The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_lockf.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
    5  * Authors: Doug Rabson <dfr@rabson.org>
    6  * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
    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  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 /*-
   30  * Copyright (c) 1982, 1986, 1989, 1993
   31  *      The Regents of the University of California.  All rights reserved.
   32  *
   33  * This code is derived from software contributed to Berkeley by
   34  * Scooter Morris at Genentech Inc.
   35  *
   36  * Redistribution and use in source and binary forms, with or without
   37  * modification, are permitted provided that the following conditions
   38  * are met:
   39  * 1. Redistributions of source code must retain the above copyright
   40  *    notice, this list of conditions and the following disclaimer.
   41  * 2. Redistributions in binary form must reproduce the above copyright
   42  *    notice, this list of conditions and the following disclaimer in the
   43  *    documentation and/or other materials provided with the distribution.
   44  * 3. Neither the name of the University nor the names of its contributors
   45  *    may be used to endorse or promote products derived from this software
   46  *    without specific prior written permission.
   47  *
   48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   58  * SUCH DAMAGE.
   59  *
   60  *      @(#)ufs_lockf.c 8.3 (Berkeley) 1/6/94
   61  */
   62 
   63 #include <sys/cdefs.h>
   64 __FBSDID("$FreeBSD: releng/12.0/sys/kern/kern_lockf.c 333855 2018-05-19 05:04:38Z mmacy $");
   65 
   66 #include "opt_debug_lockf.h"
   67 
   68 #include <sys/param.h>
   69 #include <sys/systm.h>
   70 #include <sys/hash.h>
   71 #include <sys/kernel.h>
   72 #include <sys/limits.h>
   73 #include <sys/lock.h>
   74 #include <sys/mount.h>
   75 #include <sys/mutex.h>
   76 #include <sys/proc.h>
   77 #include <sys/sx.h>
   78 #include <sys/unistd.h>
   79 #include <sys/vnode.h>
   80 #include <sys/malloc.h>
   81 #include <sys/fcntl.h>
   82 #include <sys/lockf.h>
   83 #include <sys/taskqueue.h>
   84 
   85 #ifdef LOCKF_DEBUG
   86 #include <sys/sysctl.h>
   87 
   88 #include <ufs/ufs/extattr.h>
   89 #include <ufs/ufs/quota.h>
   90 #include <ufs/ufs/ufsmount.h>
   91 #include <ufs/ufs/inode.h>
   92 
   93 static int      lockf_debug = 0; /* control debug output */
   94 SYSCTL_INT(_debug, OID_AUTO, lockf_debug, CTLFLAG_RW, &lockf_debug, 0, "");
   95 #endif
   96 
   97 static MALLOC_DEFINE(M_LOCKF, "lockf", "Byte-range locking structures");
   98 
   99 struct owner_edge;
  100 struct owner_vertex;
  101 struct owner_vertex_list;
  102 struct owner_graph;
  103 
  104 #define NOLOCKF (struct lockf_entry *)0
  105 #define SELF    0x1
  106 #define OTHERS  0x2
  107 static void      lf_init(void *);
  108 static int       lf_hash_owner(caddr_t, struct vnode *, struct flock *, int);
  109 static int       lf_owner_matches(struct lock_owner *, caddr_t, struct flock *,
  110     int);
  111 static struct lockf_entry *
  112                  lf_alloc_lock(struct lock_owner *);
  113 static int       lf_free_lock(struct lockf_entry *);
  114 static int       lf_clearlock(struct lockf *, struct lockf_entry *);
  115 static int       lf_overlaps(struct lockf_entry *, struct lockf_entry *);
  116 static int       lf_blocks(struct lockf_entry *, struct lockf_entry *);
  117 static void      lf_free_edge(struct lockf_edge *);
  118 static struct lockf_edge *
  119                  lf_alloc_edge(void);
  120 static void      lf_alloc_vertex(struct lockf_entry *);
  121 static int       lf_add_edge(struct lockf_entry *, struct lockf_entry *);
  122 static void      lf_remove_edge(struct lockf_edge *);
  123 static void      lf_remove_outgoing(struct lockf_entry *);
  124 static void      lf_remove_incoming(struct lockf_entry *);
  125 static int       lf_add_outgoing(struct lockf *, struct lockf_entry *);
  126 static int       lf_add_incoming(struct lockf *, struct lockf_entry *);
  127 static int       lf_findoverlap(struct lockf_entry **, struct lockf_entry *,
  128     int);
  129 static struct lockf_entry *
  130                  lf_getblock(struct lockf *, struct lockf_entry *);
  131 static int       lf_getlock(struct lockf *, struct lockf_entry *, struct flock *);
  132 static void      lf_insert_lock(struct lockf *, struct lockf_entry *);
  133 static void      lf_wakeup_lock(struct lockf *, struct lockf_entry *);
  134 static void      lf_update_dependancies(struct lockf *, struct lockf_entry *,
  135     int all, struct lockf_entry_list *);
  136 static void      lf_set_start(struct lockf *, struct lockf_entry *, off_t,
  137         struct lockf_entry_list*);
  138 static void      lf_set_end(struct lockf *, struct lockf_entry *, off_t,
  139         struct lockf_entry_list*);
  140 static int       lf_setlock(struct lockf *, struct lockf_entry *,
  141     struct vnode *, void **cookiep);
  142 static int       lf_cancel(struct lockf *, struct lockf_entry *, void *);
  143 static void      lf_split(struct lockf *, struct lockf_entry *,
  144     struct lockf_entry *, struct lockf_entry_list *);
  145 #ifdef LOCKF_DEBUG
  146 static int       graph_reaches(struct owner_vertex *x, struct owner_vertex *y,
  147     struct owner_vertex_list *path);
  148 static void      graph_check(struct owner_graph *g, int checkorder);
  149 static void      graph_print_vertices(struct owner_vertex_list *set);
  150 #endif
  151 static int       graph_delta_forward(struct owner_graph *g,
  152     struct owner_vertex *x, struct owner_vertex *y,
  153     struct owner_vertex_list *delta);
  154 static int       graph_delta_backward(struct owner_graph *g,
  155     struct owner_vertex *x, struct owner_vertex *y,
  156     struct owner_vertex_list *delta);
  157 static int       graph_add_indices(int *indices, int n,
  158     struct owner_vertex_list *set);
  159 static int       graph_assign_indices(struct owner_graph *g, int *indices,
  160     int nextunused, struct owner_vertex_list *set);
  161 static int       graph_add_edge(struct owner_graph *g,
  162     struct owner_vertex *x, struct owner_vertex *y);
  163 static void      graph_remove_edge(struct owner_graph *g,
  164     struct owner_vertex *x, struct owner_vertex *y);
  165 static struct owner_vertex *graph_alloc_vertex(struct owner_graph *g,
  166     struct lock_owner *lo);
  167 static void      graph_free_vertex(struct owner_graph *g,
  168     struct owner_vertex *v);
  169 static struct owner_graph * graph_init(struct owner_graph *g);
  170 #ifdef LOCKF_DEBUG
  171 static void      lf_print(char *, struct lockf_entry *);
  172 static void      lf_printlist(char *, struct lockf_entry *);
  173 static void      lf_print_owner(struct lock_owner *);
  174 #endif
  175 
  176 /*
  177  * This structure is used to keep track of both local and remote lock
  178  * owners. The lf_owner field of the struct lockf_entry points back at
  179  * the lock owner structure. Each possible lock owner (local proc for
  180  * POSIX fcntl locks, local file for BSD flock locks or <pid,sysid>
  181  * pair for remote locks) is represented by a unique instance of
  182  * struct lock_owner.
  183  *
  184  * If a lock owner has a lock that blocks some other lock or a lock
  185  * that is waiting for some other lock, it also has a vertex in the
  186  * owner_graph below.
  187  *
  188  * Locks:
  189  * (s)          locked by state->ls_lock
  190  * (S)          locked by lf_lock_states_lock
  191  * (g)          locked by lf_owner_graph_lock
  192  * (c)          const until freeing
  193  */
  194 #define LOCK_OWNER_HASH_SIZE    256
  195 
  196 struct lock_owner {
  197         LIST_ENTRY(lock_owner) lo_link; /* (l) hash chain */
  198         int     lo_refs;            /* (l) Number of locks referring to this */
  199         int     lo_flags;           /* (c) Flags passwd to lf_advlock */
  200         caddr_t lo_id;              /* (c) Id value passed to lf_advlock */
  201         pid_t   lo_pid;             /* (c) Process Id of the lock owner */
  202         int     lo_sysid;           /* (c) System Id of the lock owner */
  203         int     lo_hash;            /* (c) Used to lock the appropriate chain */
  204         struct owner_vertex *lo_vertex; /* (g) entry in deadlock graph */
  205 };
  206 
  207 LIST_HEAD(lock_owner_list, lock_owner);
  208 
  209 struct lock_owner_chain {
  210         struct sx               lock;
  211         struct lock_owner_list  list;
  212 };
  213 
  214 static struct sx                lf_lock_states_lock;
  215 static struct lockf_list        lf_lock_states; /* (S) */
  216 static struct lock_owner_chain  lf_lock_owners[LOCK_OWNER_HASH_SIZE];
  217 
  218 /*
  219  * Structures for deadlock detection.
  220  *
  221  * We have two types of directed graph, the first is the set of locks,
  222  * both active and pending on a vnode. Within this graph, active locks
  223  * are terminal nodes in the graph (i.e. have no out-going
  224  * edges). Pending locks have out-going edges to each blocking active
  225  * lock that prevents the lock from being granted and also to each
  226  * older pending lock that would block them if it was active. The
  227  * graph for each vnode is naturally acyclic; new edges are only ever
  228  * added to or from new nodes (either new pending locks which only add
  229  * out-going edges or new active locks which only add in-coming edges)
  230  * therefore they cannot create loops in the lock graph.
  231  *
  232  * The second graph is a global graph of lock owners. Each lock owner
  233  * is a vertex in that graph and an edge is added to the graph
  234  * whenever an edge is added to a vnode graph, with end points
  235  * corresponding to owner of the new pending lock and the owner of the
  236  * lock upon which it waits. In order to prevent deadlock, we only add
  237  * an edge to this graph if the new edge would not create a cycle.
  238  * 
  239  * The lock owner graph is topologically sorted, i.e. if a node has
  240  * any outgoing edges, then it has an order strictly less than any
  241  * node to which it has an outgoing edge. We preserve this ordering
  242  * (and detect cycles) on edge insertion using Algorithm PK from the
  243  * paper "A Dynamic Topological Sort Algorithm for Directed Acyclic
  244  * Graphs" (ACM Journal of Experimental Algorithms, Vol 11, Article
  245  * No. 1.7)
  246  */
  247 struct owner_vertex;
  248 
  249 struct owner_edge {
  250         LIST_ENTRY(owner_edge) e_outlink; /* (g) link from's out-edge list */
  251         LIST_ENTRY(owner_edge) e_inlink;  /* (g) link to's in-edge list */
  252         int             e_refs;           /* (g) number of times added */
  253         struct owner_vertex *e_from;      /* (c) out-going from here */
  254         struct owner_vertex *e_to;        /* (c) in-coming to here */
  255 };
  256 LIST_HEAD(owner_edge_list, owner_edge);
  257 
  258 struct owner_vertex {
  259         TAILQ_ENTRY(owner_vertex) v_link; /* (g) workspace for edge insertion */
  260         uint32_t        v_gen;            /* (g) workspace for edge insertion */
  261         int             v_order;          /* (g) order of vertex in graph */
  262         struct owner_edge_list v_outedges;/* (g) list of out-edges */
  263         struct owner_edge_list v_inedges; /* (g) list of in-edges */
  264         struct lock_owner *v_owner;       /* (c) corresponding lock owner */
  265 };
  266 TAILQ_HEAD(owner_vertex_list, owner_vertex);
  267 
  268 struct owner_graph {
  269         struct owner_vertex** g_vertices; /* (g) pointers to vertices */
  270         int             g_size;           /* (g) number of vertices */
  271         int             g_space;          /* (g) space allocated for vertices */
  272         int             *g_indexbuf;      /* (g) workspace for loop detection */
  273         uint32_t        g_gen;            /* (g) increment when re-ordering */
  274 };
  275 
  276 static struct sx                lf_owner_graph_lock;
  277 static struct owner_graph       lf_owner_graph;
  278 
  279 /*
  280  * Initialise various structures and locks.
