2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
5 * Authors: Doug Rabson <dfr@rabson.org>
6 * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * Copyright (c) 1982, 1986, 1989, 1993
31 * The Regents of the University of California. All rights reserved.
33 * This code is derived from software contributed to Berkeley by
34 * Scooter Morris at Genentech Inc.
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions
39 * 1. Redistributions of source code must retain the above copyright
40 * notice, this list of conditions and the following disclaimer.
41 * 2. Redistributions in binary form must reproduce the above copyright
42 * notice, this list of conditions and the following disclaimer in the
43 * documentation and/or other materials provided with the distribution.
44 * 3. Neither the name of the University nor the names of its contributors
45 * may be used to endorse or promote products derived from this software
46 * without specific prior written permission.
48 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
49 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
50 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
51 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
52 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
53 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
54 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
55 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
56 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
57 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60 * @(#)ufs_lockf.c 8.3 (Berkeley) 1/6/94
63 #include <sys/cdefs.h>
64 __FBSDID("$FreeBSD$");
66 #include "opt_debug_lockf.h"
68 #include <sys/param.h>
69 #include <sys/systm.h>
71 #include <sys/kernel.h>
72 #include <sys/limits.h>
74 #include <sys/mount.h>
75 #include <sys/mutex.h>
78 #include <sys/unistd.h>
79 #include <sys/vnode.h>
80 #include <sys/malloc.h>
81 #include <sys/fcntl.h>
82 #include <sys/lockf.h>
83 #include <sys/taskqueue.h>
86 #include <sys/sysctl.h>
88 #include <ufs/ufs/extattr.h>
89 #include <ufs/ufs/quota.h>
90 #include <ufs/ufs/ufsmount.h>
91 #include <ufs/ufs/inode.h>
93 static int lockf_debug = 0; /* control debug output */
94 SYSCTL_INT(_debug, OID_AUTO, lockf_debug, CTLFLAG_RW, &lockf_debug, 0, "");
97 static MALLOC_DEFINE(M_LOCKF, "lockf", "Byte-range locking structures");
101 struct owner_vertex_list;
104 #define NOLOCKF (struct lockf_entry *)0
107 static void lf_init(void *);
108 static int lf_hash_owner(caddr_t, struct flock *, int);
109 static int lf_owner_matches(struct lock_owner *, caddr_t, struct flock *,
111 static struct lockf_entry *
112 lf_alloc_lock(struct lock_owner *);
113 static int lf_free_lock(struct lockf_entry *);
114 static int lf_clearlock(struct lockf *, struct lockf_entry *);
115 static int lf_overlaps(struct lockf_entry *, struct lockf_entry *);
116 static int lf_blocks(struct lockf_entry *, struct lockf_entry *);
117 static void lf_free_edge(struct lockf_edge *);
118 static struct lockf_edge *
120 static void lf_alloc_vertex(struct lockf_entry *);
121 static int lf_add_edge(struct lockf_entry *, struct lockf_entry *);
122 static void lf_remove_edge(struct lockf_edge *);
123 static void lf_remove_outgoing(struct lockf_entry *);
124 static void lf_remove_incoming(struct lockf_entry *);
125 static int lf_add_outgoing(struct lockf *, struct lockf_entry *);
126 static int lf_add_incoming(struct lockf *, struct lockf_entry *);
127 static int lf_findoverlap(struct lockf_entry **, struct lockf_entry *,
129 static struct lockf_entry *
130 lf_getblock(struct lockf *, struct lockf_entry *);
131 static int lf_getlock(struct lockf *, struct lockf_entry *, struct flock *);
132 static void lf_insert_lock(struct lockf *, struct lockf_entry *);
133 static void lf_wakeup_lock(struct lockf *, struct lockf_entry *);
134 static void lf_update_dependancies(struct lockf *, struct lockf_entry *,
135 int all, struct lockf_entry_list *);
136 static void lf_set_start(struct lockf *, struct lockf_entry *, off_t,
137 struct lockf_entry_list*);
138 static void lf_set_end(struct lockf *, struct lockf_entry *, off_t,
139 struct lockf_entry_list*);
140 static int lf_setlock(struct lockf *, struct lockf_entry *,
141 struct vnode *, void **cookiep);
142 static int lf_cancel(struct lockf *, struct lockf_entry *, void *);
143 static void lf_split(struct lockf *, struct lockf_entry *,
144 struct lockf_entry *, struct lockf_entry_list *);
146 static int graph_reaches(struct owner_vertex *x, struct owner_vertex *y,
147 struct owner_vertex_list *path);
148 static void graph_check(struct owner_graph *g, int checkorder);
149 static void graph_print_vertices(struct owner_vertex_list *set);
151 static int graph_delta_forward(struct owner_graph *g,
152 struct owner_vertex *x, struct owner_vertex *y,
153 struct owner_vertex_list *delta);
154 static int graph_delta_backward(struct owner_graph *g,
155 struct owner_vertex *x, struct owner_vertex *y,
156 struct owner_vertex_list *delta);
157 static int graph_add_indices(int *indices, int n,
158 struct owner_vertex_list *set);
159 static int graph_assign_indices(struct owner_graph *g, int *indices,
160 int nextunused, struct owner_vertex_list *set);
161 static int graph_add_edge(struct owner_graph *g,
162 struct owner_vertex *x, struct owner_vertex *y);
163 static void graph_remove_edge(struct owner_graph *g,
164 struct owner_vertex *x, struct owner_vertex *y);
165 static struct owner_vertex *graph_alloc_vertex(struct owner_graph *g,
166 struct lock_owner *lo);
167 static void graph_free_vertex(struct owner_graph *g,
168 struct owner_vertex *v);
169 static struct owner_graph * graph_init(struct owner_graph *g);
171 static void lf_print(char *, struct lockf_entry *);
172 static void lf_printlist(char *, struct lockf_entry *);
173 static void lf_print_owner(struct lock_owner *);
177 * This structure is used to keep track of both local and remote lock
178 * owners. The lf_owner field of the struct lockf_entry points back at
179 * the lock owner structure. Each possible lock owner (local proc for
180 * POSIX fcntl locks, local file for BSD flock locks or <pid,sysid>
181 * pair for remote locks) is represented by a unique instance of
184 * If a lock owner has a lock that blocks some other lock or a lock
185 * that is waiting for some other lock, it also has a vertex in the
189 * (s) locked by state->ls_lock
190 * (S) locked by lf_lock_states_lock
191 * (l) locked by lf_lock_owners_lock
192 * (g) locked by lf_owner_graph_lock
193 * (c) const until freeing
195 #define LOCK_OWNER_HASH_SIZE 256
198 LIST_ENTRY(lock_owner) lo_link; /* (l) hash chain */
199 int lo_refs; /* (l) Number of locks referring to this */
200 int lo_flags; /* (c) Flags passwd to lf_advlock */
201 caddr_t lo_id; /* (c) Id value passed to lf_advlock */
202 pid_t lo_pid; /* (c) Process Id of the lock owner */
203 int lo_sysid; /* (c) System Id of the lock owner */
204 struct owner_vertex *lo_vertex; /* (g) entry in deadlock graph */
207 LIST_HEAD(lock_owner_list, lock_owner);
209 static struct sx lf_lock_states_lock;
210 static struct lockf_list lf_lock_states; /* (S) */
211 static struct sx lf_lock_owners_lock;
212 static struct lock_owner_list lf_lock_owners[LOCK_OWNER_HASH_SIZE]; /* (l) */
215 * Structures for deadlock detection.
217 * We have two types of directed graph, the first is the set of locks,
218 * both active and pending on a vnode. Within this graph, active locks
219 * are terminal nodes in the graph (i.e. have no out-going
220 * edges). Pending locks have out-going edges to each blocking active
221 * lock that prevents the lock from being granted and also to each
222 * older pending lock that would block them if it was active. The
223 * graph for each vnode is naturally acyclic; new edges are only ever
224 * added to or from new nodes (either new pending locks which only add
225 * out-going edges or new active locks which only add in-coming edges)
226 * therefore they cannot create loops in the lock graph.
228 * The second graph is a global graph of lock owners. Each lock owner
229 * is a vertex in that graph and an edge is added to the graph
230 * whenever an edge is added to a vnode graph, with end points
231 * corresponding to owner of the new pending lock and the owner of the
232 * lock upon which it waits. In order to prevent deadlock, we only add
233 * an edge to this graph if the new edge would not create a cycle.
