nfs_lock.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. Berkeley Software Design Inc's name may not be used to endorse or
   15  *    promote products derived from this software without specific prior
   16  *    written permission.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
   22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  *
   30  *      from BSDI nfs_lock.c,v 2.4 1998/12/14 23:49:56 jch Exp
   31  */
   32 
   33 #include <sys/cdefs.h>
   34 __FBSDID("$FreeBSD$");
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/conf.h>
   39 #include <sys/fcntl.h>
   40 #include <sys/kernel.h>         /* for hz */
   41 #include <sys/limits.h>
   42 #include <sys/lock.h>
   43 #include <sys/malloc.h>
   44 #include <sys/lockf.h>          /* for hz */ /* Must come after sys/malloc.h */
   45 #include <sys/mbuf.h>
   46 #include <sys/mount.h>
   47 #include <sys/namei.h>
   48 #include <sys/priv.h>
   49 #include <sys/proc.h>
   50 #include <sys/resourcevar.h>
   51 #include <sys/socket.h>
   52 #include <sys/socket.h>
   53 #include <sys/unistd.h>
   54 #include <sys/vnode.h>
   55 
   56 #include <net/if.h>
   57 
   58 #include <nfs/nfsproto.h>
   59 #include <nfs/nfs_lock.h>
   60 #include <nfsclient/nfs.h>
   61 #include <nfsclient/nfsmount.h>
   62 #include <nfsclient/nfsnode.h>
   63 #include <nfsclient/nlminfo.h>
   64 
   65 extern void (*nlminfo_release_p)(struct proc *p);
   66 
   67 vop_advlock_t   *nfs_advlock_p = nfs_dolock;
   68 vop_reclaim_t   *nfs_reclaim_p = NULL;
   69 
   70 static MALLOC_DEFINE(M_NFSLOCK, "nfsclient_lock", "NFS lock request");
   71 static MALLOC_DEFINE(M_NLMINFO, "nfsclient_nlminfo",
   72     "NFS lock process structure");
   73 
   74 static int nfslockdans(struct thread *td, struct lockd_ans *ansp);
   75 static void nlminfo_release(struct proc *p);
   76 /*
   77  * --------------------------------------------------------------------
   78  * A miniature device driver which the userland uses to talk to us.
   79  *
   80  */
   81 
   82 static struct cdev *nfslock_dev;
   83 static struct mtx nfslock_mtx;
   84 static int nfslock_isopen;
   85 static TAILQ_HEAD(,__lock_msg)  nfslock_list;
   86 
   87 static int
   88 nfslock_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
   89 {
   90         int error;
   91 
   92         error = priv_check(td, PRIV_NFS_LOCKD);
   93         if (error)
   94                 return (error);
   95 
   96         mtx_lock(&nfslock_mtx);
   97         if (!nfslock_isopen) {
   98                 error = 0;
   99                 nfslock_isopen = 1;
  100         } else {
  101                 error = EOPNOTSUPP;
  102         }
  103         mtx_unlock(&nfslock_mtx);
  104                 
  105         return (error);
  106 }
  107 
  108 static int
  109 nfslock_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
  110 {
  111         struct __lock_msg *lm;
  112 
  113         mtx_lock(&nfslock_mtx);
  114         nfslock_isopen = 0;
  115         while (!TAILQ_EMPTY(&nfslock_list)) {
  116                 lm = TAILQ_FIRST(&nfslock_list);
  117                 /* XXX: answer request */
  118                 TAILQ_REMOVE(&nfslock_list, lm, lm_link);
  119                 free(lm, M_NFSLOCK);
  120         }
  121         mtx_unlock(&nfslock_mtx);
  122         return (0);
  123 }
  124 
  125 static int
  126 nfslock_read(struct cdev *dev, struct uio *uio, int ioflag)
  127 {
  128         int error;
  129         struct __lock_msg *lm;
  130 
  131         if (uio->uio_resid != sizeof *lm)
  132                 return (EOPNOTSUPP);
  133         lm = NULL;
  134         error = 0;
  135         mtx_lock(&nfslock_mtx);
  136         while (TAILQ_EMPTY(&nfslock_list)) {
  137                 error = msleep(&nfslock_list, &nfslock_mtx, PSOCK | PCATCH,
  138                     "nfslockd", 0);
  139                 if (error)
  140                         break;
  141         }
  142         if (!error) {
  143                 lm = TAILQ_FIRST(&nfslock_list);
  144                 TAILQ_REMOVE(&nfslock_list, lm, lm_link);
  145         }
  146         mtx_unlock(&nfslock_mtx);
  147         if (!error) {
  148                 error = uiomove(lm, sizeof *lm, uio);
  149                 free(lm, M_NFSLOCK);
  150         }
  151         return (error);
  152 }
  153 
  154 static int