  281  */
  282 static void
  283 lf_init(void *dummy)
  284 {
  285         int i;
  286 
  287         sx_init(&lf_lock_states_lock, "lock states lock");
  288         LIST_INIT(&lf_lock_states);
  289 
  290         for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++) {
  291                 sx_init(&lf_lock_owners[i].lock, "lock owners lock");
  292                 LIST_INIT(&lf_lock_owners[i].list);
  293         }
  294 
  295         sx_init(&lf_owner_graph_lock, "owner graph lock");
  296         graph_init(&lf_owner_graph);
  297 }
  298 SYSINIT(lf_init, SI_SUB_LOCK, SI_ORDER_FIRST, lf_init, NULL);
  299 
  300 /*
  301  * Generate a hash value for a lock owner.
  302  */
  303 static int
  304 lf_hash_owner(caddr_t id, struct vnode *vp, struct flock *fl, int flags)
  305 {
  306         uint32_t h;
  307 
  308         if (flags & F_REMOTE) {
  309                 h = HASHSTEP(0, fl->l_pid);
  310                 h = HASHSTEP(h, fl->l_sysid);
  311         } else if (flags & F_FLOCK) {
  312                 h = ((uintptr_t) id) >> 7;
  313         } else {
  314                 h = ((uintptr_t) vp) >> 7;
  315         }
  316 
  317         return (h % LOCK_OWNER_HASH_SIZE);
  318 }
  319 
  320 /*
  321  * Return true if a lock owner matches the details passed to
  322  * lf_advlock.
  323  */
  324 static int
  325 lf_owner_matches(struct lock_owner *lo, caddr_t id, struct flock *fl,
  326     int flags)
  327 {
  328         if (flags & F_REMOTE) {
  329                 return lo->lo_pid == fl->l_pid
  330                         && lo->lo_sysid == fl->l_sysid;
  331         } else {
  332                 return lo->lo_id == id;
  333         }
  334 }
  335 
  336 static struct lockf_entry *
  337 lf_alloc_lock(struct lock_owner *lo)
  338 {
  339         struct lockf_entry *lf;
  340 
  341         lf = malloc(sizeof(struct lockf_entry), M_LOCKF, M_WAITOK|M_ZERO);
  342 
  343 #ifdef LOCKF_DEBUG
  344         if (lockf_debug & 4)
  345                 printf("Allocated lock %p\n", lf);
  346 #endif
  347         if (lo) {
  348                 sx_xlock(&lf_lock_owners[lo->lo_hash].lock);
  349                 lo->lo_refs++;
  350                 sx_xunlock(&lf_lock_owners[lo->lo_hash].lock);
  351                 lf->lf_owner = lo;
  352         }
  353 
  354         return (lf);
  355 }
  356 
  357 static int
  358 lf_free_lock(struct lockf_entry *lock)
  359 {
  360         struct sx *chainlock;
  361 
  362         KASSERT(lock->lf_refs > 0, ("lockf_entry negative ref count %p", lock));
  363         if (--lock->lf_refs > 0)
  364                 return (0);
  365         /*
  366          * Adjust the lock_owner reference count and
  367          * reclaim the entry if this is the last lock
  368          * for that owner.
  369          */
  370         struct lock_owner *lo = lock->lf_owner;
  371         if (lo) {
  372                 KASSERT(LIST_EMPTY(&lock->lf_outedges),
  373                     ("freeing lock with dependencies"));
  374                 KASSERT(LIST_EMPTY(&lock->lf_inedges),
  375                     ("freeing lock with dependants"));
  376                 chainlock = &lf_lock_owners[lo->lo_hash].lock;
  377                 sx_xlock(chainlock);
  378                 KASSERT(lo->lo_refs > 0, ("lock owner refcount"));
  379                 lo->lo_refs--;
  380                 if (lo->lo_refs == 0) {
  381 #ifdef LOCKF_DEBUG
  382                         if (lockf_debug & 1)
  383                                 printf("lf_free_lock: freeing lock owner %p\n",
  384                                     lo);
  385 #endif
  386                         if (lo->lo_vertex) {
  387                                 sx_xlock(&lf_owner_graph_lock);
  388                                 graph_free_vertex(&lf_owner_graph,
  389                                     lo->lo_vertex);
  390                                 sx_xunlock(&lf_owner_graph_lock);
  391                         }
  392                         LIST_REMOVE(lo, lo_link);
  393                         free(lo, M_LOCKF);
  394 #ifdef LOCKF_DEBUG
  395                         if (lockf_debug & 4)
  396                                 printf("Freed lock owner %p\n", lo);
  397 #endif
  398                 }
  399                 sx_unlock(chainlock);
  400         }
  401         if ((lock->lf_flags & F_REMOTE) && lock->lf_vnode) {
  402                 vrele(lock->lf_vnode);
  403                 lock->lf_vnode = NULL;
  404         }
  405 #ifdef LOCKF_DEBUG
  406         if (lockf_debug & 4)
  407                 printf("Freed lock %p\n", lock);
  408 #endif
  409         free(lock, M_LOCKF);
  410         return (1);
  411 }
  412 
  413 /*
  414  * Advisory record locking support
  415  */
  416 int
  417 lf_advlockasync(struct vop_advlockasync_args *ap, struct lockf **statep,
  418     u_quad_t size)
  419 {
  420         struct lockf *state;
  421         struct flock *fl = ap->a_fl;
  422         struct lockf_entry *lock;
  423         struct vnode *vp = ap->a_vp;
  424         caddr_t id = ap->a_id;
  425         int flags = ap->a_flags;
  426         int hash;
  427         struct lock_owner *lo;
  428         off_t start, end, oadd;
  429         int error;
  430 
  431         /*
  432          * Handle the F_UNLKSYS case first - no need to mess about
  433          * creating a lock owner for this one.
  434          */
  435         if (ap->a_op == F_UNLCKSYS) {
  436                 lf_clearremotesys(fl->l_sysid);
  437                 return (0);
  438         }
  439 
  440         /*
  441          * Convert the flock structure into a start and end.
  442          */
  443         switch (fl->l_whence) {
  444 
  445         case SEEK_SET:
  446         case SEEK_CUR:
  447                 /*
  448                  * Caller is responsible for adding any necessary offset
  449                  * when SEEK_CUR is used.
  450                  */
  451                 start = fl->l_start;
  452                 break;
  453 
  454         case SEEK_END:
  455                 if (size > OFF_MAX ||
  456                     (fl->l_start > 0 && size > OFF_MAX - fl->l_start))
  457                         return (EOVERFLOW);
  458                 start = size + fl->l_start;
  459                 break;
  460 
  461         default:
  462                 return (EINVAL);
  463         }
  464         if (start < 0)
  465                 return (EINVAL);
  466         if (fl->l_len < 0) {
  467                 if (start == 0)
  468                         return (EINVAL);
  469                 end = start - 1;
  470                 start += fl->l_len;
  471                 if (start < 0)
  472                         return (EINVAL);
  473         } else if (fl->l_len == 0) {
  474                 end = OFF_MAX;
  475         } else {
  476                 oadd = fl->l_len - 1;
  477                 if (oadd > OFF_MAX - start)
  478                         return (EOVERFLOW);
  479                 end = start + oadd;
  480         }
  481 
  482 retry_setlock:
  483 
  484         /*
  485          * Avoid the common case of unlocking when inode has no locks.
  486          */
  487         if (ap->a_op != F_SETLK && (*statep) == NULL) {
  488                 VI_LOCK(vp);
  489                 if ((*statep) == NULL) {
  490                         fl->l_type = F_UNLCK;
  491                         VI_UNLOCK(vp);
  492                         return (0);
  493                 }
  494                 VI_UNLOCK(vp);
  495         }
  496 
  497         /*
  498          * Map our arguments to an existing lock owner or create one
  499          * if this is the first time we have seen this owner.
  500          */
  501         hash = lf_hash_owner(id, vp, fl, flags);
  502         sx_xlock(&lf_lock_owners[hash].lock);
  503         LIST_FOREACH(lo, &lf_lock_owners[hash].list, lo_link)
  504                 if (lf_owner_matches(lo, id, fl, flags))
  505                         break;
  506         if (!lo) {
  507                 /*
  508                  * We initialise the lock with a reference
  509                  * count which matches the new lockf_entry
  510                  * structure created below.
  511                  */
  512                 lo = malloc(sizeof(struct lock_owner), M_LOCKF,
  513                     M_WAITOK|M_ZERO);
  514 #ifdef LOCKF_DEBUG
  515                 if (lockf_debug & 4)
  516                         printf("Allocated lock owner %p\n", lo);
  517 #endif
  518 
  519                 lo->lo_refs = 1;
  520                 lo->lo_flags = flags;
  521                 lo->lo_id = id;
  522                 lo->lo_hash = hash;
  523                 if (flags & F_REMOTE) {
  524                         lo->lo_pid = fl->l_pid;
  525                         lo->lo_sysid = fl->l_sysid;
  526                 } else if (flags & F_FLOCK) {
  527                         lo->lo_pid = -1;
  528                         lo->lo_sysid = 0;
  529                 } else {
  530                         struct proc *p = (struct proc *) id;
  531                         lo->lo_pid = p->p_pid;
  532                         lo->lo_sysid = 0;
  533                 }
  534                 lo->lo_vertex = NULL;
  535 
  536 #ifdef LOCKF_DEBUG
  537                 if (lockf_debug & 1) {
  538                         printf("lf_advlockasync: new lock owner %p ", lo);
  539                         lf_print_owner(lo);
  540                         printf("\n");
  541                 }
  542 #endif
  543 
  544                 LIST_INSERT_HEAD(&lf_lock_owners[hash].list, lo, lo_link);
  545         } else {
  546                 /*
  547                  * We have seen this lock owner before, increase its
  548                  * reference count to account for the new lockf_entry
  549                  * structure we create below.
  550                  */
  551                 lo->lo_refs++;
  552         }
  553         sx_xunlock(&lf_lock_owners[hash].lock);
  554 
  555         /*
  556          * Create the lockf structure. We initialise the lf_owner
  557          * field here instead of in lf_alloc_lock() to avoid paying
  558          * the lf_lock_owners_lock tax twice.
  559          */
  560         lock = lf_alloc_lock(NULL);
  561         lock->lf_refs = 1;
  562         lock->lf_start = start;
  563         lock->lf_end = end;
  564         lock->lf_owner = lo;
  565         lock->lf_vnode = vp;
  566         if (flags & F_REMOTE) {
  567                 /*
  568                  * For remote locks, the caller may release its ref to
  569                  * the vnode at any time - we have to ref it here to
  570                  * prevent it from being recycled unexpectedly.
  571                  */
  572                 vref(vp);
  573         }
  574 
  575         /*
  576          * XXX The problem is that VTOI is ufs specific, so it will
  577          * break LOCKF_DEBUG for all other FS's other than UFS because
  578          * it casts the vnode->data ptr to struct inode *.
  579          */
  580 /*      lock->lf_inode = VTOI(ap->a_vp); */
  581         lock->lf_inode = (struct inode *)0;
  582         lock->lf_type = fl->l_type;
  583         LIST_INIT(&lock->lf_outedges);
  584         LIST_INIT(&lock->lf_inedges);
  585         lock->lf_async_task = ap->a_task;
  586         lock->lf_flags = ap->a_flags;
  587 
  588         /*
  589          * Do the requested operation. First find our state structure
  590          * and create a new one if necessary - the caller's *statep
  591          * variable and the state's ls_threads count is protected by
  592          * the vnode interlock.
  593          */
  594         VI_LOCK(vp);
  595         if (vp->v_iflag & VI_DOOMED) {
  596                 VI_UNLOCK(vp);
  597                 lf_free_lock(lock);
  598                 return (ENOENT);
  599         }
  600 
  601         /*
  602          * Allocate a state structure if necessary.
  603          */
  604         state = *statep;
  605         if (state == NULL) {
  606                 struct lockf *ls;
  607 
  608                 VI_UNLOCK(vp);
  609 
  610                 ls = malloc(sizeof(struct lockf), M_LOCKF, M_WAITOK|M_ZERO);
  611                 sx_init(&ls->ls_lock, "ls_lock");
  612                 LIST_INIT(&ls->ls_active);
  613                 LIST_INIT(&ls->ls_pending);
  614                 ls->ls_threads = 1;
  615 
  616                 sx_xlock(&lf_lock_states_lock);
  617                 LIST_INSERT_HEAD(&lf_lock_states, ls, ls_link);
  618                 sx_xunlock(&lf_lock_states_lock);
  619 
  620                 /*
  621                  * Cope if we lost a race with some other thread while
  622                  * trying to allocate memory.