235 * The lock owner graph is topologically sorted, i.e. if a node has
236 * any outgoing edges, then it has an order strictly less than any
237 * node to which it has an outgoing edge. We preserve this ordering
238 * (and detect cycles) on edge insertion using Algorithm PK from the
239 * paper "A Dynamic Topological Sort Algorithm for Directed Acyclic
240 * Graphs" (ACM Journal of Experimental Algorithms, Vol 11, Article
246 LIST_ENTRY(owner_edge) e_outlink; /* (g) link from's out-edge list */
247 LIST_ENTRY(owner_edge) e_inlink; /* (g) link to's in-edge list */
248 int e_refs; /* (g) number of times added */
249 struct owner_vertex *e_from; /* (c) out-going from here */
250 struct owner_vertex *e_to; /* (c) in-coming to here */
252 LIST_HEAD(owner_edge_list, owner_edge);
254 struct owner_vertex {
255 TAILQ_ENTRY(owner_vertex) v_link; /* (g) workspace for edge insertion */
256 uint32_t v_gen; /* (g) workspace for edge insertion */
257 int v_order; /* (g) order of vertex in graph */
258 struct owner_edge_list v_outedges;/* (g) list of out-edges */
259 struct owner_edge_list v_inedges; /* (g) list of in-edges */
260 struct lock_owner *v_owner; /* (c) corresponding lock owner */
262 TAILQ_HEAD(owner_vertex_list, owner_vertex);
265 struct owner_vertex** g_vertices; /* (g) pointers to vertices */
266 int g_size; /* (g) number of vertices */
267 int g_space; /* (g) space allocated for vertices */
268 int *g_indexbuf; /* (g) workspace for loop detection */
269 uint32_t g_gen; /* (g) increment when re-ordering */
272 static struct sx lf_owner_graph_lock;
273 static struct owner_graph lf_owner_graph;
276 * Initialise various structures and locks.
283 sx_init(&lf_lock_states_lock, "lock states lock");
284 LIST_INIT(&lf_lock_states);
286 sx_init(&lf_lock_owners_lock, "lock owners lock");
287 for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++)
288 LIST_INIT(&lf_lock_owners[i]);
290 sx_init(&lf_owner_graph_lock, "owner graph lock");
291 graph_init(&lf_owner_graph);
293 SYSINIT(lf_init, SI_SUB_LOCK, SI_ORDER_FIRST, lf_init, NULL);
296 * Generate a hash value for a lock owner.
299 lf_hash_owner(caddr_t id, struct flock *fl, int flags)
303 if (flags & F_REMOTE) {
304 h = HASHSTEP(0, fl->l_pid);
305 h = HASHSTEP(h, fl->l_sysid);
306 } else if (flags & F_FLOCK) {
307 h = ((uintptr_t) id) >> 7;
309 struct proc *p = (struct proc *) id;
310 h = HASHSTEP(0, p->p_pid);
314 return (h % LOCK_OWNER_HASH_SIZE);
318 * Return true if a lock owner matches the details passed to
322 lf_owner_matches(struct lock_owner *lo, caddr_t id, struct flock *fl,
325 if (flags & F_REMOTE) {
326 return lo->lo_pid == fl->l_pid
327 && lo->lo_sysid == fl->l_sysid;
329 return lo->lo_id == id;
333 static struct lockf_entry *
334 lf_alloc_lock(struct lock_owner *lo)
336 struct lockf_entry *lf;
338 lf = malloc(sizeof(struct lockf_entry), M_LOCKF, M_WAITOK|M_ZERO);
342 printf("Allocated lock %p\n", lf);
345 sx_xlock(&lf_lock_owners_lock);
347 sx_xunlock(&lf_lock_owners_lock);
355 lf_free_lock(struct lockf_entry *lock)
358 KASSERT(lock->lf_refs > 0, ("lockf_entry negative ref count %p", lock));
359 if (--lock->lf_refs > 0)
362 * Adjust the lock_owner reference count and
363 * reclaim the entry if this is the last lock
366 struct lock_owner *lo = lock->lf_owner;
368 KASSERT(LIST_EMPTY(&lock->lf_outedges),
369 ("freeing lock with dependencies"));
370 KASSERT(LIST_EMPTY(&lock->lf_inedges),
371 ("freeing lock with dependants"));
372 sx_xlock(&lf_lock_owners_lock);
373 KASSERT(lo->lo_refs > 0, ("lock owner refcount"));
375 if (lo->lo_refs == 0) {
378 printf("lf_free_lock: freeing lock owner %p\n",
382 sx_xlock(&lf_owner_graph_lock);
383 graph_free_vertex(&lf_owner_graph,
385 sx_xunlock(&lf_owner_graph_lock);
387 LIST_REMOVE(lo, lo_link);
391 printf("Freed lock owner %p\n", lo);
394 sx_unlock(&lf_lock_owners_lock);
396 if ((lock->lf_flags & F_REMOTE) && lock->lf_vnode) {
397 vrele(lock->lf_vnode);
398 lock->lf_vnode = NULL;
402 printf("Freed lock %p\n", lock);
409 * Advisory record locking support
412 lf_advlockasync(struct vop_advlockasync_args *ap, struct lockf **statep,
416 struct flock *fl = ap->a_fl;
417 struct lockf_entry *lock;
418 struct vnode *vp = ap->a_vp;
419 caddr_t id = ap->a_id;
420 int flags = ap->a_flags;
422 struct lock_owner *lo;
423 off_t start, end, oadd;
427 * Handle the F_UNLKSYS case first - no need to mess about
428 * creating a lock owner for this one.
430 if (ap->a_op == F_UNLCKSYS) {
431 lf_clearremotesys(fl->l_sysid);
436 * Convert the flock structure into a start and end.
438 switch (fl->l_whence) {
443 * Caller is responsible for adding any necessary offset
444 * when SEEK_CUR is used.
450 if (size > OFF_MAX ||
451 (fl->l_start > 0 && size > OFF_MAX - fl->l_start))
453 start = size + fl->l_start;
468 } else if (fl->l_len == 0) {
471 oadd = fl->l_len - 1;
472 if (oadd > OFF_MAX - start)
480 * Avoid the common case of unlocking when inode has no locks.
482 if (ap->a_op != F_SETLK && (*statep) == NULL) {
484 if ((*statep) == NULL) {
485 fl->l_type = F_UNLCK;
493 * Map our arguments to an existing lock owner or create one
494 * if this is the first time we have seen this owner.
496 hash = lf_hash_owner(id, fl, flags);
497 sx_xlock(&lf_lock_owners_lock);
498 LIST_FOREACH(lo, &lf_lock_owners[hash], lo_link)
499 if (lf_owner_matches(lo, id, fl, flags))
503 * We initialise the lock with a reference
504 * count which matches the new lockf_entry
505 * structure created below.
507 lo = malloc(sizeof(struct lock_owner), M_LOCKF,
511 printf("Allocated lock owner %p\n", lo);
515 lo->lo_flags = flags;
517 if (flags & F_REMOTE) {
518 lo->lo_pid = fl->l_pid;
519 lo->lo_sysid = fl->l_sysid;
520 } else if (flags & F_FLOCK) {
524 struct proc *p = (struct proc *) id;
525 lo->lo_pid = p->p_pid;
528 lo->lo_vertex = NULL;
531 if (lockf_debug & 1) {
532 printf("lf_advlockasync: new lock owner %p ", lo);
538 LIST_INSERT_HEAD(&lf_lock_owners[hash], lo, lo_link);
541 * We have seen this lock owner before, increase its
542 * reference count to account for the new lockf_entry
543 * structure we create below.
547 sx_xunlock(&lf_lock_owners_lock);
550 * Create the lockf structure. We initialise the lf_owner
551 * field here instead of in lf_alloc_lock() to avoid paying
552 * the lf_lock_owners_lock tax twice.
554 lock = lf_alloc_lock(NULL);
556 lock->lf_start = start;
560 if (flags & F_REMOTE) {
562 * For remote locks, the caller may release its ref to
563 * the vnode at any time - we have to ref it here to
564 * prevent it from being recycled unexpectedly.
570 * XXX The problem is that VTOI is ufs specific, so it will
571 * break LOCKF_DEBUG for all other FS's other than UFS because
572 * it casts the vnode->data ptr to struct inode *.