  155 nfslock_write(struct cdev *dev, struct uio *uio, int ioflag)
  156 {
  157         struct lockd_ans la;
  158         int error;
  159 
  160         if (uio->uio_resid != sizeof la)
  161                 return (EOPNOTSUPP);
  162         error = uiomove(&la, sizeof la, uio);
  163         if (!error)
  164                 error = nfslockdans(curthread, &la);
  165         return (error);
  166 }
  167 
  168 static int
  169 nfslock_send(struct __lock_msg *lm)
  170 {
  171         struct __lock_msg *lm2;
  172         int error;
  173 
  174         error = 0;
  175         lm2 = malloc(sizeof *lm2, M_NFSLOCK, M_WAITOK);
  176         mtx_lock(&nfslock_mtx);
  177         if (nfslock_isopen) {
  178                 memcpy(lm2, lm, sizeof *lm2);
  179                 TAILQ_INSERT_TAIL(&nfslock_list, lm2, lm_link);
  180                 wakeup(&nfslock_list);
  181         } else {
  182                 error = EOPNOTSUPP;
  183         }
  184         mtx_unlock(&nfslock_mtx);
  185         if (error)
  186                 free(lm2, M_NFSLOCK);
  187         return (error);
  188 }
  189 
  190 static struct cdevsw nfslock_cdevsw = {
  191         .d_version =    D_VERSION,
  192         .d_open =       nfslock_open,
  193         .d_close =      nfslock_close,
  194         .d_read =       nfslock_read,
  195         .d_write =      nfslock_write,
  196         .d_name =       "nfslock"
  197 };
  198 
  199 static int
  200 nfslock_modevent(module_t mod __unused, int type, void *data __unused)
  201 {
  202 
  203         switch (type) {
  204         case MOD_LOAD:
  205                 if (bootverbose)
  206                         printf("nfslock: pseudo-device\n");
  207                 mtx_init(&nfslock_mtx, "nfslock", NULL, MTX_DEF);
  208                 TAILQ_INIT(&nfslock_list);
  209                 nlminfo_release_p = nlminfo_release;
  210                 nfslock_dev = make_dev(&nfslock_cdevsw, 0,
  211                     UID_ROOT, GID_KMEM, 0600, _PATH_NFSLCKDEV);
  212                 return (0);
  213         default:
  214                 return (EOPNOTSUPP);
  215         }
  216 }
  217 
  218 DEV_MODULE(nfslock, nfslock_modevent, NULL);
  219 MODULE_VERSION(nfslock, 1);
  220 
  221 
  222 /*
  223  * XXX
  224  * We have to let the process know if the call succeeded.  I'm using an extra
  225  * field in the p_nlminfo field in the proc structure, as it is already for
  226  * lockd stuff.
  227  */
  228 
  229 /*
  230  * nfs_advlock --
  231  *      NFS advisory byte-level locks.
  232  *
  233  * The vnode shall be (shared) locked on the entry, it is
  234  * unconditionally unlocked after.
  235  */
  236 int
  237 nfs_dolock(struct vop_advlock_args *ap)
  238 {
  239         LOCKD_MSG msg;
  240         struct thread *td;
  241         struct vnode *vp;
  242         int error;
  243         struct flock *fl;
  244         struct proc *p;
  245         struct nfsmount *nmp;
  246         struct timeval boottime;
  247 
  248         td = curthread;
  249         p = td->td_proc;
  250 
  251         vp = ap->a_vp;
  252         fl = ap->a_fl;
  253         nmp = VFSTONFS(vp->v_mount);
  254 
  255         ASSERT_VOP_LOCKED(vp, "nfs_dolock");
  256 
  257         nmp->nm_getinfo(vp, msg.lm_fh, &msg.lm_fh_len, &msg.lm_addr,
  258             &msg.lm_nfsv3, NULL, NULL);
  259         VOP_UNLOCK(vp, 0);
  260 
  261         /*
  262          * the NLM protocol doesn't allow the server to return an error
  263          * on ranges, so we do it.
  264          */
  265         if (fl->l_whence != SEEK_END) {
  266                 if ((fl->l_whence != SEEK_CUR && fl->l_whence != SEEK_SET) ||
  267                     fl->l_start < 0 ||
  268                     (fl->l_len < 0 &&
  269                      (fl->l_start == 0 || fl->l_start + fl->l_len < 0)))
  270                         return (EINVAL);
  271                 if (fl->l_len > 0 &&
  272                          (fl->l_len - 1 > OFF_MAX - fl->l_start))
  273                         return (EOVERFLOW);
  274         }
  275 
  276         /*
  277          * Fill in the information structure.
  278          */
  279         msg.lm_version = LOCKD_MSG_VERSION;
  280         msg.lm_msg_ident.pid = p->p_pid;
  281 
  282         mtx_lock(&Giant);
  283         /*
  284          * if there is no nfsowner table yet, allocate one.