  623                  */
  624                 VI_LOCK(vp);
  625                 if (vp->v_iflag & VI_DOOMED) {
  626                         VI_UNLOCK(vp);
  627                         sx_xlock(&lf_lock_states_lock);
  628                         LIST_REMOVE(ls, ls_link);
  629                         sx_xunlock(&lf_lock_states_lock);
  630                         sx_destroy(&ls->ls_lock);
  631                         free(ls, M_LOCKF);
  632                         lf_free_lock(lock);
  633                         return (ENOENT);
  634                 }
  635                 if ((*statep) == NULL) {
  636                         state = *statep = ls;
  637                         VI_UNLOCK(vp);
  638                 } else {
  639                         state = *statep;
  640                         state->ls_threads++;
  641                         VI_UNLOCK(vp);
  642 
  643                         sx_xlock(&lf_lock_states_lock);
  644                         LIST_REMOVE(ls, ls_link);
  645                         sx_xunlock(&lf_lock_states_lock);
  646                         sx_destroy(&ls->ls_lock);
  647                         free(ls, M_LOCKF);
  648                 }
  649         } else {
  650                 state->ls_threads++;
  651                 VI_UNLOCK(vp);
  652         }
  653 
  654         sx_xlock(&state->ls_lock);
  655         /*
  656          * Recheck the doomed vnode after state->ls_lock is
  657          * locked. lf_purgelocks() requires that no new threads add
  658          * pending locks when vnode is marked by VI_DOOMED flag.
  659          */
  660         VI_LOCK(vp);
  661         if (vp->v_iflag & VI_DOOMED) {
  662                 state->ls_threads--;
  663                 wakeup(state);
  664                 VI_UNLOCK(vp);
  665                 sx_xunlock(&state->ls_lock);
  666                 lf_free_lock(lock);
  667                 return (ENOENT);
  668         }
  669         VI_UNLOCK(vp);
  670 
  671         switch (ap->a_op) {
  672         case F_SETLK:
  673                 error = lf_setlock(state, lock, vp, ap->a_cookiep);
  674                 break;
  675 
  676         case F_UNLCK:
  677                 error = lf_clearlock(state, lock);
  678                 lf_free_lock(lock);
  679                 break;
  680 
  681         case F_GETLK:
  682                 error = lf_getlock(state, lock, fl);
  683                 lf_free_lock(lock);
  684                 break;
  685 
  686         case F_CANCEL:
  687                 if (ap->a_cookiep)
  688                         error = lf_cancel(state, lock, *ap->a_cookiep);
  689                 else
  690                         error = EINVAL;
  691                 lf_free_lock(lock);
  692                 break;
  693 
  694         default:
  695                 lf_free_lock(lock);
  696                 error = EINVAL;
  697                 break;
  698         }
  699 
  700 #ifdef DIAGNOSTIC
  701         /*
  702          * Check for some can't happen stuff. In this case, the active
  703          * lock list becoming disordered or containing mutually
  704          * blocking locks. We also check the pending list for locks
  705          * which should be active (i.e. have no out-going edges).
  706          */
  707         LIST_FOREACH(lock, &state->ls_active, lf_link) {
  708                 struct lockf_entry *lf;
  709                 if (LIST_NEXT(lock, lf_link))
  710                         KASSERT((lock->lf_start
  711                                 <= LIST_NEXT(lock, lf_link)->lf_start),
  712                             ("locks disordered"));
  713                 LIST_FOREACH(lf, &state->ls_active, lf_link) {
  714                         if (lock == lf)
  715                                 break;
  716                         KASSERT(!lf_blocks(lock, lf),
  717                             ("two conflicting active locks"));
  718                         if (lock->lf_owner == lf->lf_owner)
  719                                 KASSERT(!lf_overlaps(lock, lf),
  720                                     ("two overlapping locks from same owner"));
  721                 }
  722         }
  723         LIST_FOREACH(lock, &state->ls_pending, lf_link) {
  724                 KASSERT(!LIST_EMPTY(&lock->lf_outedges),
  725                     ("pending lock which should be active"));
  726         }
  727 #endif
  728         sx_xunlock(&state->ls_lock);
  729 
  730         VI_LOCK(vp);
  731 
  732         state->ls_threads--;
  733         if (LIST_EMPTY(&state->ls_active) && state->ls_threads == 0) {
  734                 KASSERT(LIST_EMPTY(&state->ls_pending),
  735                     ("freeable state with pending locks"));
  736         } else {
  737                 wakeup(state);
  738         }
  739 
  740         VI_UNLOCK(vp);
  741 
  742         if (error == EDOOFUS) {
  743                 KASSERT(ap->a_op == F_SETLK, ("EDOOFUS"));
  744                 goto retry_setlock;
  745         }
  746         return (error);
  747 }
  748 
  749 int
  750 lf_advlock(struct vop_advlock_args *ap, struct lockf **statep, u_quad_t size)
  751 {
  752         struct vop_advlockasync_args a;
  753 
  754         a.a_vp = ap->a_vp;
  755         a.a_id = ap->a_id;
  756         a.a_op = ap->a_op;
  757         a.a_fl = ap->a_fl;
  758         a.a_flags = ap->a_flags;
  759         a.a_task = NULL;
  760         a.a_cookiep = NULL;
  761 
  762         return (lf_advlockasync(&a, statep, size));
  763 }
  764 
  765 void
  766 lf_purgelocks(struct vnode *vp, struct lockf **statep)
  767 {
  768         struct lockf *state;
  769         struct lockf_entry *lock, *nlock;
  770 
  771         /*
  772          * For this to work correctly, the caller must ensure that no
  773          * other threads enter the locking system for this vnode,
  774          * e.g. by checking VI_DOOMED. We wake up any threads that are
  775          * sleeping waiting for locks on this vnode and then free all
  776          * the remaining locks.
  777          */
  778         VI_LOCK(vp);
  779         KASSERT(vp->v_iflag & VI_DOOMED,
  780             ("lf_purgelocks: vp %p has not vgone yet", vp));
  781         state = *statep;
  782         if (state == NULL) {
  783                 VI_UNLOCK(vp);
  784                 return;
  785         }
  786         *statep = NULL;
  787         if (LIST_EMPTY(&state->ls_active) && state->ls_threads == 0) {
  788                 KASSERT(LIST_EMPTY(&state->ls_pending),
  789                     ("freeing state with pending locks"));
  790                 VI_UNLOCK(vp);
  791                 goto out_free;
  792         }
  793         state->ls_threads++;
  794         VI_UNLOCK(vp);
  795 
  796         sx_xlock(&state->ls_lock);
  797         sx_xlock(&lf_owner_graph_lock);
  798         LIST_FOREACH_SAFE(lock, &state->ls_pending, lf_link, nlock) {
  799                 LIST_REMOVE(lock, lf_link);
  800                 lf_remove_outgoing(lock);
  801                 lf_remove_incoming(lock);
  802 
  803                 /*
  804                  * If its an async lock, we can just free it
  805                  * here, otherwise we let the sleeping thread
  806                  * free it.
  807                  */
  808                 if (lock->lf_async_task) {
  809                         lf_free_lock(lock);
  810                 } else {
  811                         lock->lf_flags |= F_INTR;
  812                         wakeup(lock);
  813                 }
  814         }
  815         sx_xunlock(&lf_owner_graph_lock);
  816         sx_xunlock(&state->ls_lock);
  817 
  818         /*
  819          * Wait for all other threads, sleeping and otherwise
  820          * to leave.
  821          */
  822         VI_LOCK(vp);
  823         while (state->ls_threads > 1)
  824                 msleep(state, VI_MTX(vp), 0, "purgelocks", 0);
  825         VI_UNLOCK(vp);
  826 
  827         /*
  828          * We can just free all the active locks since they
  829          * will have no dependencies (we removed them all
  830          * above). We don't need to bother locking since we
  831          * are the last thread using this state structure.
  832          */
  833         KASSERT(LIST_EMPTY(&state->ls_pending),
  834             ("lock pending for %p", state));
  835         LIST_FOREACH_SAFE(lock, &state->ls_active, lf_link, nlock) {
  836                 LIST_REMOVE(lock, lf_link);
  837                 lf_free_lock(lock);
  838         }
  839 out_free:
  840         sx_xlock(&lf_lock_states_lock);
  841         LIST_REMOVE(state, ls_link);
  842         sx_xunlock(&lf_lock_states_lock);
  843         sx_destroy(&state->ls_lock);
  844         free(state, M_LOCKF);
  845 }
  846 
  847 /*
  848  * Return non-zero if locks 'x' and 'y' overlap.
  849  */
  850 static int
  851 lf_overlaps(struct lockf_entry *x, struct lockf_entry *y)
  852 {
  853 
  854         return (x->lf_start <= y->lf_end && x->lf_end >= y->lf_start);
  855 }
  856 
  857 /*
  858  * Return non-zero if lock 'x' is blocked by lock 'y' (or vice versa).
  859  */
  860 static int
  861 lf_blocks(struct lockf_entry *x, struct lockf_entry *y)
  862 {
  863 
  864         return x->lf_owner != y->lf_owner
  865                 && (x->lf_type == F_WRLCK || y->lf_type == F_WRLCK)
  866                 && lf_overlaps(x, y);
  867 }
  868 
  869 /*
  870  * Allocate a lock edge from the free list
  871  */
  872 static struct lockf_edge *
  873 lf_alloc_edge(void)
  874 {
  875 
  876         return (malloc(sizeof(struct lockf_edge), M_LOCKF, M_WAITOK|M_ZERO));
  877 }
  878 
  879 /*
  880  * Free a lock edge.
  881  */
  882 static void
  883 lf_free_edge(struct lockf_edge *e)
  884 {
  885 
  886         free(e, M_LOCKF);
  887 }
  888 
  889 
  890 /*
  891  * Ensure that the lock's owner has a corresponding vertex in the
  892  * owner graph.
  893  */
  894 static void
  895 lf_alloc_vertex(struct lockf_entry *lock)
  896 {
  897         struct owner_graph *g = &lf_owner_graph;
  898 
  899         if (!lock->lf_owner->lo_vertex)
  900                 lock->lf_owner->lo_vertex =
  901                         graph_alloc_vertex(g, lock->lf_owner);
  902 }
  903 
  904 /*
  905  * Attempt to record an edge from lock x to lock y. Return EDEADLK if
  906  * the new edge would cause a cycle in the owner graph.
  907  */
  908 static int
  909 lf_add_edge(struct lockf_entry *x, struct lockf_entry *y)
  910 {
  911         struct owner_graph *g = &lf_owner_graph;
  912         struct lockf_edge *e;
  913         int error;
  914 
  915 #ifdef DIAGNOSTIC
  916         LIST_FOREACH(e, &x->lf_outedges, le_outlink)
  917                 KASSERT(e->le_to != y, ("adding lock edge twice"));
  918 #endif
  919 
  920         /*
  921          * Make sure the two owners have entries in the owner graph.
  922          */
  923         lf_alloc_vertex(x);
  924         lf_alloc_vertex(y);
  925 
  926         error = graph_add_edge(g, x->lf_owner->lo_vertex,
  927             y->lf_owner->lo_vertex);
  928         if (error)
  929                 return (error);
  930 
  931         e = lf_alloc_edge();
  932         LIST_INSERT_HEAD(&x->lf_outedges, e, le_outlink);
  933         LIST_INSERT_HEAD(&y->lf_inedges, e, le_inlink);
  934         e->le_from = x;
  935         e->le_to = y;
  936 
  937         return (0);
  938 }
  939 
  940 /*
  941  * Remove an edge from the lock graph.
  942  */
  943 static void
  944 lf_remove_edge(struct lockf_edge *e)
  945 {
  946         struct owner_graph *g = &lf_owner_graph;
  947         struct lockf_entry *x = e->le_from;
  948         struct lockf_entry *y = e->le_to;
  949 
  950         graph_remove_edge(g, x->lf_owner->lo_vertex, y->lf_owner->lo_vertex);
  951         LIST_REMOVE(e, le_outlink);
  952         LIST_REMOVE(e, le_inlink);
  953         e->le_from = NULL;
  954         e->le_to = NULL;
  955         lf_free_edge(e);
  956 }
  957 
  958 /*
  959  * Remove all out-going edges from lock x.
