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/10.3/sys/fs/nfsclient/nfs_clnfsiod.c 249630 2013-04-18 23:20:16Z 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 #include <sys/taskqueue.h>
   63 
   64 #include <netinet/in.h>
   65 #include <netinet/tcp.h>
   66 
   67 #include <fs/nfs/nfsport.h>
   68 #include <fs/nfsclient/nfsmount.h>
   69 #include <fs/nfsclient/nfs.h>
   70 #include <fs/nfsclient/nfsnode.h>
   71 
   72 extern struct mtx       ncl_iod_mutex;
   73 extern struct task      ncl_nfsiodnew_task;
   74 
   75 int ncl_numasync;
   76 enum nfsiod_state ncl_iodwant[NFS_MAXASYNCDAEMON];
   77 struct nfsmount *ncl_iodmount[NFS_MAXASYNCDAEMON];
   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     "Max number of seconds an nfsiod kthread will sleep before exiting");
   89 
   90 /* Maximum number of nfsiod kthreads */
   91 unsigned int ncl_iodmax = 20;
   92 
   93 /* Minimum number of nfsiod kthreads to keep as spares */
   94 static unsigned int nfs_iodmin = 0;
   95 
   96 static int nfs_nfsiodnew_sync(void);
   97 
   98 static int
   99 sysctl_iodmin(SYSCTL_HANDLER_ARGS)
  100 {
  101         int error, i;
  102         int newmin;
  103 
  104         newmin = nfs_iodmin;
  105         error = sysctl_handle_int(oidp, &newmin, 0, req);
  106         if (error || (req->newptr == NULL))
  107                 return (error);
  108         mtx_lock(&ncl_iod_mutex);
  109         if (newmin > ncl_iodmax) {
  110                 error = EINVAL;
  111                 goto out;
  112         }
  113         nfs_iodmin = newmin;
  114         if (ncl_numasync >= nfs_iodmin)
  115                 goto out;
  116         /*
  117          * If the current number of nfsiod is lower
  118          * than the new minimum, create some more.
  119          */
  120         for (i = nfs_iodmin - ncl_numasync; i > 0; i--)
  121                 nfs_nfsiodnew_sync();
  122 out:
  123         mtx_unlock(&ncl_iod_mutex);     
  124         return (0);
  125 }
  126 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmin, CTLTYPE_UINT | CTLFLAG_RW, 0,
  127     sizeof (nfs_iodmin), sysctl_iodmin, "IU",
  128     "Min number of nfsiod kthreads to keep as spares");
  129 
  130 static int
  131 sysctl_iodmax(SYSCTL_HANDLER_ARGS)
  132 {
  133         int error, i;
  134         int iod, newmax;
  135 
  136         newmax = ncl_iodmax;
  137         error = sysctl_handle_int(oidp, &newmax, 0, req);
  138         if (error || (req->newptr == NULL))
  139                 return (error);
  140         if (newmax > NFS_MAXASYNCDAEMON)
  141                 return (EINVAL);
  142         mtx_lock(&ncl_iod_mutex);
  143         ncl_iodmax = newmax;
  144         if (ncl_numasync <= ncl_iodmax)
  145                 goto out;
  146         /*
  147          * If there are some asleep nfsiods that should
  148          * exit, wakeup() them so that they check ncl_iodmax
  149          * and exit.  Those who are active will exit as
  150          * soon as they finish I/O.
  151          */
  152         iod = ncl_numasync - 1;
  153         for (i = 0; i < ncl_numasync - ncl_iodmax; i++) {
  154                 if (ncl_iodwant[iod] == NFSIOD_AVAILABLE)
  155                         wakeup(&ncl_iodwant[iod]);
  156                 iod--;
  157         }
  158 out:
  159         mtx_unlock(&ncl_iod_mutex);
  160         return (0);
  161 }
  162 SYSCTL_PROC(_vfs_nfs, OID_AUTO, iodmax, CTLTYPE_UINT | CTLFLAG_RW, 0,
  163     sizeof (ncl_iodmax), sysctl_iodmax, "IU",
  164     "Max number of nfsiod kthreads");
  165 
  166 static int
  167 nfs_nfsiodnew_sync(void)
  168 {
  169         int error, i;
  170 
  171         mtx_assert(&ncl_iod_mutex, MA_OWNED);
  172         for (i = 0; i < ncl_iodmax; i++) {
  173                 if (nfs_asyncdaemon[i] == 0) {
  174                         nfs_asyncdaemon[i] = 1;
  175                         break;
  176                 }
  177         }
  178         if (i == ncl_iodmax)
  179                 return (0);
  180         mtx_unlock(&ncl_iod_mutex);
  181         error = kproc_create(nfssvc_iod, nfs_asyncdaemon + i, NULL,
  182             RFHIGHPID, 0, "newnfs %d", i);
  183         mtx_lock(&ncl_iod_mutex);
  184         if (error == 0) {
  185                 ncl_numasync++;
  186                 ncl_iodwant[i] = NFSIOD_AVAILABLE;
  187         } else
  188                 nfs_asyncdaemon[i] = 0;
  189         return (error);
  190 }
  191 
  192 void
  193 ncl_nfsiodnew_tq(__unused void *arg, int pending)
  194 {
  195 
  196         mtx_lock(&ncl_iod_mutex);
  197         while (pending > 0) {
  198                 pending--;
  199                 nfs_nfsiodnew_sync();
  200         }
  201         mtx_unlock(&ncl_iod_mutex);
  202 }
  203 
  204 void
  205 ncl_nfsiodnew(void)
  206 {
  207 
  208         mtx_assert(&ncl_iod_mutex, MA_OWNED);
  209         taskqueue_enqueue(taskqueue_thread, &ncl_nfsiodnew_task);
  210 }
  211 
  212 static void
  213 nfsiod_setup(void *dummy)
  214 {
  215         int error;
  216 
  217         TUNABLE_INT_FETCH("vfs.nfs.iodmin", &nfs_iodmin);
  218         nfscl_init();
  219         mtx_lock(&ncl_iod_mutex);
  220         /* Silently limit the start number of nfsiod's */
  221         if (nfs_iodmin > NFS_MAXASYNCDAEMON)
  222                 nfs_iodmin = NFS_MAXASYNCDAEMON;
  223 
  224         while (ncl_numasync < nfs_iodmin) {
  225                 error = nfs_nfsiodnew_sync();
  226                 if (error == -1)
  227                         panic("nfsiod_setup: nfs_nfsiodnew failed");
  228         }
  229         mtx_unlock(&ncl_iod_mutex);
  230 }
  231 SYSINIT(newnfsiod, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, nfsiod_setup, NULL);
  232 
  233 static int nfs_defect = 0;
  234 SYSCTL_INT(_vfs_nfs, OID_AUTO, defect, CTLFLAG_RW, &nfs_defect, 0,
  235     "Allow nfsiods to migrate serving different mounts");
  236 
  237 /*
  238  * Asynchronous I/O daemons for client nfs.
