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


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

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

Version: -  FREEBSD  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-2  -  FREEBSD-11-1  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-4  -  FREEBSD-10-3  -  FREEBSD-10-2  -  FREEBSD-10-1  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-3  -  FREEBSD-9-2  -  FREEBSD-9-1  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-4  -  FREEBSD-8-3  -  FREEBSD-8-2  -  FREEBSD-8-1  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-4  -  FREEBSD-7-3  -  FREEBSD-7-2  -  FREEBSD-7-1  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-4  -  FREEBSD-6-3  -  FREEBSD-6-2  -  FREEBSD-6-1  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-5  -  FREEBSD-5-4  -  FREEBSD-5-3  -  FREEBSD-5-2  -  FREEBSD-5-1  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  linux-2.6  -  linux-2.4.22  -  MK83  -  MK84  -  PLAN9  -  DFBSD  -  NETBSD  -  NETBSD5  -  NETBSD4  -  NETBSD3  -  NETBSD20  -  OPENBSD  -  xnu-517  -  xnu-792  -  xnu-792.6.70  -  xnu-1228  -  xnu-1456.1.26  -  xnu-1699.24.8  -  xnu-2050.18.24  -  OPENSOLARIS  -  minix-3-1-1 
SearchContext: -  none  -  3  -  10 

    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: stable/10/sys/kern/kern_lockf.c 313729 2017-02-14 13:45:38Z avg $");
   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 DIAGNOSTIC
  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 DIAGNOSTIC
  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 priority, error;
 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                 error = sx_sleep(lock, &state->ls_lock, priority, lockstr, 0);
 1470                 if (lf_free_lock(lock)) {
 1471                         error = EDOOFUS;
 1472                         goto out;
 1473                 }
 1474 
 1475                 /*
 1476                  * We may have been awakened by a signal and/or by a
 1477                  * debugger continuing us (in which cases we must
 1478                  * remove our lock graph edges) and/or by another
 1479                  * process releasing a lock (in which case our edges
 1480                  * have already been removed and we have been moved to
 1481                  * the active list). We may also have been woken by
 1482                  * lf_purgelocks which we report to the caller as
 1483                  * EINTR. In that case, lf_purgelocks will have
 1484                  * removed our lock graph edges.
 1485                  *
 1486                  * Note that it is possible to receive a signal after
 1487                  * we were successfully woken (and moved to the active
 1488                  * list) but before we resumed execution. In this
 1489                  * case, our lf_outedges list will be clear. We
 1490                  * pretend there was no error.
 1491                  *
 1492                  * Note also, if we have been sleeping long enough, we
 1493                  * may now have incoming edges from some newer lock
 1494                  * which is waiting behind us in the queue.
 1495                  */
 1496                 if (lock->lf_flags & F_INTR) {
 1497                         error = EINTR;
 1498                         lf_free_lock(lock);
 1499                         goto out;
 1500                 }
 1501                 if (LIST_EMPTY(&lock->lf_outedges)) {
 1502                         error = 0;
 1503                 } else {
 1504                         lf_cancel_lock(state, lock);
 1505                         goto out;
 1506                 }
 1507 #ifdef LOCKF_DEBUG
 1508                 if (lockf_debug & 1) {
 1509                         lf_print("lf_setlock: granted", lock);
 1510                 }
 1511 #endif
 1512                 goto out;
 1513         }
 1514         /*
 1515          * It looks like we are going to grant the lock. First add
 1516          * edges from any currently pending lock that the new lock
 1517          * would block.
 1518          */
 1519         sx_xlock(&lf_owner_graph_lock);
 1520         error = lf_add_incoming(state, lock);
 1521         sx_xunlock(&lf_owner_graph_lock);
 1522         if (error) {
 1523 #ifdef LOCKF_DEBUG
 1524                 if (lockf_debug & 1)
 1525                         lf_print("lf_setlock: deadlock", lock);
 1526 #endif
 1527                 lf_free_lock(lock);
 1528                 goto out;
 1529         }
 1530 
 1531         /*
 1532          * No blocks!!  Add the lock.  Note that we will
 1533          * downgrade or upgrade any overlapping locks this
 1534          * process already owns.
 1535          */
 1536         lf_activate_lock(state, lock);
 1537         error = 0;
 1538 out:
 1539         return (error);
 1540 }
 1541 
 1542 /*
 1543  * Remove a byte-range lock on an inode.
 1544  *
 1545  * Generally, find the lock (or an overlap to that lock)
 1546  * and remove it (or shrink it), then wakeup anyone we can.
 1547  */
 1548 static int
 1549 lf_clearlock(struct lockf *state, struct lockf_entry *unlock)
 1550 {
 1551         struct lockf_entry *overlap;
 1552 
 1553         overlap = LIST_FIRST(&state->ls_active);
 1554 
 1555         if (overlap == NOLOCKF)
 1556                 return (0);
 1557 #ifdef LOCKF_DEBUG
 1558         if (unlock->lf_type != F_UNLCK)
 1559                 panic("lf_clearlock: bad type");
 1560         if (lockf_debug & 1)
 1561                 lf_print("lf_clearlock", unlock);
 1562 #endif /* LOCKF_DEBUG */
 1563 
 1564         lf_activate_lock(state, unlock);
 1565 
 1566         return (0);
 1567 }
 1568 
 1569 /*
 1570  * Check whether there is a blocking lock, and if so return its
 1571  * details in '*fl'.
