then defect
  282                  * so that the iods can be shared out fairly between the mounts
  283                  */
  284                 if (nfs_defect && nmp->nm_bufqiods > 1) {
  285                     NFS_DPF(ASYNCIO,
  286                             ("nfssvc_iod: iod %d defecting from mount %p\n",
  287                              myiod, nmp));
  288                     ncl_iodmount[myiod] = NULL;
  289                     nmp->nm_bufqiods--;
  290                     break;
  291                 }
  292             }
  293         }
  294 finish:
  295         nfs_asyncdaemon[myiod] = 0;
  296         if (nmp)
  297             nmp->nm_bufqiods--;
  298         ncl_iodwant[myiod] = NULL;
  299         ncl_iodmount[myiod] = NULL;
  300         /* Someone may be waiting for the last nfsiod to terminate. */
  301         if (--ncl_numasync == 0)
  302                 wakeup(&ncl_numasync);
  303         mtx_unlock(&ncl_iod_mutex);
  304         if ((error == 0) || (error == EWOULDBLOCK))
  305                 kproc_exit(0);
  306         /* Abnormal termination */
  307         kproc_exit(1);
  308 }

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