  960  */
  961 static void
  962 lf_remove_outgoing(struct lockf_entry *x)
  963 {
  964         struct lockf_edge *e;
  965 
  966         while ((e = LIST_FIRST(&x->lf_outedges)) != NULL) {
  967                 lf_remove_edge(e);
  968         }
  969 }
  970 
  971 /*
  972  * Remove all in-coming edges from lock x.
  973  */
  974 static void
  975 lf_remove_incoming(struct lockf_entry *x)
  976 {
  977         struct lockf_edge *e;
  978 
  979         while ((e = LIST_FIRST(&x->lf_inedges)) != NULL) {
  980                 lf_remove_edge(e);
  981         }
  982 }
  983 
  984 /*
  985  * Walk the list of locks for the file and create an out-going edge
  986  * from lock to each blocking lock.
  987  */
  988 static int
  989 lf_add_outgoing(struct lockf *state, struct lockf_entry *lock)
  990 {
  991         struct lockf_entry *overlap;
  992         int error;
  993 
  994         LIST_FOREACH(overlap, &state->ls_active, lf_link) {
  995                 /*
  996                  * We may assume that the active list is sorted by
  997                  * lf_start.
  998                  */
  999                 if (overlap->lf_start > lock->lf_end)
 1000                         break;
 1001                 if (!lf_blocks(lock, overlap))
 1002                         continue;
 1003 
 1004                 /*
 1005                  * We've found a blocking lock. Add the corresponding
 1006                  * edge to the graphs and see if it would cause a
 1007                  * deadlock.
 1008                  */
 1009                 error = lf_add_edge(lock, overlap);
 1010 
 1011                 /*
 1012                  * The only error that lf_add_edge returns is EDEADLK.
 1013                  * Remove any edges we added and return the error.
 1014                  */
 1015                 if (error) {
 1016                         lf_remove_outgoing(lock);
 1017                         return (error);
 1018                 }
 1019         }
 1020 
 1021         /*
 1022          * We also need to add edges to sleeping locks that block
 1023          * us. This ensures that lf_wakeup_lock cannot grant two
 1024          * mutually blocking locks simultaneously and also enforces a
 1025          * 'first come, first served' fairness model. Note that this
 1026          * only happens if we are blocked by at least one active lock
 1027          * due to the call to lf_getblock in lf_setlock below.
 1028          */
 1029         LIST_FOREACH(overlap, &state->ls_pending, lf_link) {
 1030                 if (!lf_blocks(lock, overlap))
 1031                         continue;
 1032                 /*
 1033                  * We've found a blocking lock. Add the corresponding
 1034                  * edge to the graphs and see if it would cause a
 1035                  * deadlock.
 1036                  */
 1037                 error = lf_add_edge(lock, overlap);
 1038 
 1039                 /*
 1040                  * The only error that lf_add_edge returns is EDEADLK.
 1041                  * Remove any edges we added and return the error.
 1042                  */
 1043                 if (error) {
 1044                         lf_remove_outgoing(lock);
 1045                         return (error);
 1046                 }
 1047         }
 1048 
 1049         return (0);
 1050 }
 1051 
 1052 /*
 1053  * Walk the list of pending locks for the file and create an in-coming
 1054  * edge from lock to each blocking lock.
 1055  */
 1056 static int
 1057 lf_add_incoming(struct lockf *state, struct lockf_entry *lock)
 1058 {
 1059         struct lockf_entry *overlap;
 1060         int error;
 1061 
 1062         sx_assert(&state->ls_lock, SX_XLOCKED);
 1063         if (LIST_EMPTY(&state->ls_pending))
 1064                 return (0);
 1065 
 1066         error = 0;
 1067         sx_xlock(&lf_owner_graph_lock);
 1068         LIST_FOREACH(overlap, &state->ls_pending, lf_link) {
 1069                 if (!lf_blocks(lock, overlap))
 1070                         continue;
 1071 
 1072                 /*
 1073                  * We've found a blocking lock. Add the corresponding
 1074                  * edge to the graphs and see if it would cause a
 1075                  * deadlock.
 1076                  */
 1077                 error = lf_add_edge(overlap, lock);
 1078 
 1079                 /*
 1080                  * The only error that lf_add_edge returns is EDEADLK.
 1081                  * Remove any edges we added and return the error.
 1082                  */
 1083                 if (error) {
 1084                         lf_remove_incoming(lock);
 1085                         break;
 1086                 }
 1087         }
 1088         sx_xunlock(&lf_owner_graph_lock);
 1089         return (error);
 1090 }
 1091 
 1092 /*
 1093  * Insert lock into the active list, keeping list entries ordered by
 1094  * increasing values of lf_start.
 1095  */
 1096 static void
 1097 lf_insert_lock(struct lockf *state, struct lockf_entry *lock)
 1098 {
 1099         struct lockf_entry *lf, *lfprev;
 1100 
 1101         if (LIST_EMPTY(&state->ls_active)) {
 1102                 LIST_INSERT_HEAD(&state->ls_active, lock, lf_link);
 1103                 return;
 1104         }
 1105 
 1106         lfprev = NULL;
 1107         LIST_FOREACH(lf, &state->ls_active, lf_link) {
 1108                 if (lf->lf_start > lock->lf_start) {
 1109                         LIST_INSERT_BEFORE(lf, lock, lf_link);
 1110                         return;
 1111                 }
 1112                 lfprev = lf;
 1113         }
 1114         LIST_INSERT_AFTER(lfprev, lock, lf_link);
 1115 }
 1116 
 1117 /*
 1118  * Wake up a sleeping lock and remove it from the pending list now
 1119  * that all its dependencies have been resolved. The caller should
 1120  * arrange for the lock to be added to the active list, adjusting any
 1121  * existing locks for the same owner as needed.
 1122  */
 1123 static void
 1124 lf_wakeup_lock(struct lockf *state, struct lockf_entry *wakelock)
 1125 {
 1126 
 1127         /*
 1128          * Remove from ls_pending list and wake up the caller
 1129          * or start the async notification, as appropriate.
 1130          */
 1131         LIST_REMOVE(wakelock, lf_link);
 1132 #ifdef LOCKF_DEBUG
 1133         if (lockf_debug & 1)
 1134                 lf_print("lf_wakeup_lock: awakening", wakelock);
 1135 #endif /* LOCKF_DEBUG */
 1136         if (wakelock->lf_async_task) {
 1137                 taskqueue_enqueue(taskqueue_thread, wakelock->lf_async_task);
 1138         } else {
 1139                 wakeup(wakelock);
 1140         }
 1141 }
 1142 
 1143 /*
 1144  * Re-check all dependent locks and remove edges to locks that we no
 1145  * longer block. If 'all' is non-zero, the lock has been removed and
 1146  * we must remove all the dependencies, otherwise it has simply been
 1147  * reduced but remains active. Any pending locks which have been been
 1148  * unblocked are added to 'granted'
 1149  */
 1150 static void
 1151 lf_update_dependancies(struct lockf *state, struct lockf_entry *lock, int all,
 1152         struct lockf_entry_list *granted)
 1153 {
 1154         struct lockf_edge *e, *ne;
 1155         struct lockf_entry *deplock;
 1156 
 1157         LIST_FOREACH_SAFE(e, &lock->lf_inedges, le_inlink, ne) {
 1158                 deplock = e->le_from;
 1159                 if (all || !lf_blocks(lock, deplock)) {
 1160                         sx_xlock(&lf_owner_graph_lock);
 1161                         lf_remove_edge(e);
 1162                         sx_xunlock(&lf_owner_graph_lock);
 1163                         if (LIST_EMPTY(&deplock->lf_outedges)) {
 1164                                 lf_wakeup_lock(state, deplock);
 1165                                 LIST_INSERT_HEAD(granted, deplock, lf_link);
 1166                         }
 1167                 }
 1168         }
 1169 }
 1170 
 1171 /*
 1172  * Set the start of an existing active lock, updating dependencies and
 1173  * adding any newly woken locks to 'granted'.
 1174  */
 1175 static void
 1176 lf_set_start(struct lockf *state, struct lockf_entry *lock, off_t new_start,
 1177         struct lockf_entry_list *granted)
 1178 {
 1179 
 1180         KASSERT(new_start >= lock->lf_start, ("can't increase lock"));
 1181         lock->lf_start = new_start;
 1182         LIST_REMOVE(lock, lf_link);
 1183         lf_insert_lock(state, lock);
 1184         lf_update_dependancies(state, lock, FALSE, granted);
 1185 }
 1186 
 1187 /*
 1188  * Set the end of an existing active lock, updating dependencies and
 1189  * adding any newly woken locks to 'granted'.
 1190  */
 1191 static void
 1192 lf_set_end(struct lockf *state, struct lockf_entry *lock, off_t new_end,
 1193         struct lockf_entry_list *granted)
 1194 {
 1195 
 1196         KASSERT(new_end <= lock->lf_end, ("can't increase lock"));
 1197         lock->lf_end = new_end;
 1198         lf_update_dependancies(state, lock, FALSE, granted);
 1199 }
 1200 
 1201 /*
 1202  * Add a lock to the active list, updating or removing any current
 1203  * locks owned by the same owner and processing any pending locks that
 1204  * become unblocked as a result. This code is also used for unlock
 1205  * since the logic for updating existing locks is identical.
 1206  *
 1207  * As a result of processing the new lock, we may unblock existing
 1208  * pending locks as a result of downgrading/unlocking. We simply
 1209  * activate the newly granted locks by looping.
 1210  *
 1211  * Since the new lock already has its dependencies set up, we always
 1212  * add it to the list (unless its an unlock request). This may
 1213  * fragment the lock list in some pathological cases but its probably
 1214  * not a real problem.
 1215  */
 1216 static void
 1217 lf_activate_lock(struct lockf *state, struct lockf_entry *lock)
 1218 {
 1219         struct lockf_entry *overlap, *lf;
 1220         struct lockf_entry_list granted;
 1221         int ovcase;
 1222 
 1223         LIST_INIT(&granted);
 1224         LIST_INSERT_HEAD(&granted, lock, lf_link);
 1225 
 1226         while (!LIST_EMPTY(&granted)) {
 1227                 lock = LIST_FIRST(&granted);
 1228                 LIST_REMOVE(lock, lf_link);
 1229 
 1230                 /*
 1231                  * Skip over locks owned by other processes.  Handle
 1232                  * any locks that overlap and are owned by ourselves.
 1233                  */
 1234                 overlap = LIST_FIRST(&state->ls_active);
 1235                 for (;;) {
 1236                         ovcase = lf_findoverlap(&overlap, lock, SELF);
 1237 
 1238 #ifdef LOCKF_DEBUG
 1239                         if (ovcase && (lockf_debug & 2)) {
 1240                                 printf("lf_setlock: overlap %d", ovcase);
 1241                                 lf_print("", overlap);
 1242                         }
 1243 #endif
 1244                         /*
 1245                          * Six cases:
 1246                          *      0) no overlap
 1247                          *      1) overlap == lock
 1248                          *      2) overlap contains lock
 1249                          *      3) lock contains overlap
 1250                          *      4) overlap starts before lock
 1251                          *      5) overlap ends after lock
 1252                          */
 1253                         switch (ovcase) {
 1254                         case 0: /* no overlap */
 1255                                 break;
 1256 
 1257                         case 1: /* overlap == lock */
 1258                                 /*
 1259                                  * We have already setup the
 1260                                  * dependants for the new lock, taking
 1261                                  * into account a possible downgrade
 1262                                  * or unlock. Remove the old lock.
 1263                                  */
 1264                                 LIST_REMOVE(overlap, lf_link);
 1265                                 lf_update_dependancies(state, overlap, TRUE,
 1266                                         &granted);
 1267                                 lf_free_lock(overlap);
 1268                                 break;
 1269 
 1270                         case 2: /* overlap contains lock */
 1271                                 /*
 1272                                  * Just split the existing lock.
 1273                                  */
 1274                                 lf_split(state, overlap, lock, &granted);
 1275                                 break;
 1276 
 1277                         case 3: /* lock contains overlap */
 1278                                 /*
 1279                                  * Delete the overlap and advance to
 1280                                  * the next entry in the list.