 1572  */
 1573 static int
 1574 lf_getlock(struct lockf *state, struct lockf_entry *lock, struct flock *fl)
 1575 {
 1576         struct lockf_entry *block;
 1577 
 1578 #ifdef LOCKF_DEBUG
 1579         if (lockf_debug & 1)
 1580                 lf_print("lf_getlock", lock);
 1581 #endif /* LOCKF_DEBUG */
 1582 
 1583         if ((block = lf_getblock(state, lock))) {
 1584                 fl->l_type = block->lf_type;
 1585                 fl->l_whence = SEEK_SET;
 1586                 fl->l_start = block->lf_start;
 1587                 if (block->lf_end == OFF_MAX)
 1588                         fl->l_len = 0;
 1589                 else
 1590                         fl->l_len = block->lf_end - block->lf_start + 1;
 1591                 fl->l_pid = block->lf_owner->lo_pid;
 1592                 fl->l_sysid = block->lf_owner->lo_sysid;
 1593         } else {
 1594                 fl->l_type = F_UNLCK;
 1595         }
 1596         return (0);
 1597 }
 1598 
 1599 /*
 1600  * Cancel an async lock request.
 1601  */
 1602 static int
 1603 lf_cancel(struct lockf *state, struct lockf_entry *lock, void *cookie)
 1604 {
 1605         struct lockf_entry *reallock;
 1606 
 1607         /*
 1608          * We need to match this request with an existing lock
 1609          * request.
 1610          */
 1611         LIST_FOREACH(reallock, &state->ls_pending, lf_link) {
 1612                 if ((void *) reallock == cookie) {
 1613                         /*
 1614                          * Double-check that this lock looks right
 1615                          * (maybe use a rolling ID for the cancel
 1616                          * cookie instead?)
 1617                          */
 1618                         if (!(reallock->lf_vnode == lock->lf_vnode
 1619                                 && reallock->lf_start == lock->lf_start
 1620                                 && reallock->lf_end == lock->lf_end)) {
 1621                                 return (ENOENT);
 1622                         }
 1623 
 1624                         /*
 1625                          * Make sure this lock was async and then just
 1626                          * remove it from its wait lists.
 1627                          */
 1628                         if (!reallock->lf_async_task) {
 1629                                 return (ENOENT);
 1630                         }
 1631 
 1632                         /*
 1633                          * Note that since any other thread must take
 1634                          * state->ls_lock before it can possibly
 1635                          * trigger the async callback, we are safe
 1636                          * from a race with lf_wakeup_lock, i.e. we
 1637                          * can free the lock (actually our caller does
 1638                          * this).
 1639                          */
 1640                         lf_cancel_lock(state, reallock);
 1641                         return (0);
 1642                 }
 1643         }
 1644 
 1645         /*
 1646          * We didn't find a matching lock - not much we can do here.
 1647          */
 1648         return (ENOENT);
 1649 }
 1650 
 1651 /*
 1652  * Walk the list of locks for an inode and
 1653  * return the first blocking lock.
 1654  */
 1655 static struct lockf_entry *
 1656 lf_getblock(struct lockf *state, struct lockf_entry *lock)
 1657 {
 1658         struct lockf_entry *overlap;
 1659 
 1660         LIST_FOREACH(overlap, &state->ls_active, lf_link) {
 1661                 /*
 1662                  * We may assume that the active list is sorted by
 1663                  * lf_start.
 1664                  */
 1665                 if (overlap->lf_start > lock->lf_end)
 1666                         break;
 1667                 if (!lf_blocks(lock, overlap))
 1668                         continue;
 1669                 return (overlap);
 1670         }
 1671         return (NOLOCKF);
 1672 }
 1673 
 1674 /*
 1675  * Walk the list of locks for an inode to find an overlapping lock (if
 1676  * any) and return a classification of that overlap.
 1677  *
 1678  * Arguments:
 1679  *      *overlap        The place in the lock list to start looking
 1680  *      lock            The lock which is being tested
 1681  *      type            Pass 'SELF' to test only locks with the same
 1682  *                      owner as lock, or 'OTHER' to test only locks
 1683  *                      with a different owner
 1684  *
 1685  * Returns one of six values:
 1686  *      0) no overlap
 1687  *      1) overlap == lock
 1688  *      2) overlap contains lock
 1689  *      3) lock contains overlap
 1690  *      4) overlap starts before lock
 1691  *      5) overlap ends after lock
 1692  *
 1693  * If there is an overlapping lock, '*overlap' is set to point at the
 1694  * overlapping lock.
 1695  *
 1696  * NOTE: this returns only the FIRST overlapping lock.  There
 1697  *       may be more than one.