574 /* lock->lf_inode = VTOI(ap->a_vp); */
575 lock->lf_inode = (struct inode *)0;
576 lock->lf_type = fl->l_type;
577 LIST_INIT(&lock->lf_outedges);
578 LIST_INIT(&lock->lf_inedges);
579 lock->lf_async_task = ap->a_task;
580 lock->lf_flags = ap->a_flags;
583 * Do the requested operation. First find our state structure
584 * and create a new one if necessary - the caller's *statep
585 * variable and the state's ls_threads count is protected by
586 * the vnode interlock.
589 if (vp->v_iflag & VI_DOOMED) {
596 * Allocate a state structure if necessary.
604 ls = malloc(sizeof(struct lockf), M_LOCKF, M_WAITOK|M_ZERO);
605 sx_init(&ls->ls_lock, "ls_lock");
606 LIST_INIT(&ls->ls_active);
607 LIST_INIT(&ls->ls_pending);
610 sx_xlock(&lf_lock_states_lock);
611 LIST_INSERT_HEAD(&lf_lock_states, ls, ls_link);
612 sx_xunlock(&lf_lock_states_lock);
615 * Cope if we lost a race with some other thread while
616 * trying to allocate memory.
619 if (vp->v_iflag & VI_DOOMED) {
621 sx_xlock(&lf_lock_states_lock);
622 LIST_REMOVE(ls, ls_link);
623 sx_xunlock(&lf_lock_states_lock);
624 sx_destroy(&ls->ls_lock);
629 if ((*statep) == NULL) {
630 state = *statep = ls;
637 sx_xlock(&lf_lock_states_lock);
638 LIST_REMOVE(ls, ls_link);
639 sx_xunlock(&lf_lock_states_lock);
640 sx_destroy(&ls->ls_lock);
648 sx_xlock(&state->ls_lock);
650 * Recheck the doomed vnode after state->ls_lock is
651 * locked. lf_purgelocks() requires that no new threads add
652 * pending locks when vnode is marked by VI_DOOMED flag.
655 if (vp->v_iflag & VI_DOOMED) {
659 sx_xunlock(&state->ls_lock);
667 error = lf_setlock(state, lock, vp, ap->a_cookiep);
671 error = lf_clearlock(state, lock);
676 error = lf_getlock(state, lock, fl);
682 error = lf_cancel(state, lock, *ap->a_cookiep);
696 * Check for some can't happen stuff. In this case, the active
697 * lock list becoming disordered or containing mutually
698 * blocking locks. We also check the pending list for locks
699 * which should be active (i.e. have no out-going edges).
701 LIST_FOREACH(lock, &state->ls_active, lf_link) {
702 struct lockf_entry *lf;
703 if (LIST_NEXT(lock, lf_link))
704 KASSERT((lock->lf_start
705 <= LIST_NEXT(lock, lf_link)->lf_start),
706 ("locks disordered"));
707 LIST_FOREACH(lf, &state->ls_active, lf_link) {
710 KASSERT(!lf_blocks(lock, lf),
711 ("two conflicting active locks"));
712 if (lock->lf_owner == lf->lf_owner)
713 KASSERT(!lf_overlaps(lock, lf),
714 ("two overlapping locks from same owner"));
717 LIST_FOREACH(lock, &state->ls_pending, lf_link) {
718 KASSERT(!LIST_EMPTY(&lock->lf_outedges),
719 ("pending lock which should be active"));
722 sx_xunlock(&state->ls_lock);
728 if (LIST_EMPTY(&state->ls_active) && state->ls_threads == 0) {
729 KASSERT(LIST_EMPTY(&state->ls_pending),
730 ("freeable state with pending locks"));
735 if (error == EDOOFUS) {
736 KASSERT(ap->a_op == F_SETLK, ("EDOOFUS"));
743 lf_advlock(struct vop_advlock_args *ap, struct lockf **statep, u_quad_t size)
745 struct vop_advlockasync_args a;
751 a.a_flags = ap->a_flags;
755 return (lf_advlockasync(&a, statep, size));
759 lf_purgelocks(struct vnode *vp, struct lockf **statep)
762 struct lockf_entry *lock, *nlock;
765 * For this to work correctly, the caller must ensure that no
766 * other threads enter the locking system for this vnode,
767 * e.g. by checking VI_DOOMED. We wake up any threads that are
768 * sleeping waiting for locks on this vnode and then free all
769 * the remaining locks.
772 KASSERT(vp->v_iflag & VI_DOOMED,
773 ("lf_purgelocks: vp %p has not vgone yet", vp));
780 if (LIST_EMPTY(&state->ls_active) && state->ls_threads == 0) {
781 KASSERT(LIST_EMPTY(&state->ls_pending),
782 ("freeing state with pending locks"));
789 sx_xlock(&state->ls_lock);
790 sx_xlock(&lf_owner_graph_lock);
791 LIST_FOREACH_SAFE(lock, &state->ls_pending, lf_link, nlock) {
792 LIST_REMOVE(lock, lf_link);
793 lf_remove_outgoing(lock);
794 lf_remove_incoming(lock);
797 * If its an async lock, we can just free it
798 * here, otherwise we let the sleeping thread
801 if (lock->lf_async_task) {
804 lock->lf_flags |= F_INTR;
808 sx_xunlock(&lf_owner_graph_lock);
809 sx_xunlock(&state->ls_lock);
812 * Wait for all other threads, sleeping and otherwise
816 while (state->ls_threads > 1)
817 msleep(state, VI_MTX(vp), 0, "purgelocks", 0);
821 * We can just free all the active locks since they
822 * will have no dependencies (we removed them all
823 * above). We don't need to bother locking since we
824 * are the last thread using this state structure.
826 KASSERT(LIST_EMPTY(&state->ls_pending),
827 ("lock pending for %p", state));
828 LIST_FOREACH_SAFE(lock, &state->ls_active, lf_link, nlock) {
829 LIST_REMOVE(lock, lf_link);
833 sx_xlock(&lf_lock_states_lock);
834 LIST_REMOVE(state, ls_link);
835 sx_xunlock(&lf_lock_states_lock);
836 sx_destroy(&state->ls_lock);
837 free(state, M_LOCKF);
841 * Return non-zero if locks 'x' and 'y' overlap.
844 lf_overlaps(struct lockf_entry *x, struct lockf_entry *y)
847 return (x->lf_start <= y->lf_end && x->lf_end >= y->lf_start);
851 * Return non-zero if lock 'x' is blocked by lock 'y' (or vice versa).
854 lf_blocks(struct lockf_entry *x, struct lockf_entry *y)
857 return x->lf_owner != y->lf_owner
858 && (x->lf_type == F_WRLCK || y->lf_type == F_WRLCK)
859 && lf_overlaps(x, y);
863 * Allocate a lock edge from the free list
865 static struct lockf_edge *
869 return (malloc(sizeof(struct lockf_edge), M_LOCKF, M_WAITOK|M_ZERO));
876 lf_free_edge(struct lockf_edge *e)
884 * Ensure that the lock's owner has a corresponding vertex in the
888 lf_alloc_vertex(struct lockf_entry *lock)
890 struct owner_graph *g = &lf_owner_graph;
892 if (!lock->lf_owner->lo_vertex)
893 lock->lf_owner->lo_vertex =
894 graph_alloc_vertex(g, lock->lf_owner);
898 * Attempt to record an edge from lock x to lock y. Return EDEADLK if
899 * the new edge would cause a cycle in the owner graph.
902 lf_add_edge(struct lockf_entry *x, struct lockf_entry *y)
904 struct owner_graph *g = &lf_owner_graph;
905 struct lockf_edge *e;
909 LIST_FOREACH(e, &x->lf_outedges, le_outlink)
910 KASSERT(e->le_to != y, ("adding lock edge twice"));
914 * Make sure the two owners have entries in the owner graph.
919 error = graph_add_edge(g, x->lf_owner->lo_vertex,
920 y->lf_owner->lo_vertex);
925 LIST_INSERT_HEAD(&x->lf_outedges, e, le_outlink);
926 LIST_INSERT_HEAD(&y->lf_inedges, e, le_inlink);
934 * Remove an edge from the lock graph.
937 lf_remove_edge(struct lockf_edge *e)
939 struct owner_graph *g = &lf_owner_graph;
940 struct lockf_entry *x = e->le_from;
941 struct lockf_entry *y = e->le_to;
943 graph_remove_edge(g, x->lf_owner->lo_vertex, y->lf_owner->lo_vertex);
944 LIST_REMOVE(e, le_outlink);
945 LIST_REMOVE(e, le_inlink);
952 * Remove all out-going edges from lock x.