 1281                                  */
 1282                                 lf = LIST_NEXT(overlap, lf_link);
 1283                                 LIST_REMOVE(overlap, lf_link);
 1284                                 lf_update_dependancies(state, overlap, TRUE,
 1285                                         &granted);
 1286                                 lf_free_lock(overlap);
 1287                                 overlap = lf;
 1288                                 continue;
 1289 
 1290                         case 4: /* overlap starts before lock */
 1291                                 /*
 1292                                  * Just update the overlap end and
 1293                                  * move on.
 1294                                  */
 1295                                 lf_set_end(state, overlap, lock->lf_start - 1,
 1296                                     &granted);
 1297                                 overlap = LIST_NEXT(overlap, lf_link);
 1298                                 continue;
 1299 
 1300                         case 5: /* overlap ends after lock */
 1301                                 /*
 1302                                  * Change the start of overlap and
 1303                                  * re-insert.
 1304                                  */
 1305                                 lf_set_start(state, overlap, lock->lf_end + 1,
 1306                                     &granted);
 1307                                 break;
 1308                         }
 1309                         break;
 1310                 }
 1311 #ifdef LOCKF_DEBUG
 1312                 if (lockf_debug & 1) {
 1313                         if (lock->lf_type != F_UNLCK)
 1314                                 lf_print("lf_activate_lock: activated", lock);
 1315                         else
 1316                                 lf_print("lf_activate_lock: unlocked", lock);
 1317                         lf_printlist("lf_activate_lock", lock);
 1318                 }
 1319 #endif /* LOCKF_DEBUG */
 1320                 if (lock->lf_type != F_UNLCK)
 1321                         lf_insert_lock(state, lock);
 1322         }
 1323 }
 1324 
 1325 /*
 1326  * Cancel a pending lock request, either as a result of a signal or a
 1327  * cancel request for an async lock.
 1328  */
 1329 static void
 1330 lf_cancel_lock(struct lockf *state, struct lockf_entry *lock)
 1331 {
 1332         struct lockf_entry_list granted;
 1333 
 1334         /*
 1335          * Note it is theoretically possible that cancelling this lock
 1336          * may allow some other pending lock to become
 1337          * active. Consider this case:
 1338          *
 1339          * Owner        Action          Result          Dependencies
 1340          * 
 1341          * A:           lock [0..0]     succeeds        
 1342          * B:           lock [2..2]     succeeds        
 1343          * C:           lock [1..2]     blocked         C->B
 1344          * D:           lock [0..1]     blocked         C->B,D->A,D->C
 1345          * A:           unlock [0..0]                   C->B,D->C
 1346          * C:           cancel [1..2]   
 1347          */
 1348 
 1349         LIST_REMOVE(lock, lf_link);
 1350 
 1351         /*
 1352          * Removing out-going edges is simple.
 1353          */
 1354         sx_xlock(&lf_owner_graph_lock);
 1355         lf_remove_outgoing(lock);
 1356         sx_xunlock(&lf_owner_graph_lock);
 1357 
 1358         /*
 1359          * Removing in-coming edges may allow some other lock to
 1360          * become active - we use lf_update_dependancies to figure
 1361          * this out.
 1362          */
 1363         LIST_INIT(&granted);
 1364         lf_update_dependancies(state, lock, TRUE, &granted);
 1365         lf_free_lock(lock);
 1366 
 1367         /*
 1368          * Feed any newly active locks to lf_activate_lock.
 1369          */
 1370         while (!LIST_EMPTY(&granted)) {
 1371                 lock = LIST_FIRST(&granted);
 1372                 LIST_REMOVE(lock, lf_link);
 1373                 lf_activate_lock(state, lock);
 1374         }
 1375 }
 1376 
 1377 /*
 1378  * Set a byte-range lock.
 1379  */
 1380 static int
 1381 lf_setlock(struct lockf *state, struct lockf_entry *lock, struct vnode *vp,
 1382     void **cookiep)
 1383 {
 1384         static char lockstr[] = "lockf";
 1385         int error, priority, stops_deferred;
 1386 
 1387 #ifdef LOCKF_DEBUG
 1388         if (lockf_debug & 1)
 1389                 lf_print("lf_setlock", lock);
 1390 #endif /* LOCKF_DEBUG */
 1391 
 1392         /*
 1393          * Set the priority
 1394          */
 1395         priority = PLOCK;
 1396         if (lock->lf_type == F_WRLCK)
 1397                 priority += 4;
 1398         if (!(lock->lf_flags & F_NOINTR))
 1399                 priority |= PCATCH;
 1400         /*
 1401          * Scan lock list for this file looking for locks that would block us.
 1402          */
 1403         if (lf_getblock(state, lock)) {
 1404                 /*
 1405                  * Free the structure and return if nonblocking.
 1406                  */
 1407                 if ((lock->lf_flags & F_WAIT) == 0
 1408                     && lock->lf_async_task == NULL) {
 1409                         lf_free_lock(lock);
 1410                         error = EAGAIN;
 1411                         goto out;
 1412                 }
 1413 
 1414                 /*
 1415                  * For flock type locks, we must first remove
 1416                  * any shared locks that we hold before we sleep
 1417                  * waiting for an exclusive lock.
 1418                  */
 1419                 if ((lock->lf_flags & F_FLOCK) &&
 1420                     lock->lf_type == F_WRLCK) {
 1421                         lock->lf_type = F_UNLCK;
 1422                         lf_activate_lock(state, lock);
 1423                         lock->lf_type = F_WRLCK;
 1424                 }
 1425 
 1426                 /*
 1427                  * We are blocked. Create edges to each blocking lock,
 1428                  * checking for deadlock using the owner graph. For
 1429                  * simplicity, we run deadlock detection for all
 1430                  * locks, posix and otherwise.
 1431                  */
 1432                 sx_xlock(&lf_owner_graph_lock);
 1433                 error = lf_add_outgoing(state, lock);
 1434                 sx_xunlock(&lf_owner_graph_lock);
 1435 
 1436                 if (error) {
 1437 #ifdef LOCKF_DEBUG
 1438                         if (lockf_debug & 1)
 1439                                 lf_print("lf_setlock: deadlock", lock);
 1440 #endif
 1441                         lf_free_lock(lock);
 1442                         goto out;
 1443                 }
 1444 
 1445                 /*
 1446                  * We have added edges to everything that blocks
 1447                  * us. Sleep until they all go away.
 1448                  */
 1449                 LIST_INSERT_HEAD(&state->ls_pending, lock, lf_link);
 1450 #ifdef LOCKF_DEBUG
 1451                 if (lockf_debug & 1) {
 1452                         struct lockf_edge *e;
 1453                         LIST_FOREACH(e, &lock->lf_outedges, le_outlink) {
 1454                                 lf_print("lf_setlock: blocking on", e->le_to);
 1455                                 lf_printlist("lf_setlock", e->le_to);
 1456                         }
 1457                 }
 1458 #endif /* LOCKF_DEBUG */
 1459 
 1460                 if ((lock->lf_flags & F_WAIT) == 0) {
 1461                         /*
 1462                          * The caller requested async notification -
 1463                          * this callback happens when the blocking
 1464                          * lock is released, allowing the caller to
 1465                          * make another attempt to take the lock.
 1466                          */
 1467                         *cookiep = (void *) lock;
 1468                         error = EINPROGRESS;
 1469                         goto out;
 1470                 }
 1471 
 1472                 lock->lf_refs++;
 1473                 stops_deferred = sigdeferstop(SIGDEFERSTOP_ERESTART);
 1474                 error = sx_sleep(lock, &state->ls_lock, priority, lockstr, 0);
 1475                 sigallowstop(stops_deferred);
 1476                 if (lf_free_lock(lock)) {
 1477                         error = EDOOFUS;
 1478                         goto out;
 1479                 }
 1480 
 1481                 /*
 1482                  * We may have been awakened by a signal and/or by a
 1483                  * debugger continuing us (in which cases we must
 1484                  * remove our lock graph edges) and/or by another
 1485                  * process releasing a lock (in which case our edges
 1486                  * have already been removed and we have been moved to
 1487                  * the active list). We may also have been woken by
 1488                  * lf_purgelocks which we report to the caller as
 1489                  * EINTR. In that case, lf_purgelocks will have
 1490                  * removed our lock graph edges.
 1491                  *
 1492                  * Note that it is possible to receive a signal after
 1493                  * we were successfully woken (and moved to the active
 1494                  * list) but before we resumed execution. In this
 1495                  * case, our lf_outedges list will be clear. We
 1496                  * pretend there was no error.
 1497                  *
 1498                  * Note also, if we have been sleeping long enough, we
 1499                  * may now have incoming edges from some newer lock
 1500                  * which is waiting behind us in the queue.
 1501                  */
 1502                 if (lock->lf_flags & F_INTR) {
 1503                         error = EINTR;
 1504                         lf_free_lock(lock);
 1505                         goto out;
 1506                 }
 1507                 if (LIST_EMPTY(&lock->lf_outedges)) {
 1508                         error = 0;
 1509                 } else {
 1510                         lf_cancel_lock(state, lock);
 1511                         goto out;
 1512                 }
 1513 #ifdef LOCKF_DEBUG
 1514                 if (lockf_debug & 1) {
 1515                         lf_print("lf_setlock: granted", lock);
 1516                 }
 1517 #endif
 1518                 goto out;
 1519         }
 1520         /*
 1521          * It looks like we are going to grant the lock. First add
 1522          * edges from any currently pending lock that the new lock
 1523          * would block.
 1524          */
 1525         error = lf_add_incoming(state, lock);
 1526         if (error) {
 1527 #ifdef LOCKF_DEBUG
 1528                 if (lockf_debug & 1)
 1529                         lf_print("lf_setlock: deadlock", lock);
 1530 #endif
 1531                 lf_free_lock(lock);
 1532                 goto out;
 1533         }
 1534 
 1535         /*
 1536          * No blocks!!  Add the lock.  Note that we will
 1537          * downgrade or upgrade any overlapping locks this
 1538          * process already owns.
 1539          */
 1540         lf_activate_lock(state, lock);
 1541         error = 0;
 1542 out:
 1543         return (error);
 1544 }
 1545 
 1546 /*
 1547  * Remove a byte-range lock on an inode.
 1548  *
 1549  * Generally, find the lock (or an overlap to that lock)
 1550  * and remove it (or shrink it), then wakeup anyone we can.
 1551  */
 1552 static int
 1553 lf_clearlock(struct lockf *state, struct lockf_entry *unlock)
 1554 {
 1555         struct lockf_entry *overlap;
 1556 
 1557         overlap = LIST_FIRST(&state->ls_active);
 1558 
 1559         if (overlap == NOLOCKF)
 1560                 return (0);
 1561 #ifdef LOCKF_DEBUG
 1562         if (unlock->lf_type != F_UNLCK)
 1563                 panic("lf_clearlock: bad type");
 1564         if (lockf_debug & 1)
 1565                 lf_print("lf_clearlock", unlock);
 1566 #endif /* LOCKF_DEBUG */
 1567 
 1568         lf_activate_lock(state, unlock);
 1569 
 1570         return (0);
 1571 }
 1572 
 1573 /*
 1574  * Check whether there is a blocking lock, and if so return its
 1575  * details in '*fl'.
 1576  */
 1577 static int
 1578 lf_getlock(struct lockf *state, struct lockf_entry *lock, struct flock *fl)
 1579 {
 1580         struct lockf_entry *block;
 1581 
 1582 #ifdef LOCKF_DEBUG
 1583         if (lockf_debug & 1)
 1584                 lf_print("lf_getlock", lock);
 1585 #endif /* LOCKF_DEBUG */
 1586 
 1587         if ((block = lf_getblock(state, lock))) {
 1588                 fl->l_type = block->lf_type;
 1589                 fl->l_whence = SEEK_SET;
 1590                 fl->l_start = block->lf_start;
 1591                 if (block->lf_end == OFF_MAX)
 1592                         fl->l_len = 0;
 1593                 else
 1594                         fl->l_len = block->lf_end - block->lf_start + 1;
 1595                 fl->l_pid = block->lf_owner->lo_pid;
 1596                 fl->l_sysid = block->lf_owner->lo_sysid;
 1597         } else {
 1598                 fl->l_type = F_UNLCK;
 1599         }
 1600         return (0);
 1601 }
 1602 
 1603 /*
 1604  * Cancel an async lock request.
 1605  */
 1606 static int
 1607 lf_cancel(struct lockf *state, struct lockf_entry *lock, void *cookie)
 1608 {
 1609         struct lockf_entry *reallock;
 1610 
 1611         /*
 1612          * We need to match this request with an existing lock
 1613          * request.