 1698  */
 1699 static int
 1700 lf_findoverlap(struct lockf_entry **overlap, struct lockf_entry *lock, int type)
 1701 {
 1702         struct lockf_entry *lf;
 1703         off_t start, end;
 1704         int res;
 1705 
 1706         if ((*overlap) == NOLOCKF) {
 1707                 return (0);
 1708         }
 1709 #ifdef LOCKF_DEBUG
 1710         if (lockf_debug & 2)
 1711                 lf_print("lf_findoverlap: looking for overlap in", lock);
 1712 #endif /* LOCKF_DEBUG */
 1713         start = lock->lf_start;
 1714         end = lock->lf_end;
 1715         res = 0;
 1716         while (*overlap) {
 1717                 lf = *overlap;
 1718                 if (lf->lf_start > end)
 1719                         break;
 1720                 if (((type & SELF) && lf->lf_owner != lock->lf_owner) ||
 1721                     ((type & OTHERS) && lf->lf_owner == lock->lf_owner)) {
 1722                         *overlap = LIST_NEXT(lf, lf_link);
 1723                         continue;
 1724                 }
 1725 #ifdef LOCKF_DEBUG
 1726                 if (lockf_debug & 2)
 1727                         lf_print("\tchecking", lf);
 1728 #endif /* LOCKF_DEBUG */
 1729                 /*
 1730                  * OK, check for overlap
 1731                  *
 1732                  * Six cases:
 1733                  *      0) no overlap
 1734                  *      1) overlap == lock
 1735                  *      2) overlap contains lock
 1736                  *      3) lock contains overlap
 1737                  *      4) overlap starts before lock
 1738                  *      5) overlap ends after lock
 1739                  */
 1740                 if (start > lf->lf_end) {
 1741                         /* Case 0 */
 1742 #ifdef LOCKF_DEBUG
 1743                         if (lockf_debug & 2)
 1744                                 printf("no overlap\n");
 1745 #endif /* LOCKF_DEBUG */
 1746                         *overlap = LIST_NEXT(lf, lf_link);
 1747                         continue;
 1748                 }
 1749                 if (lf->lf_start == start && lf->lf_end == end) {
 1750                         /* Case 1 */
 1751 #ifdef LOCKF_DEBUG
 1752                         if (lockf_debug & 2)
 1753                                 printf("overlap == lock\n");
 1754 #endif /* LOCKF_DEBUG */
 1755                         res = 1;
 1756                         break;
 1757                 }
 1758                 if (lf->lf_start <= start && lf->lf_end >= end) {
 1759                         /* Case 2 */
 1760 #ifdef LOCKF_DEBUG
 1761                         if (lockf_debug & 2)
 1762                                 printf("overlap contains lock\n");
 1763 #endif /* LOCKF_DEBUG */
 1764                         res = 2;
 1765                         break;
 1766                 }
 1767                 if (start <= lf->lf_start && end >= lf->lf_end) {
 1768                         /* Case 3 */
 1769 #ifdef LOCKF_DEBUG
 1770                         if (lockf_debug & 2)
 1771                                 printf("lock contains overlap\n");
 1772 #endif /* LOCKF_DEBUG */
 1773                         res = 3;
 1774                         break;
 1775                 }
 1776                 if (lf->lf_start < start && lf->lf_end >= start) {
 1777                         /* Case 4 */
 1778 #ifdef LOCKF_DEBUG
 1779                         if (lockf_debug & 2)
 1780                                 printf("overlap starts before lock\n");
 1781 #endif /* LOCKF_DEBUG */
 1782                         res = 4;
 1783                         break;
 1784                 }
 1785                 if (lf->lf_start > start && lf->lf_end > end) {
 1786                         /* Case 5 */
 1787 #ifdef LOCKF_DEBUG
 1788                         if (lockf_debug & 2)
 1789                                 printf("overlap ends after lock\n");
 1790 #endif /* LOCKF_DEBUG */
 1791                         res = 5;
 1792                         break;
 1793                 }
 1794                 panic("lf_findoverlap: default");
 1795         }
 1796         return (res);
 1797 }
 1798 
 1799 /*
 1800  * Split an the existing 'lock1', based on the extent of the lock
 1801  * described by 'lock2'. The existing lock should cover 'lock2'
 1802  * entirely.
 1803  *
 1804  * Any pending locks which have been been unblocked are added to
 1805  * 'granted'
 1806  */
 1807 static void
 1808 lf_split(struct lockf *state, struct lockf_entry *lock1,
 1809     struct lockf_entry *lock2, struct lockf_entry_list *granted)
 1810 {
 1811         struct lockf_entry *splitlock;
 1812 
 1813 #ifdef LOCKF_DEBUG
 1814         if (lockf_debug & 2) {
 1815                 lf_print("lf_split", lock1);
 1816                 lf_print("splitting from", lock2);
 1817         }
 1818 #endif /* LOCKF_DEBUG */
 1819         /*
 1820          * Check to see if we don't need to split at all.
 1821          */
 1822         if (lock1->lf_start == lock2->lf_start) {
 1823                 lf_set_start(state, lock1, lock2->lf_end + 1, granted);
 1824                 return;
 1825         }
 1826         if (lock1->lf_end == lock2->lf_end) {
 1827                 lf_set_end(state, lock1, lock2->lf_start - 1, granted);
 1828                 return;
 1829         }
 1830         /*
 1831          * Make a new lock consisting of the last part of
 1832          * the encompassing lock.
 1833          */
 1834         splitlock = lf_alloc_lock(lock1->lf_owner);
 1835         memcpy(splitlock, lock1, sizeof *splitlock);
 1836         splitlock->lf_refs = 1;
 1837         if (splitlock->lf_flags & F_REMOTE)
 1838                 vref(splitlock->lf_vnode);
 1839 
 1840         /*
 1841          * This cannot cause a deadlock since any edges we would add
 1842          * to splitlock already exist in lock1. We must be sure to add
 1843          * necessary dependencies to splitlock before we reduce lock1
 1844          * otherwise we may accidentally grant a pending lock that
 1845          * was blocked by the tail end of lock1.