955 lf_remove_outgoing(struct lockf_entry *x)
957 struct lockf_edge *e;
959 while ((e = LIST_FIRST(&x->lf_outedges)) != NULL) {
965 * Remove all in-coming edges from lock x.
968 lf_remove_incoming(struct lockf_entry *x)
970 struct lockf_edge *e;
972 while ((e = LIST_FIRST(&x->lf_inedges)) != NULL) {
978 * Walk the list of locks for the file and create an out-going edge
979 * from lock to each blocking lock.
982 lf_add_outgoing(struct lockf *state, struct lockf_entry *lock)
984 struct lockf_entry *overlap;
987 LIST_FOREACH(overlap, &state->ls_active, lf_link) {
989 * We may assume that the active list is sorted by
992 if (overlap->lf_start > lock->lf_end)
994 if (!lf_blocks(lock, overlap))
998 * We've found a blocking lock. Add the corresponding
999 * edge to the graphs and see if it would cause a
1002 error = lf_add_edge(lock, overlap);
1005 * The only error that lf_add_edge returns is EDEADLK.
1006 * Remove any edges we added and return the error.
1009 lf_remove_outgoing(lock);
1015 * We also need to add edges to sleeping locks that block
1016 * us. This ensures that lf_wakeup_lock cannot grant two
1017 * mutually blocking locks simultaneously and also enforces a
1018 * 'first come, first served' fairness model. Note that this
1019 * only happens if we are blocked by at least one active lock
1020 * due to the call to lf_getblock in lf_setlock below.
1022 LIST_FOREACH(overlap, &state->ls_pending, lf_link) {
1023 if (!lf_blocks(lock, overlap))
1026 * We've found a blocking lock. Add the corresponding
1027 * edge to the graphs and see if it would cause a
1030 error = lf_add_edge(lock, overlap);
1033 * The only error that lf_add_edge returns is EDEADLK.
1034 * Remove any edges we added and return the error.
1037 lf_remove_outgoing(lock);
1046 * Walk the list of pending locks for the file and create an in-coming
1047 * edge from lock to each blocking lock.
1050 lf_add_incoming(struct lockf *state, struct lockf_entry *lock)
1052 struct lockf_entry *overlap;
1055 LIST_FOREACH(overlap, &state->ls_pending, lf_link) {
1056 if (!lf_blocks(lock, overlap))
1060 * We've found a blocking lock. Add the corresponding
1061 * edge to the graphs and see if it would cause a
1064 error = lf_add_edge(overlap, lock);
1067 * The only error that lf_add_edge returns is EDEADLK.
1068 * Remove any edges we added and return the error.
1071 lf_remove_incoming(lock);
1079 * Insert lock into the active list, keeping list entries ordered by
1080 * increasing values of lf_start.
1083 lf_insert_lock(struct lockf *state, struct lockf_entry *lock)
1085 struct lockf_entry *lf, *lfprev;
1087 if (LIST_EMPTY(&state->ls_active)) {
1088 LIST_INSERT_HEAD(&state->ls_active, lock, lf_link);
1093 LIST_FOREACH(lf, &state->ls_active, lf_link) {
1094 if (lf->lf_start > lock->lf_start) {
1095 LIST_INSERT_BEFORE(lf, lock, lf_link);
1100 LIST_INSERT_AFTER(lfprev, lock, lf_link);
1104 * Wake up a sleeping lock and remove it from the pending list now
1105 * that all its dependencies have been resolved. The caller should
1106 * arrange for the lock to be added to the active list, adjusting any
1107 * existing locks for the same owner as needed.
1110 lf_wakeup_lock(struct lockf *state, struct lockf_entry *wakelock)
1114 * Remove from ls_pending list and wake up the caller
1115 * or start the async notification, as appropriate.
1117 LIST_REMOVE(wakelock, lf_link);
1119 if (lockf_debug & 1)
1120 lf_print("lf_wakeup_lock: awakening", wakelock);
1121 #endif /* LOCKF_DEBUG */
1122 if (wakelock->lf_async_task) {
1123 taskqueue_enqueue(taskqueue_thread, wakelock->lf_async_task);
1130 * Re-check all dependent locks and remove edges to locks that we no
1131 * longer block. If 'all' is non-zero, the lock has been removed and
1132 * we must remove all the dependencies, otherwise it has simply been
1133 * reduced but remains active. Any pending locks which have been been
1134 * unblocked are added to 'granted'
1137 lf_update_dependancies(struct lockf *state, struct lockf_entry *lock, int all,
1138 struct lockf_entry_list *granted)
1140 struct lockf_edge *e, *ne;
1141 struct lockf_entry *deplock;
1143 LIST_FOREACH_SAFE(e, &lock->lf_inedges, le_inlink, ne) {
1144 deplock = e->le_from;
1145 if (all || !lf_blocks(lock, deplock)) {
1146 sx_xlock(&lf_owner_graph_lock);
1148 sx_xunlock(&lf_owner_graph_lock);
1149 if (LIST_EMPTY(&deplock->lf_outedges)) {
1150 lf_wakeup_lock(state, deplock);
1151 LIST_INSERT_HEAD(granted, deplock, lf_link);
1158 * Set the start of an existing active lock, updating dependencies and
1159 * adding any newly woken locks to 'granted'.
1162 lf_set_start(struct lockf *state, struct lockf_entry *lock, off_t new_start,
1163 struct lockf_entry_list *granted)
1166 KASSERT(new_start >= lock->lf_start, ("can't increase lock"));
1167 lock->lf_start = new_start;
1168 LIST_REMOVE(lock, lf_link);
1169 lf_insert_lock(state, lock);
1170 lf_update_dependancies(state, lock, FALSE, granted);
1174 * Set the end of an existing active lock, updating dependencies and
1175 * adding any newly woken locks to 'granted'.
1178 lf_set_end(struct lockf *state, struct lockf_entry *lock, off_t new_end,
1179 struct lockf_entry_list *granted)
1182 KASSERT(new_end <= lock->lf_end, ("can't increase lock"));
1183 lock->lf_end = new_end;
1184 lf_update_dependancies(state, lock, FALSE, granted);
1188 * Add a lock to the active list, updating or removing any current
1189 * locks owned by the same owner and processing any pending locks that
1190 * become unblocked as a result. This code is also used for unlock
1191 * since the logic for updating existing locks is identical.
1193 * As a result of processing the new lock, we may unblock existing
1194 * pending locks as a result of downgrading/unlocking. We simply
1195 * activate the newly granted locks by looping.
1197 * Since the new lock already has its dependencies set up, we always
1198 * add it to the list (unless its an unlock request). This may
1199 * fragment the lock list in some pathological cases but its probably
1200 * not a real problem.
1203 lf_activate_lock(struct lockf *state, struct lockf_entry *lock)
1205 struct lockf_entry *overlap, *lf;
1206 struct lockf_entry_list granted;
1209 LIST_INIT(&granted);
1210 LIST_INSERT_HEAD(&granted, lock, lf_link);
1212 while (!LIST_EMPTY(&granted)) {
1213 lock = LIST_FIRST(&granted);
1214 LIST_REMOVE(lock, lf_link);
1217 * Skip over locks owned by other processes. Handle
1218 * any locks that overlap and are owned by ourselves.
1220 overlap = LIST_FIRST(&state->ls_active);
1222 ovcase = lf_findoverlap(&overlap, lock, SELF);
1225 if (ovcase && (lockf_debug & 2)) {
1226 printf("lf_setlock: overlap %d", ovcase);
1227 lf_print("", overlap);
1233 * 1) overlap == lock
1234 * 2) overlap contains lock
1235 * 3) lock contains overlap
1236 * 4) overlap starts before lock
1237 * 5) overlap ends after lock
1240 case 0: /* no overlap */
1243 case 1: /* overlap == lock */
1245 * We have already setup the
1246 * dependants for the new lock, taking
1247 * into account a possible downgrade
1248 * or unlock. Remove the old lock.
1250 LIST_REMOVE(overlap, lf_link);
1251 lf_update_dependancies(state, overlap, TRUE,
1253 lf_free_lock(overlap);
1256 case 2: /* overlap contains lock */
1258 * Just split the existing lock.
1260 lf_split(state, overlap, lock, &granted);
1263 case 3: /* lock contains overlap */
1265 * Delete the overlap and advance to
1266 * the next entry in the list.
