The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_lockf.c

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    1 /*-
    2  * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
    3  * Authors: Doug Rabson <dfr@rabson.org>
    4  * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  */
   27 /*-
   28  * Copyright (c) 1982, 1986, 1989, 1993
   29  *      The Regents of the University of California.  All rights reserved.
   30  *
   31  * This code is derived from software contributed to Berkeley by
   32  * Scooter Morris at Genentech Inc.
   33  *
   34  * Redistribution and use in source and binary forms, with or without
   35  * modification, are permitted provided that the following conditions
   36  * are met:
   37  * 1. Redistributions of source code must retain the above copyright
   38  *    notice, this list of conditions and the following disclaimer.
   39  * 2. Redistributions in binary form must reproduce the above copyright
   40  *    notice, this list of conditions and the following disclaimer in the
   41  *    documentation and/or other materials provided with the distribution.
   42  * 4. Neither the name of the University nor the names of its contributors
   43  *    may be used to endorse or promote products derived from this software
   44  *    without specific prior written permission.
   45  *
   46  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   47  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   48  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   49  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   50  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   51  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   52  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   53  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   54  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   55  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   56  * SUCH DAMAGE.
   57  *
   58  *      @(#)ufs_lockf.c 8.3 (Berkeley) 1/6/94
   59  */
   60 
   61 #include <sys/cdefs.h>
   62 __FBSDID("$FreeBSD: releng/11.0/sys/kern/kern_lockf.c 302216 2016-06-26 20:08:42Z kib $");
   63 
   64 #include "opt_debug_lockf.h"
   65 
   66 #include <sys/param.h>
   67 #include <sys/systm.h>
   68 #include <sys/hash.h>
   69 #include <sys/kernel.h>
   70 #include <sys/limits.h>
   71 #include <sys/lock.h>
   72 #include <sys/mount.h>
   73 #include <sys/mutex.h>
   74 #include <sys/proc.h>
   75 #include <sys/sx.h>
   76 #include <sys/unistd.h>
   77 #include <sys/vnode.h>
   78 #include <sys/malloc.h>
   79 #include <sys/fcntl.h>
   80 #include <sys/lockf.h>
   81 #include <sys/taskqueue.h>
   82 
   83 #ifdef LOCKF_DEBUG
   84 #include <sys/sysctl.h>
   85 
   86 #include <ufs/ufs/quota.h>
   87 #include <ufs/ufs/inode.h>
   88 
   89 static int      lockf_debug = 0; /* control debug output */
   90 SYSCTL_INT(_debug, OID_AUTO, lockf_debug, CTLFLAG_RW, &lockf_debug, 0, "");
   91 #endif
   92 
   93 static MALLOC_DEFINE(M_LOCKF, "lockf", "Byte-range locking structures");
   94 
   95 struct owner_edge;
   96 struct owner_vertex;
   97 struct owner_vertex_list;
   98 struct owner_graph;
   99 
  100 #define NOLOCKF (struct lockf_entry *)0
  101 #define SELF    0x1
  102 #define OTHERS  0x2
  103 static void      lf_init(void *);
  104 static int       lf_hash_owner(caddr_t, struct flock *, int);
  105 static int       lf_owner_matches(struct lock_owner *, caddr_t, struct flock *,
  106     int);
  107 static struct lockf_entry *
  108                  lf_alloc_lock(struct lock_owner *);
  109 static int       lf_free_lock(struct lockf_entry *);
  110 static int       lf_clearlock(struct lockf *, struct lockf_entry *);
  111 static int       lf_overlaps(struct lockf_entry *, struct lockf_entry *);
  112 static int       lf_blocks(struct lockf_entry *, struct lockf_entry *);
  113 static void      lf_free_edge(struct lockf_edge *);
  114 static struct lockf_edge *
  115                  lf_alloc_edge(void);
  116 static void      lf_alloc_vertex(struct lockf_entry *);
  117 static int       lf_add_edge(struct lockf_entry *, struct lockf_entry *);
  118 static void      lf_remove_edge(struct lockf_edge *);
  119 static void      lf_remove_outgoing(struct lockf_entry *);
  120 static void      lf_remove_incoming(struct lockf_entry *);
  121 static int       lf_add_outgoing(struct lockf *, struct lockf_entry *);
  122 static int       lf_add_incoming(struct lockf *, struct lockf_entry *);
  123 static int       lf_findoverlap(struct lockf_entry **, struct lockf_entry *,
  124     int);
  125 static struct lockf_entry *
  126                  lf_getblock(struct lockf *, struct lockf_entry *);
  127 static int       lf_getlock(struct lockf *, struct lockf_entry *, struct flock *);
  128 static void      lf_insert_lock(struct lockf *, struct lockf_entry *);
  129 static void      lf_wakeup_lock(struct lockf *, struct lockf_entry *);
  130 static void      lf_update_dependancies(struct lockf *, struct lockf_entry *,
  131     int all, struct lockf_entry_list *);
  132 static void      lf_set_start(struct lockf *, struct lockf_entry *, off_t,
  133         struct lockf_entry_list*);
  134 static void      lf_set_end(struct lockf *, struct lockf_entry *, off_t,
  135         struct lockf_entry_list*);
  136 static int       lf_setlock(struct lockf *, struct lockf_entry *,
  137     struct vnode *, void **cookiep);
  138 static int       lf_cancel(struct lockf *, struct lockf_entry *, void *);
  139 static void      lf_split(struct lockf *, struct lockf_entry *,
  140     struct lockf_entry *, struct lockf_entry_list *);
  141 #ifdef LOCKF_DEBUG
  142 static int       graph_reaches(struct owner_vertex *x, struct owner_vertex *y,
  143     struct owner_vertex_list *path);
  144 static void      graph_check(struct owner_graph *g, int checkorder);
  145 static void      graph_print_vertices(struct owner_vertex_list *set);
  146 #endif
  147 static int       graph_delta_forward(struct owner_graph *g,
  148     struct owner_vertex *x, struct owner_vertex *y,
  149     struct owner_vertex_list *delta);
  150 static int       graph_delta_backward(struct owner_graph *g,
  151     struct owner_vertex *x, struct owner_vertex *y,
  152     struct owner_vertex_list *delta);
  153 static int       graph_add_indices(int *indices, int n,
  154     struct owner_vertex_list *set);
  155 static int       graph_assign_indices(struct owner_graph *g, int *indices,
  156     int nextunused, struct owner_vertex_list *set);
  157 static int       graph_add_edge(struct owner_graph *g,
  158     struct owner_vertex *x, struct owner_vertex *y);
  159 static void      graph_remove_edge(struct owner_graph *g,
  160     struct owner_vertex *x, struct owner_vertex *y);
  161 static struct owner_vertex *graph_alloc_vertex(struct owner_graph *g,
  162     struct lock_owner *lo);
  163 static void      graph_free_vertex(struct owner_graph *g,
  164     struct owner_vertex *v);
  165 static struct owner_graph * graph_init(struct owner_graph *g);
  166 #ifdef LOCKF_DEBUG
  167 static void      lf_print(char *, struct lockf_entry *);
  168 static void      lf_printlist(char *, struct lockf_entry *);
  169 static void      lf_print_owner(struct lock_owner *);
  170 #endif
  171 
  172 /*
  173  * This structure is used to keep track of both local and remote lock
  174  * owners. The lf_owner field of the struct lockf_entry points back at
  175  * the lock owner structure. Each possible lock owner (local proc for
  176  * POSIX fcntl locks, local file for BSD flock locks or <pid,sysid>
  177  * pair for remote locks) is represented by a unique instance of
  178  * struct lock_owner.
  179  *
  180  * If a lock owner has a lock that blocks some other lock or a lock
  181  * that is waiting for some other lock, it also has a vertex in the
  182  * owner_graph below.
  183  *
  184  * Locks:
  185  * (s)          locked by state->ls_lock
  186  * (S)          locked by lf_lock_states_lock
  187  * (l)          locked by lf_lock_owners_lock
  188  * (g)          locked by lf_owner_graph_lock
  189  * (c)          const until freeing
  190  */
  191 #define LOCK_OWNER_HASH_SIZE    256
  192 
  193 struct lock_owner {
  194         LIST_ENTRY(lock_owner) lo_link; /* (l) hash chain */
  195         int     lo_refs;            /* (l) Number of locks referring to this */
  196         int     lo_flags;           /* (c) Flags passwd to lf_advlock */
  197         caddr_t lo_id;              /* (c) Id value passed to lf_advlock */
  198         pid_t   lo_pid;             /* (c) Process Id of the lock owner */
  199         int     lo_sysid;           /* (c) System Id of the lock owner */
  200         struct owner_vertex *lo_vertex; /* (g) entry in deadlock graph */
  201 };
  202 
  203 LIST_HEAD(lock_owner_list, lock_owner);
  204 
  205 static struct sx                lf_lock_states_lock;
  206 static struct lockf_list        lf_lock_states; /* (S) */
  207 static struct sx                lf_lock_owners_lock;
  208 static struct lock_owner_list   lf_lock_owners[LOCK_OWNER_HASH_SIZE]; /* (l) */
  209 
  210 /*
  211  * Structures for deadlock detection.
  212  *
  213  * We have two types of directed graph, the first is the set of locks,
  214  * both active and pending on a vnode. Within this graph, active locks
  215  * are terminal nodes in the graph (i.e. have no out-going
  216  * edges). Pending locks have out-going edges to each blocking active
  217  * lock that prevents the lock from being granted and also to each
  218  * older pending lock that would block them if it was active. The
  219  * graph for each vnode is naturally acyclic; new edges are only ever
  220  * added to or from new nodes (either new pending locks which only add
  221  * out-going edges or new active locks which only add in-coming edges)
  222  * therefore they cannot create loops in the lock graph.
  223  *
  224  * The second graph is a global graph of lock owners. Each lock owner
  225  * is a vertex in that graph and an edge is added to the graph
  226  * whenever an edge is added to a vnode graph, with end points
  227  * corresponding to owner of the new pending lock and the owner of the
  228  * lock upon which it waits. In order to prevent deadlock, we only add
  229  * an edge to this graph if the new edge would not create a cycle.
  230  * 
  231  * The lock owner graph is topologically sorted, i.e. if a node has
  232  * any outgoing edges, then it has an order strictly less than any
  233  * node to which it has an outgoing edge. We preserve this ordering
  234  * (and detect cycles) on edge insertion using Algorithm PK from the
  235  * paper "A Dynamic Topological Sort Algorithm for Directed Acyclic
  236  * Graphs" (ACM Journal of Experimental Algorithms, Vol 11, Article
  237  * No. 1.7)
  238  */
  239 struct owner_vertex;
  240 
  241 struct owner_edge {
  242         LIST_ENTRY(owner_edge) e_outlink; /* (g) link from's out-edge list */
  243         LIST_ENTRY(owner_edge) e_inlink;  /* (g) link to's in-edge list */
  244         int             e_refs;           /* (g) number of times added */
  245         struct owner_vertex *e_from;      /* (c) out-going from here */
  246         struct owner_vertex *e_to;        /* (c) in-coming to here */
  247 };
  248 LIST_HEAD(owner_edge_list, owner_edge);
  249 
  250 struct owner_vertex {
  251         TAILQ_ENTRY(owner_vertex) v_link; /* (g) workspace for edge insertion */
  252         uint32_t        v_gen;            /* (g) workspace for edge insertion */
  253         int             v_order;          /* (g) order of vertex in graph */
  254         struct owner_edge_list v_outedges;/* (g) list of out-edges */
  255         struct owner_edge_list v_inedges; /* (g) list of in-edges */
  256         struct lock_owner *v_owner;       /* (c) corresponding lock owner */
  257 };
  258 TAILQ_HEAD(owner_vertex_list, owner_vertex);
  259 
  260 struct owner_graph {
  261         struct owner_vertex** g_vertices; /* (g) pointers to vertices */
  262         int             g_size;           /* (g) number of vertices */
  263         int             g_space;          /* (g) space allocated for vertices */
  264         int             *g_indexbuf;      /* (g) workspace for loop detection */
  265         uint32_t        g_gen;            /* (g) increment when re-ordering */
  266 };
  267 
  268 static struct sx                lf_owner_graph_lock;
  269 static struct owner_graph       lf_owner_graph;
  270 
  271 /*
  272  * Initialise various structures and locks.