 1846          */
 1847         splitlock->lf_start = lock2->lf_end + 1;
 1848         LIST_INIT(&splitlock->lf_outedges);
 1849         LIST_INIT(&splitlock->lf_inedges);
 1850         sx_xlock(&lf_owner_graph_lock);
 1851         lf_add_incoming(state, splitlock);
 1852         sx_xunlock(&lf_owner_graph_lock);
 1853 
 1854         lf_set_end(state, lock1, lock2->lf_start - 1, granted);
 1855 
 1856         /*
 1857          * OK, now link it in
 1858          */
 1859         lf_insert_lock(state, splitlock);
 1860 }
 1861 
 1862 struct lockdesc {
 1863         STAILQ_ENTRY(lockdesc) link;
 1864         struct vnode *vp;
 1865         struct flock fl;
 1866 };
 1867 STAILQ_HEAD(lockdesclist, lockdesc);
 1868 
 1869 int
 1870 lf_iteratelocks_sysid(int sysid, lf_iterator *fn, void *arg)
 1871 {
 1872         struct lockf *ls;
 1873         struct lockf_entry *lf;
 1874         struct lockdesc *ldesc;
 1875         struct lockdesclist locks;
 1876         int error;
 1877 
 1878         /*
 1879          * In order to keep the locking simple, we iterate over the
 1880          * active lock lists to build a list of locks that need
 1881          * releasing. We then call the iterator for each one in turn.
 1882          *
 1883          * We take an extra reference to the vnode for the duration to
 1884          * make sure it doesn't go away before we are finished.
 1885          */
 1886         STAILQ_INIT(&locks);
 1887         sx_xlock(&lf_lock_states_lock);
 1888         LIST_FOREACH(ls, &lf_lock_states, ls_link) {
 1889                 sx_xlock(&ls->ls_lock);
 1890                 LIST_FOREACH(lf, &ls->ls_active, lf_link) {
 1891                         if (lf->lf_owner->lo_sysid != sysid)
 1892                                 continue;
 1893 
 1894                         ldesc = malloc(sizeof(struct lockdesc), M_LOCKF,
 1895                             M_WAITOK);
 1896                         ldesc->vp = lf->lf_vnode;
 1897                         vref(ldesc->vp);
 1898                         ldesc->fl.l_start = lf->lf_start;
 1899                         if (lf->lf_end == OFF_MAX)
 1900                                 ldesc->fl.l_len = 0;
 1901                         else
 1902                                 ldesc->fl.l_len =
 1903                                         lf->lf_end - lf->lf_start + 1;
 1904                         ldesc->fl.l_whence = SEEK_SET;
 1905                         ldesc->fl.l_type = F_UNLCK;
 1906                         ldesc->fl.l_pid = lf->lf_owner->lo_pid;
 1907                         ldesc->fl.l_sysid = sysid;
 1908                         STAILQ_INSERT_TAIL(&locks, ldesc, link);
 1909                 }
 1910                 sx_xunlock(&ls->ls_lock);
 1911         }
 1912         sx_xunlock(&lf_lock_states_lock);
 1913 
 1914         /*
 1915          * Call the iterator function for each lock in turn. If the
 1916          * iterator returns an error code, just free the rest of the
 1917          * lockdesc structures.
 1918          */
 1919         error = 0;
 1920         while ((ldesc = STAILQ_FIRST(&locks)) != NULL) {
 1921                 STAILQ_REMOVE_HEAD(&locks, link);
 1922                 if (!error)
 1923                         error = fn(ldesc->vp, &ldesc->fl, arg);
 1924                 vrele(ldesc->vp);
 1925                 free(ldesc, M_LOCKF);
 1926         }
 1927 
 1928         return (error);
 1929 }
 1930 
 1931 int
 1932 lf_iteratelocks_vnode(struct vnode *vp, lf_iterator *fn, void *arg)
 1933 {
 1934         struct lockf *ls;
 1935         struct lockf_entry *lf;
 1936         struct lockdesc *ldesc;
 1937         struct lockdesclist locks;
 1938         int error;
 1939 
 1940         /*
 1941          * In order to keep the locking simple, we iterate over the
 1942          * active lock lists to build a list of locks that need
 1943          * releasing. We then call the iterator for each one in turn.
 1944          *
 1945          * We take an extra reference to the vnode for the duration to
 1946          * make sure it doesn't go away before we are finished.
 1947          */
 1948         STAILQ_INIT(&locks);
 1949         VI_LOCK(vp);
 1950         ls = vp->v_lockf;
 1951         if (!ls) {
 1952                 VI_UNLOCK(vp);
 1953                 return (0);
 1954         }
 1955         ls->ls_threads++;
 1956         VI_UNLOCK(vp);
 1957 
 1958         sx_xlock(&ls->ls_lock);
 1959         LIST_FOREACH(lf, &ls->ls_active, lf_link) {
 1960                 ldesc = malloc(sizeof(struct lockdesc), M_LOCKF,
 1961                     M_WAITOK);
 1962                 ldesc->vp = lf->lf_vnode;
 1963                 vref(ldesc->vp);
 1964                 ldesc->fl.l_start = lf->lf_start;
 1965                 if (lf->lf_end == OFF_MAX)
 1966                         ldesc->fl.l_len = 0;
 1967                 else
 1968                         ldesc->fl.l_len =
 1969                                 lf->lf_end - lf->lf_start + 1;
 1970                 ldesc->fl.l_whence = SEEK_SET;
 1971                 ldesc->fl.l_type = F_UNLCK;
 1972                 ldesc->fl.l_pid = lf->lf_owner->lo_pid;
 1973                 ldesc->fl.l_sysid = lf->lf_owner->lo_sysid;
 1974                 STAILQ_INSERT_TAIL(&locks, ldesc, link);
 1975         }
 1976         sx_xunlock(&ls->ls_lock);
 1977         VI_LOCK(vp);
 1978         ls->ls_threads--;
 1979         wakeup(ls);
 1980         VI_UNLOCK(vp);
 1981 
 1982         /*
 1983          * Call the iterator function for each lock in turn. If the
 1984          * iterator returns an error code, just free the rest of the
 1985          * lockdesc structures.