1268 lf = LIST_NEXT(overlap, lf_link);
1269 LIST_REMOVE(overlap, lf_link);
1270 lf_update_dependancies(state, overlap, TRUE,
1272 lf_free_lock(overlap);
1276 case 4: /* overlap starts before lock */
1278 * Just update the overlap end and
1281 lf_set_end(state, overlap, lock->lf_start - 1,
1283 overlap = LIST_NEXT(overlap, lf_link);
1286 case 5: /* overlap ends after lock */
1288 * Change the start of overlap and
1291 lf_set_start(state, overlap, lock->lf_end + 1,
1298 if (lockf_debug & 1) {
1299 if (lock->lf_type != F_UNLCK)
1300 lf_print("lf_activate_lock: activated", lock);
1302 lf_print("lf_activate_lock: unlocked", lock);
1303 lf_printlist("lf_activate_lock", lock);
1305 #endif /* LOCKF_DEBUG */
1306 if (lock->lf_type != F_UNLCK)
1307 lf_insert_lock(state, lock);
1312 * Cancel a pending lock request, either as a result of a signal or a
1313 * cancel request for an async lock.
1316 lf_cancel_lock(struct lockf *state, struct lockf_entry *lock)
1318 struct lockf_entry_list granted;
1321 * Note it is theoretically possible that cancelling this lock
1322 * may allow some other pending lock to become
1323 * active. Consider this case:
1325 * Owner Action Result Dependencies
1327 * A: lock [0..0] succeeds
1328 * B: lock [2..2] succeeds
1329 * C: lock [1..2] blocked C->B
1330 * D: lock [0..1] blocked C->B,D->A,D->C
1331 * A: unlock [0..0] C->B,D->C
1335 LIST_REMOVE(lock, lf_link);
1338 * Removing out-going edges is simple.
1340 sx_xlock(&lf_owner_graph_lock);
1341 lf_remove_outgoing(lock);
1342 sx_xunlock(&lf_owner_graph_lock);
1345 * Removing in-coming edges may allow some other lock to
1346 * become active - we use lf_update_dependancies to figure
1349 LIST_INIT(&granted);
1350 lf_update_dependancies(state, lock, TRUE, &granted);
1354 * Feed any newly active locks to lf_activate_lock.
1356 while (!LIST_EMPTY(&granted)) {
1357 lock = LIST_FIRST(&granted);
1358 LIST_REMOVE(lock, lf_link);
1359 lf_activate_lock(state, lock);
1364 * Set a byte-range lock.
1367 lf_setlock(struct lockf *state, struct lockf_entry *lock, struct vnode *vp,
1370 static char lockstr[] = "lockf";
1371 int error, priority, stops_deferred;
1374 if (lockf_debug & 1)
1375 lf_print("lf_setlock", lock);
1376 #endif /* LOCKF_DEBUG */
1382 if (lock->lf_type == F_WRLCK)
1384 if (!(lock->lf_flags & F_NOINTR))
1387 * Scan lock list for this file looking for locks that would block us.
1389 if (lf_getblock(state, lock)) {
1391 * Free the structure and return if nonblocking.
1393 if ((lock->lf_flags & F_WAIT) == 0
1394 && lock->lf_async_task == NULL) {
1401 * For flock type locks, we must first remove
1402 * any shared locks that we hold before we sleep
1403 * waiting for an exclusive lock.
1405 if ((lock->lf_flags & F_FLOCK) &&
1406 lock->lf_type == F_WRLCK) {
1407 lock->lf_type = F_UNLCK;
1408 lf_activate_lock(state, lock);
1409 lock->lf_type = F_WRLCK;
1413 * We are blocked. Create edges to each blocking lock,
1414 * checking for deadlock using the owner graph. For
1415 * simplicity, we run deadlock detection for all
1416 * locks, posix and otherwise.
1418 sx_xlock(&lf_owner_graph_lock);
1419 error = lf_add_outgoing(state, lock);
1420 sx_xunlock(&lf_owner_graph_lock);
1424 if (lockf_debug & 1)
1425 lf_print("lf_setlock: deadlock", lock);
1432 * We have added edges to everything that blocks
1433 * us. Sleep until they all go away.
1435 LIST_INSERT_HEAD(&state->ls_pending, lock, lf_link);
1437 if (lockf_debug & 1) {
1438 struct lockf_edge *e;
1439 LIST_FOREACH(e, &lock->lf_outedges, le_outlink) {
1440 lf_print("lf_setlock: blocking on", e->le_to);
1441 lf_printlist("lf_setlock", e->le_to);
1444 #endif /* LOCKF_DEBUG */
1446 if ((lock->lf_flags & F_WAIT) == 0) {
1448 * The caller requested async notification -
1449 * this callback happens when the blocking
1450 * lock is released, allowing the caller to
1451 * make another attempt to take the lock.
1453 *cookiep = (void *) lock;
1454 error = EINPROGRESS;
1459 stops_deferred = sigdeferstop(SIGDEFERSTOP_ERESTART);
1460 error = sx_sleep(lock, &state->ls_lock, priority, lockstr, 0);
1461 sigallowstop(stops_deferred);
1462 if (lf_free_lock(lock)) {
1468 * We may have been awakened by a signal and/or by a
1469 * debugger continuing us (in which cases we must
1470 * remove our lock graph edges) and/or by another
1471 * process releasing a lock (in which case our edges
1472 * have already been removed and we have been moved to
1473 * the active list). We may also have been woken by
1474 * lf_purgelocks which we report to the caller as
1475 * EINTR. In that case, lf_purgelocks will have
1476 * removed our lock graph edges.
1478 * Note that it is possible to receive a signal after
1479 * we were successfully woken (and moved to the active
1480 * list) but before we resumed execution. In this
1481 * case, our lf_outedges list will be clear. We
1482 * pretend there was no error.
1484 * Note also, if we have been sleeping long enough, we
1485 * may now have incoming edges from some newer lock
1486 * which is waiting behind us in the queue.
1488 if (lock->lf_flags & F_INTR) {
1493 if (LIST_EMPTY(&lock->lf_outedges)) {
1496 lf_cancel_lock(state, lock);
1500 if (lockf_debug & 1) {
1501 lf_print("lf_setlock: granted", lock);
1507 * It looks like we are going to grant the lock. First add
1508 * edges from any currently pending lock that the new lock
1511 sx_xlock(&lf_owner_graph_lock);
1512 error = lf_add_incoming(state, lock);
1513 sx_xunlock(&lf_owner_graph_lock);
1516 if (lockf_debug & 1)
1517 lf_print("lf_setlock: deadlock", lock);
1524 * No blocks!! Add the lock. Note that we will
1525 * downgrade or upgrade any overlapping locks this
1526 * process already owns.
1528 lf_activate_lock(state, lock);
1535 * Remove a byte-range lock on an inode.
1537 * Generally, find the lock (or an overlap to that lock)
1538 * and remove it (or shrink it), then wakeup anyone we can.
1541 lf_clearlock(struct lockf *state, struct lockf_entry *unlock)
1543 struct lockf_entry *overlap;
1545 overlap = LIST_FIRST(&state->ls_active);
1547 if (overlap == NOLOCKF)
1550 if (unlock->lf_type != F_UNLCK)
1551 panic("lf_clearlock: bad type");
1552 if (lockf_debug & 1)
1553 lf_print("lf_clearlock", unlock);
1554 #endif /* LOCKF_DEBUG */
1556 lf_activate_lock(state, unlock);
1562 * Check whether there is a blocking lock, and if so return its
1566 lf_getlock(struct lockf *state, struct lockf_entry *lock, struct flock *fl)
1568 struct lockf_entry *block;
1571 if (lockf_debug & 1)
1572 lf_print("lf_getlock", lock);
1573 #endif /* LOCKF_DEBUG */
1575 if ((block = lf_getblock(state, lock))) {
1576 fl->l_type = block->lf_type;
1577 fl->l_whence = SEEK_SET;
1578 fl->l_start = block->lf_start;
1579 if (block->lf_end == OFF_MAX)
1582 fl->l_len = block->lf_end - block->lf_start + 1;
1583 fl->l_pid = block->lf_owner->lo_pid;
1584 fl->l_sysid = block->lf_owner->lo_sysid;
1586 fl->l_type = F_UNLCK;
1592 * Cancel an async lock request.