  273  */
  274 static void
  275 lf_init(void *dummy)
  276 {
  277         int i;
  278 
  279         sx_init(&lf_lock_states_lock, "lock states lock");
  280         LIST_INIT(&lf_lock_states);
  281 
  282         sx_init(&lf_lock_owners_lock, "lock owners lock");
  283         for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++)
  284                 LIST_INIT(&lf_lock_owners[i]);
  285 
  286         sx_init(&lf_owner_graph_lock, "owner graph lock");
  287         graph_init(&lf_owner_graph);
  288 }
  289 SYSINIT(lf_init, SI_SUB_LOCK, SI_ORDER_FIRST, lf_init, NULL);
  290 
  291 /*
  292  * Generate a hash value for a lock owner.
  293  */
  294 static int
  295 lf_hash_owner(caddr_t id, struct flock *fl, int flags)
  296 {
  297         uint32_t h;
  298 
  299         if (flags & F_REMOTE) {
  300                 h = HASHSTEP(0, fl->l_pid);
  301                 h = HASHSTEP(h, fl->l_sysid);
  302         } else if (flags & F_FLOCK) {
  303                 h = ((uintptr_t) id) >> 7;
  304         } else {
  305                 struct proc *p = (struct proc *) id;
  306                 h = HASHSTEP(0, p->p_pid);
  307                 h = HASHSTEP(h, 0);
  308         }
  309 
  310         return (h % LOCK_OWNER_HASH_SIZE);
  311 }
  312 
  313 /*
  314  * Return true if a lock owner matches the details passed to
  315  * lf_advlock.
  316  */
  317 static int
  318 lf_owner_matches(struct lock_owner *lo, caddr_t id, struct flock *fl,
  319     int flags)
  320 {
  321         if (flags & F_REMOTE) {
  322                 return lo->lo_pid == fl->l_pid
  323                         && lo->lo_sysid == fl->l_sysid;
  324         } else {
  325                 return lo->lo_id == id;
  326         }
  327 }
  328 
  329 static struct lockf_entry *
  330 lf_alloc_lock(struct lock_owner *lo)
  331 {
  332         struct lockf_entry *lf;
  333 
  334         lf = malloc(sizeof(struct lockf_entry), M_LOCKF, M_WAITOK|M_ZERO);
  335 
  336 #ifdef LOCKF_DEBUG
  337         if (lockf_debug & 4)
  338                 printf("Allocated lock %p\n", lf);
  339 #endif
  340         if (lo) {
  341                 sx_xlock(&lf_lock_owners_lock);
  342                 lo->lo_refs++;
  343                 sx_xunlock(&lf_lock_owners_lock);
  344                 lf->lf_owner = lo;
  345         }
  346 
  347         return (lf);
  348 }
  349 
  350 static int
  351 lf_free_lock(struct lockf_entry *lock)
  352 {
  353 
  354         KASSERT(lock->lf_refs > 0, ("lockf_entry negative ref count %p", lock));
  355         if (--lock->lf_refs > 0)
  356                 return (0);
  357         /*
  358          * Adjust the lock_owner reference count and
  359          * reclaim the entry if this is the last lock
  360          * for that owner.
  361          */
  362         struct lock_owner *lo = lock->lf_owner;
  363         if (lo) {
  364                 KASSERT(LIST_EMPTY(&lock->lf_outedges),
  365                     ("freeing lock with dependencies"));
  366                 KASSERT(LIST_EMPTY(&lock->lf_inedges),
  367                     ("freeing lock with dependants"));
  368                 sx_xlock(&lf_lock_owners_lock);
  369                 KASSERT(lo->lo_refs > 0, ("lock owner refcount"));
  370                 lo->lo_refs--;
  371                 if (lo->lo_refs == 0) {
  372 #ifdef LOCKF_DEBUG
  373                         if (lockf_debug & 1)
  374                                 printf("lf_free_lock: freeing lock owner %p\n",
  375                                     lo);
  376 #endif
  377                         if (lo->lo_vertex) {
  378                                 sx_xlock(&lf_owner_graph_lock);
  379                                 graph_free_vertex(&lf_owner_graph,
  380                                     lo->lo_vertex);
  381                                 sx_xunlock(&lf_owner_graph_lock);
  382                         }
  383                         LIST_REMOVE(lo, lo_link);
  384                         free(lo, M_LOCKF);
  385 #ifdef LOCKF_DEBUG
  386                         if (lockf_debug & 4)
  387                                 printf("Freed lock owner %p\n", lo);
  388 #endif
  389                 }
  390                 sx_unlock(&lf_lock_owners_lock);
  391         }
  392         if ((lock->lf_flags & F_REMOTE) && lock->lf_vnode) {
  393                 vrele(lock->lf_vnode);
  394                 lock->lf_vnode = NULL;
  395         }
  396 #ifdef LOCKF_DEBUG
  397         if (lockf_debug & 4)
  398                 printf("Freed lock %p\n", lock);
  399 #endif
  400         free(lock, M_LOCKF);
  401         return (1);
  402 }
  403 
  404 /*
  405  * Advisory record locking support
  406  */
  407 int
  408 lf_advlockasync(struct vop_advlockasync_args *ap, struct lockf **statep,
  409     u_quad_t size)
  410 {
  411         struct lockf *state, *freestate = NULL;
  412         struct flock *fl = ap->a_fl;
  413         struct lockf_entry *lock;
  414         struct vnode *vp = ap->a_vp;
  415         caddr_t id = ap->a_id;
  416         int flags = ap->a_flags;
  417         int hash;
  418         struct lock_owner *lo;
  419         off_t start, end, oadd;
  420         int error;
  421 
  422         /*
  423          * Handle the F_UNLKSYS case first - no need to mess about
  424          * creating a lock owner for this one.
  425          */
  426         if (ap->a_op == F_UNLCKSYS) {
  427                 lf_clearremotesys(fl->l_sysid);
  428                 return (0);
  429         }
  430 
  431         /*
  432          * Convert the flock structure into a start and end.
  433          */
  434         switch (fl->l_whence) {
  435 
  436         case SEEK_SET:
  437         case SEEK_CUR:
  438                 /*
  439                  * Caller is responsible for adding any necessary offset
  440                  * when SEEK_CUR is used.
  441                  */
  442                 start = fl->l_start;
  443                 break;
  444 
  445         case SEEK_END:
  446                 if (size > OFF_MAX ||
  447                     (fl->l_start > 0 && size > OFF_MAX - fl->l_start))
  448                         return (EOVERFLOW);
  449                 start = size + fl->l_start;
  450                 break;
  451 
  452         default:
  453                 return (EINVAL);
  454         }
  455         if (start < 0)
  456                 return (EINVAL);
  457         if (fl->l_len < 0) {
  458                 if (start == 0)
  459                         return (EINVAL);
  460                 end = start - 1;
  461                 start += fl->l_len;
  462                 if (start < 0)
  463                         return (EINVAL);
  464         } else if (fl->l_len == 0) {
  465                 end = OFF_MAX;
  466         } else {
  467                 oadd = fl->l_len - 1;
  468                 if (oadd > OFF_MAX - start)
  469                         return (EOVERFLOW);
  470                 end = start + oadd;
  471         }
  472 
  473 retry_setlock:
  474 
  475         /*
  476          * Avoid the common case of unlocking when inode has no locks.
  477          */
  478         VI_LOCK(vp);
  479         if ((*statep) == NULL) {
  480                 if (ap->a_op != F_SETLK) {
  481                         fl->l_type = F_UNLCK;
  482                         VI_UNLOCK(vp);
  483                         return (0);
  484                 }
  485         }
  486         VI_UNLOCK(vp);
  487 
  488         /*
  489          * Map our arguments to an existing lock owner or create one
  490          * if this is the first time we have seen this owner.
  491          */
  492         hash = lf_hash_owner(id, fl, flags);
  493         sx_xlock(&lf_lock_owners_lock);
  494         LIST_FOREACH(lo, &lf_lock_owners[hash], lo_link)
  495                 if (lf_owner_matches(lo, id, fl, flags))
  496                         break;
  497         if (!lo) {
  498                 /*
  499                  * We initialise the lock with a reference
  500                  * count which matches the new lockf_entry
  501                  * structure created below.
  502                  */
  503                 lo = malloc(sizeof(struct lock_owner), M_LOCKF,
  504                     M_WAITOK|M_ZERO);
  505 #ifdef LOCKF_DEBUG
  506                 if (lockf_debug & 4)
  507                         printf("Allocated lock owner %p\n", lo);
  508 #endif
  509 
  510                 lo->lo_refs = 1;
  511                 lo->lo_flags = flags;
  512                 lo->lo_id = id;
  513                 if (flags & F_REMOTE) {
  514                         lo->lo_pid = fl->l_pid;
  515                         lo->lo_sysid = fl->l_sysid;
  516                 } else if (flags & F_FLOCK) {
  517                         lo->lo_pid = -1;
  518                         lo->lo_sysid = 0;
  519                 } else {
  520                         struct proc *p = (struct proc *) id;
  521                         lo->lo_pid = p->p_pid;
  522                         lo->lo_sysid = 0;
  523                 }
  524                 lo->lo_vertex = NULL;
  525 
  526 #ifdef LOCKF_DEBUG
  527                 if (lockf_debug & 1) {
  528                         printf("lf_advlockasync: new lock owner %p ", lo);
  529                         lf_print_owner(lo);
  530                         printf("\n");
  531                 }
  532 #endif
  533 
  534                 LIST_INSERT_HEAD(&lf_lock_owners[hash], lo, lo_link);
  535         } else {
  536                 /*
  537                  * We have seen this lock owner before, increase its
  538                  * reference count to account for the new lockf_entry
  539                  * structure we create below.
  540                  */
  541                 lo->lo_refs++;
  542         }
  543         sx_xunlock(&lf_lock_owners_lock);
  544 
  545         /*
  546          * Create the lockf structure. We initialise the lf_owner
  547          * field here instead of in lf_alloc_lock() to avoid paying
  548          * the lf_lock_owners_lock tax twice.
  549          */
  550         lock = lf_alloc_lock(NULL);
  551         lock->lf_refs = 1;
  552         lock->lf_start = start;
  553         lock->lf_end = end;
  554         lock->lf_owner = lo;
  555         lock->lf_vnode = vp;
  556         if (flags & F_REMOTE) {
  557                 /*
  558                  * For remote locks, the caller may release its ref to
  559                  * the vnode at any time - we have to ref it here to
  560                  * prevent it from being recycled unexpectedly.
  561                  */
  562                 vref(vp);
  563         }
  564 
  565         /*
  566          * XXX The problem is that VTOI is ufs specific, so it will
  567          * break LOCKF_DEBUG for all other FS's other than UFS because
  568          * it casts the vnode->data ptr to struct inode *.