  239  * They do read-ahead and write-behind operations on the block I/O cache.
  240  * Returns if we hit the timeout defined by the iodmaxidle sysctl.
  241  */
  242 static void
  243 nfssvc_iod(void *instance)
  244 {
  245         struct buf *bp;
  246         struct nfsmount *nmp;
  247         int myiod, timo;
  248         int error = 0;
  249 
  250         mtx_lock(&ncl_iod_mutex);
  251         myiod = (int *)instance - nfs_asyncdaemon;
  252         /*
  253          * Main loop
  254          */
  255         for (;;) {
  256             while (((nmp = ncl_iodmount[myiod]) == NULL)
  257                    || !TAILQ_FIRST(&nmp->nm_bufq)) {
  258                 if (myiod >= ncl_iodmax)
  259                         goto finish;
  260                 if (nmp)
  261                         nmp->nm_bufqiods--;
  262                 if (ncl_iodwant[myiod] == NFSIOD_NOT_AVAILABLE)
  263                         ncl_iodwant[myiod] = NFSIOD_AVAILABLE;
  264                 ncl_iodmount[myiod] = NULL;
  265                 /*
  266                  * Always keep at least nfs_iodmin kthreads.
  267                  */
  268                 timo = (myiod < nfs_iodmin) ? 0 : nfs_iodmaxidle * hz;
  269                 error = msleep(&ncl_iodwant[myiod], &ncl_iod_mutex, PWAIT | PCATCH,
  270                     "-", timo);
  271                 if (error) {
  272                         nmp = ncl_iodmount[myiod];
  273                         /*
  274                          * Rechecking the nm_bufq closes a rare race where the 
  275                          * nfsiod is woken up at the exact time the idle timeout
  276                          * fires
  277                          */
  278                         if (nmp && TAILQ_FIRST(&nmp->nm_bufq))
  279                                 error = 0;
  280                         break;
  281                 }
  282             }
  283             if (error)
  284                     break;
  285             while ((bp = TAILQ_FIRST(&nmp->nm_bufq)) != NULL) {
  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 <= ncl_numasync) {
  290                     nmp->nm_bufqwant = 0;
  291                     wakeup(&nmp->nm_bufq);
  292                 }
  293                 mtx_unlock(&ncl_iod_mutex);
  294                 if (bp->b_flags & B_DIRECT) {
  295                         KASSERT((bp->b_iocmd == BIO_WRITE), ("nfscvs_iod: BIO_WRITE not set"));
  296                         (void)ncl_doio_directwrite(bp);
  297                 } else {
  298                         if (bp->b_iocmd == BIO_READ)
  299                                 (void) ncl_doio(bp->b_vp, bp, bp->b_rcred,
  300                                     NULL, 0);
  301                         else
  302                                 (void) ncl_doio(bp->b_vp, bp, bp->b_wcred,
  303                                     NULL, 0);
  304                 }
  305                 mtx_lock(&ncl_iod_mutex);
  306                 /*
  307                  * Make sure the nmp hasn't been dismounted as soon as
  308                  * ncl_doio() completes for the last buffer.
  309                  */
  310                 nmp = ncl_iodmount[myiod];
  311                 if (nmp == NULL)
  312                         break;
  313 
  314                 /*
  315                  * If there are more than one iod on this mount, then defect
  316                  * so that the iods can be shared out fairly between the mounts
  317                  */
  318                 if (nfs_defect && nmp->nm_bufqiods > 1) {
  319                     NFS_DPF(ASYNCIO,
  320                             ("nfssvc_iod: iod %d defecting from mount %p\n",
  321                              myiod, nmp));
  322                     ncl_iodmount[myiod] = NULL;
  323                     nmp->nm_bufqiods--;
  324                     break;
  325                 }
  326             }
  327         }
  328 finish:
  329         nfs_asyncdaemon[myiod] = 0;
  330         if (nmp)
  331             nmp->nm_bufqiods--;
  332         ncl_iodwant[myiod] = NFSIOD_NOT_AVAILABLE;
  333         ncl_iodmount[myiod] = NULL;
  334         /* Someone may be waiting for the last nfsiod to terminate. */
  335         if (--ncl_numasync == 0)
  336                 wakeup(&ncl_numasync);
  337         mtx_unlock(&ncl_iod_mutex);
  338         if ((error == 0) || (error == EWOULDBLOCK))
  339                 kproc_exit(0);
  340         /* Abnormal termination */
  341         kproc_exit(1);
  342 }

Cache object: e172ccf68c042ce63e5bccd3782f17d1


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