1595 lf_cancel(struct lockf *state, struct lockf_entry *lock, void *cookie)
1597 struct lockf_entry *reallock;
1600 * We need to match this request with an existing lock
1603 LIST_FOREACH(reallock, &state->ls_pending, lf_link) {
1604 if ((void *) reallock == cookie) {
1606 * Double-check that this lock looks right
1607 * (maybe use a rolling ID for the cancel
1610 if (!(reallock->lf_vnode == lock->lf_vnode
1611 && reallock->lf_start == lock->lf_start
1612 && reallock->lf_end == lock->lf_end)) {
1617 * Make sure this lock was async and then just
1618 * remove it from its wait lists.
1620 if (!reallock->lf_async_task) {
1625 * Note that since any other thread must take
1626 * state->ls_lock before it can possibly
1627 * trigger the async callback, we are safe
1628 * from a race with lf_wakeup_lock, i.e. we
1629 * can free the lock (actually our caller does
1632 lf_cancel_lock(state, reallock);
1638 * We didn't find a matching lock - not much we can do here.
1644 * Walk the list of locks for an inode and
1645 * return the first blocking lock.
1647 static struct lockf_entry *
1648 lf_getblock(struct lockf *state, struct lockf_entry *lock)
1650 struct lockf_entry *overlap;
1652 LIST_FOREACH(overlap, &state->ls_active, lf_link) {
1654 * We may assume that the active list is sorted by
1657 if (overlap->lf_start > lock->lf_end)
1659 if (!lf_blocks(lock, overlap))
1667 * Walk the list of locks for an inode to find an overlapping lock (if
1668 * any) and return a classification of that overlap.
1671 * *overlap The place in the lock list to start looking
1672 * lock The lock which is being tested
1673 * type Pass 'SELF' to test only locks with the same
1674 * owner as lock, or 'OTHER' to test only locks
1675 * with a different owner
1677 * Returns one of six values:
1679 * 1) overlap == lock
1680 * 2) overlap contains lock
1681 * 3) lock contains overlap
1682 * 4) overlap starts before lock
1683 * 5) overlap ends after lock
1685 * If there is an overlapping lock, '*overlap' is set to point at the
1688 * NOTE: this returns only the FIRST overlapping lock. There
1689 * may be more than one.
1692 lf_findoverlap(struct lockf_entry **overlap, struct lockf_entry *lock, int type)
1694 struct lockf_entry *lf;
1698 if ((*overlap) == NOLOCKF) {
1702 if (lockf_debug & 2)
1703 lf_print("lf_findoverlap: looking for overlap in", lock);
1704 #endif /* LOCKF_DEBUG */
1705 start = lock->lf_start;
1710 if (lf->lf_start > end)
1712 if (((type & SELF) && lf->lf_owner != lock->lf_owner) ||
1713 ((type & OTHERS) && lf->lf_owner == lock->lf_owner)) {
1714 *overlap = LIST_NEXT(lf, lf_link);
1718 if (lockf_debug & 2)
1719 lf_print("\tchecking", lf);
1720 #endif /* LOCKF_DEBUG */
1722 * OK, check for overlap
1726 * 1) overlap == lock
1727 * 2) overlap contains lock
1728 * 3) lock contains overlap
1729 * 4) overlap starts before lock
1730 * 5) overlap ends after lock
1732 if (start > lf->lf_end) {
1735 if (lockf_debug & 2)
1736 printf("no overlap\n");
1737 #endif /* LOCKF_DEBUG */
1738 *overlap = LIST_NEXT(lf, lf_link);
1741 if (lf->lf_start == start && lf->lf_end == end) {
1744 if (lockf_debug & 2)
1745 printf("overlap == lock\n");
1746 #endif /* LOCKF_DEBUG */
1750 if (lf->lf_start <= start && lf->lf_end >= end) {
1753 if (lockf_debug & 2)
1754 printf("overlap contains lock\n");
1755 #endif /* LOCKF_DEBUG */
1759 if (start <= lf->lf_start && end >= lf->lf_end) {
1762 if (lockf_debug & 2)
1763 printf("lock contains overlap\n");
1764 #endif /* LOCKF_DEBUG */
1768 if (lf->lf_start < start && lf->lf_end >= start) {
1771 if (lockf_debug & 2)
1772 printf("overlap starts before lock\n");
1773 #endif /* LOCKF_DEBUG */
1777 if (lf->lf_start > start && lf->lf_end > end) {
1780 if (lockf_debug & 2)
1781 printf("overlap ends after lock\n");
1782 #endif /* LOCKF_DEBUG */
1786 panic("lf_findoverlap: default");
1792 * Split an the existing 'lock1', based on the extent of the lock
1793 * described by 'lock2'. The existing lock should cover 'lock2'
1796 * Any pending locks which have been been unblocked are added to
1800 lf_split(struct lockf *state, struct lockf_entry *lock1,
1801 struct lockf_entry *lock2, struct lockf_entry_list *granted)
1803 struct lockf_entry *splitlock;
1806 if (lockf_debug & 2) {
1807 lf_print("lf_split", lock1);
1808 lf_print("splitting from", lock2);
1810 #endif /* LOCKF_DEBUG */
1812 * Check to see if we don't need to split at all.
1814 if (lock1->lf_start == lock2->lf_start) {
1815 lf_set_start(state, lock1, lock2->lf_end + 1, granted);
1818 if (lock1->lf_end == lock2->lf_end) {
1819 lf_set_end(state, lock1, lock2->lf_start - 1, granted);
1823 * Make a new lock consisting of the last part of
1824 * the encompassing lock.
1826 splitlock = lf_alloc_lock(lock1->lf_owner);
1827 memcpy(splitlock, lock1, sizeof *splitlock);
1828 splitlock->lf_refs = 1;
1829 if (splitlock->lf_flags & F_REMOTE)
1830 vref(splitlock->lf_vnode);
1833 * This cannot cause a deadlock since any edges we would add
1834 * to splitlock already exist in lock1. We must be sure to add
1835 * necessary dependencies to splitlock before we reduce lock1
1836 * otherwise we may accidentally grant a pending lock that
1837 * was blocked by the tail end of lock1.
1839 splitlock->lf_start = lock2->lf_end + 1;
1840 LIST_INIT(&splitlock->lf_outedges);
1841 LIST_INIT(&splitlock->lf_inedges);
1842 sx_xlock(&lf_owner_graph_lock);
1843 lf_add_incoming(state, splitlock);
1844 sx_xunlock(&lf_owner_graph_lock);
1846 lf_set_end(state, lock1, lock2->lf_start - 1, granted);
1849 * OK, now link it in
1851 lf_insert_lock(state, splitlock);
1855 STAILQ_ENTRY(lockdesc) link;
1859 STAILQ_HEAD(lockdesclist, lockdesc);
1862 lf_iteratelocks_sysid(int sysid, lf_iterator *fn, void *arg)
1865 struct lockf_entry *lf;
1866 struct lockdesc *ldesc;
1867 struct lockdesclist locks;
1871 * In order to keep the locking simple, we iterate over the
1872 * active lock lists to build a list of locks that need
1873 * releasing. We then call the iterator for each one in turn.
1875 * We take an extra reference to the vnode for the duration to
1876 * make sure it doesn't go away before we are finished.
1878 STAILQ_INIT(&locks);
1879 sx_xlock(&lf_lock_states_lock);
1880 LIST_FOREACH(ls, &lf_lock_states, ls_link) {
1881 sx_xlock(&ls->ls_lock);
1882 LIST_FOREACH(lf, &ls->ls_active, lf_link) {
1883 if (lf->lf_owner->lo_sysid != sysid)
1886 ldesc = malloc(sizeof(struct lockdesc), M_LOCKF,
1888 ldesc->vp = lf->lf_vnode;
1890 ldesc->fl.l_start = lf->lf_start;
1891 if (lf->lf_end == OFF_MAX)
1892 ldesc->fl.l_len = 0;
1895 lf->lf_end - lf->lf_start + 1;
1896 ldesc->fl.l_whence = SEEK_SET;
1897 ldesc->fl.l_type = F_UNLCK;
1898 ldesc->fl.l_pid = lf->lf_owner->lo_pid;
1899 ldesc->fl.l_sysid = sysid;
1900 STAILQ_INSERT_TAIL(&locks, ldesc, link);
1902 sx_xunlock(&ls->ls_lock);
1904 sx_xunlock(&lf_lock_states_lock);
1907 * Call the iterator function for each lock in turn. If the
1908 * iterator returns an error code, just free the rest of the
1909 * lockdesc structures.