 1614          */
 1615         LIST_FOREACH(reallock, &state->ls_pending, lf_link) {
 1616                 if ((void *) reallock == cookie) {
 1617                         /*
 1618                          * Double-check that this lock looks right
 1619                          * (maybe use a rolling ID for the cancel
 1620                          * cookie instead?)
 1621                          */
 1622                         if (!(reallock->lf_vnode == lock->lf_vnode
 1623                                 && reallock->lf_start == lock->lf_start
 1624                                 && reallock->lf_end == lock->lf_end)) {
 1625                                 return (ENOENT);
 1626                         }
 1627 
 1628                         /*
 1629                          * Make sure this lock was async and then just
 1630                          * remove it from its wait lists.
 1631                          */
 1632                         if (!reallock->lf_async_task) {
 1633                                 return (ENOENT);
 1634                         }
 1635 
 1636                         /*
 1637                          * Note that since any other thread must take
 1638                          * state->ls_lock before it can possibly
 1639                          * trigger the async callback, we are safe
 1640                          * from a race with lf_wakeup_lock, i.e. we
 1641                          * can free the lock (actually our caller does
 1642                          * this).
 1643                          */
 1644                         lf_cancel_lock(state, reallock);
 1645                         return (0);
 1646                 }
 1647         }
 1648 
 1649         /*
 1650          * We didn't find a matching lock - not much we can do here.
 1651          */
 1652         return (ENOENT);
 1653 }
 1654 
 1655 /*
 1656  * Walk the list of locks for an inode and
 1657  * return the first blocking lock.
 1658  */
 1659 static struct lockf_entry *
 1660 lf_getblock(struct lockf *state, struct lockf_entry *lock)
 1661 {
 1662         struct lockf_entry *overlap;
 1663 
 1664         LIST_FOREACH(overlap, &state->ls_active, lf_link) {
 1665                 /*
 1666                  * We may assume that the active list is sorted by
 1667                  * lf_start.
 1668                  */
 1669                 if (overlap->lf_start > lock->lf_end)
 1670                         break;
 1671                 if (!lf_blocks(lock, overlap))
 1672                         continue;
 1673                 return (overlap);
 1674         }
 1675         return (NOLOCKF);
 1676 }
 1677 
 1678 /*
 1679  * Walk the list of locks for an inode to find an overlapping lock (if
 1680  * any) and return a classification of that overlap.
 1681  *
 1682  * Arguments:
 1683  *      *overlap        The place in the lock list to start looking
 1684  *      lock            The lock which is being tested
 1685  *      type            Pass 'SELF' to test only locks with the same
 1686  *                      owner as lock, or 'OTHER' to test only locks
 1687  *                      with a different owner
 1688  *
 1689  * Returns one of six values:
 1690  *      0) no overlap
 1691  *      1) overlap == lock
 1692  *      2) overlap contains lock
 1693  *      3) lock contains overlap
 1694  *      4) overlap starts before lock
 1695  *      5) overlap ends after lock
 1696  *
 1697  * If there is an overlapping lock, '*overlap' is set to point at the
 1698  * overlapping lock.
 1699  *
 1700  * NOTE: this returns only the FIRST overlapping lock.  There
 1701  *       may be more than one.
 1702  */
 1703 static int
 1704 lf_findoverlap(struct lockf_entry **overlap, struct lockf_entry *lock, int type)
 1705 {
 1706         struct lockf_entry *lf;
 1707         off_t start, end;
 1708         int res;
 1709 
 1710         if ((*overlap) == NOLOCKF) {
 1711                 return (0);
 1712         }
 1713 #ifdef LOCKF_DEBUG
 1714         if (lockf_debug & 2)
 1715                 lf_print("lf_findoverlap: looking for overlap in", lock);
 1716 #endif /* LOCKF_DEBUG */
 1717         start = lock->lf_start;
 1718         end = lock->lf_end;
 1719         res = 0;
 1720         while (*overlap) {
 1721                 lf = *overlap;
 1722                 if (lf->lf_start > end)
 1723                         break;
 1724                 if (((type & SELF) && lf->lf_owner != lock->lf_owner) ||
 1725                     ((type & OTHERS) && lf->lf_owner == lock->lf_owner)) {
 1726                         *overlap = LIST_NEXT(lf, lf_link);
 1727                         continue;
 1728                 }
 1729 #ifdef LOCKF_DEBUG
 1730                 if (lockf_debug & 2)
 1731                         lf_print("\tchecking", lf);
 1732 #endif /* LOCKF_DEBUG */
 1733                 /*
 1734                  * OK, check for overlap
 1735                  *
 1736                  * Six cases:
 1737                  *      0) no overlap
 1738                  *      1) overlap == lock
 1739                  *      2) overlap contains lock
 1740                  *      3) lock contains overlap
 1741                  *      4) overlap starts before lock
 1742                  *      5) overlap ends after lock
 1743                  */
 1744                 if (start > lf->lf_end) {
 1745                         /* Case 0 */
 1746 #ifdef LOCKF_DEBUG
 1747                         if (lockf_debug & 2)
 1748                                 printf("no overlap\n");
 1749 #endif /* LOCKF_DEBUG */
 1750                         *overlap = LIST_NEXT(lf, lf_link);
 1751                         continue;
 1752                 }
 1753                 if (lf->lf_start == start && lf->lf_end == end) {
 1754                         /* Case 1 */
 1755 #ifdef LOCKF_DEBUG
 1756                         if (lockf_debug & 2)
 1757                                 printf("overlap == lock\n");
 1758 #endif /* LOCKF_DEBUG */
 1759                         res = 1;
 1760                         break;
 1761                 }
 1762                 if (lf->lf_start <= start && lf->lf_end >= end) {
 1763                         /* Case 2 */
 1764 #ifdef LOCKF_DEBUG
 1765                         if (lockf_debug & 2)
 1766                                 printf("overlap contains lock\n");
 1767 #endif /* LOCKF_DEBUG */
 1768                         res = 2;
 1769                         break;
 1770                 }
 1771                 if (start <= lf->lf_start && end >= lf->lf_end) {
 1772                         /* Case 3 */
 1773 #ifdef LOCKF_DEBUG
 1774                         if (lockf_debug & 2)
 1775                                 printf("lock contains overlap\n");
 1776 #endif /* LOCKF_DEBUG */
 1777                         res = 3;
 1778                         break;
 1779                 }
 1780                 if (lf->lf_start < start && lf->lf_end >= start) {
 1781                         /* Case 4 */
 1782 #ifdef LOCKF_DEBUG
 1783                         if (lockf_debug & 2)
 1784                                 printf("overlap starts before lock\n");
 1785 #endif /* LOCKF_DEBUG */
 1786                         res = 4;
 1787                         break;
 1788                 }
 1789                 if (lf->lf_start > start && lf->lf_end > end) {
 1790                         /* Case 5 */
 1791 #ifdef LOCKF_DEBUG
 1792                         if (lockf_debug & 2)
 1793                                 printf("overlap ends after lock\n");
 1794 #endif /* LOCKF_DEBUG */
 1795                         res = 5;
 1796                         break;
 1797                 }
 1798                 panic("lf_findoverlap: default");
 1799         }
 1800         return (res);
 1801 }
 1802 
 1803 /*
 1804  * Split an the existing 'lock1', based on the extent of the lock
 1805  * described by 'lock2'. The existing lock should cover 'lock2'
 1806  * entirely.
 1807  *
 1808  * Any pending locks which have been been unblocked are added to
 1809  * 'granted'
 1810  */
 1811 static void
 1812 lf_split(struct lockf *state, struct lockf_entry *lock1,
 1813     struct lockf_entry *lock2, struct lockf_entry_list *granted)
 1814 {
 1815         struct lockf_entry *splitlock;
 1816 
 1817 #ifdef LOCKF_DEBUG
 1818         if (lockf_debug & 2) {
 1819                 lf_print("lf_split", lock1);
 1820                 lf_print("splitting from", lock2);
 1821         }
 1822 #endif /* LOCKF_DEBUG */
 1823         /*
 1824          * Check to see if we don't need to split at all.
 1825          */
 1826         if (lock1->lf_start == lock2->lf_start) {
 1827                 lf_set_start(state, lock1, lock2->lf_end + 1, granted);
 1828                 return;
 1829         }
 1830         if (lock1->lf_end == lock2->lf_end) {
 1831                 lf_set_end(state, lock1, lock2->lf_start - 1, granted);
 1832                 return;
 1833         }
 1834         /*
 1835          * Make a new lock consisting of the last part of
 1836          * the encompassing lock.
 1837          */
 1838         splitlock = lf_alloc_lock(lock1->lf_owner);
 1839         memcpy(splitlock, lock1, sizeof *splitlock);
 1840         splitlock->lf_refs = 1;
 1841         if (splitlock->lf_flags & F_REMOTE)
 1842                 vref(splitlock->lf_vnode);
 1843 
 1844         /*
 1845          * This cannot cause a deadlock since any edges we would add
 1846          * to splitlock already exist in lock1. We must be sure to add
 1847          * necessary dependencies to splitlock before we reduce lock1
 1848          * otherwise we may accidentally grant a pending lock that
 1849          * was blocked by the tail end of lock1.
 1850          */
 1851         splitlock->lf_start = lock2->lf_end + 1;
 1852         LIST_INIT(&splitlock->lf_outedges);
 1853         LIST_INIT(&splitlock->lf_inedges);
 1854         lf_add_incoming(state, splitlock);
 1855 
 1856         lf_set_end(state, lock1, lock2->lf_start - 1, granted);
 1857 
 1858         /*
 1859          * OK, now link it in
 1860          */
 1861         lf_insert_lock(state, splitlock);
 1862 }
 1863 
 1864 struct lockdesc {
 1865         STAILQ_ENTRY(lockdesc) link;
 1866         struct vnode *vp;
 1867         struct flock fl;
 1868 };
 1869 STAILQ_HEAD(lockdesclist, lockdesc);
 1870 
 1871 int
 1872 lf_iteratelocks_sysid(int sysid, lf_iterator *fn, void *arg)
 1873 {
 1874         struct lockf *ls;
 1875         struct lockf_entry *lf;
 1876         struct lockdesc *ldesc;
 1877         struct lockdesclist locks;
 1878         int error;
 1879 
 1880         /*
 1881          * In order to keep the locking simple, we iterate over the
 1882          * active lock lists to build a list of locks that need
 1883          * releasing. We then call the iterator for each one in turn.
 1884          *
 1885          * We take an extra reference to the vnode for the duration to
 1886          * make sure it doesn't go away before we are finished.
 1887          */
 1888         STAILQ_INIT(&locks);
 1889         sx_xlock(&lf_lock_states_lock);
 1890         LIST_FOREACH(ls, &lf_lock_states, ls_link) {
 1891                 sx_xlock(&ls->ls_lock);
 1892                 LIST_FOREACH(lf, &ls->ls_active, lf_link) {
 1893                         if (lf->lf_owner->lo_sysid != sysid)
 1894                                 continue;
 1895 
 1896                         ldesc = malloc(sizeof(struct lockdesc), M_LOCKF,
 1897                             M_WAITOK);
 1898                         ldesc->vp = lf->lf_vnode;
 1899                         vref(ldesc->vp);
 1900                         ldesc->fl.l_start = lf->lf_start;
 1901                         if (lf->lf_end == OFF_MAX)
 1902                                 ldesc->fl.l_len = 0;
 1903                         else
 1904                                 ldesc->fl.l_len =
 1905                                         lf->lf_end - lf->lf_start + 1;
 1906                         ldesc->fl.l_whence = SEEK_SET;
 1907                         ldesc->fl.l_type = F_UNLCK;
 1908                         ldesc->fl.l_pid = lf->lf_owner->lo_pid;
 1909                         ldesc->fl.l_sysid = sysid;
 1910                         STAILQ_INSERT_TAIL(&locks, ldesc, link);
 1911                 }
 1912                 sx_xunlock(&ls->ls_lock);
 1913         }
 1914         sx_xunlock(&lf_lock_states_lock);
 1915 
 1916         /*
 1917          * Call the iterator function for each lock in turn. If the
 1918          * iterator returns an error code, just free the rest of the
 1919          * lockdesc structures.
