/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 2008 Isilon Inc http://www.isilon.com/ * Authors: Doug Rabson * Developed with Red Inc: Alfred Perlstein * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /*- * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Scooter Morris at Genentech Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)ufs_lockf.c 8.3 (Berkeley) 1/6/94 */ #include __FBSDID("$FreeBSD$"); #include "opt_debug_lockf.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef LOCKF_DEBUG #include static int lockf_debug = 0; /* control debug output */ SYSCTL_INT(_debug, OID_AUTO, lockf_debug, CTLFLAG_RW, &lockf_debug, 0, ""); #endif static MALLOC_DEFINE(M_LOCKF, "lockf", "Byte-range locking structures"); struct owner_edge; struct owner_vertex; struct owner_vertex_list; struct owner_graph; #define NOLOCKF (struct lockf_entry *)0 #define SELF 0x1 #define OTHERS 0x2 static void lf_init(void *); static int lf_hash_owner(caddr_t, struct vnode *, struct flock *, int); static int lf_owner_matches(struct lock_owner *, caddr_t, struct flock *, int); static struct lockf_entry * lf_alloc_lock(struct lock_owner *); static int lf_free_lock(struct lockf_entry *); static int lf_clearlock(struct lockf *, struct lockf_entry *); static int lf_overlaps(struct lockf_entry *, struct lockf_entry *); static int lf_blocks(struct lockf_entry *, struct lockf_entry *); static void lf_free_edge(struct lockf_edge *); static struct lockf_edge * lf_alloc_edge(void); static void lf_alloc_vertex(struct lockf_entry *); static int lf_add_edge(struct lockf_entry *, struct lockf_entry *); static void lf_remove_edge(struct lockf_edge *); static void lf_remove_outgoing(struct lockf_entry *); static void lf_remove_incoming(struct lockf_entry *); static int lf_add_outgoing(struct lockf *, struct lockf_entry *); static int lf_add_incoming(struct lockf *, struct lockf_entry *); static int lf_findoverlap(struct lockf_entry **, struct lockf_entry *, int); static struct lockf_entry * lf_getblock(struct lockf *, struct lockf_entry *); static int lf_getlock(struct lockf *, struct lockf_entry *, struct flock *); static void lf_insert_lock(struct lockf *, struct lockf_entry *); static void lf_wakeup_lock(struct lockf *, struct lockf_entry *); static void lf_update_dependancies(struct lockf *, struct lockf_entry *, int all, struct lockf_entry_list *); static void lf_set_start(struct lockf *, struct lockf_entry *, off_t, struct lockf_entry_list*); static void lf_set_end(struct lockf *, struct lockf_entry *, off_t, struct lockf_entry_list*); static int lf_setlock(struct lockf *, struct lockf_entry *, struct vnode *, void **cookiep); static int lf_cancel(struct lockf *, struct lockf_entry *, void *); static void lf_split(struct lockf *, struct lockf_entry *, struct lockf_entry *, struct lockf_entry_list *); #ifdef LOCKF_DEBUG static int graph_reaches(struct owner_vertex *x, struct owner_vertex *y, struct owner_vertex_list *path); static void graph_check(struct owner_graph *g, int checkorder); static void graph_print_vertices(struct owner_vertex_list *set); #endif static int graph_delta_forward(struct owner_graph *g, struct owner_vertex *x, struct owner_vertex *y, struct owner_vertex_list *delta); static int graph_delta_backward(struct owner_graph *g, struct owner_vertex *x, struct owner_vertex *y, struct owner_vertex_list *delta); static int graph_add_indices(int *indices, int n, struct owner_vertex_list *set); static int graph_assign_indices(struct owner_graph *g, int *indices, int nextunused, struct owner_vertex_list *set); static int graph_add_edge(struct owner_graph *g, struct owner_vertex *x, struct owner_vertex *y); static void graph_remove_edge(struct owner_graph *g, struct owner_vertex *x, struct owner_vertex *y); static struct owner_vertex *graph_alloc_vertex(struct owner_graph *g, struct lock_owner *lo); static void graph_free_vertex(struct owner_graph *g, struct owner_vertex *v); static struct owner_graph * graph_init(struct owner_graph *g); #ifdef LOCKF_DEBUG static void lf_print(char *, struct lockf_entry *); static void lf_printlist(char *, struct lockf_entry *); static void lf_print_owner(struct lock_owner *); #endif /* * This structure is used to keep track of both local and remote lock * owners. The lf_owner field of the struct lockf_entry points back at * the lock owner structure. Each possible lock owner (local proc for * POSIX fcntl locks, local file for BSD flock locks or * pair for remote locks) is represented by a unique instance of * struct lock_owner. * * If a lock owner has a lock that blocks some other lock or a lock * that is waiting for some other lock, it also has a vertex in the * owner_graph below. * * Locks: * (s) locked by state->ls_lock * (S) locked by lf_lock_states_lock * (g) locked by lf_owner_graph_lock * (c) const until freeing */ #define LOCK_OWNER_HASH_SIZE 256 struct lock_owner { LIST_ENTRY(lock_owner) lo_link; /* (l) hash chain */ int lo_refs; /* (l) Number of locks referring to this */ int lo_flags; /* (c) Flags passed to lf_advlock */ caddr_t lo_id; /* (c) Id value passed to lf_advlock */ pid_t lo_pid; /* (c) Process Id of the lock owner */ int lo_sysid; /* (c) System Id of the lock owner */ int lo_hash; /* (c) Used to lock the appropriate chain */ struct owner_vertex *lo_vertex; /* (g) entry in deadlock graph */ }; LIST_HEAD(lock_owner_list, lock_owner); struct lock_owner_chain { struct sx lock; struct lock_owner_list list; }; static struct sx lf_lock_states_lock; static struct lockf_list lf_lock_states; /* (S) */ static struct lock_owner_chain lf_lock_owners[LOCK_OWNER_HASH_SIZE]; /* * Structures for deadlock detection. * * We have two types of directed graph, the first is the set of locks, * both active and pending on a vnode. Within this graph, active locks * are terminal nodes in the graph (i.e. have no out-going * edges). Pending locks have out-going edges to each blocking active * lock that prevents the lock from being granted and also to each * older pending lock that would block them if it was active. The * graph for each vnode is naturally acyclic; new edges are only ever * added to or from new nodes (either new pending locks which only add * out-going edges or new active locks which only add in-coming edges) * therefore they cannot create loops in the lock graph. * * The second graph is a global graph of lock owners. Each lock owner * is a vertex in that graph and an edge is added to the graph * whenever an edge is added to a vnode graph, with end points * corresponding to owner of the new pending lock and the owner of the * lock upon which it waits. In order to prevent deadlock, we only add * an edge to this graph if the new edge would not create