 1986          */
 1987         error = 0;
 1988         while ((ldesc = STAILQ_FIRST(&locks)) != NULL) {
 1989                 STAILQ_REMOVE_HEAD(&locks, link);
 1990                 if (!error)
 1991                         error = fn(ldesc->vp, &ldesc->fl, arg);
 1992                 vrele(ldesc->vp);
 1993                 free(ldesc, M_LOCKF);
 1994         }
 1995 
 1996         return (error);
 1997 }
 1998 
 1999 static int
 2000 lf_clearremotesys_iterator(struct vnode *vp, struct flock *fl, void *arg)
 2001 {
 2002 
 2003         VOP_ADVLOCK(vp, 0, F_UNLCK, fl, F_REMOTE);
 2004         return (0);
 2005 }
 2006 
 2007 void
 2008 lf_clearremotesys(int sysid)
 2009 {
 2010 
 2011         KASSERT(sysid != 0, ("Can't clear local locks with F_UNLCKSYS"));
 2012         lf_iteratelocks_sysid(sysid, lf_clearremotesys_iterator, NULL);
 2013 }
 2014 
 2015 int
 2016 lf_countlocks(int sysid)
 2017 {
 2018         int i;
 2019         struct lock_owner *lo;
 2020         int count;
 2021 
 2022         count = 0;
 2023         sx_xlock(&lf_lock_owners_lock);
 2024         for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++)
 2025                 LIST_FOREACH(lo, &lf_lock_owners[i], lo_link)
 2026                         if (lo->lo_sysid == sysid)
 2027                                 count += lo->lo_refs;
 2028         sx_xunlock(&lf_lock_owners_lock);
 2029 
 2030         return (count);
 2031 }
 2032 
 2033 #ifdef LOCKF_DEBUG
 2034 
 2035 /*
 2036  * Return non-zero if y is reachable from x using a brute force
 2037  * search. If reachable and path is non-null, return the route taken
 2038  * in path.
 2039  */
 2040 static int
 2041 graph_reaches(struct owner_vertex *x, struct owner_vertex *y,
 2042     struct owner_vertex_list *path)
 2043 {
 2044         struct owner_edge *e;
 2045 
 2046         if (x == y) {
 2047                 if (path)
 2048                         TAILQ_INSERT_HEAD(path, x, v_link);
 2049                 return 1;
 2050         }
 2051 
 2052         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2053                 if (graph_reaches(e->e_to, y, path)) {
 2054                         if (path)
 2055                                 TAILQ_INSERT_HEAD(path, x, v_link);
 2056                         return 1;
 2057                 }
 2058         }
 2059         return 0;
 2060 }
 2061 
 2062 /*
 2063  * Perform consistency checks on the graph. Make sure the values of
 2064  * v_order are correct. If checkorder is non-zero, check no vertex can
 2065  * reach any other vertex with a smaller order.
 2066  */
 2067 static void
 2068 graph_check(struct owner_graph *g, int checkorder)
 2069 {
 2070         int i, j;
 2071 
 2072         for (i = 0; i < g->g_size; i++) {
 2073                 if (!g->g_vertices[i]->v_owner)
 2074                         continue;
 2075                 KASSERT(g->g_vertices[i]->v_order == i,
 2076                     ("lock graph vertices disordered"));
 2077                 if (checkorder) {
 2078                         for (j = 0; j < i; j++) {
 2079                                 if (!g->g_vertices[j]->v_owner)
 2080                                         continue;
 2081                                 KASSERT(!graph_reaches(g->g_vertices[i],
 2082                                         g->g_vertices[j], NULL),
 2083                                     ("lock graph vertices disordered"));
 2084                         }
 2085                 }
 2086         }
 2087 }
 2088 
 2089 static void
 2090 graph_print_vertices(struct owner_vertex_list *set)
 2091 {
 2092         struct owner_vertex *v;
 2093 
 2094         printf("{ ");
 2095         TAILQ_FOREACH(v, set, v_link) {
 2096                 printf("%d:", v->v_order);
 2097                 lf_print_owner(v->v_owner);
 2098                 if (TAILQ_NEXT(v, v_link))
 2099                         printf(", ");
 2100         }
 2101         printf(" }\n");
 2102 }
 2103 
 2104 #endif
 2105 
 2106 /*
 2107  * Calculate the sub-set of vertices v from the affected region [y..x]
 2108  * where v is reachable from y. Return -1 if a loop was detected
 2109  * (i.e. x is reachable from y, otherwise the number of vertices in
 2110  * this subset.
 2111  */
 2112 static int
 2113 graph_delta_forward(struct owner_graph *g, struct owner_vertex *x,
 2114     struct owner_vertex *y, struct owner_vertex_list *delta)
 2115 {
 2116         uint32_t gen;
 2117         struct owner_vertex *v;
 2118         struct owner_edge *e;
 2119         int n;
 2120 
 2121         /*
 2122          * We start with a set containing just y. Then for each vertex
 2123          * v in the set so far unprocessed, we add each vertex that v
 2124          * has an out-edge to and that is within the affected region
 2125          * [y..x]. If we see the vertex x on our travels, stop
 2126          * immediately.
 2127          */
 2128         TAILQ_INIT(delta);
 2129         TAILQ_INSERT_TAIL(delta, y, v_link);
 2130         v = y;
 2131         n = 1;
 2132         gen = g->g_gen;
 2133         while (v) {
 2134                 LIST_FOREACH(e, &v->v_outedges, e_outlink) {
 2135                         if (e->e_to == x)
 2136                                 return -1;
 2137                         if (e->e_to->v_order < x->v_order
 2138                             && e->e_to->v_gen != gen) {
 2139                                 e->e_to->v_gen = gen;
 2140                                 TAILQ_INSERT_TAIL(delta, e->e_to, v_link);
 2141                                 n++;
 2142                         }
 2143                 }
 2144                 v = TAILQ_NEXT(v, v_link);
 2145         }
 2146 
 2147         return (n);
 2148 }
 2149 
 2150 /*
 2151  * Calculate the sub-set of vertices v from the affected region [y..x]
 2152  * where v reaches x. Return the number of vertices in this subset.