 1920          */
 1921         error = 0;
 1922         while ((ldesc = STAILQ_FIRST(&locks)) != NULL) {
 1923                 STAILQ_REMOVE_HEAD(&locks, link);
 1924                 if (!error)
 1925                         error = fn(ldesc->vp, &ldesc->fl, arg);
 1926                 vrele(ldesc->vp);
 1927                 free(ldesc, M_LOCKF);
 1928         }
 1929 
 1930         return (error);
 1931 }
 1932 
 1933 int
 1934 lf_iteratelocks_vnode(struct vnode *vp, lf_iterator *fn, void *arg)
 1935 {
 1936         struct lockf *ls;
 1937         struct lockf_entry *lf;
 1938         struct lockdesc *ldesc;
 1939         struct lockdesclist locks;
 1940         int error;
 1941 
 1942         /*
 1943          * In order to keep the locking simple, we iterate over the
 1944          * active lock lists to build a list of locks that need
 1945          * releasing. We then call the iterator for each one in turn.
 1946          *
 1947          * We take an extra reference to the vnode for the duration to
 1948          * make sure it doesn't go away before we are finished.
 1949          */
 1950         STAILQ_INIT(&locks);
 1951         VI_LOCK(vp);
 1952         ls = vp->v_lockf;
 1953         if (!ls) {
 1954                 VI_UNLOCK(vp);
 1955                 return (0);
 1956         }
 1957         ls->ls_threads++;
 1958         VI_UNLOCK(vp);
 1959 
 1960         sx_xlock(&ls->ls_lock);
 1961         LIST_FOREACH(lf, &ls->ls_active, lf_link) {
 1962                 ldesc = malloc(sizeof(struct lockdesc), M_LOCKF,
 1963                     M_WAITOK);
 1964                 ldesc->vp = lf->lf_vnode;
 1965                 vref(ldesc->vp);
 1966                 ldesc->fl.l_start = lf->lf_start;
 1967                 if (lf->lf_end == OFF_MAX)
 1968                         ldesc->fl.l_len = 0;
 1969                 else
 1970                         ldesc->fl.l_len =
 1971                                 lf->lf_end - lf->lf_start + 1;
 1972                 ldesc->fl.l_whence = SEEK_SET;
 1973                 ldesc->fl.l_type = F_UNLCK;
 1974                 ldesc->fl.l_pid = lf->lf_owner->lo_pid;
 1975                 ldesc->fl.l_sysid = lf->lf_owner->lo_sysid;
 1976                 STAILQ_INSERT_TAIL(&locks, ldesc, link);
 1977         }
 1978         sx_xunlock(&ls->ls_lock);
 1979         VI_LOCK(vp);
 1980         ls->ls_threads--;
 1981         wakeup(ls);
 1982         VI_UNLOCK(vp);
 1983 
 1984         /*
 1985          * Call the iterator function for each lock in turn. If the
 1986          * iterator returns an error code, just free the rest of the
 1987          * lockdesc structures.
 1988          */
 1989         error = 0;
 1990         while ((ldesc = STAILQ_FIRST(&locks)) != NULL) {
 1991                 STAILQ_REMOVE_HEAD(&locks, link);
 1992                 if (!error)
 1993                         error = fn(ldesc->vp, &ldesc->fl, arg);
 1994                 vrele(ldesc->vp);
 1995                 free(ldesc, M_LOCKF);
 1996         }
 1997 
 1998         return (error);
 1999 }
 2000 
 2001 static int
 2002 lf_clearremotesys_iterator(struct vnode *vp, struct flock *fl, void *arg)
 2003 {
 2004 
 2005         VOP_ADVLOCK(vp, 0, F_UNLCK, fl, F_REMOTE);
 2006         return (0);
 2007 }
 2008 
 2009 void
 2010 lf_clearremotesys(int sysid)
 2011 {
 2012 
 2013         KASSERT(sysid != 0, ("Can't clear local locks with F_UNLCKSYS"));
 2014         lf_iteratelocks_sysid(sysid, lf_clearremotesys_iterator, NULL);
 2015 }
 2016 
 2017 int
 2018 lf_countlocks(int sysid)
 2019 {
 2020         int i;
 2021         struct lock_owner *lo;
 2022         int count;
 2023 
 2024         count = 0;
 2025         for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++) {
 2026                 sx_xlock(&lf_lock_owners[i].lock);
 2027                 LIST_FOREACH(lo, &lf_lock_owners[i].list, lo_link)
 2028                         if (lo->lo_sysid == sysid)
 2029                                 count += lo->lo_refs;
 2030                 sx_xunlock(&lf_lock_owners[i].lock);
 2031         }
 2032 
 2033         return (count);
 2034 }
 2035 
 2036 #ifdef LOCKF_DEBUG
 2037 
 2038 /*
 2039  * Return non-zero if y is reachable from x using a brute force
 2040  * search. If reachable and path is non-null, return the route taken
 2041  * in path.
 2042  */
 2043 static int
 2044 graph_reaches(struct owner_vertex *x, struct owner_vertex *y,
 2045     struct owner_vertex_list *path)
 2046 {
 2047         struct owner_edge *e;
 2048 
 2049         if (x == y) {
 2050                 if (path)
 2051                         TAILQ_INSERT_HEAD(path, x, v_link);
 2052                 return 1;
 2053         }
 2054 
 2055         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2056                 if (graph_reaches(e->e_to, y, path)) {
 2057                         if (path)
 2058                                 TAILQ_INSERT_HEAD(path, x, v_link);
 2059                         return 1;
 2060                 }
 2061         }
 2062         return 0;
 2063 }
 2064 
 2065 /*
 2066  * Perform consistency checks on the graph. Make sure the values of
 2067  * v_order are correct. If checkorder is non-zero, check no vertex can
 2068  * reach any other vertex with a smaller order.
 2069  */
 2070 static void
 2071 graph_check(struct owner_graph *g, int checkorder)
 2072 {
 2073         int i, j;
 2074 
 2075         for (i = 0; i < g->g_size; i++) {
 2076                 if (!g->g_vertices[i]->v_owner)
 2077                         continue;
 2078                 KASSERT(g->g_vertices[i]->v_order == i,
 2079                     ("lock graph vertices disordered"));
 2080                 if (checkorder) {
 2081                         for (j = 0; j < i; j++) {
 2082                                 if (!g->g_vertices[j]->v_owner)
 2083                                         continue;
 2084                                 KASSERT(!graph_reaches(g->g_vertices[i],
 2085                                         g->g_vertices[j], NULL),
 2086                                     ("lock graph vertices disordered"));
 2087                         }
 2088                 }
 2089         }
 2090 }
 2091 
 2092 static void
 2093 graph_print_vertices(struct owner_vertex_list *set)
 2094 {
 2095         struct owner_vertex *v;
 2096 
 2097         printf("{ ");
 2098         TAILQ_FOREACH(v, set, v_link) {
 2099                 printf("%d:", v->v_order);
 2100                 lf_print_owner(v->v_owner);
 2101                 if (TAILQ_NEXT(v, v_link))
 2102                         printf(", ");
 2103         }
 2104         printf(" }\n");
 2105 }
 2106 
 2107 #endif
 2108 
 2109 /*
 2110  * Calculate the sub-set of vertices v from the affected region [y..x]
 2111  * where v is reachable from y. Return -1 if a loop was detected
 2112  * (i.e. x is reachable from y, otherwise the number of vertices in
 2113  * this subset.
 2114  */
 2115 static int
 2116 graph_delta_forward(struct owner_graph *g, struct owner_vertex *x,
 2117     struct owner_vertex *y, struct owner_vertex_list *delta)
 2118 {
 2119         uint32_t gen;
 2120         struct owner_vertex *v;
 2121         struct owner_edge *e;
 2122         int n;
 2123 
 2124         /*
 2125          * We start with a set containing just y. Then for each vertex
 2126          * v in the set so far unprocessed, we add each vertex that v
 2127          * has an out-edge to and that is within the affected region
 2128          * [y..x]. If we see the vertex x on our travels, stop
 2129          * immediately.
 2130          */
 2131         TAILQ_INIT(delta);
 2132         TAILQ_INSERT_TAIL(delta, y, v_link);
 2133         v = y;
 2134         n = 1;
 2135         gen = g->g_gen;
 2136         while (v) {
 2137                 LIST_FOREACH(e, &v->v_outedges, e_outlink) {
 2138                         if (e->e_to == x)
 2139                                 return -1;
 2140                         if (e->e_to->v_order < x->v_order
 2141                             && e->e_to->v_gen != gen) {
 2142                                 e->e_to->v_gen = gen;
 2143                                 TAILQ_INSERT_TAIL(delta, e->e_to, v_link);
 2144                                 n++;
 2145                         }
 2146                 }
 2147                 v = TAILQ_NEXT(v, v_link);
 2148         }
 2149 
 2150         return (n);
 2151 }
 2152 
 2153 /*
 2154  * Calculate the sub-set of vertices v from the affected region [y..x]
 2155  * where v reaches x. Return the number of vertices in this subset.
 2156  */
 2157 static int
 2158 graph_delta_backward(struct owner_graph *g, struct owner_vertex *x,
 2159     struct owner_vertex *y, struct owner_vertex_list *delta)
 2160 {
 2161         uint32_t gen;
 2162         struct owner_vertex *v;
 2163         struct owner_edge *e;
 2164         int n;
 2165 
 2166         /*
 2167          * We start with a set containing just x. Then for each vertex
 2168          * v in the set so far unprocessed, we add each vertex that v
 2169          * has an in-edge from and that is within the affected region
 2170          * [y..x].
 2171          */
 2172         TAILQ_INIT(delta);
 2173         TAILQ_INSERT_TAIL(delta, x, v_link);
 2174         v = x;
 2175         n = 1;
 2176         gen = g->g_gen;
 2177         while (v) {
 2178                 LIST_FOREACH(e, &v->v_inedges, e_inlink) {
 2179                         if (e->e_from->v_order > y->v_order
 2180                             && e->e_from->v_gen != gen) {
 2181                                 e->e_from->v_gen = gen;
 2182                                 TAILQ_INSERT_HEAD(delta, e->e_from, v_link);
 2183                                 n++;
 2184                         }
 2185                 }
 2186                 v = TAILQ_PREV(v, owner_vertex_list, v_link);
 2187         }
 2188 
 2189         return (n);
 2190 }
 2191 
 2192 static int
 2193 graph_add_indices(int *indices, int n, struct owner_vertex_list *set)
 2194 {
 2195         struct owner_vertex *v;
 2196         int i, j;
 2197 
 2198         TAILQ_FOREACH(v, set, v_link) {
 2199                 for (i = n;
 2200                      i > 0 && indices[i - 1] > v->v_order; i--)
 2201                         ;
 2202                 for (j = n - 1; j >= i; j--)
 2203                         indices[j + 1] = indices[j];
 2204                 indices[i] = v->v_order;
 2205                 n++;
 2206         }
 2207 
 2208         return (n);
 2209 }
 2210 
 2211 static int
 2212 graph_assign_indices(struct owner_graph *g, int *indices, int nextunused,
 2213     struct owner_vertex_list *set)
 2214 {
 2215         struct owner_vertex *v, *vlowest;
 2216 
 2217         while (!TAILQ_EMPTY(set)) {
 2218                 vlowest = NULL;
 2219                 TAILQ_FOREACH(v, set, v_link) {
 2220                         if (!vlowest || v->v_order < vlowest->v_order)
 2221                                 vlowest = v;
 2222                 }
 2223                 TAILQ_REMOVE(set, vlowest, v_link);
 2224                 vlowest->v_order = indices[nextunused];
 2225                 g->g_vertices[vlowest->v_order] = vlowest;
 2226                 nextunused++;
 2227         }
 2228 
 2229         return (nextunused);
 2230 }
 2231 
 2232 static int
 2233 graph_add_edge(struct owner_graph *g, struct owner_vertex *x,
 2234     struct owner_vertex *y)
 2235 {
 2236         struct owner_edge *e;
 2237         struct owner_vertex_list deltaF, deltaB;
 2238         int nF, n, vi, i;
 2239         int *indices;
 2240         int nB __unused;
 2241 
 2242         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2243 
 2244         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2245                 if (e->e_to == y) {
 2246                         e->e_refs++;
 2247                         return (0);
 2248                 }
 2249         }
 2250 
 2251 #ifdef LOCKF_DEBUG
 2252         if (lockf_debug & 8) {
 2253                 printf("adding edge %d:", x->v_order);
 2254                 lf_print_owner(x->v_owner);
 2255                 printf(" -> %d:", y->v_order);
 2256                 lf_print_owner(y->v_owner);
 2257                 printf("\n");
 2258         }
 2259 #endif
 2260         if (y->v_order < x->v_order) {
 2261                 /*
 2262                  * The new edge violates the order. First find the set
 2263                  * of affected vertices reachable from y (deltaF) and
 2264                  * the set of affect vertices affected that reach x
 2265                  * (deltaB), using the graph generation number to
 2266                  * detect whether we have visited a given vertex
 2267                  * already. We re-order the graph so that each vertex
 2268                  * in deltaB appears before each vertex in deltaF.