a cycle. * * The lock owner graph is topologically sorted, i.e. if a node has * any outgoing edges, then it has an order strictly less than any * node to which it has an outgoing edge. We preserve this ordering * (and detect cycles) on edge insertion using Algorithm PK from the * paper "A Dynamic Topological Sort Algorithm for Directed Acyclic * Graphs" (ACM Journal of Experimental Algorithms, Vol 11, Article * No. 1.7) */ struct owner_vertex; struct owner_edge { LIST_ENTRY(owner_edge) e_outlink; /* (g) link from's out-edge list */ LIST_ENTRY(owner_edge) e_inlink; /* (g) link to's in-edge list */ int e_refs; /* (g) number of times added */ struct owner_vertex *e_from; /* (c) out-going from here */ struct owner_vertex *e_to; /* (c) in-coming to here */ }; LIST_HEAD(owner_edge_list, owner_edge); struct owner_vertex { TAILQ_ENTRY(owner_vertex) v_link; /* (g) workspace for edge insertion */ uint32_t v_gen; /* (g) workspace for edge insertion */ int v_order; /* (g) order of vertex in graph */ struct owner_edge_list v_outedges;/* (g) list of out-edges */ struct owner_edge_list v_inedges; /* (g) list of in-edges */ struct lock_owner *v_owner; /* (c) corresponding lock owner */ }; TAILQ_HEAD(owner_vertex_list, owner_vertex); struct owner_graph { struct owner_vertex** g_vertices; /* (g) pointers to vertices */ int g_size; /* (g) number of vertices */ int g_space; /* (g) space allocated for vertices */ int *g_indexbuf; /* (g) workspace for loop detection */ uint32_t g_gen; /* (g) increment when re-ordering */ }; static struct sx lf_owner_graph_lock; static struct owner_graph lf_owner_graph; /* * Initialise various structures and locks. */ static void lf_init(void *dummy) { int i; sx_init(&lf_lock_states_lock, "lock states lock"); LIST_INIT(&lf_lock_states); for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++) { sx_init(&lf_lock_owners[i].lock, "lock owners lock"); LIST_INIT(&lf_lock_owners[i].list); } sx_init(&lf_owner_graph_lock, "owner graph lock"); graph_init(&lf_owner_graph); } SYSINIT(lf_init, SI_SUB_LOCK, SI_ORDER_FIRST, lf_init, NULL); /* * Generate a hash value for a lock owner. */ static int lf_hash_owner(caddr_t id, struct vnode *vp, struct flock *fl, int flags) { uint32_t h; if (flags & F_REMOTE) { h = HASHSTEP(0, fl->l_pid); h = HASHSTEP(h, fl->l_sysid); } else if (flags & F_FLOCK) { h = ((uintptr_t) id) >> 7; } else { h = ((uintptr_t) vp) >> 7; } return (h % LOCK_OWNER_HASH_SIZE); } /* * Return true if a lock owner matches the details passed to * lf_advlock. */ static int lf_owner_matches(struct lock_owner *lo, caddr_t id, struct flock *fl, int flags) { if (flags & F_REMOTE) { return lo->lo_pid == fl->l_pid && lo->lo_sysid == fl->l_sysid; } else { return lo->lo_id == id; } } static struct lockf_entry * lf_alloc_lock(struct lock_owner *lo) { struct lockf_entry *lf; lf = malloc(sizeof(struct lockf_entry), M_LOCKF, M_WAITOK|M_ZERO); #ifdef LOCKF_DEBUG if (lockf_debug & 4) printf("Allocated lock %p\n", lf); #endif if (lo) { sx_xlock(&lf_lock_owners[lo->lo_hash].lock); lo->lo_refs++; sx_xunlock(&lf_lock_owners[lo->lo_hash].lock); lf->lf_owner = lo; } return (lf); } static int lf_free_lock(struct lockf_entry *lock) { struct sx *chainlock; KASSERT(lock->lf_refs > 0, ("lockf_entry negative ref count %p", lock)); if (--lock->lf_refs > 0) return (0); /* * Adjust the lock_owner reference