 2153  */
 2154 static int
 2155 graph_delta_backward(struct owner_graph *g, struct owner_vertex *x,
 2156     struct owner_vertex *y, struct owner_vertex_list *delta)
 2157 {
 2158         uint32_t gen;
 2159         struct owner_vertex *v;
 2160         struct owner_edge *e;
 2161         int n;
 2162 
 2163         /*
 2164          * We start with a set containing just x. Then for each vertex
 2165          * v in the set so far unprocessed, we add each vertex that v
 2166          * has an in-edge from and that is within the affected region
 2167          * [y..x].
 2168          */
 2169         TAILQ_INIT(delta);
 2170         TAILQ_INSERT_TAIL(delta, x, v_link);
 2171         v = x;
 2172         n = 1;
 2173         gen = g->g_gen;
 2174         while (v) {
 2175                 LIST_FOREACH(e, &v->v_inedges, e_inlink) {
 2176                         if (e->e_from->v_order > y->v_order
 2177                             && e->e_from->v_gen != gen) {
 2178                                 e->e_from->v_gen = gen;
 2179                                 TAILQ_INSERT_HEAD(delta, e->e_from, v_link);
 2180                                 n++;
 2181                         }
 2182                 }
 2183                 v = TAILQ_PREV(v, owner_vertex_list, v_link);
 2184         }
 2185 
 2186         return (n);
 2187 }
 2188 
 2189 static int
 2190 graph_add_indices(int *indices, int n, struct owner_vertex_list *set)
 2191 {
 2192         struct owner_vertex *v;
 2193         int i, j;
 2194 
 2195         TAILQ_FOREACH(v, set, v_link) {
 2196                 for (i = n;
 2197                      i > 0 && indices[i - 1] > v->v_order; i--)
 2198                         ;
 2199                 for (j = n - 1; j >= i; j--)
 2200                         indices[j + 1] = indices[j];
 2201                 indices[i] = v->v_order;
 2202                 n++;
 2203         }
 2204 
 2205         return (n);
 2206 }
 2207 
 2208 static int
 2209 graph_assign_indices(struct owner_graph *g, int *indices, int nextunused,
 2210     struct owner_vertex_list *set)
 2211 {
 2212         struct owner_vertex *v, *vlowest;
 2213 
 2214         while (!TAILQ_EMPTY(set)) {
 2215                 vlowest = NULL;
 2216                 TAILQ_FOREACH(v, set, v_link) {
 2217                         if (!vlowest || v->v_order < vlowest->v_order)
 2218                                 vlowest = v;
 2219                 }
 2220                 TAILQ_REMOVE(set, vlowest, v_link);
 2221                 vlowest->v_order = indices[nextunused];
 2222                 g->g_vertices[vlowest->v_order] = vlowest;
 2223                 nextunused++;
 2224         }
 2225 
 2226         return (nextunused);
 2227 }
 2228 
 2229 static int
 2230 graph_add_edge(struct owner_graph *g, struct owner_vertex *x,
 2231     struct owner_vertex *y)
 2232 {
 2233         struct owner_edge *e;
 2234         struct owner_vertex_list deltaF, deltaB;
 2235         int nF, nB, n, vi, i;
 2236         int *indices;
 2237 
 2238         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2239 
 2240         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2241                 if (e->e_to == y) {
 2242                         e->e_refs++;
 2243                         return (0);
 2244                 }
 2245         }
 2246 
 2247 #ifdef LOCKF_DEBUG
 2248         if (lockf_debug & 8) {
 2249                 printf("adding edge %d:", x->v_order);
 2250                 lf_print_owner(x->v_owner);
 2251                 printf(" -> %d:", y->v_order);
 2252                 lf_print_owner(y->v_owner);
 2253                 printf("\n");
 2254         }
 2255 #endif
 2256         if (y->v_order < x->v_order) {
 2257                 /*
 2258                  * The new edge violates the order. First find the set
 2259                  * of affected vertices reachable from y (deltaF) and
 2260                  * the set of affect vertices affected that reach x
 2261                  * (deltaB), using the graph generation number to
 2262                  * detect whether we have visited a given vertex
 2263                  * already. We re-order the graph so that each vertex
 2264                  * in deltaB appears before each vertex in deltaF.
 2265                  *
 2266                  * If x is a member of deltaF, then the new edge would
 2267                  * create a cycle. Otherwise, we may assume that
 2268                  * deltaF and deltaB are disjoint.
 2269                  */
 2270                 g->g_gen++;
 2271                 if (g->g_gen == 0) {
 2272                         /*
 2273                          * Generation wrap.