  569          */
  570 /*      lock->lf_inode = VTOI(ap->a_vp); */
  571         lock->lf_inode = (struct inode *)0;
  572         lock->lf_type = fl->l_type;
  573         LIST_INIT(&lock->lf_outedges);
  574         LIST_INIT(&lock->lf_inedges);
  575         lock->lf_async_task = ap->a_task;
  576         lock->lf_flags = ap->a_flags;
  577 
  578         /*
  579          * Do the requested operation. First find our state structure
  580          * and create a new one if necessary - the caller's *statep
  581          * variable and the state's ls_threads count is protected by
  582          * the vnode interlock.
  583          */
  584         VI_LOCK(vp);
  585         if (vp->v_iflag & VI_DOOMED) {
  586                 VI_UNLOCK(vp);
  587                 lf_free_lock(lock);
  588                 return (ENOENT);
  589         }
  590 
  591         /*
  592          * Allocate a state structure if necessary.
  593          */
  594         state = *statep;
  595         if (state == NULL) {
  596                 struct lockf *ls;
  597 
  598                 VI_UNLOCK(vp);
  599 
  600                 ls = malloc(sizeof(struct lockf), M_LOCKF, M_WAITOK|M_ZERO);
  601                 sx_init(&ls->ls_lock, "ls_lock");
  602                 LIST_INIT(&ls->ls_active);
  603                 LIST_INIT(&ls->ls_pending);
  604                 ls->ls_threads = 1;
  605 
  606                 sx_xlock(&lf_lock_states_lock);
  607                 LIST_INSERT_HEAD(&lf_lock_states, ls, ls_link);
  608                 sx_xunlock(&lf_lock_states_lock);
  609 
  610                 /*
  611                  * Cope if we lost a race with some other thread while
  612                  * trying to allocate memory.
  613                  */
  614                 VI_LOCK(vp);
  615                 if (vp->v_iflag & VI_DOOMED) {
  616                         VI_UNLOCK(vp);
  617                         sx_xlock(&lf_lock_states_lock);
  618                         LIST_REMOVE(ls, ls_link);
  619                         sx_xunlock(&lf_lock_states_lock);
  620                         sx_destroy(&ls->ls_lock);
  621                         free(ls, M_LOCKF);
  622                         lf_free_lock(lock);
  623                         return (ENOENT);
  624                 }
  625                 if ((*statep) == NULL) {
  626                         state = *statep = ls;
  627                         VI_UNLOCK(vp);
  628                 } else {
  629                         state = *statep;
  630                         state->ls_threads++;
  631                         VI_UNLOCK(vp);
  632 
  633                         sx_xlock(&lf_lock_states_lock);
  634                         LIST_REMOVE(ls, ls_link);
  635                         sx_xunlock(&lf_lock_states_lock);
  636                         sx_destroy(&ls->ls_lock);
  637                         free(ls, M_LOCKF);
  638                 }
  639         } else {
  640                 state->ls_threads++;
  641                 VI_UNLOCK(vp);
  642         }
  643 
  644         sx_xlock(&state->ls_lock);
  645         /*
  646          * Recheck the doomed vnode after state->ls_lock is
  647          * locked. lf_purgelocks() requires that no new threads add
  648          * pending locks when vnode is marked by VI_DOOMED flag.
  649          */
  650         VI_LOCK(vp);
  651         if (vp->v_iflag & VI_DOOMED) {
  652                 state->ls_threads--;
  653                 wakeup(state);
  654                 VI_UNLOCK(vp);
  655                 sx_xunlock(&state->ls_lock);
  656                 lf_free_lock(lock);
  657                 return (ENOENT);
  658         }
  659         VI_UNLOCK(vp);
  660 
  661         switch (ap->a_op) {
  662         case F_SETLK:
  663                 error = lf_setlock(state, lock, vp, ap->a_cookiep);
  664                 break;
  665 
  666         case F_UNLCK:
  667                 error = lf_clearlock(state, lock);
  668                 lf_free_lock(lock);
  669                 break;
  670 
  671         case F_GETLK:
  672                 error = lf_getlock(state, lock, fl);
  673                 lf_free_lock(lock);
  674                 break;
  675 
  676         case F_CANCEL:
  677                 if (ap->a_cookiep)
  678                         error = lf_cancel(state, lock, *ap->a_cookiep);
  679                 else
  680                         error = EINVAL;
  681                 lf_free_lock(lock);
  682                 break;
  683 
  684         default:
  685                 lf_free_lock(lock);
  686                 error = EINVAL;
  687                 break;
  688         }
  689 
  690 #ifdef INVARIANTS
  691         /*
  692          * Check for some can't happen stuff. In this case, the active
  693          * lock list becoming disordered or containing mutually
  694          * blocking locks. We also check the pending list for locks
  695          * which should be active (i.e. have no out-going edges).
  696          */
  697         LIST_FOREACH(lock, &state->ls_active, lf_link) {
  698                 struct lockf_entry *lf;
  699                 if (LIST_NEXT(lock, lf_link))
  700                         KASSERT((lock->lf_start
  701                                 <= LIST_NEXT(lock, lf_link)->lf_start),
  702                             ("locks disordered"));
  703                 LIST_FOREACH(lf, &state->ls_active, lf_link) {
  704                         if (lock == lf)
  705                                 break;
  706                         KASSERT(!lf_blocks(lock, lf),
  707                             ("two conflicting active locks"));
  708                         if (lock->lf_owner == lf->lf_owner)
  709                                 KASSERT(!lf_overlaps(lock, lf),
  710                                     ("two overlapping locks from same owner"));
  711                 }
  712         }
  713         LIST_FOREACH(lock, &state->ls_pending, lf_link) {
  714                 KASSERT(!LIST_EMPTY(&lock->lf_outedges),
  715                     ("pending lock which should be active"));
  716         }
  717 #endif
  718         sx_xunlock(&state->ls_lock);
  719 
  720         /*
  721          * If we have removed the last active lock on the vnode and
  722          * this is the last thread that was in-progress, we can free
  723          * the state structure. We update the caller's pointer inside
  724          * the vnode interlock but call free outside.
  725          *
  726          * XXX alternatively, keep the state structure around until
  727          * the filesystem recycles - requires a callback from the
  728          * filesystem.
  729          */
  730         VI_LOCK(vp);
  731 
  732         state->ls_threads--;
  733         wakeup(state);
  734         if (LIST_EMPTY(&state->ls_active) && state->ls_threads == 0) {
  735                 KASSERT(LIST_EMPTY(&state->ls_pending),
  736                     ("freeing state with pending locks"));
  737                 freestate = state;
  738                 *statep = NULL;
  739         }
  740 
  741         VI_UNLOCK(vp);
  742 
  743         if (freestate != NULL) {
  744                 sx_xlock(&lf_lock_states_lock);
  745                 LIST_REMOVE(freestate, ls_link);
  746                 sx_xunlock(&lf_lock_states_lock);
  747                 sx_destroy(&freestate->ls_lock);
  748                 free(freestate, M_LOCKF);
  749                 freestate = NULL;
  750         }
  751 
  752         if (error == EDOOFUS) {
  753                 KASSERT(ap->a_op == F_SETLK, ("EDOOFUS"));
  754                 goto retry_setlock;
  755         }
  756         return (error);
  757 }
  758 
  759 int
  760 lf_advlock(struct vop_advlock_args *ap, struct lockf **statep, u_quad_t size)
  761 {
  762         struct vop_advlockasync_args a;
  763 
  764         a.a_vp = ap->a_vp;
  765         a.a_id = ap->a_id;
  766         a.a_op = ap->a_op;
  767         a.a_fl = ap->a_fl;
  768         a.a_flags = ap->a_flags;
  769         a.a_task = NULL;
  770         a.a_cookiep = NULL;
  771 
  772         return (lf_advlockasync(&a, statep, size));
  773 }
  774 
  775 void
  776 lf_purgelocks(struct vnode *vp, struct lockf **statep)
  777 {
  778         struct lockf *state;
  779         struct lockf_entry *lock, *nlock;
  780 
  781         /*
  782          * For this to work correctly, the caller must ensure that no
  783          * other threads enter the locking system for this vnode,
  784          * e.g. by checking VI_DOOMED. We wake up any threads that are
  785          * sleeping waiting for locks on this vnode and then free all
  786          * the remaining locks.
  787          */
  788         VI_LOCK(vp);
  789         KASSERT(vp->v_iflag & VI_DOOMED,
  790             ("lf_purgelocks: vp %p has not vgone yet", vp));
  791         state = *statep;
  792         if (state) {
  793                 *statep = NULL;
  794                 state->ls_threads++;
  795                 VI_UNLOCK(vp);
  796 
  797                 sx_xlock(&state->ls_lock);
  798                 sx_xlock(&lf_owner_graph_lock);
  799                 LIST_FOREACH_SAFE(lock, &state->ls_pending, lf_link, nlock) {
  800                         LIST_REMOVE(lock, lf_link);
  801                         lf_remove_outgoing(lock);
  802                         lf_remove_incoming(lock);
  803 
  804                         /*
  805                          * If its an async lock, we can just free it
  806                          * here, otherwise we let the sleeping thread
  807                          * free it.
  808                          */
  809                         if (lock->lf_async_task) {
  810                                 lf_free_lock(lock);
  811                         } else {
  812                                 lock->lf_flags |= F_INTR;
  813                                 wakeup(lock);
  814                         }
  815                 }
  816                 sx_xunlock(&lf_owner_graph_lock);
  817                 sx_xunlock(&state->ls_lock);
  818 
  819                 /*
  820                  * Wait for all other threads, sleeping and otherwise
  821                  * to leave.
  822                  */
  823                 VI_LOCK(vp);
  824                 while (state->ls_threads > 1)
  825                         msleep(state, VI_MTX(vp), 0, "purgelocks", 0);
  826                 VI_UNLOCK(vp);
  827 
  828                 /*
  829                  * We can just free all the active locks since they
  830                  * will have no dependencies (we removed them all
  831                  * above). We don't need to bother locking since we
  832                  * are the last thread using this state structure.
  833                  */
  834                 KASSERT(LIST_EMPTY(&state->ls_pending),
  835                     ("lock pending for %p", state));
  836                 LIST_FOREACH_SAFE(lock, &state->ls_active, lf_link, nlock) {
  837                         LIST_REMOVE(lock, lf_link);
  838                         lf_free_lock(lock);
  839                 }
  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         } else {
  846                 VI_UNLOCK(vp);
  847         }
  848 }
  849 
  850 /*
  851  * Return non-zero if locks 'x' and 'y' overlap.
  852  */
  853 static int
  854 lf_overlaps(struct lockf_entry *x, struct lockf_entry *y)
  855 {
  856 
  857         return (x->lf_start <= y->lf_end && x->lf_end >= y->lf_start);
  858 }
  859 
  860 /*
  861  * Return non-zero if lock 'x' is blocked by lock 'y' (or vice versa).
  862  */
  863 static int
  864 lf_blocks(struct lockf_entry *x, struct lockf_entry *y)
  865 {
  866 
  867         return x->lf_owner != y->lf_owner
  868                 && (x->lf_type == F_WRLCK || y->lf_type == F_WRLCK)
  869                 && lf_overlaps(x, y);
  870 }
  871 
  872 /*
  873  * Allocate a lock edge from the free list
  874  */
  875 static struct lockf_edge *
  876 lf_alloc_edge(void)
  877 {
  878 
  879         return (malloc(sizeof(struct lockf_edge), M_LOCKF, M_WAITOK|M_ZERO));
  880 }
  881 
  882 /*
  883  * Free a lock edge.