 2269                  *
 2270                  * If x is a member of deltaF, then the new edge would
 2271                  * create a cycle. Otherwise, we may assume that
 2272                  * deltaF and deltaB are disjoint.
 2273                  */
 2274                 g->g_gen++;
 2275                 if (g->g_gen == 0) {
 2276                         /*
 2277                          * Generation wrap.
 2278                          */
 2279                         for (vi = 0; vi < g->g_size; vi++) {
 2280                                 g->g_vertices[vi]->v_gen = 0;
 2281                         }
 2282                         g->g_gen++;
 2283                 }
 2284                 nF = graph_delta_forward(g, x, y, &deltaF);
 2285                 if (nF < 0) {
 2286 #ifdef LOCKF_DEBUG
 2287                         if (lockf_debug & 8) {
 2288                                 struct owner_vertex_list path;
 2289                                 printf("deadlock: ");
 2290                                 TAILQ_INIT(&path);
 2291                                 graph_reaches(y, x, &path);
 2292                                 graph_print_vertices(&path);
 2293                         }
 2294 #endif
 2295                         return (EDEADLK);
 2296                 }
 2297 
 2298 #ifdef LOCKF_DEBUG
 2299                 if (lockf_debug & 8) {
 2300                         printf("re-ordering graph vertices\n");
 2301                         printf("deltaF = ");
 2302                         graph_print_vertices(&deltaF);
 2303                 }
 2304 #endif
 2305 
 2306                 nB = graph_delta_backward(g, x, y, &deltaB);
 2307 
 2308 #ifdef LOCKF_DEBUG
 2309                 if (lockf_debug & 8) {
 2310                         printf("deltaB = ");
 2311                         graph_print_vertices(&deltaB);
 2312                 }
 2313 #endif
 2314 
 2315                 /*
 2316                  * We first build a set of vertex indices (vertex
 2317                  * order values) that we may use, then we re-assign
 2318                  * orders first to those vertices in deltaB, then to
 2319                  * deltaF. Note that the contents of deltaF and deltaB
 2320                  * may be partially disordered - we perform an
 2321                  * insertion sort while building our index set.
 2322                  */
 2323                 indices = g->g_indexbuf;
 2324                 n = graph_add_indices(indices, 0, &deltaF);
 2325                 graph_add_indices(indices, n, &deltaB);
 2326 
 2327                 /*
 2328                  * We must also be sure to maintain the relative
 2329                  * ordering of deltaF and deltaB when re-assigning
 2330                  * vertices. We do this by iteratively removing the
 2331                  * lowest ordered element from the set and assigning
 2332                  * it the next value from our new ordering.
 2333                  */
 2334                 i = graph_assign_indices(g, indices, 0, &deltaB);
 2335                 graph_assign_indices(g, indices, i, &deltaF);
 2336 
 2337 #ifdef LOCKF_DEBUG
 2338                 if (lockf_debug & 8) {
 2339                         struct owner_vertex_list set;
 2340                         TAILQ_INIT(&set);
 2341                         for (i = 0; i < nB + nF; i++)
 2342                                 TAILQ_INSERT_TAIL(&set,
 2343                                     g->g_vertices[indices[i]], v_link);
 2344                         printf("new ordering = ");
 2345                         graph_print_vertices(&set);
 2346                 }
 2347 #endif
 2348         }
 2349 
 2350         KASSERT(x->v_order < y->v_order, ("Failed to re-order graph"));
 2351 
 2352 #ifdef LOCKF_DEBUG
 2353         if (lockf_debug & 8) {
 2354                 graph_check(g, TRUE);
 2355         }
 2356 #endif
 2357 
 2358         e = malloc(sizeof(struct owner_edge), M_LOCKF, M_WAITOK);
 2359 
 2360         LIST_INSERT_HEAD(&x->v_outedges, e, e_outlink);
 2361         LIST_INSERT_HEAD(&y->v_inedges, e, e_inlink);
 2362         e->e_refs = 1;
 2363         e->e_from = x;
 2364         e->e_to = y;
 2365 
 2366         return (0);
 2367 }
 2368 
 2369 /*
 2370  * Remove an edge x->y from the graph.
 2371  */
 2372 static void
 2373 graph_remove_edge(struct owner_graph *g, struct owner_vertex *x,
 2374     struct owner_vertex *y)
 2375 {
 2376         struct owner_edge *e;
 2377 
 2378         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2379 
 2380         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2381                 if (e->e_to == y)
 2382                         break;
 2383         }
 2384         KASSERT(e, ("Removing non-existent edge from deadlock graph"));
 2385 
 2386         e->e_refs--;
 2387         if (e->e_refs == 0) {
 2388 #ifdef LOCKF_DEBUG
 2389                 if (lockf_debug & 8) {
 2390                         printf("removing edge %d:", x->v_order);
 2391                         lf_print_owner(x->v_owner);
 2392                         printf(" -> %d:", y->v_order);
 2393                         lf_print_owner(y->v_owner);
 2394                         printf("\n");
 2395                 }
 2396 #endif
 2397                 LIST_REMOVE(e, e_outlink);
 2398                 LIST_REMOVE(e, e_inlink);
 2399                 free(e, M_LOCKF);
 2400         }
 2401 }
 2402 
 2403 /*
 2404  * Allocate a vertex from the free list. Return ENOMEM if there are
 2405  * none.
 2406  */
 2407 static struct owner_vertex *
 2408 graph_alloc_vertex(struct owner_graph *g, struct lock_owner *lo)
 2409 {
 2410         struct owner_vertex *v;
 2411 
 2412         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2413 
 2414         v = malloc(sizeof(struct owner_vertex), M_LOCKF, M_WAITOK);
 2415         if (g->g_size == g->g_space) {
 2416                 g->g_vertices = realloc(g->g_vertices,
 2417                     2 * g->g_space * sizeof(struct owner_vertex *),
 2418                     M_LOCKF, M_WAITOK);
 2419                 free(g->g_indexbuf, M_LOCKF);
 2420                 g->g_indexbuf = malloc(2 * g->g_space * sizeof(int),
 2421                     M_LOCKF, M_WAITOK);
 2422                 g->g_space = 2 * g->g_space;
 2423         }
 2424         v->v_order = g->g_size;
 2425         v->v_gen = g->g_gen;
 2426         g->g_vertices[g->g_size] = v;
 2427         g->g_size++;
 2428 
 2429         LIST_INIT(&v->v_outedges);
 2430         LIST_INIT(&v->v_inedges);
 2431         v->v_owner = lo;
 2432 
 2433         return (v);
 2434 }
 2435 
 2436 static void
 2437 graph_free_vertex(struct owner_graph *g, struct owner_vertex *v)
 2438 {
 2439         struct owner_vertex *w;
 2440         int i;
 2441 
 2442         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2443         
 2444         KASSERT(LIST_EMPTY(&v->v_outedges), ("Freeing vertex with edges"));
 2445         KASSERT(LIST_EMPTY(&v->v_inedges), ("Freeing vertex with edges"));
 2446 
 2447         /*
 2448          * Remove from the graph's array and close up the gap,
 2449          * renumbering the other vertices.
 2450          */
 2451         for (i = v->v_order + 1; i < g->g_size; i++) {
 2452                 w = g->g_vertices[i];
 2453                 w->v_order--;
 2454                 g->g_vertices[i - 1] = w;
 2455         }
 2456         g->g_size--;
 2457 
 2458         free(v, M_LOCKF);
 2459 }
 2460 
 2461 static struct owner_graph *
 2462 graph_init(struct owner_graph *g)
 2463 {
 2464 
 2465         g->g_vertices = malloc(10 * sizeof(struct owner_vertex *),
 2466             M_LOCKF, M_WAITOK);
 2467         g->g_size = 0;
 2468         g->g_space = 10;
 2469         g->g_indexbuf = malloc(g->g_space * sizeof(int), M_LOCKF, M_WAITOK);
 2470         g->g_gen = 0;
 2471 
 2472         return (g);
 2473 }
 2474 
 2475 #ifdef LOCKF_DEBUG
 2476 /*
 2477  * Print description of a lock owner
 2478  */
 2479 static void
 2480 lf_print_owner(struct lock_owner *lo)
 2481 {
 2482 
 2483         if (lo->lo_flags & F_REMOTE) {
 2484                 printf("remote pid %d, system %d",
 2485                     lo->lo_pid, lo->lo_sysid);
 2486         } else if (lo->lo_flags & F_FLOCK) {
 2487                 printf("file %p", lo->lo_id);
 2488         } else {
 2489                 printf("local pid %d", lo->lo_pid);
 2490         }
 2491 }
 2492 
 2493 /*
 2494  * Print out a lock.
 2495  */
 2496 static void
 2497 lf_print(char *tag, struct lockf_entry *lock)
 2498 {
 2499 
 2500         printf("%s: lock %p for ", tag, (void *)lock);
 2501         lf_print_owner(lock->lf_owner);
 2502         if (lock->lf_inode != (struct inode *)0)
 2503                 printf(" in ino %ju on dev <%s>,",
 2504                     (uintmax_t)lock->lf_inode->i_number,
 2505                     devtoname(ITODEV(lock->lf_inode)));
 2506         printf(" %s, start %jd, end ",
 2507             lock->lf_type == F_RDLCK ? "shared" :
 2508             lock->lf_type == F_WRLCK ? "exclusive" :
 2509             lock->lf_type == F_UNLCK ? "unlock" : "unknown",
 2510             (intmax_t)lock->lf_start);
 2511         if (lock->lf_end == OFF_MAX)
 2512                 printf("EOF");
 2513         else
 2514                 printf("%jd", (intmax_t)lock->lf_end);
 2515         if (!LIST_EMPTY(&lock->lf_outedges))
 2516                 printf(" block %p\n",
 2517                     (void *)LIST_FIRST(&lock->lf_outedges)->le_to);
 2518         else
 2519                 printf("\n");
 2520 }
 2521 
 2522 static void
 2523 lf_printlist(char *tag, struct lockf_entry *lock)
 2524 {
 2525         struct lockf_entry *lf, *blk;
 2526         struct lockf_edge *e;
 2527 
 2528         if (lock->lf_inode == (struct inode *)0)
 2529                 return;
 2530 
 2531         printf("%s: Lock list for ino %ju on dev <%s>:\n",
 2532             tag, (uintmax_t)lock->lf_inode->i_number,
 2533             devtoname(ITODEV(lock->lf_inode)));
 2534         LIST_FOREACH(lf, &lock->lf_vnode->v_lockf->ls_active, lf_link) {
 2535                 printf("\tlock %p for ",(void *)lf);
 2536                 lf_print_owner(lock->lf_owner);
 2537                 printf(", %s, start %jd, end %jd",
 2538                     lf->lf_type == F_RDLCK ? "shared" :
 2539                     lf->lf_type == F_WRLCK ? "exclusive" :
 2540                     lf->lf_type == F_UNLCK ? "unlock" :
 2541                     "unknown", (intmax_t)lf->lf_start, (intmax_t)lf->lf_end);
 2542                 LIST_FOREACH(e, &lf->lf_outedges, le_outlink) {
 2543                         blk = e->le_to;
 2544                         printf("\n\t\tlock request %p for ", (void *)blk);
 2545                         lf_print_owner(blk->lf_owner);
 2546                         printf(", %s, start %jd, end %jd",
 2547                             blk->lf_type == F_RDLCK ? "shared" :
 2548                             blk->lf_type == F_WRLCK ? "exclusive" :
 2549                             blk->lf_type == F_UNLCK ? "unlock" :
 2550                             "unknown", (intmax_t)blk->lf_start,
 2551                             (intmax_t)blk->lf_end);
 2552                         if (!LIST_EMPTY(&blk->lf_inedges))
 2553                                 panic("lf_printlist: bad list");
 2554                 }
 2555                 printf("\n");
 2556         }
 2557 }
 2558 #endif /* LOCKF_DEBUG */

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