count and * reclaim the entry if this is the last lock * for that owner. */ struct lock_owner *lo = lock->lf_owner; if (lo) { KASSERT(LIST_EMPTY(&lock->lf_outedges), ("freeing lock with dependencies")); KASSERT(LIST_EMPTY(&lock->lf_inedges), ("freeing lock with dependants")); chainlock = &lf_lock_owners[lo->lo_hash].lock; sx_xlock(chainlock); KASSERT(lo->lo_refs > 0, ("lock owner refcount")); lo->lo_refs--; if (lo->lo_refs == 0) { #ifdef LOCKF_DEBUG if (lockf_debug & 1) printf("lf_free_lock: freeing lock owner %p\n", lo); #endif if (lo->lo_vertex) { sx_xlock(&lf_owner_graph_lock); graph_free_vertex(&lf_owner_graph, lo->lo_vertex); sx_xunlock(&lf_owner_graph_lock); } LIST_REMOVE(lo, lo_link); free(lo, M_LOCKF); #ifdef LOCKF_DEBUG if (lockf_debug & 4) printf("Freed lock owner %p\n", lo); #endif } sx_unlock(chainlock); } if ((lock->lf_flags & F_REMOTE) && lock->lf_vnode) { vrele(lock->lf_vnode); lock->lf_vnode = NULL; } #ifdef LOCKF_DEBUG if (lockf_debug & 4) printf("Freed lock %p\n", lock); #endif free(lock, M_LOCKF); return (1); } /* * Advisory record locking support */ int lf_advlockasync(struct vop_advlockasync_args *ap, struct lockf **statep, u_quad_t size) { struct lockf *state; struct flock *fl = ap->a_fl; struct lockf_entry *lock; struct vnode *vp = ap->a_vp; caddr_t id = ap->a_id; int flags = ap->a_flags; int hash; struct lock_owner *lo; off_t start, end, oadd; int error; /* * Handle the F_UNLKSYS case first - no need to mess about * creating a lock owner for this one. */ if (ap->a_op == F_UNLCKSYS) { lf_clearremotesys(fl->l_sysid); return (0); } /* * Convert the flock structure into a start and end. */ switch (fl->l_whence) { case SEEK_SET: case SEEK_CUR: /* * Caller is responsible for adding any necessary offset * when SEEK_CUR is used. */ start = fl->l_start; break; case SEEK_END: if (size > OFF_MAX || (fl->l_start > 0 && size > OFF_MAX - fl->l_start)) return (EOVERFLOW); start = size + fl->l_start; break; default: return (EINVAL); } if (start < 0) return (EINVAL); if (fl->l_len < 0) { if (start == 0) return (EINVAL); end = start - 1; start += fl->l_len; if (start < 0) return (EINVAL); } else if (fl->l_len == 0) { end = OFF_MAX; } else { oadd = fl->l_len - 1; if (oadd > OFF_MAX - start) return (EOVERFLOW); end = start + oadd; } retry_setlock: /* * Avoid the common case of unlocking when inode has no locks. */ if (ap->a_op != F_SETLK && (*statep) == NULL) { VI_LOCK(vp); if ((*statep) == NULL) { fl->l_type = F_UNLCK; VI_UNLOCK(vp); return (0); } VI_UNLOCK(vp); } /* * Map our arguments to an existing lock owner or create one * if this is the first time we have seen this owner. */ hash = lf_hash_owner(id, vp, fl, flags); sx_xlock(&lf_lock_owners[hash].lock); LIST_FOREACH(lo, &lf_lock_owners[hash].list, lo_link) if (lf_owner_matches(lo, id, fl, flags)) break; if (!lo) { /* * We initialise the lock with a reference * count which matches the new lockf_entry * structure created below. */ lo = malloc(sizeof(struct lock_owner), M_LOCKF, M_WAITOK|M_ZERO); #ifdef LOCKF_DEBUG if (lockf_debug & 4) printf("Allocated lock owner %p\n", lo); #endif lo->lo_refs = 1; lo->lo_flags = flags; lo->lo_id = id; lo->lo_hash = hash; if (flags & F_REMOTE) { lo->lo_pid = fl->l_pid; lo->lo_sysid = fl->l_sysid; } else if (flags & F_FLOCK) { lo->lo_pid = -1; lo->lo_sysid = 0; } else { struct proc *p = (struct