  884  */
  885 static void
  886 lf_free_edge(struct lockf_edge *e)
  887 {
  888 
  889         free(e, M_LOCKF);
  890 }
  891 
  892 
  893 /*
  894  * Ensure that the lock's owner has a corresponding vertex in the
  895  * owner graph.
  896  */
  897 static void
  898 lf_alloc_vertex(struct lockf_entry *lock)
  899 {
  900         struct owner_graph *g = &lf_owner_graph;
  901 
  902         if (!lock->lf_owner->lo_vertex)
  903                 lock->lf_owner->lo_vertex =
  904                         graph_alloc_vertex(g, lock->lf_owner);
  905 }
  906 
  907 /*
  908  * Attempt to record an edge from lock x to lock y. Return EDEADLK if
  909  * the new edge would cause a cycle in the owner graph.
  910  */
  911 static int
  912 lf_add_edge(struct lockf_entry *x, struct lockf_entry *y)
  913 {
  914         struct owner_graph *g = &lf_owner_graph;
  915         struct lockf_edge *e;
  916         int error;
  917 
  918 #ifdef INVARIANTS
  919         LIST_FOREACH(e, &x->lf_outedges, le_outlink)
  920                 KASSERT(e->le_to != y, ("adding lock edge twice"));
  921 #endif
  922 
  923         /*
  924          * Make sure the two owners have entries in the owner graph.
  925          */
  926         lf_alloc_vertex(x);
  927         lf_alloc_vertex(y);
  928 
  929         error = graph_add_edge(g, x->lf_owner->lo_vertex,
  930             y->lf_owner->lo_vertex);
  931         if (error)
  932                 return (error);
  933 
  934         e = lf_alloc_edge();
  935         LIST_INSERT_HEAD(&x->lf_outedges, e, le_outlink);
  936         LIST_INSERT_HEAD(&y->lf_inedges, e, le_inlink);
  937         e->le_from = x;
  938         e->le_to = y;
  939 
  940         return (0);
  941 }
  942 
  943 /*
  944  * Remove an edge from the lock graph.
  945  */
  946 static void
  947 lf_remove_edge(struct lockf_edge *e)
  948 {
  949         struct owner_graph *g = &lf_owner_graph;
  950         struct lockf_entry *x = e->le_from;
  951         struct lockf_entry *y = e->le_to;
  952 
  953         graph_remove_edge(g, x->lf_owner->lo_vertex, y->lf_owner->lo_vertex);
  954         LIST_REMOVE(e, le_outlink);
  955         LIST_REMOVE(e, le_inlink);
  956         e->le_from = NULL;
  957         e->le_to = NULL;
  958         lf_free_edge(e);
  959 }
  960 
  961 /*
  962  * Remove all out-going edges from lock x.
  963  */
  964 static void
  965 lf_remove_outgoing(struct lockf_entry *x)
  966 {
  967         struct lockf_edge *e;
  968 
  969         while ((e = LIST_FIRST(&x->lf_outedges)) != NULL) {
  970                 lf_remove_edge(e);
  971         }
  972 }
  973 
  974 /*
  975  * Remove all in-coming edges from lock x.
  976  */
  977 static void
  978 lf_remove_incoming(struct lockf_entry *x)
  979 {
  980         struct lockf_edge *e;
  981 
  982         while ((e = LIST_FIRST(&x->lf_inedges)) != NULL) {
  983                 lf_remove_edge(e);
  984         }
  985 }
  986 
  987 /*
  988  * Walk the list of locks for the file and create an out-going edge
  989  * from lock to each blocking lock.
  990  */
  991 static int
  992 lf_add_outgoing(struct lockf *state, struct lockf_entry *lock)
  993 {
  994         struct lockf_entry *overlap;
  995         int error;
  996 
  997         LIST_FOREACH(overlap, &state->ls_active, lf_link) {
  998                 /*
  999                  * We may assume that the active list is sorted by
 1000                  * lf_start.
 1001                  */
 1002                 if (overlap->lf_start > lock->lf_end)
 1003                         break;
 1004                 if (!lf_blocks(lock, overlap))
 1005                         continue;
 1006 
 1007                 /*
 1008                  * We've found a blocking lock. Add the corresponding
 1009                  * edge to the graphs and see if it would cause a
 1010                  * deadlock.
 1011                  */
 1012                 error = lf_add_edge(lock, overlap);
 1013 
 1014                 /*
 1015                  * The only error that lf_add_edge returns is EDEADLK.
 1016                  * Remove any edges we added and return the error.
 1017                  */
 1018                 if (error) {
 1019                         lf_remove_outgoing(lock);
 1020                         return (error);
 1021                 }
 1022         }
 1023 
 1024         /*
 1025          * We also need to add edges to sleeping locks that block
 1026          * us. This ensures that lf_wakeup_lock cannot grant two
 1027          * mutually blocking locks simultaneously and also enforces a
 1028          * 'first come, first served' fairness model. Note that this
 1029          * only happens if we are blocked by at least one active lock
 1030          * due to the call to lf_getblock in lf_setlock below.
 1031          */
 1032         LIST_FOREACH(overlap, &state->ls_pending, lf_link) {
 1033                 if (!lf_blocks(lock, overlap))
 1034                         continue;
 1035                 /*
 1036                  * We've found a blocking lock. Add the corresponding
 1037                  * edge to the graphs and see if it would cause a
 1038                  * deadlock.
 1039                  */
 1040                 error = lf_add_edge(lock, overlap);
 1041 
 1042                 /*
 1043                  * The only error that lf_add_edge returns is EDEADLK.
 1044                  * Remove any edges we added and return the error.
 1045                  */
 1046                 if (error) {
 1047                         lf_remove_outgoing(lock);
 1048                         return (error);
 1049                 }
 1050         }
 1051 
 1052         return (0);
 1053 }
 1054 
 1055 /*
 1056  * Walk the list of pending locks for the file and create an in-coming
 1057  * edge from lock to each blocking lock.
 1058  */
 1059 static int
 1060 lf_add_incoming(struct lockf *state, struct lockf_entry *lock)
 1061 {
 1062         struct lockf_entry *overlap;
 1063         int error;
 1064 
 1065         LIST_FOREACH(overlap, &state->ls_pending, lf_link) {
 1066                 if (!lf_blocks(lock, overlap))
 1067                         continue;
 1068 
 1069                 /*
 1070                  * We've found a blocking lock. Add the corresponding
 1071                  * edge to the graphs and see if it would cause a
 1072                  * deadlock.
 1073                  */
 1074                 error = lf_add_edge(overlap, lock);
 1075 
 1076                 /*
 1077                  * The only error that lf_add_edge returns is EDEADLK.
 1078                  * Remove any edges we added and return the error.
 1079                  */
 1080                 if (error) {
 1081                         lf_remove_incoming(lock);
 1082                         return (error);
 1083                 }
 1084         }
 1085         return (0);
 1086 }
 1087 
 1088 /*
 1089  * Insert lock into the active list, keeping list entries ordered by
 1090  * increasing values of lf_start.
 1091  */
 1092 static void
 1093 lf_insert_lock(struct lockf *state, struct lockf_entry *lock)
 1094 {
 1095         struct lockf_entry *lf, *lfprev;
 1096 
 1097         if (LIST_EMPTY(&state->ls_active)) {
 1098                 LIST_INSERT_HEAD(&state->ls_active, lock, lf_link);
 1099                 return;
 1100         }
 1101 
 1102         lfprev = NULL;
 1103         LIST_FOREACH(lf, &state->ls_active, lf_link) {
 1104                 if (lf->lf_start > lock->lf_start) {
 1105                         LIST_INSERT_BEFORE(lf, lock, lf_link);
 1106                         return;
 1107                 }
 1108                 lfprev = lf;
 1109         }
 1110         LIST_INSERT_AFTER(lfprev, lock, lf_link);
 1111 }
 1112 
 1113 /*
 1114  * Wake up a sleeping lock and remove it from the pending list now
 1115  * that all its dependencies have been resolved. The caller should
 1116  * arrange for the lock to be added to the active list, adjusting any
 1117  * existing locks for the same owner as needed.
 1118  */
 1119 static void
 1120 lf_wakeup_lock(struct lockf *state, struct lockf_entry *wakelock)
 1121 {
 1122 
 1123         /*
 1124          * Remove from ls_pending list and wake up the caller
 1125          * or start the async notification, as appropriate.
 1126          */
 1127         LIST_REMOVE(wakelock, lf_link);
 1128 #ifdef LOCKF_DEBUG
 1129         if (lockf_debug & 1)
 1130                 lf_print("lf_wakeup_lock: awakening", wakelock);
 1131 #endif /* LOCKF_DEBUG */
 1132         if (wakelock->lf_async_task) {
 1133                 taskqueue_enqueue(taskqueue_thread, wakelock->lf_async_task);
 1134         } else {
 1135                 wakeup(wakelock);
 1136         }
 1137 }
 1138 
 1139 /*
 1140  * Re-check all dependent locks and remove edges to locks that we no
 1141  * longer block. If 'all' is non-zero, the lock has been removed and
 1142  * we must remove all the dependencies, otherwise it has simply been
 1143  * reduced but remains active. Any pending locks which have been been
 1144  * unblocked are added to 'granted'
 1145  */
 1146 static void
 1147 lf_update_dependancies(struct lockf *state, struct lockf_entry *lock, int all,
 1148         struct lockf_entry_list *granted)
 1149 {
 1150         struct lockf_edge *e, *ne;
 1151         struct lockf_entry *deplock;
 1152 
 1153         LIST_FOREACH_SAFE(e, &lock->lf_inedges, le_inlink, ne) {
 1154                 deplock = e->le_from;
 1155                 if (all || !lf_blocks(lock, deplock)) {
 1156                         sx_xlock(&lf_owner_graph_lock);
 1157                         lf_remove_edge(e);
 1158                         sx_xunlock(&lf_owner_graph_lock);
 1159                         if (LIST_EMPTY(&deplock->lf_outedges)) {
 1160                                 lf_wakeup_lock(state, deplock);
 1161                                 LIST_INSERT_HEAD(granted, deplock, lf_link);
 1162                         }
 1163                 }
 1164         }
 1165 }
 1166 
 1167 /*
 1168  * Set the start of an existing active lock, updating dependencies and
 1169  * adding any newly woken locks to 'granted'.
 1170  */
 1171 static void
 1172 lf_set_start(struct lockf *state, struct lockf_entry *lock, off_t new_start,
 1173         struct lockf_entry_list *granted)
 1174 {
 1175 
 1176         KASSERT(new_start >= lock->lf_start, ("can't increase lock"));
 1177         lock->lf_start = new_start;
 1178         LIST_REMOVE(lock, lf_link);
 1179         lf_insert_lock(state, lock);
 1180         lf_update_dependancies(state, lock, FALSE, granted);
 1181 }
 1182 
 1183 /*
 1184  * Set the end of an existing active lock, updating dependencies and
 1185  * adding any newly woken locks to 'granted'.
 1186  */
 1187 static void
 1188 lf_set_end(struct lockf *state, struct lockf_entry *lock, off_t new_end,
 1189         struct lockf_entry_list *granted)
 1190 {
 1191 
 1192         KASSERT(new_end <= lock->lf_end, ("can't increase lock"));
 1193         lock->lf_end = new_end;
 1194         lf_update_dependancies(state, lock, FALSE, granted);
 1195 }
 1196 
 1197 /*
 1198  * Add a lock to the active list, updating or removing any current
 1199  * locks owned by the same owner and processing any pending locks that
 1200  * become unblocked as a result. This code is also used for unlock
 1201  * since the logic for updating existing locks is identical.