  285          */
  286         if (p->p_nlminfo == NULL) {
  287                 p->p_nlminfo = malloc(sizeof(struct nlminfo),
  288                     M_NLMINFO, M_WAITOK | M_ZERO);
  289                 p->p_nlminfo->pid_start = p->p_stats->p_start;
  290                 getboottime(&boottime);
  291                 timevaladd(&p->p_nlminfo->pid_start, &boottime);
  292         }
  293         msg.lm_msg_ident.pid_start = p->p_nlminfo->pid_start;
  294         msg.lm_msg_ident.msg_seq = ++(p->p_nlminfo->msg_seq);
  295 
  296         msg.lm_fl = *fl;
  297         msg.lm_wait = ap->a_flags & F_WAIT;
  298         msg.lm_getlk = ap->a_op == F_GETLK;
  299         cru2x(td->td_ucred, &msg.lm_cred);
  300 
  301         for (;;) {
  302                 error = nfslock_send(&msg);
  303                 if (error)
  304                         goto out;
  305 
  306                 /* Unlocks succeed immediately.  */
  307                 if (fl->l_type == F_UNLCK)
  308                         goto out;
  309 
  310                 /*
  311                  * Retry after 20 seconds if we haven't gotten a response yet.
  312                  * This number was picked out of thin air... but is longer
  313                  * then even a reasonably loaded system should take (at least
  314                  * on a local network).  XXX Probably should use a back-off
  315                  * scheme.
  316                  *
  317                  * XXX: No PCATCH here since we currently have no useful
  318                  * way to signal to the userland rpc.lockd that the request
  319                  * has been aborted.  Once the rpc.lockd implementation
  320                  * can handle aborts, and we report them properly,
  321                  * PCATCH can be put back.  In the mean time, if we did
  322                  * permit aborting, the lock attempt would "get lost"
  323                  * and the lock would get stuck in the locked state.
  324                  */
  325                 error = tsleep(p->p_nlminfo, PUSER, "lockd", 20*hz);
  326                 if (error != 0) {
  327                         if (error == EWOULDBLOCK) {
  328                                 /*
  329                                  * We timed out, so we rewrite the request
  330                                  * to the fifo.
  331                                  */
  332                                 continue;
  333                         }
  334 
  335                         break;
  336                 }
  337 
  338                 if (msg.lm_getlk && p->p_nlminfo->retcode == 0) {
  339                         if (p->p_nlminfo->set_getlk_pid) {
  340                                 fl->l_sysid = 0; /* XXX */
  341                                 fl->l_pid = p->p_nlminfo->getlk_pid;
  342                         } else {
  343                                 fl->l_type = F_UNLCK;
  344                         }
  345                 }
  346                 error = p->p_nlminfo->retcode;
  347                 break;
  348         }
  349  out:
  350         mtx_unlock(&Giant);
  351         return (error);
  352 }
  353 
  354 /*
  355  * nfslockdans --
  356  *      NFS advisory byte-level locks answer from the lock daemon.
  357  */
  358 static int
  359 nfslockdans(struct thread *td, struct lockd_ans *ansp)
  360 {
  361         struct proc *targetp;
  362 
  363         /* the version should match, or we're out of sync */
  364         if (ansp->la_vers != LOCKD_ANS_VERSION)
  365                 return (EINVAL);
  366 
  367         /* Find the process, set its return errno and wake it up. */
  368         if ((targetp = pfind(ansp->la_msg_ident.pid)) == NULL)
  369                 return (ESRCH);
  370 
  371         /* verify the pid hasn't been reused (if we can), and it isn't waiting
  372          * for an answer from a more recent request.  We return an EPIPE if
  373          * the match fails, because we've already used ESRCH above, and this
  374          * is sort of like writing on a pipe after the reader has closed it.
  375          */
  376         if (targetp->p_nlminfo == NULL ||
  377             ((ansp->la_msg_ident.msg_seq != -1) &&
  378               (timevalcmp(&targetp->p_nlminfo->pid_start,
  379                         &ansp->la_msg_ident.pid_start, !=) ||
  380                targetp->p_nlminfo->msg_seq != ansp->la_msg_ident.msg_seq))) {
  381                 PROC_UNLOCK(targetp);
  382                 return (EPIPE);
  383         }
  384 
  385         targetp->p_nlminfo->retcode = ansp->la_errno;
  386         targetp->p_nlminfo->set_getlk_pid = ansp->la_set_getlk_pid;
  387         targetp->p_nlminfo->getlk_pid = ansp->la_getlk_pid;
  388 
  389         wakeup(targetp->p_nlminfo);
  390 
  391         PROC_UNLOCK(targetp);
  392         return (0);
  393 }
  394 
  395 /*
  396  * Free nlminfo attached to process.
  397  */
  398 void        
  399 nlminfo_release(struct proc *p)
  400 {  
  401         free(p->p_nlminfo, M_NLMINFO);
  402         p->p_nlminfo = NULL;
  403 }
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FreeBSD/Linux Kernel Cross Reference sys/nfs/nfs_lock.c

FreeBSD/Linux Kernel Cross Reference
sys/nfs/nfs_lock.c