 2274                          */
 2275                         for (vi = 0; vi < g->g_size; vi++) {
 2276                                 g->g_vertices[vi]->v_gen = 0;
 2277                         }
 2278                         g->g_gen++;
 2279                 }
 2280                 nF = graph_delta_forward(g, x, y, &deltaF);
 2281                 if (nF < 0) {
 2282 #ifdef LOCKF_DEBUG
 2283                         if (lockf_debug & 8) {
 2284                                 struct owner_vertex_list path;
 2285                                 printf("deadlock: ");
 2286                                 TAILQ_INIT(&path);
 2287                                 graph_reaches(y, x, &path);
 2288                                 graph_print_vertices(&path);
 2289                         }
 2290 #endif
 2291                         return (EDEADLK);
 2292                 }
 2293 
 2294 #ifdef LOCKF_DEBUG
 2295                 if (lockf_debug & 8) {
 2296                         printf("re-ordering graph vertices\n");
 2297                         printf("deltaF = ");
 2298                         graph_print_vertices(&deltaF);
 2299                 }
 2300 #endif
 2301 
 2302                 nB = graph_delta_backward(g, x, y, &deltaB);
 2303 
 2304 #ifdef LOCKF_DEBUG
 2305                 if (lockf_debug & 8) {
 2306                         printf("deltaB = ");
 2307                         graph_print_vertices(&deltaB);
 2308                 }
 2309 #endif
 2310 
 2311                 /*
 2312                  * We first build a set of vertex indices (vertex
 2313                  * order values) that we may use, then we re-assign
 2314                  * orders first to those vertices in deltaB, then to
 2315                  * deltaF. Note that the contents of deltaF and deltaB
 2316                  * may be partially disordered - we perform an
 2317                  * insertion sort while building our index set.
 2318                  */
 2319                 indices = g->g_indexbuf;
 2320                 n = graph_add_indices(indices, 0, &deltaF);
 2321                 graph_add_indices(indices, n, &deltaB);
 2322 
 2323                 /*
 2324                  * We must also be sure to maintain the relative
 2325                  * ordering of deltaF and deltaB when re-assigning
 2326                  * vertices. We do this by iteratively removing the
 2327                  * lowest ordered element from the set and assigning
 2328                  * it the next value from our new ordering.
 2329                  */
 2330                 i = graph_assign_indices(g, indices, 0, &deltaB);
 2331                 graph_assign_indices(g, indices, i, &deltaF);
 2332 
 2333 #ifdef LOCKF_DEBUG
 2334                 if (lockf_debug & 8) {
 2335                         struct owner_vertex_list set;
 2336                         TAILQ_INIT(&set);
 2337                         for (i = 0; i < nB + nF; i++)
 2338                                 TAILQ_INSERT_TAIL(&set,
 2339                                     g->g_vertices[indices[i]], v_link);
 2340                         printf("new ordering = ");
 2341                         graph_print_vertices(&set);
 2342                 }
 2343 #endif
 2344         }
 2345 
 2346         KASSERT(x->v_order < y->v_order, ("Failed to re-order graph"));
 2347 
 2348 #ifdef LOCKF_DEBUG
 2349         if (lockf_debug & 8) {
 2350                 graph_check(g, TRUE);
 2351         }
 2352 #endif
 2353 
 2354         e = malloc(sizeof(struct owner_edge), M_LOCKF, M_WAITOK);
 2355 
 2356         LIST_INSERT_HEAD(&x->v_outedges, e, e_outlink);
 2357         LIST_INSERT_HEAD(&y->v_inedges, e, e_inlink);
 2358         e->e_refs = 1;
 2359         e->e_from = x;
 2360         e->e_to = y;
 2361 
 2362         return (0);
 2363 }
 2364 
 2365 /*
 2366  * Remove an edge x->y from the graph.
 2367  */
 2368 static void
 2369 graph_remove_edge(struct owner_graph *g, struct owner_vertex *x,
 2370     struct owner_vertex *y)
 2371 {
 2372         struct owner_edge *e;
 2373 
 2374         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2375 
 2376         LIST_FOREACH(e, &x->v_outedges, e_outlink) {
 2377                 if (e->e_to == y)
 2378                         break;
 2379         }
 2380         KASSERT(e, ("Removing non-existent edge from deadlock graph"));
 2381 
 2382         e->e_refs--;
 2383         if (e->e_refs == 0) {
 2384 #ifdef LOCKF_DEBUG
 2385                 if (lockf_debug & 8) {
 2386                         printf("removing edge %d:", x->v_order);
 2387                         lf_print_owner(x->v_owner);
 2388                         printf(" -> %d:", y->v_order);
 2389                         lf_print_owner(y->v_owner);
 2390                         printf("\n");
 2391                 }
 2392 #endif
 2393                 LIST_REMOVE(e, e_outlink);
 2394                 LIST_REMOVE(e, e_inlink);
 2395                 free(e, M_LOCKF);
 2396         }
 2397 }
 2398 
 2399 /*
 2400  * Allocate a vertex from the free list. Return ENOMEM if there are
 2401  * none.
 2402  */
 2403 static struct owner_vertex *
 2404 graph_alloc_vertex(struct owner_graph *g, struct lock_owner *lo)
 2405 {
 2406         struct owner_vertex *v;
 2407 
 2408         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2409 
 2410         v = malloc(sizeof(struct owner_vertex), M_LOCKF, M_WAITOK);
 2411         if (g->g_size == g->g_space) {
 2412                 g->g_vertices = realloc(g->g_vertices,
 2413                     2 * g->g_space * sizeof(struct owner_vertex *),
 2414                     M_LOCKF, M_WAITOK);
 2415                 free(g->g_indexbuf, M_LOCKF);
 2416                 g->g_indexbuf = malloc(2 * g->g_space * sizeof(int),
 2417                     M_LOCKF, M_WAITOK);
 2418                 g->g_space = 2 * g->g_space;
 2419         }
 2420         v->v_order = g->g_size;
 2421         v->v_gen = g->g_gen;
 2422         g->g_vertices[g->g_size] = v;
 2423         g->g_size++;
 2424 
 2425         LIST_INIT(&v->v_outedges);
 2426         LIST_INIT(&v->v_inedges);
 2427         v->v_owner = lo;
 2428 
 2429         return (v);
 2430 }
 2431 
 2432 static void
 2433 graph_free_vertex(struct owner_graph *g, struct owner_vertex *v)
 2434 {
 2435         struct owner_vertex *w;
 2436         int i;
 2437 
 2438         sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
 2439         
 2440         KASSERT(LIST_EMPTY(&v->v_outedges), ("Freeing vertex with edges"));
 2441         KASSERT(LIST_EMPTY(&v->v_inedges), ("Freeing vertex with edges"));
 2442 
 2443         /*
 2444          * Remove from the graph's array and close up the gap,
 2445          * renumbering the other vertices.