1912 while ((ldesc = STAILQ_FIRST(&locks)) != NULL) {
1913 STAILQ_REMOVE_HEAD(&locks, link);
1915 error = fn(ldesc->vp, &ldesc->fl, arg);
1917 free(ldesc, M_LOCKF);
1924 lf_iteratelocks_vnode(struct vnode *vp, lf_iterator *fn, void *arg)
1927 struct lockf_entry *lf;
1928 struct lockdesc *ldesc;
1929 struct lockdesclist locks;
1933 * In order to keep the locking simple, we iterate over the
1934 * active lock lists to build a list of locks that need
1935 * releasing. We then call the iterator for each one in turn.
1937 * We take an extra reference to the vnode for the duration to
1938 * make sure it doesn't go away before we are finished.
1940 STAILQ_INIT(&locks);
1950 sx_xlock(&ls->ls_lock);
1951 LIST_FOREACH(lf, &ls->ls_active, lf_link) {
1952 ldesc = malloc(sizeof(struct lockdesc), M_LOCKF,
1954 ldesc->vp = lf->lf_vnode;
1956 ldesc->fl.l_start = lf->lf_start;
1957 if (lf->lf_end == OFF_MAX)
1958 ldesc->fl.l_len = 0;
1961 lf->lf_end - lf->lf_start + 1;
1962 ldesc->fl.l_whence = SEEK_SET;
1963 ldesc->fl.l_type = F_UNLCK;
1964 ldesc->fl.l_pid = lf->lf_owner->lo_pid;
1965 ldesc->fl.l_sysid = lf->lf_owner->lo_sysid;
1966 STAILQ_INSERT_TAIL(&locks, ldesc, link);
1968 sx_xunlock(&ls->ls_lock);
1975 * Call the iterator function for each lock in turn. If the
1976 * iterator returns an error code, just free the rest of the
1977 * lockdesc structures.
1980 while ((ldesc = STAILQ_FIRST(&locks)) != NULL) {
1981 STAILQ_REMOVE_HEAD(&locks, link);
1983 error = fn(ldesc->vp, &ldesc->fl, arg);
1985 free(ldesc, M_LOCKF);
1992 lf_clearremotesys_iterator(struct vnode *vp, struct flock *fl, void *arg)
1995 VOP_ADVLOCK(vp, 0, F_UNLCK, fl, F_REMOTE);
2000 lf_clearremotesys(int sysid)
2003 KASSERT(sysid != 0, ("Can't clear local locks with F_UNLCKSYS"));
2004 lf_iteratelocks_sysid(sysid, lf_clearremotesys_iterator, NULL);
2008 lf_countlocks(int sysid)
2011 struct lock_owner *lo;
2015 sx_xlock(&lf_lock_owners_lock);
2016 for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++)
2017 LIST_FOREACH(lo, &lf_lock_owners[i], lo_link)
2018 if (lo->lo_sysid == sysid)
2019 count += lo->lo_refs;
2020 sx_xunlock(&lf_lock_owners_lock);
2028 * Return non-zero if y is reachable from x using a brute force
2029 * search. If reachable and path is non-null, return the route taken
2033 graph_reaches(struct owner_vertex *x, struct owner_vertex *y,
2034 struct owner_vertex_list *path)
2036 struct owner_edge *e;
2040 TAILQ_INSERT_HEAD(path, x, v_link);
2044 LIST_FOREACH(e, &x->v_outedges, e_outlink) {
2045 if (graph_reaches(e->e_to, y, path)) {
2047 TAILQ_INSERT_HEAD(path, x, v_link);
2055 * Perform consistency checks on the graph. Make sure the values of
2056 * v_order are correct. If checkorder is non-zero, check no vertex can
2057 * reach any other vertex with a smaller order.
2060 graph_check(struct owner_graph *g, int checkorder)
2064 for (i = 0; i < g->g_size; i++) {
2065 if (!g->g_vertices[i]->v_owner)
2067 KASSERT(g->g_vertices[i]->v_order == i,
2068 ("lock graph vertices disordered"));
2070 for (j = 0; j < i; j++) {
2071 if (!g->g_vertices[j]->v_owner)
2073 KASSERT(!graph_reaches(g->g_vertices[i],
2074 g->g_vertices[j], NULL),
2075 ("lock graph vertices disordered"));
2082 graph_print_vertices(struct owner_vertex_list *set)
2084 struct owner_vertex *v;
2087 TAILQ_FOREACH(v, set, v_link) {
2088 printf("%d:", v->v_order);
2089 lf_print_owner(v->v_owner);
2090 if (TAILQ_NEXT(v, v_link))
2099 * Calculate the sub-set of vertices v from the affected region [y..x]
2100 * where v is reachable from y. Return -1 if a loop was detected
2101 * (i.e. x is reachable from y, otherwise the number of vertices in
2105 graph_delta_forward(struct owner_graph *g, struct owner_vertex *x,
2106 struct owner_vertex *y, struct owner_vertex_list *delta)
2109 struct owner_vertex *v;
2110 struct owner_edge *e;
2114 * We start with a set containing just y. Then for each vertex
2115 * v in the set so far unprocessed, we add each vertex that v
2116 * has an out-edge to and that is within the affected region
2117 * [y..x]. If we see the vertex x on our travels, stop
2121 TAILQ_INSERT_TAIL(delta, y, v_link);
2126 LIST_FOREACH(e, &v->v_outedges, e_outlink) {
2129 if (e->e_to->v_order < x->v_order
2130 && e->e_to->v_gen != gen) {
2131 e->e_to->v_gen = gen;
2132 TAILQ_INSERT_TAIL(delta, e->e_to, v_link);
2136 v = TAILQ_NEXT(v, v_link);
2143 * Calculate the sub-set of vertices v from the affected region [y..x]
2144 * where v reaches x. Return the number of vertices in this subset.
2147 graph_delta_backward(struct owner_graph *g, struct owner_vertex *x,
2148 struct owner_vertex *y, struct owner_vertex_list *delta)
2151 struct owner_vertex *v;
2152 struct owner_edge *e;
2156 * We start with a set containing just x. Then for each vertex
2157 * v in the set so far unprocessed, we add each vertex that v
2158 * has an in-edge from and that is within the affected region
2162 TAILQ_INSERT_TAIL(delta, x, v_link);
2167 LIST_FOREACH(e, &v->v_inedges, e_inlink) {
2168 if (e->e_from->v_order > y->v_order
2169 && e->e_from->v_gen != gen) {
2170 e->e_from->v_gen = gen;
2171 TAILQ_INSERT_HEAD(delta, e->e_from, v_link);
2175 v = TAILQ_PREV(v, owner_vertex_list, v_link);
2182 graph_add_indices(int *indices, int n, struct owner_vertex_list *set)
2184 struct owner_vertex *v;
2187 TAILQ_FOREACH(v, set, v_link) {
2189 i > 0 && indices[i - 1] > v->v_order; i--)
2191 for (j = n - 1; j >= i; j--)
2192 indices[j + 1] = indices[j];
2193 indices[i] = v->v_order;
2201 graph_assign_indices(struct owner_graph *g, int *indices, int nextunused,
2202 struct owner_vertex_list *set)
2204 struct owner_vertex *v, *vlowest;
2206 while (!TAILQ_EMPTY(set)) {
2208 TAILQ_FOREACH(v, set, v_link) {
2209 if (!vlowest || v->v_order < vlowest->v_order)
2212 TAILQ_REMOVE(set, vlowest, v_link);
2213 vlowest->v_order = indices[nextunused];
2214 g->g_vertices[vlowest->v_order] = vlowest;
2218 return (nextunused);
2222 graph_add_edge(struct owner_graph *g, struct owner_vertex *x,
2223 struct owner_vertex *y)
2225 struct owner_edge *e;
2226 struct owner_vertex_list deltaF, deltaB;
2227 int nF, nB, n, vi, i;
2230 sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
2232 LIST_FOREACH(e, &x->v_outedges, e_outlink) {
2240 if (lockf_debug & 8) {
2241 printf("adding edge %d:", x->v_order);
2242 lf_print_owner(x->v_owner);
2243 printf(" -> %d:", y->v_order);
2244 lf_print_owner(y->v_owner);
2248 if (y->v_order < x->v_order) {
2250 * The new edge violates the order. First find the set
2251 * of affected vertices reachable from y (deltaF) and
2252 * the set of affect vertices affected that reach x
2253 * (deltaB), using the graph generation number to
2254 * detect whether we have visited a given vertex
2255 * already. We re-order the graph so that each vertex
2256 * in deltaB appears before each vertex in deltaF.