 1202  *
 1203  * As a result of processing the new lock, we may unblock existing
 1204  * pending locks as a result of downgrading/unlocking. We simply
 1205  * activate the newly granted locks by looping.
 1206  *
 1207  * Since the new lock already has its dependencies set up, we always
 1208  * add it to the list (unless its an unlock request). This may
 1209  * fragment the lock list in some pathological cases but its probably
 1210  * not a real problem.
 1211  */
 1212 static void
 1213 lf_activate_lock(struct lockf *state, struct lockf_entry *lock)
 1214 {
 1215         struct lockf_entry *overlap, *lf;
 1216         struct lockf_entry_list granted;
 1217         int ovcase;
 1218 
 1219         LIST_INIT(&granted);
 1220         LIST_INSERT_HEAD(&granted, lock, lf_link);
 1221 
 1222         while (!LIST_EMPTY(&granted)) {
 1223                 lock = LIST_FIRST(&granted);
 1224                 LIST_REMOVE(lock, lf_link);
 1225 
 1226                 /*
 1227                  * Skip over locks owned by other processes.  Handle
 1228                  * any locks that overlap and are owned by ourselves.
 1229                  */
 1230                 overlap = LIST_FIRST(&state->ls_active);
 1231                 for (;;) {
 1232                         ovcase = lf_findoverlap(&overlap, lock, SELF);
 1233 
 1234 #ifdef LOCKF_DEBUG
 1235                         if (ovcase && (lockf_debug & 2)) {
 1236                                 printf("lf_setlock: overlap %d", ovcase);
 1237                                 lf_print("", overlap);
 1238                         }
 1239 #endif
 1240                         /*
 1241                          * Six cases:
 1242                          *      0) no overlap
 1243                          *      1) overlap == lock
 1244                          *      2) overlap contains lock
 1245                          *      3) lock contains overlap
 1246                          *      4) overlap starts before lock
 1247                          *      5) overlap ends after lock
 1248                          */
 1249                         switch (ovcase) {
 1250                         case 0: /* no overlap */
 1251                                 break;
 1252 
 1253                         case 1: /* overlap == lock */
 1254                                 /*
 1255                                  * We have already setup the
 1256                                  * dependants for the new lock, taking
 1257                                  * into account a possible downgrade
 1258                                  * or unlock. Remove the old lock.
 1259                                  */
 1260                                 LIST_REMOVE(overlap, lf_link);
 1261                                 lf_update_dependancies(state, overlap, TRUE,
 1262                                         &granted);
 1263                                 lf_free_lock(overlap);
 1264                                 break;
 1265 
 1266                         case 2: /* overlap contains lock */
 1267                                 /*
 1268                                  * Just split the existing lock.
 1269                                  */
 1270                                 lf_split(state, overlap, lock, &granted);
 1271                                 break;
 1272 
 1273                         case 3: /* lock contains overlap */
 1274                                 /*
 1275                                  * Delete the overlap and advance to
 1276                                  * the next entry in the list.
 1277                                  */
 1278                                 lf = LIST_NEXT(overlap, lf_link);
 1279                                 LIST_REMOVE(overlap, lf_link);
 1280                                 lf_update_dependancies(state, overlap, TRUE,
 1281                                         &granted);
 1282                                 lf_free_lock(overlap);
 1283                                 overlap = lf;
 1284                                 continue;
 1285 
 1286                         case 4: /* overlap starts before lock */
 1287                                 /*
 1288                                  * Just update the overlap end and
 1289                                  * move on.
 1290                                  */
 1291                                 lf_set_end(state, overlap, lock->lf_start - 1,
 1292                                     &granted);
 1293                                 overlap = LIST_NEXT(overlap, lf_link);
 1294                                 continue;
 1295 
 1296                         case 5: /* overlap ends after lock */
 1297                                 /*
 1298                                  * Change the start of overlap and
 1299                                  * re-insert.
 1300                                  */
 1301                                 lf_set_start(state, overlap, lock->lf_end + 1,
 1302                                     &granted);
 1303                                 break;
 1304                         }
 1305                         break;
 1306                 }
 1307 #ifdef LOCKF_DEBUG
 1308                 if (lockf_debug & 1) {
 1309                         if (lock->lf_type != F_UNLCK)
 1310                                 lf_print("lf_activate_lock: activated", lock);
 1311                         else
 1312                                 lf_print("lf_activate_lock: unlocked", lock);
 1313                         lf_printlist("lf_activate_lock", lock);
 1314                 }
 1315 #endif /* LOCKF_DEBUG */
 1316                 if (lock->lf_type != F_UNLCK)
 1317                         lf_insert_lock(state, lock);
 1318         }
 1319 }
 1320 
 1321 /*
 1322  * Cancel a pending lock request, either as a result of a signal or a
 1323  * cancel request for an async lock.
 1324  */
 1325 static void
 1326 lf_cancel_lock(struct lockf *state, struct lockf_entry *lock)
 1327 {
 1328         struct lockf_entry_list granted;
 1329 
 1330         /*
 1331          * Note it is theoretically possible that cancelling this lock
 1332          * may allow some other pending lock to become
 1333          * active. Consider this case:
 1334          *
 1335          * Owner        Action          Result          Dependencies
 1336          * 
 1337          * A:           lock [0..0]     succeeds        
 1338          * B:           lock [2..2]     succeeds        
 1339          * C:           lock [1..2]     blocked         C->B
 1340          * D:           lock [0..1]     blocked         C->B,D->A,D->C
 1341          * A:           unlock [0..0]                   C->B,D->C
 1342          * C:           cancel [1..2]   
 1343          */
 1344 
 1345         LIST_REMOVE(lock, lf_link);
 1346 
 1347         /*
 1348          * Removing out-going edges is simple.
 1349          */
 1350         sx_xlock(&lf_owner_graph_lock);
 1351         lf_remove_outgoing(lock);
 1352         sx_xunlock(&lf_owner_graph_lock);
 1353 
 1354         /*
 1355          * Removing in-coming edges may allow some other lock to
 1356          * become active - we use lf_update_dependancies to figure
 1357          * this out.
 1358          */
 1359         LIST_INIT(&granted);
 1360         lf_update_dependancies(state, lock, TRUE, &granted);
 1361         lf_free_lock(lock);
 1362 
 1363         /*
 1364          * Feed any newly active locks to lf_activate_lock.
 1365          */
 1366         while (!LIST_EMPTY(&granted)) {
 1367                 lock = LIST_FIRST(&granted);
 1368                 LIST_REMOVE(lock, lf_link);
 1369                 lf_activate_lock(state, lock);
 1370         }
 1371 }
 1372 
 1373 /*
 1374  * Set a byte-range lock.
 1375  */
 1376 static int
 1377 lf_setlock(struct lockf *state, struct lockf_entry *lock, struct vnode *vp,
 1378     void **cookiep)
 1379 {
 1380         static char lockstr[] = "lockf";
 1381         int error, priority, stops_deferred;
 1382 
 1383 #ifdef LOCKF_DEBUG
 1384         if (lockf_debug & 1)
 1385                 lf_print("lf_setlock", lock);
 1386 #endif /* LOCKF_DEBUG */
 1387 
 1388         /*
 1389          * Set the priority
 1390          */
 1391         priority = PLOCK;
 1392         if (lock->lf_type == F_WRLCK)
 1393                 priority += 4;
 1394         if (!(lock->lf_flags & F_NOINTR))
 1395                 priority |= PCATCH;
 1396         /*
 1397          * Scan lock list for this file looking for locks that would block us.
 1398          */
 1399         if (lf_getblock(state, lock)) {
 1400                 /*
 1401                  * Free the structure and return if nonblocking.
 1402                  */
 1403                 if ((lock->lf_flags & F_WAIT) == 0
 1404                     && lock->lf_async_task == NULL) {
 1405                         lf_free_lock(lock);
 1406                         error = EAGAIN;
 1407                         goto out;
 1408                 }
 1409 
 1410                 /*
 1411                  * For flock type locks, we must first remove
 1412                  * any shared locks that we hold before we sleep
 1413                  * waiting for an exclusive lock.
 1414                  */
 1415                 if ((lock->lf_flags & F_FLOCK) &&
 1416                     lock->lf_type == F_WRLCK) {
 1417                         lock->lf_type = F_UNLCK;
 1418                         lf_activate_lock(state, lock);
 1419                         lock->lf_type = F_WRLCK;
 1420                 }
 1421 
 1422                 /*
 1423                  * We are blocked. Create edges to each blocking lock,
 1424                  * checking for deadlock using the owner graph. For
 1425                  * simplicity, we run deadlock detection for all
 1426                  * locks, posix and otherwise.
 1427                  */
 1428                 sx_xlock(&lf_owner_graph_lock);
 1429                 error = lf_add_outgoing(state, lock);
 1430                 sx_xunlock(&lf_owner_graph_lock);
 1431 
 1432                 if (error) {
 1433 #ifdef LOCKF_DEBUG
 1434                         if (lockf_debug & 1)
 1435                                 lf_print("lf_setlock: deadlock", lock);
 1436 #endif
 1437                         lf_free_lock(lock);
 1438                         goto out;
 1439                 }
 1440 
 1441                 /*
 1442                  * We have added edges to everything that blocks
 1443                  * us. Sleep until they all go away.
 1444                  */
 1445                 LIST_INSERT_HEAD(&state->ls_pending, lock, lf_link);
 1446 #ifdef LOCKF_DEBUG
 1447                 if (lockf_debug & 1) {
 1448                         struct lockf_edge *e;
 1449                         LIST_FOREACH(e, &lock->lf_outedges, le_outlink) {
 1450                                 lf_print("lf_setlock: blocking on", e->le_to);
 1451                                 lf_printlist("lf_setlock", e->le_to);
 1452                         }
 1453                 }
 1454 #endif /* LOCKF_DEBUG */
 1455 
 1456                 if ((lock->lf_flags & F_WAIT) == 0) {
 1457                         /*
 1458                          * The caller requested async notification -
 1459                          * this callback happens when the blocking
 1460                          * lock is released, allowing the caller to
 1461                          * make another attempt to take the lock.
 1462                          */
 1463                         *cookiep = (void *) lock;
 1464                         error = EINPROGRESS;
 1465                         goto out;
 1466                 }
 1467 
 1468                 lock->lf_refs++;
 1469                 stops_deferred = sigdeferstop(SIGDEFERSTOP_ERESTART);
 1470                 error = sx_sleep(lock, &state->ls_lock, priority, lockstr, 0);
 1471                 sigallowstop(stops_deferred);
 1472                 if (lf_free_lock(lock)) {
 1473                         error = EDOOFUS;
 1474                         goto out;
 1475                 }
 1476 
 1477                 /*
 1478                  * We may have been awakened by a signal and/or by a
 1479                  * debugger continuing us (in which cases we must
 1480                  * remove our lock graph edges) and/or by another
 1481                  * process releasing a lock (in which case our edges
 1482                  * have already been removed and we have been moved to
 1483                  * the active list). We may also have been woken by
 1484                  * lf_purgelocks which we report to the caller as
 1485                  * EINTR. In that case, lf_purgelocks will have
 1486                  * removed our lock graph edges.
 1487                  *
 1488                  * Note that it is possible to receive a signal after
 1489                  * we were successfully woken (and moved to the active
 1490                  * list) but before we resumed execution. In this
 1491                  * case, our lf_outedges list will be clear. We
 1492                  * pretend there was no error.