 2446          */
 2447         for (i = v->v_order + 1; i < g->g_size; i++) {
 2448                 w = g->g_vertices[i];
 2449                 w->v_order--;
 2450                 g->g_vertices[i - 1] = w;
 2451         }
 2452         g->g_size--;
 2453 
 2454         free(v, M_LOCKF);
 2455 }
 2456 
 2457 static struct owner_graph *
 2458 graph_init(struct owner_graph *g)
 2459 {
 2460 
 2461         g->g_vertices = malloc(10 * sizeof(struct owner_vertex *),
 2462             M_LOCKF, M_WAITOK);
 2463         g->g_size = 0;
 2464         g->g_space = 10;
 2465         g->g_indexbuf = malloc(g->g_space * sizeof(int), M_LOCKF, M_WAITOK);
 2466         g->g_gen = 0;
 2467 
 2468         return (g);
 2469 }
 2470 
 2471 #ifdef LOCKF_DEBUG
 2472 /*
 2473  * Print description of a lock owner
 2474  */
 2475 static void
 2476 lf_print_owner(struct lock_owner *lo)
 2477 {
 2478 
 2479         if (lo->lo_flags & F_REMOTE) {
 2480                 printf("remote pid %d, system %d",
 2481                     lo->lo_pid, lo->lo_sysid);
 2482         } else if (lo->lo_flags & F_FLOCK) {
 2483                 printf("file %p", lo->lo_id);
 2484         } else {
 2485                 printf("local pid %d", lo->lo_pid);
 2486         }
 2487 }
 2488 
 2489 /*
 2490  * Print out a lock.
 2491  */
 2492 static void
 2493 lf_print(char *tag, struct lockf_entry *lock)
 2494 {
 2495 
 2496         printf("%s: lock %p for ", tag, (void *)lock);
 2497         lf_print_owner(lock->lf_owner);
 2498         if (lock->lf_inode != (struct inode *)0)
 2499                 printf(" in ino %ju on dev <%s>,",
 2500                     (uintmax_t)lock->lf_inode->i_number,
 2501                     devtoname(lock->lf_inode->i_dev));
 2502         printf(" %s, start %jd, end ",
 2503             lock->lf_type == F_RDLCK ? "shared" :
 2504             lock->lf_type == F_WRLCK ? "exclusive" :
 2505             lock->lf_type == F_UNLCK ? "unlock" : "unknown",
 2506             (intmax_t)lock->lf_start);
 2507         if (lock->lf_end == OFF_MAX)
 2508                 printf("EOF");
 2509         else
 2510                 printf("%jd", (intmax_t)lock->lf_end);
 2511         if (!LIST_EMPTY(&lock->lf_outedges))
 2512                 printf(" block %p\n",
 2513                     (void *)LIST_FIRST(&lock->lf_outedges)->le_to);
 2514         else
 2515                 printf("\n");
 2516 }
 2517 
 2518 static void
 2519 lf_printlist(char *tag, struct lockf_entry *lock)
 2520 {
 2521         struct lockf_entry *lf, *blk;
 2522         struct lockf_edge *e;
 2523 
 2524         if (lock->lf_inode == (struct inode *)0)
 2525                 return;
 2526 
 2527         printf("%s: Lock list for ino %ju on dev <%s>:\n",
 2528             tag, (uintmax_t)lock->lf_inode->i_number,
 2529             devtoname(lock->lf_inode->i_dev));
 2530         LIST_FOREACH(lf, &lock->lf_vnode->v_lockf->ls_active, lf_link) {
 2531                 printf("\tlock %p for ",(void *)lf);
 2532                 lf_print_owner(lock->lf_owner);
 2533                 printf(", %s, start %jd, end %jd",
 2534                     lf->lf_type == F_RDLCK ? "shared" :
 2535                     lf->lf_type == F_WRLCK ? "exclusive" :
 2536                     lf->lf_type == F_UNLCK ? "unlock" :
 2537                     "unknown", (intmax_t)lf->lf_start, (intmax_t)lf->lf_end);
 2538                 LIST_FOREACH(e, &lf->lf_outedges, le_outlink) {
 2539                         blk = e->le_to;
 2540                         printf("\n\t\tlock request %p for ", (void *)blk);
 2541                         lf_print_owner(blk->lf_owner);
 2542                         printf(", %s, start %jd, end %jd",
 2543                             blk->lf_type == F_RDLCK ? "shared" :
 2544                             blk->lf_type == F_WRLCK ? "exclusive" :
 2545                             blk->lf_type == F_UNLCK ? "unlock" :
 2546                             "unknown", (intmax_t)blk->lf_start,
 2547                             (intmax_t)blk->lf_end);
 2548                         if (!LIST_EMPTY(&blk->lf_inedges))
 2549                                 panic("lf_printlist: bad list");
 2550                 }
 2551                 printf("\n");
 2552         }
 2553 }
 2554 #endif /* LOCKF_DEBUG */

Cache object: 3d5d4bf96a9f24875eac8694da652efa


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.