2258 * If x is a member of deltaF, then the new edge would
2259 * create a cycle. Otherwise, we may assume that
2260 * deltaF and deltaB are disjoint.
2263 if (g->g_gen == 0) {
2267 for (vi = 0; vi < g->g_size; vi++) {
2268 g->g_vertices[vi]->v_gen = 0;
2272 nF = graph_delta_forward(g, x, y, &deltaF);
2275 if (lockf_debug & 8) {
2276 struct owner_vertex_list path;
2277 printf("deadlock: ");
2279 graph_reaches(y, x, &path);
2280 graph_print_vertices(&path);
2287 if (lockf_debug & 8) {
2288 printf("re-ordering graph vertices\n");
2289 printf("deltaF = ");
2290 graph_print_vertices(&deltaF);
2294 nB = graph_delta_backward(g, x, y, &deltaB);
2297 if (lockf_debug & 8) {
2298 printf("deltaB = ");
2299 graph_print_vertices(&deltaB);
2304 * We first build a set of vertex indices (vertex
2305 * order values) that we may use, then we re-assign
2306 * orders first to those vertices in deltaB, then to
2307 * deltaF. Note that the contents of deltaF and deltaB
2308 * may be partially disordered - we perform an
2309 * insertion sort while building our index set.
2311 indices = g->g_indexbuf;
2312 n = graph_add_indices(indices, 0, &deltaF);
2313 graph_add_indices(indices, n, &deltaB);
2316 * We must also be sure to maintain the relative
2317 * ordering of deltaF and deltaB when re-assigning
2318 * vertices. We do this by iteratively removing the
2319 * lowest ordered element from the set and assigning
2320 * it the next value from our new ordering.
2322 i = graph_assign_indices(g, indices, 0, &deltaB);
2323 graph_assign_indices(g, indices, i, &deltaF);
2326 if (lockf_debug & 8) {
2327 struct owner_vertex_list set;
2329 for (i = 0; i < nB + nF; i++)
2330 TAILQ_INSERT_TAIL(&set,
2331 g->g_vertices[indices[i]], v_link);
2332 printf("new ordering = ");
2333 graph_print_vertices(&set);
2338 KASSERT(x->v_order < y->v_order, ("Failed to re-order graph"));
2341 if (lockf_debug & 8) {
2342 graph_check(g, TRUE);
2346 e = malloc(sizeof(struct owner_edge), M_LOCKF, M_WAITOK);
2348 LIST_INSERT_HEAD(&x->v_outedges, e, e_outlink);
2349 LIST_INSERT_HEAD(&y->v_inedges, e, e_inlink);
2358 * Remove an edge x->y from the graph.
2361 graph_remove_edge(struct owner_graph *g, struct owner_vertex *x,
2362 struct owner_vertex *y)
2364 struct owner_edge *e;
2366 sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
2368 LIST_FOREACH(e, &x->v_outedges, e_outlink) {
2372 KASSERT(e, ("Removing non-existent edge from deadlock graph"));
2375 if (e->e_refs == 0) {
2377 if (lockf_debug & 8) {
2378 printf("removing edge %d:", x->v_order);
2379 lf_print_owner(x->v_owner);
2380 printf(" -> %d:", y->v_order);
2381 lf_print_owner(y->v_owner);
2385 LIST_REMOVE(e, e_outlink);
2386 LIST_REMOVE(e, e_inlink);
2392 * Allocate a vertex from the free list. Return ENOMEM if there are
2395 static struct owner_vertex *
2396 graph_alloc_vertex(struct owner_graph *g, struct lock_owner *lo)
2398 struct owner_vertex *v;
2400 sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
2402 v = malloc(sizeof(struct owner_vertex), M_LOCKF, M_WAITOK);
2403 if (g->g_size == g->g_space) {
2404 g->g_vertices = realloc(g->g_vertices,
2405 2 * g->g_space * sizeof(struct owner_vertex *),
2407 free(g->g_indexbuf, M_LOCKF);
2408 g->g_indexbuf = malloc(2 * g->g_space * sizeof(int),
2410 g->g_space = 2 * g->g_space;
2412 v->v_order = g->g_size;
2413 v->v_gen = g->g_gen;
2414 g->g_vertices[g->g_size] = v;
2417 LIST_INIT(&v->v_outedges);
2418 LIST_INIT(&v->v_inedges);
2425 graph_free_vertex(struct owner_graph *g, struct owner_vertex *v)
2427 struct owner_vertex *w;
2430 sx_assert(&lf_owner_graph_lock, SX_XLOCKED);
2432 KASSERT(LIST_EMPTY(&v->v_outedges), ("Freeing vertex with edges"));
2433 KASSERT(LIST_EMPTY(&v->v_inedges), ("Freeing vertex with edges"));
2436 * Remove from the graph's array and close up the gap,
2437 * renumbering the other vertices.
2439 for (i = v->v_order + 1; i < g->g_size; i++) {
2440 w = g->g_vertices[i];
2442 g->g_vertices[i - 1] = w;
2449 static struct owner_graph *
2450 graph_init(struct owner_graph *g)
2453 g->g_vertices = malloc(10 * sizeof(struct owner_vertex *),
2457 g->g_indexbuf = malloc(g->g_space * sizeof(int), M_LOCKF, M_WAITOK);
2465 * Print description of a lock owner
2468 lf_print_owner(struct lock_owner *lo)
2471 if (lo->lo_flags & F_REMOTE) {
2472 printf("remote pid %d, system %d",
2473 lo->lo_pid, lo->lo_sysid);
2474 } else if (lo->lo_flags & F_FLOCK) {
2475 printf("file %p", lo->lo_id);
2477 printf("local pid %d", lo->lo_pid);
2485 lf_print(char *tag, struct lockf_entry *lock)
2488 printf("%s: lock %p for ", tag, (void *)lock);
2489 lf_print_owner(lock->lf_owner);
2490 if (lock->lf_inode != (struct inode *)0)
2491 printf(" in ino %ju on dev <%s>,",
2492 (uintmax_t)lock->lf_inode->i_number,
2493 devtoname(ITODEV(lock->lf_inode)));
2494 printf(" %s, start %jd, end ",
2495 lock->lf_type == F_RDLCK ? "shared" :
2496 lock->lf_type == F_WRLCK ? "exclusive" :
2497 lock->lf_type == F_UNLCK ? "unlock" : "unknown",
2498 (intmax_t)lock->lf_start);
2499 if (lock->lf_end == OFF_MAX)
2502 printf("%jd", (intmax_t)lock->lf_end);
2503 if (!LIST_EMPTY(&lock->lf_outedges))
2504 printf(" block %p\n",
2505 (void *)LIST_FIRST(&lock->lf_outedges)->le_to);
2511 lf_printlist(char *tag, struct lockf_entry *lock)
2513 struct lockf_entry *lf, *blk;
2514 struct lockf_edge *e;
2516 if (lock->lf_inode == (struct inode *)0)
2519 printf("%s: Lock list for ino %ju on dev <%s>:\n",
2520 tag, (uintmax_t)lock->lf_inode->i_number,
2521 devtoname(ITODEV(lock->lf_inode)));
2522 LIST_FOREACH(lf, &lock->lf_vnode->v_lockf->ls_active, lf_link) {
2523 printf("\tlock %p for ",(void *)lf);
2524 lf_print_owner(lock->lf_owner);
2525 printf(", %s, start %jd, end %jd",
2526 lf->lf_type == F_RDLCK ? "shared" :
2527 lf->lf_type == F_WRLCK ? "exclusive" :
2528 lf->lf_type == F_UNLCK ? "unlock" :
2529 "unknown", (intmax_t)lf->lf_start, (intmax_t)lf->lf_end);
2530 LIST_FOREACH(e, &lf->lf_outedges, le_outlink) {
2532 printf("\n\t\tlock request %p for ", (void *)blk);
2533 lf_print_owner(blk->lf_owner);
2534 printf(", %s, start %jd, end %jd",
2535 blk->lf_type == F_RDLCK ? "shared" :
2536 blk->lf_type == F_WRLCK ? "exclusive" :
2537 blk->lf_type == F_UNLCK ? "unlock" :
2538 "unknown", (intmax_t)blk->lf_start,
2539 (intmax_t)blk->lf_end);
2540 if (!LIST_EMPTY(&blk->lf_inedges))
2541 panic("lf_printlist: bad list");
2546 #endif /* LOCKF_DEBUG */