 1493                  *
 1494                  * Note also, if we have been sleeping long enough, we
 1495                  * may now have incoming edges from some newer lock
 1496                  * which is waiting behind us in the queue.
 1497                  */
 1498                 if (lock->lf_flags & F_INTR) {
 1499                         error = EINTR;
 1500                         lf_free_lock(lock);
 1501                         goto out;
 1502                 }
 1503                 if (LIST_EMPTY(&lock->lf_outedges)) {
 1504                         error = 0;
 1505                 } else {
 1506                         lf_cancel_lock(state, lock);
 1507                         goto out;
 1508                 }
 1509 #ifdef LOCKF_DEBUG
 1510                 if (lockf_debug & 1) {
 1511                         lf_print("lf_setlock: granted", lock);
 1512                 }
 1513 #endif
 1514                 goto out;
 1515         }
 1516         /*
 1517          * It looks like we are going to grant the lock. First add
 1518          * edges from any currently pending lock that the new lock
 1519          * would block.
 1520          */
 1521         sx_xlock(&lf_owner_graph_lock);
 1522         error = lf_add_incoming(state, lock);
 1523         sx_xunlock(&lf_owner_graph_lock);
 1524         if (error) {
 1525 #ifdef LOCKF_DEBUG
 1526                 if (lockf_debug & 1)
 1527                         lf_print("lf_setlock: deadlock", lock);
 1528 #endif
 1529                 lf_free_lock(lock);
 1530                 goto out;
 1531         }
 1532 
 1533         /*
 1534          * No blocks!!  Add the lock.  Note that we will
 1535          * downgrade or upgrade any overlapping locks this
 1536          * process already owns.
 1537          */
 1538         lf_activate_lock(state, lock);
 1539         error = 0;
 1540 out:
 1541         return (error);
 1542 }
 1543 
 1544 /*
 1545  * Remove a byte-range lock on an inode.
 1546  *
 1547  * Generally, find the lock (or an overlap to that lock)
 1548  * and remove it (or shrink it), then wakeup anyone we can.
 1549  */
 1550 static int
 1551 lf_clearlock(struct lockf *state, struct lockf_entry *unlock)
 1552 {
 1553         struct lockf_entry *overlap;
 1554 
 1555         overlap = LIST_FIRST(&state->ls_active);
 1556 
 1557         if (overlap == NOLOCKF)
 1558                 return (0);
 1559 #ifdef LOCKF_DEBUG
 1560         if (unlock->lf_type != F_UNLCK)
 1561                 panic("lf_clearlock: bad type");
 1562         if (lockf_debug & 1)
 1563                 lf_print("lf_clearlock", unlock);
 1564 #endif /* LOCKF_DEBUG */
 1565 
 1566         lf_activate_lock(state, unlock);
 1567 
 1568         return (0);
 1569 }
 1570 
 1571 /*
 1572  * Check whether there is a blocking lock, and if so return its
 1573  * details in '*fl'.
 1574  */
 1575 static int
 1576 lf_getlock(struct lockf *state, struct lockf_entry *lock, struct flock *fl)
 1577 {
 1578         struct lockf_entry *block;
 1579 
 1580 #ifdef LOCKF_DEBUG
 1581         if (lockf_debug & 1)
 1582                 lf_print("lf_getlock", lock);
 1583 #endif /* LOCKF_DEBUG */
 1584 
 1585         if ((block = lf_getblock(state, lock))) {
 1586                 fl->l_type = block->lf_type;
 1587                 fl->l_whence = SEEK_SET;
 1588                 fl->l_start = block->lf_start;
 1589                 if (block->lf_end == OFF_MAX)
 1590                         fl->l_len = 0;
 1591                 else
 1592                         fl->l_len = block->lf_end - block->lf_start + 1;
 1593                 fl->l_pid = block->lf_owner->lo_pid;
 1594                 fl->l_sysid = block->lf_owner->lo_sysid;
 1595         } else {
 1596                 fl->l_type = F_UNLCK;
 1597         }
 1598         return (0);
 1599 }
 1600 
 1601 /*
 1602  * Cancel an async lock request.
 1603  */
 1604 static int
 1605 lf_cancel(struct lockf *state, struct lockf_entry *lock, void *cookie)
 1606 {
 1607         struct lockf_entry *reallock;
 1608 
 1609         /*
 1610          * We need to match this request with an existing lock
 1611          * request.
 1612          */
 1613         LIST_FOREACH(reallock, &state->ls_pending, lf_link) {
 1614                 if ((void *) reallock == cookie) {
 1615                         /*
 1616                          * Double-check that this lock looks right
 1617                          * (maybe use a rolling ID for the cancel
 1618                          * cookie instead?)
 1619                          */
 1620                         if (!(reallock->lf_vnode == lock->lf_vnode
 1621                                 && reallock->lf_start == lock->lf_start
 1622                                 && reallock->lf_end == lock->lf_end)) {
 1623                                 return (ENOENT);
 1624                         }
 1625 
 1626                         /*
 1627                          * Make sure this lock was async and then just
 1628                          * remove it from its wait lists.
 1629                          */
 1630                         if (!reallock->lf_async_task) {
 1631                                 return (ENOENT);
 1632                         }
 1633 
 1634                         /*
 1635                          * Note that since any other thread must take
 1636                          * state->ls_lock before it can possibly
 1637                          * trigger the async callback, we are safe
 1638                          * from a race with lf_wakeup_lock, i.e. we
 1639                          * can free the lock (actually our caller does
 1640                          * this).
 1641                          */
 1642                         lf_cancel_lock(state, reallock);
 1643                         return (0);
 1644                 }
 1645         }
 1646 
 1647         /*
 1648          * We didn't find a matching lock - not much we can do here.
 1649          */
 1650         return (ENOENT);
 1651 }
 1652 
 1653 /*
 1654  * Walk the list of locks for an inode and
 1655  * return the first blocking lock.
 1656  */
 1657 static struct lockf_entry *
 1658 lf_getblock(struct lockf *state, struct lockf_entry *lock)
 1659 {
 1660         struct lockf_entry *overlap;
 1661 
 1662         LIST_FOREACH(overlap, &state->ls_active, lf_link) {
 1663                 /*
 1664                  * We may assume that the active list is sorted by
 1665                  * lf_start.
 1666                  */
 1667                 if (overlap->lf_start > lock->lf_end)
 1668                         break;
 1669                 if (!lf_blocks(lock, overlap))
 1670                         continue;
 1671                 return (overlap);
 1672         }
 1673         return (NOLOCKF);
 1674 }
 1675 
 1676 /*
 1677  * Walk the list of locks for an inode to find an overlapping lock (if
 1678  * any) and return a classification of that overlap.
 1679  *
 1680  * Arguments:
 1681  *      *overlap        The place in the lock list to start looking
 1682  *      lock            The lock which is being tested
 1683  *      type            Pass 'SELF' to test only locks with the same
 1684  *                      owner as lock, or 'OTHER' to test only locks
 1685  *                      with a different owner
 1686  *
 1687  * Returns one of six values:
 1688  *      0) no overlap
 1689  *      1) overlap == lock
 1690  *      2) overlap contains lock
 1691  *      3) lock contains overlap
 1692  *      4) overlap starts before lock
 1693  *      5) overlap ends after lock
 1694  *
 1695  * If there is an overlapping lock, '*overlap' is set to point at the
 1696  * overlapping lock.
 1697  *
 1698  * NOTE: this returns only the FIRST overlapping lock.  There
 1699  *       may be more than one.
 1700  */
 1701 static int
 1702 lf_findoverlap(struct lockf_entry **overlap, struct lockf_entry *lock, int type)
 1703 {
 1704         struct lockf_entry *lf;
 1705         off_t start, end;
 1706         int res;
 1707 
 1708         if ((*overlap) == NOLOCKF) {
 1709                 return (0);
 1710         }
 1711 #ifdef LOCKF_DEBUG
 1712         if (lockf_debug & 2)
 1713                 lf_print("lf_findoverlap: looking for overlap in", lock);
 1714 #endif /* LOCKF_DEBUG */
 1715         start = lock->lf_start;
 1716         end = lock->lf_end;
 1717         res = 0;
 1718         while (*overlap) {
 1719                 lf = *overlap;
 1720                 if (lf->lf_start > end)
 1721                         break;
 1722                 if (((type & SELF) && lf->lf_owner != lock->lf_owner) ||
 1723                     ((type & OTHERS) && lf->lf_owner == lock->lf_owner)) {
 1724                         *overlap = LIST_NEXT(lf, lf_link);
 1725                         continue;
 1726                 }
 1727 #ifdef LOCKF_DEBUG
 1728                 if (lockf_debug & 2)
 1729                         lf_print("\tchecking", lf);
 1730 #endif /* LOCKF_DEBUG */
 1731                 /*
 1732                  * OK, check for overlap
 1733                  *
 1734                  * Six cases:
 1735                  *      0) no overlap
 1736                  *      1) overlap == lock
 1737                  *      2) overlap contains lock
 1738                  *      3) lock contains overlap
 1739                  *      4) overlap starts before lock
 1740                  *      5) overlap ends after lock
 1741                  */
 1742                 if (start > lf->lf_end) {
 1743                         /* Case 0 */
 1744 #ifdef LOCKF_DEBUG
 1745                         if (lockf_debug & 2)
 1746                                 printf("no overlap\n");
 1747 #endif /* LOCKF_DEBUG */
 1748                         *overlap = LIST_NEXT(lf, lf_link);
 1749                         continue;
 1750                 }
 1751                 if (lf->lf_start == start && lf->lf_end == end) {
 1752                         /* Case 1 */
 1753 #ifdef LOCKF_DEBUG
 1754                         if (lockf_debug & 2)
 1755                                 printf("overlap == lock\n");
 1756 #endif /* LOCKF_DEBUG */
 1757                         res = 1;
 1758                         break;
 1759                 }
 1760                 if (lf->lf_start <= start && lf->lf_end >= end) {
 1761                         /* Case 2 */
 1762 #ifdef LOCKF_DEBUG
 1763                         if (lockf_debug & 2)
 1764                                 printf("overlap contains lock\n");
 1765 #endif /* LOCKF_DEBUG */
 1766                         res = 2;
 1767                         break;
 1768                 }
 1769                 if (start <= lf->lf_start && end >= lf->lf_end) {
 1770                         /* Case 3 */
 1771 #ifdef LOCKF_DEBUG
 1772                         if (lockf_debug & 2)
 1773                                 printf("lock contains overlap\n");
 1774 #endif /* LOCKF_DEBUG */
 1775                         res = 3;
 1776                         break;
 1777                 }
 1778                 if (lf->lf_start < start && lf->lf_end >= start) {
 1779                         /* Case 4 */
 1780 #ifdef LOCKF_DEBUG
 1781                         if (lockf_debug & 2)
 1782                                 printf("overlap starts before lock\n");
 1783 #endif /* LOCKF_DEBUG */
 1784                         res = 4;
 1785                         break;
 1786                 }
 1787                 if (lf->lf_start > start && lf->lf_end > end) {
 1788                         /* Case 5 */
 1789 #ifdef LOCKF_DEBUG
 1790                         if (lockf_debug & 2)
 1791                                 printf("overlap ends after lock\n");
 1792 #endif /* LOCKF_DEBUG */
 1793                         res = 5;
 1794                         break;
 1795                 }
 1796                 panic("lf_findoverlap: default");
 1797         }
 1798         return (res);
 1799 }
 1800 
 1801 /*
 1802  * Split an the existing 'lock1', based on the extent of the lock
 1803  * described by 'lock2'. The existing lock should cover 'lock2'
 1804  * entirely.
 1805  *
 1806  * Any pending locks which have been been unblocked are added to
 1807  * 'granted'
 1808  */
 1809 static void
 1810 lf_split(struct lockf *state, struct lockf_entry *lock1,
 1811     struct lockf_entry *lock2, struct lockf_entry_list *granted)
 1812 {
 1813         struct lockf_entry *splitlock;
 1814 
 1815 #ifdef LOCKF_DEBUG
 1816         if (lockf_debug & 2) {
 1817                 lf_print("lf_split", lock1);
 1818                 lf_print("splitting from", lock2);
 1819         }
 1820 #endif /* LOCKF_DEBUG */
 1821         /*
 1822          * Check to see if we don't need to split at all.
 1823          */
 1824         if (lock1->lf_start == lock2->lf_start) {
 1825                 lf_set_start(state, lock1, lock2->lf_end + 1, granted);
 1826                 return;
 1827         }
 1828         if (lock1->lf_end == lock2->lf_end) {
 1829                 lf_set_end(state, lock1, lock2->lf_start - 1, granted);
 1830                 return;
 1831         }
 1832         /*
 1833          * Make a new lock consisting of the last part of
 1834          * the encompassing lock.
 1835          */
 1836         splitlock = lf_alloc_lock(lock1->lf_owner);
 1837         memcpy(splitlock, lock1, sizeof *splitlock);
 1838         splitlock->lf_refs = 1;
 1839         if (splitlock->lf_flags & F_REMOTE)
 1840                 vref(splitlock->lf_vnode);
 1841 
 1842         /*
 1843          * This cannot cause a deadlock since any edges we would add
 1844          * to splitlock already exist in lock1. We must be sure to add
 1845          * necessary dependencies to splitlock before we reduce lock1
 1846          * otherwise we may accidentally grant a pending lock that
 1847          * was blocked by the tail end of lock1.
 1848          */
 1849         splitlock->lf_start = lock2->lf_end + 1;
 1850         LIST_INIT(&splitlock->lf_outedges);
 1851         LIST_INIT(&splitlock->lf_inedges);
 1852         sx_xlock(&lf_owner_graph_lock);
 1853         lf_add_incoming(state, splitlock);
 1854         sx_xunlock(&lf_owner_graph_lock);
 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         sx_xlock(&lf_lock_owners_lock);
 2026         for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++)
 2027                 LIST_FOREACH(lo, &lf_lock_owners[i], lo_link)
 2028                         if (lo->lo_sysid == sysid)
 2029                                 count += lo->lo_refs;
 2030         sx_xunlock(&lf_lock_owners_lock);
 2031 
 2032         return (count);
 2033 }
 2034 
 2035 #ifdef LOCKF_DEBUG
 2036 
 2037 /*
 2038  * Return non-zero if y is reachable from x using a brute force
 2039  * search. If reachable and path is non-null, return the route taken
 2040  * in path.
 2041  */
 2042 static int
 2043 graph_reaches(struct owner_vertex *x, struct owner_vertex *y,
 2044     struct owner_vertex_list *path)
 2045 {
 2046         struct owner_edge *e;
 2047 
 2048         if (x == y) {
 2049                 if (path)
 2050                         TAILQ_INSERT_HEAD(path, x, v_link);
 2051                 return 1;
 2052         }
 2053 
 2054         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2055                 if (graph_reaches(e->e_to, y, path)) {
 2056                         if (path)
 2057                                 TAILQ_INSERT_HEAD(path, x, v_link);
 2058                         return 1;
 2059                 }
 2060         }
 2061         return 0;
 2062 }
 2063 
 2064 /*
 2065  * Perform consistency checks on the graph. Make sure the values of
 2066  * v_order are correct. If checkorder is non-zero, check no vertex can
 2067  * reach any other vertex with a smaller order.
 2068  */
 2069 static void
 2070 graph_check(struct owner_graph *g, int checkorder)
 2071 {
 2072         int i, j;
 2073 
 2074         for (i = 0; i < g->g_size; i++) {
 2075                 if (!g->g_vertices[i]->v_owner)
 2076                         continue;
 2077                 KASSERT(g->g_vertices[i]->v_order == i,
 2078                     ("lock graph vertices disordered"));
 2079                 if (checkorder) {
 2080                         for (j = 0; j < i; j++) {
 2081                                 if (!g->g_vertices[j]->v_owner)
 2082                                         continue;
 2083                                 KASSERT(!graph_reaches(g->g_vertices[i],
 2084                                         g->g_vertices[j], NULL),
 2085                                     ("lock graph vertices disordered"));
 2086                         }
 2087                 }
 2088         }
 2089 }
 2090 
 2091 static void
 2092 graph_print_vertices(struct owner_vertex_list *set)
 2093 {
 2094         struct owner_vertex *v;
 2095 
 2096         printf("{ ");
 2097         TAILQ_FOREACH(v, set, v_link) {
 2098                 printf("%d:", v->v_order);
 2099                 lf_print_owner(v->v_owner);
 2100                 if (TAILQ_NEXT(v, v_link))
 2101                         printf(", ");
 2102         }
 2103         printf(" }\n");
 2104 }
 2105 
 2106 #endif
 2107 
 2108 /*
 2109  * Calculate the sub-set of vertices v from the affected region [y..x]
 2110  * where v is reachable from y. Return -1 if a loop was detected
 2111  * (i.e. x is reachable from y, otherwise the number of vertices in
 2112  * this subset.
 2113  */
 2114 static int
 2115 graph_delta_forward(struct owner_graph *g, struct owner_vertex *x,
 2116     struct owner_vertex *y, struct owner_vertex_list *delta)
 2117 {
 2118         uint32_t gen;
 2119         struct owner_vertex *v;
 2120         struct owner_edge *e;
 2121         int n;
 2122 
 2123         /*
 2124          * We start with a set containing just y. Then for each vertex
 2125          * v in the set so far unprocessed, we add each vertex that v
 2126          * has an out-edge to and that is within the affected region
 2127          * [y..x]. If we see the vertex x on our travels, stop
 2128          * immediately.
 2129          */
 2130         TAILQ_INIT(delta);
 2131         TAILQ_INSERT_TAIL(delta, y, v_link);
 2132         v = y;
 2133         n = 1;
 2134         gen = g->g_gen;
 2135         while (v) {
 2136                 LIST_FOREACH(e, &v->v_outedges, e_outlink) {
 2137                         if (e->e_to == x)
 2138                                 return -1;
 2139                         if (e->e_to->v_order < x->v_order
 2140                             && e->e_to->v_gen != gen) {
 2141                                 e->e_to->v_gen = gen;
 2142                                 TAILQ_INSERT_TAIL(delta, e->e_to, v_link);
 2143                                 n++;
 2144                         }
 2145                 }
 2146                 v = TAILQ_NEXT(v, v_link);
 2147         }
 2148 
 2149         return (n);
 2150 }
 2151 
 2152 /*
 2153  * Calculate the sub-set of vertices v from the affected region [y..x]
 2154  * where v reaches x. Return the number of vertices in this subset.
 2155  */
 2156 static int
 2157 graph_delta_backward(struct owner_graph *g, struct owner_vertex *x,
 2158     struct owner_vertex *y, struct owner_vertex_list *delta)
 2159 {
 2160         uint32_t gen;
 2161         struct owner_vertex *v;
 2162         struct owner_edge *e;
 2163         int n;
 2164 
 2165         /*
 2166          * We start with a set containing just x. Then for each vertex
 2167          * v in the set so far unprocessed, we add each vertex that v
 2168          * has an in-edge from and that is within the affected region
 2169          * [y..x].
 2170          */
 2171         TAILQ_INIT(delta);
 2172         TAILQ_INSERT_TAIL(delta, x, v_link);
 2173         v = x;
 2174         n = 1;
 2175         gen = g->g_gen;
 2176         while (v) {
 2177                 LIST_FOREACH(e, &v->v_inedges, e_inlink) {
 2178                         if (e->e_from->v_order > y->v_order
 2179                             && e->e_from->v_gen != gen) {
 2180                                 e->e_from->v_gen = gen;
 2181                                 TAILQ_INSERT_HEAD(delta, e->e_from, v_link);
 2182                                 n++;
 2183                         }
 2184                 }
 2185                 v = TAILQ_PREV(v, owner_vertex_list, v_link);
 2186         }
 2187 
 2188         return (n);
 2189 }
 2190 
 2191 static int
 2192 graph_add_indices(int *indices, int n, struct owner_vertex_list *set)
 2193 {
 2194         struct owner_vertex *v;
 2195         int i, j;
 2196 
 2197         TAILQ_FOREACH(v, set, v_link) {
 2198                 for (i = n;
 2199                      i > 0 && indices[i - 1] > v->v_order; i--)
 2200                         ;
 2201                 for (j = n - 1; j >= i; j--)
 2202                         indices[j + 1] = indices[j];
 2203                 indices[i] = v->v_order;
 2204                 n++;
 2205         }
 2206 
 2207         return (n);
 2208 }
 2209 
 2210 static int
 2211 graph_assign_indices(struct owner_graph *g, int *indices, int nextunused,
 2212     struct owner_vertex_list *set)
 2213 {
 2214         struct owner_vertex *v, *vlowest;
 2215 
 2216         while (!TAILQ_EMPTY(set)) {
 2217                 vlowest = NULL;
 2218                 TAILQ_FOREACH(v, set, v_link) {
 2219                         if (!vlowest || v->v_order < vlowest->v_order)
 2220                                 vlowest = v;
 2221                 }
 2222                 TAILQ_REMOVE(set, vlowest, v_link);
 2223                 vlowest->v_order = indices[nextunused];
 2224                 g->g_vertices[vlowest->v_order] = vlowest;
 2225                 nextunused++;
 2226         }
 2227 
 2228         return (nextunused);
 2229 }
 2230 
 2231 static int
 2232 graph_add_edge(struct owner_graph *g, struct owner_vertex *x,
 2233     struct owner_vertex *y)
 2234 {
 2235         struct owner_edge *e;
 2236         struct owner_vertex_list deltaF, deltaB;
 2237         int nF, nB, n, vi, i;
 2238         int *indices;
 2239 
 2240         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2241 
 2242         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2243                 if (e->e_to == y) {
 2244                         e->e_refs++;
 2245                         return (0);
 2246                 }
 2247         }
 2248 
 2249 #ifdef LOCKF_DEBUG
 2250         if (lockf_debug & 8) {
 2251                 printf("adding edge %d:", x->v_order);
 2252                 lf_print_owner(x->v_owner);
 2253                 printf(" -> %d:", y->v_order);
 2254                 lf_print_owner(y->v_owner);
 2255                 printf("\n");
 2256         }
 2257 #endif
 2258         if (y->v_order < x->v_order) {
 2259                 /*
 2260                  * The new edge violates the order. First find the set
 2261                  * of affected vertices reachable from y (deltaF) and
 2262                  * the set of affect vertices affected that reach x
 2263                  * (deltaB), using the graph generation number to
 2264                  * detect whether we have visited a given vertex
 2265                  * already. We re-order the graph so that each vertex
 2266                  * in deltaB appears before each vertex in deltaF.
 2267                  *
 2268                  * If x is a member of deltaF, then the new edge would
 2269                  * create a cycle. Otherwise, we may assume that
 2270                  * deltaF and deltaB are disjoint.
 2271                  */
 2272                 g->g_gen++;
 2273                 if (g->g_gen == 0) {
 2274                         /*
 2275                          * Generation wrap.
 2276                          */
 2277                         for (vi = 0; vi < g->g_size; vi++) {
 2278                                 g->g_vertices[vi]->v_gen = 0;
 2279                         }
 2280                         g->g_gen++;
 2281                 }
 2282                 nF = graph_delta_forward(g, x, y, &deltaF);
 2283                 if (nF < 0) {
 2284 #ifdef LOCKF_DEBUG
 2285                         if (lockf_debug & 8) {
 2286                                 struct owner_vertex_list path;
 2287                                 printf("deadlock: ");
 2288                                 TAILQ_INIT(&path);
 2289                                 graph_reaches(y, x, &path);
 2290                                 graph_print_vertices(&path);
 2291                         }
 2292 #endif
 2293                         return (EDEADLK);
 2294                 }
 2295 
 2296 #ifdef LOCKF_DEBUG
 2297                 if (lockf_debug & 8) {
 2298                         printf("re-ordering graph vertices\n");
 2299                         printf("deltaF = ");
 2300                         graph_print_vertices(&deltaF);
 2301                 }
 2302 #endif
 2303 
 2304                 nB = graph_delta_backward(g, x, y, &deltaB);
 2305 
 2306 #ifdef LOCKF_DEBUG
 2307                 if (lockf_debug & 8) {
 2308                         printf("deltaB = ");
 2309                         graph_print_vertices(&deltaB);
 2310                 }
 2311 #endif
 2312 
 2313                 /*
 2314                  * We first build a set of vertex indices (vertex
 2315                  * order values) that we may use, then we re-assign
 2316                  * orders first to those vertices in deltaB, then to
 2317                  * deltaF. Note that the contents of deltaF and deltaB
 2318                  * may be partially disordered - we perform an
 2319                  * insertion sort while building our index set.
 2320                  */
 2321                 indices = g->g_indexbuf;
 2322                 n = graph_add_indices(indices, 0, &deltaF);
 2323                 graph_add_indices(indices, n, &deltaB);
 2324 
 2325                 /*
 2326                  * We must also be sure to maintain the relative
 2327                  * ordering of deltaF and deltaB when re-assigning
 2328                  * vertices. We do this by iteratively removing the
 2329                  * lowest ordered element from the set and assigning
 2330                  * it the next value from our new ordering.
 2331                  */
 2332                 i = graph_assign_indices(g, indices, 0, &deltaB);
 2333                 graph_assign_indices(g, indices, i, &deltaF);
 2334 
 2335 #ifdef LOCKF_DEBUG
 2336                 if (lockf_debug & 8) {
 2337                         struct owner_vertex_list set;
 2338                         TAILQ_INIT(&set);
 2339                         for (i = 0; i < nB + nF; i++)
 2340                                 TAILQ_INSERT_TAIL(&set,
 2341                                     g->g_vertices[indices[i]], v_link);
 2342                         printf("new ordering = ");
 2343                         graph_print_vertices(&set);
 2344                 }
 2345 #endif
 2346         }
 2347 
 2348         KASSERT(x->v_order < y->v_order, ("Failed to re-order graph"));
 2349 
 2350 #ifdef LOCKF_DEBUG
 2351         if (lockf_debug & 8) {
 2352                 graph_check(g, TRUE);
 2353         }
 2354 #endif
 2355 
 2356         e = malloc(sizeof(struct owner_edge), M_LOCKF, M_WAITOK);
 2357 
 2358         LIST_INSERT_HEAD(&x->v_outedges, e, e_outlink);
 2359         LIST_INSERT_HEAD(&y->v_inedges, e, e_inlink);
 2360         e->e_refs = 1;
 2361         e->e_from = x;
 2362         e->e_to = y;
 2363 
 2364         return (0);
 2365 }
 2366 
 2367 /*
 2368  * Remove an edge x->y from the graph.
 2369  */
 2370 static void
 2371 graph_remove_edge(struct owner_graph *g, struct owner_vertex *x,
 2372     struct owner_vertex *y)
 2373 {
 2374         struct owner_edge *e;
 2375 
 2376         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2377 
 2378         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2379                 if (e->e_to == y)
 2380                         break;
 2381         }
 2382         KASSERT(e, ("Removing non-existent edge from deadlock graph"));
 2383 
 2384         e->e_refs--;
 2385         if (e->e_refs == 0) {
 2386 #ifdef LOCKF_DEBUG
 2387                 if (lockf_debug & 8) {
 2388                         printf("removing edge %d:", x->v_order);
 2389                         lf_print_owner(x->v_owner);
 2390                         printf(" -> %d:", y->v_order);
 2391                         lf_print_owner(y->v_owner);
 2392                         printf("\n");
 2393                 }
 2394 #endif
 2395                 LIST_REMOVE(e, e_outlink);
 2396                 LIST_REMOVE(e, e_inlink);
 2397                 free(e, M_LOCKF);
 2398         }
 2399 }
 2400 
 2401 /*
 2402  * Allocate a vertex from the free list. Return ENOMEM if there are
 2403  * none.
 2404  */
 2405 static struct owner_vertex *
 2406 graph_alloc_vertex(struct owner_graph *g, struct lock_owner *lo)
 2407 {
 2408         struct owner_vertex *v;
 2409 
 2410         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2411 
 2412         v = malloc(sizeof(struct owner_vertex), M_LOCKF, M_WAITOK);
 2413         if (g->g_size == g->g_space) {
 2414                 g->g_vertices = realloc(g->g_vertices,
 2415                     2 * g->g_space * sizeof(struct owner_vertex *),
 2416                     M_LOCKF, M_WAITOK);
 2417                 free(g->g_indexbuf, M_LOCKF);
 2418                 g->g_indexbuf = malloc(2 * g->g_space * sizeof(int),
 2419                     M_LOCKF, M_WAITOK);
 2420                 g->g_space = 2 * g->g_space;
 2421         }
 2422         v->v_order = g->g_size;
 2423         v->v_gen = g->g_gen;
 2424         g->g_vertices[g->g_size] = v;
 2425         g->g_size++;
 2426 
 2427         LIST_INIT(&v->v_outedges);
 2428         LIST_INIT(&v->v_inedges);
 2429         v->v_owner = lo;
 2430 
 2431         return (v);
 2432 }
 2433 
 2434 static void
 2435 graph_free_vertex(struct owner_graph *g, struct owner_vertex *v)
 2436 {
 2437         struct owner_vertex *w;
 2438         int i;
 2439 
 2440         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2441         
 2442         KASSERT(LIST_EMPTY(&v->v_outedges), ("Freeing vertex with edges"));
 2443         KASSERT(LIST_EMPTY(&v->v_inedges), ("Freeing vertex with edges"));
 2444 
 2445         /*
 2446          * Remove from the graph's array and close up the gap,
 2447          * renumbering the other vertices.
 2448          */
 2449         for (i = v->v_order + 1; i < g->g_size; i++) {
 2450                 w = g->g_vertices[i];
 2451                 w->v_order--;
 2452                 g->g_vertices[i - 1] = w;
 2453         }
 2454         g->g_size--;
 2455 
 2456         free(v, M_LOCKF);
 2457 }
 2458 
 2459 static struct owner_graph *
 2460 graph_init(struct owner_graph *g)
 2461 {
 2462 
 2463         g->g_vertices = malloc(10 * sizeof(struct owner_vertex *),
 2464             M_LOCKF, M_WAITOK);
 2465         g->g_size = 0;
 2466         g->g_space = 10;
 2467         g->g_indexbuf = malloc(g->g_space * sizeof(int), M_LOCKF, M_WAITOK);
 2468         g->g_gen = 0;
 2469 
 2470         return (g);
 2471 }
 2472 
 2473 #ifdef LOCKF_DEBUG
 2474 /*
 2475  * Print description of a lock owner
 2476  */
 2477 static void
 2478 lf_print_owner(struct lock_owner *lo)
 2479 {
 2480 
 2481         if (lo->lo_flags & F_REMOTE) {
 2482                 printf("remote pid %d, system %d",
 2483                     lo->lo_pid, lo->lo_sysid);
 2484         } else if (lo->lo_flags & F_FLOCK) {
 2485                 printf("file %p", lo->lo_id);
 2486         } else {
 2487                 printf("local pid %d", lo->lo_pid);
 2488         }
 2489 }
 2490 
 2491 /*
 2492  * Print out a lock.
 2493  */
 2494 static void
 2495 lf_print(char *tag, struct lockf_entry *lock)
 2496 {
 2497 
 2498         printf("%s: lock %p for ", tag, (void *)lock);
 2499         lf_print_owner(lock->lf_owner);
 2500         if (lock->lf_inode != (struct inode *)0)
 2501                 printf(" in ino %ju on dev <%s>,",
 2502                     (uintmax_t)lock->lf_inode->i_number,
 2503                     devtoname(lock->lf_inode->i_dev));
 2504         printf(" %s, start %jd, end ",
 2505             lock->lf_type == F_RDLCK ? "shared" :
 2506             lock->lf_type == F_WRLCK ? "exclusive" :
 2507             lock->lf_type == F_UNLCK ? "unlock" : "unknown",
 2508             (intmax_t)lock->lf_start);
 2509         if (lock->lf_end == OFF_MAX)
 2510                 printf("EOF");
 2511         else
 2512                 printf("%jd", (intmax_t)lock->lf_end);
 2513         if (!LIST_EMPTY(&lock->lf_outedges))
 2514                 printf(" block %p\n",
 2515                     (void *)LIST_FIRST(&lock->lf_outedges)->le_to);
 2516         else
 2517                 printf("\n");
 2518 }
 2519 
 2520 static void
 2521 lf_printlist(char *tag, struct lockf_entry *lock)
 2522 {
 2523         struct lockf_entry *lf, *blk;
 2524         struct lockf_edge *e;
 2525 
 2526         if (lock->lf_inode == (struct inode *)0)
 2527                 return;
 2528 
 2529         printf("%s: Lock list for ino %ju on dev <%s>:\n",
 2530             tag, (uintmax_t)lock->lf_inode->i_number,
 2531             devtoname(lock->lf_inode->i_dev));
 2532         LIST_FOREACH(lf, &lock->lf_vnode->v_lockf->ls_active, lf_link) {
 2533                 printf("\tlock %p for ",(void *)lf);
 2534                 lf_print_owner(lock->lf_owner);
 2535                 printf(", %s, start %jd, end %jd",
 2536                     lf->lf_type == F_RDLCK ? "shared" :
 2537                     lf->lf_type == F_WRLCK ? "exclusive" :
 2538                     lf->lf_type == F_UNLCK ? "unlock" :
 2539                     "unknown", (intmax_t)lf->lf_start, (intmax_t)lf->lf_end);
 2540                 LIST_FOREACH(e, &lf->lf_outedges, le_outlink) {
 2541                         blk = e->le_to;
 2542                         printf("\n\t\tlock request %p for ", (void *)blk);
 2543                         lf_print_owner(blk->lf_owner);
 2544                         printf(", %s, start %jd, end %jd",
 2545                             blk->lf_type == F_RDLCK ? "shared" :
 2546                             blk->lf_type == F_WRLCK ? "exclusive" :
 2547                             blk->lf_type == F_UNLCK ? "unlock" :
 2548                             "unknown", (intmax_t)blk->lf_start,
 2549                             (intmax_t)blk->lf_end);
 2550                         if (!LIST_EMPTY(&blk->lf_inedges))
 2551                                 panic("lf_printlist: bad list");
 2552                 }
 2553                 printf("\n");
 2554         }
 2555 }
 2556 #endif /* LOCKF_DEBUG */

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