proc *) id; lo->lo_pid = p->p_pid; lo->lo_sysid = 0; } lo->lo_vertex = NULL; #ifdef LOCKF_DEBUG if (lockf_debug & 1) { printf("lf_advlockasync: new lock owner %p ", lo); lf_print_owner(lo); printf("\n"); } #endif LIST_INSERT_HEAD(&lf_lock_owners[hash].list, lo, lo_link); } else { /* * We have seen this lock owner before, increase its * reference count to account for the new lockf_entry * structure we create below. */ lo->lo_refs++; } sx_xunlock(&lf_lock_owners[hash].lock); /* * Create the lockf structure. We initialise the lf_owner * field here instead of in lf_alloc_lock() to avoid paying * the lf_lock_owners_lock tax twice. */ lock = lf_alloc_lock(NULL); lock->lf_refs = 1; lock->lf_start = start; lock->lf_end = end; lock->lf_owner = lo; lock->lf_vnode = vp; if (flags & F_REMOTE) { /* * For remote locks, the caller may release its ref to * the vnode at any time - we have to ref it here to * prevent it from being recycled unexpectedly. */ vref(vp); } lock->lf_type = fl->l_type; LIST_INIT(&lock->lf_outedges); LIST_INIT(&lock->lf_inedges); lock->lf_async_task = ap->a_task; lock->lf_flags = ap->a_flags; /* * Do the requested operation. First find our state structure * and create a new one if necessary - the caller's *statep * variable and the state's ls_threads count is protected by * the vnode interlock. */ VI_LOCK(vp); if (VN_IS_DOOMED(vp)) { VI_UNLOCK(vp); lf_free_lock(lock); return (ENOENT); } /* * Allocate a state structure if necessary. */ state = *statep; if (state == NULL) { struct lockf *ls; VI_UNLOCK(vp); ls = malloc(sizeof(struct lockf), M_LOCKF, M_WAITOK|M_ZERO); sx_init(&ls->ls_lock, "ls_lock"); LIST_INIT(&ls->ls_active); LIST_INIT(&ls->ls_pending); ls->ls_threads = 1; sx_xlock(&lf_lock_states_lock); LIST_INSERT_HEAD(&lf_lock_states, ls, ls_link); sx_xunlock(&lf_lock_states_lock); /* * Cope if we lost a race with some other thread while * trying to allocate memory. */ VI_LOCK(vp); if (VN_IS_DOOMED(vp)) { VI_UNLOCK(vp); sx_xlock(&lf_lock_states_lock); LIST_REMOVE(ls, ls_link); sx_xunlock(&lf_lock_states_lock); sx_destroy(&ls->ls_lock); free(ls, M_LOCKF); lf_free_lock(lock); return (ENOENT); } if ((*statep) == NULL) { state = *statep = ls; VI_UNLOCK(vp); } else { state = *statep; MPASS(state->ls_threads >= 0); state->ls_threads++; VI_UNLOCK(vp); sx_xlock(&lf_lock_states_lock); LIST_REMOVE(ls, ls_link); sx_xunlock(&lf_lock_states_lock); sx_destroy(&ls->ls_lock); free(ls, M_LOCKF); } } else { MPASS(state->ls_threads >= 0); state->ls_threads++; VI_UNLOCK(vp); } sx_xlock(&state->ls_lock); /* * Recheck the doomed vnode after state->ls_lock is * locked. lf_purgelocks() requires that no new threads add * pending locks when vnode is marked by VIRF_DOOMED flag. */ if (VN_IS_DOOMED(vp)) { VI_LOCK(vp); MPASS(state->ls_threads > 0); state->ls_threads--; wakeup(state); VI_UNLOCK(vp); sx_xunlock(&state->ls_lock); lf_free_lock(lock); return (ENOENT); } switch (ap->a_op) { case F_SETLK: error = lf_setlock(state, lock, vp, ap->a_cookiep); break; case F_UNLCK: error = lf_clearlock(state, lock); lf_free_lock(lock); break; case F_GETLK: error = lf_getlock(state, lock, fl); lf_free_lock(lock); break; case F_CANCEL: if (ap->a_cookiep) error = lf_cancel(state, lock, *ap->a_cookiep); else error = EINVAL; lf_free_lock(lock); break; default: lf_free_lock(lock); error = EINVAL; break; } #ifdef DIAGNOSTIC /* * Check for some can't happen stuff. In this case, the active * lock list becoming disordered or containing mutually * blocking locks. We also check the pending list for locks * which should be active (i.e. have no out-going edges). */ LIST_FOREACH(lock, &state->ls_active, lf_link) { struct lockf_entry *lf; if (LIST_NEXT(lock, lf_link)) KASSERT((lock->lf_start <= LIST_NEXT(lock, lf_link)->lf_start), ("locks disordered")); LIST_FOREACH(lf, &state->ls_active, lf_link) { if (lock == lf) break; KASSERT(!lf_blocks(lock, lf), ("two conflicting active locks")); if (lock->lf_owner == lf->lf_owner) KASSERT(!lf_overlaps(lock, lf), ("two overlapping locks from same owner")); } } LIST_FOREACH(lock, &state->ls_pending, lf_link) { KASSERT(!LIST_EMPTY(&lock->lf_outedges), ("pending lock which should be active")); } #endif sx_xunlock(&state->ls_lock); VI_LOCK(vp); MPASS(state->ls_threads > 0); state->ls_threads--; if (state->ls_threads != 0) { wakeup(state); } VI_UNLOCK(vp); if (error == EDOOFUS) { KASSERT(ap->a_op == F_SETLK, ("EDOOFUS")); goto retry_setlock; } return (error); } int lf_advlock(struct vop_advlock_args *ap, struct lockf **statep, u_quad_t size) { struct vop_advlockasync_args a; a.a_vp = ap->a_vp; a.a_id = ap->a_id; a.a_op = ap->a_op; a.a_fl = ap->a_fl; a.a_flags = ap->a_flags; a.a_task = NULL; a.a_cookiep = NULL; return (lf_advlockasync(&a, statep, size)); } void lf_purgelocks(struct vnode *vp, struct lockf **statep) { struct lockf *state; struct lockf_entry *lock, *nlock; /* * For this to work correctly, the caller must ensure that no * other threads enter the locking system for this vnode, * e.g. by checking VIRF_DOOMED. We wake up any threads that are * sleeping waiting for locks on this vnode and then free all * the remaining locks. */ KASSERT(VN_IS_DOOMED(vp), ("lf_purgelocks: vp %p has not vgone yet", vp)); state = *statep; if (state == NULL) { return; } VI_LOCK(vp); *statep = NULL; if (LIST_EMPTY(&state->ls_active) && state->ls_threads == 0) { KASSERT(LIST_EMPTY(&state->ls_pending), ("freeing state with pending locks")); VI_UNLOCK(vp); goto out_free; } MPASS(state->ls_threads >= 0); state->ls_threads++; VI_UNLOCK(vp); sx_xlock(&state->ls_lock); sx_xlock(&lf_owner_graph_lock); LIST_FOREACH_SAFE(lock, &state->ls_pending, lf_link, nlock) { LIST_REMOVE(lock, lf_link); lf_remove_outgoing(lock); lf_remove_incoming(lock); /* * If its an async lock, we can just free it * here, otherwise we let the sleeping thread * free it. */ if (lock->lf_async_task) { lf_free_lock(lock); } else { lock->lf_flags |= F_INTR; wakeup(lock); } } sx_xunlock(&lf_owner_graph_lock); sx_xunlock(&state->ls_lock); /* * Wait for all other threads, sleeping and otherwise * to leave. */ VI_LOCK(vp); while (state->ls_threads > 1) msleep(state, VI_MTX(vp), 0, "purgelocks", 0); VI_UNLOCK(vp); /* * We can just free all the active locks since they * will have no dependencies (we removed them all * above). We don't need to bother locking since we * are the last thread using this state structure. */ KASSERT(LIST_EMPTY(&state->ls_pending), ("lock pending for %p", state)); LIST_FOREACH_SAFE(lock, &state->ls_active, lf_link, nlock) { LIST_REMOVE(lock, lf_link); lf_free_lock(lock); } out_free: sx_xlock(&lf_lock_states_lock); LIST_REMOVE(state, ls_link); sx_xunlock(&lf_lock_states_lock); sx_destroy(&state->ls_lock); free(state, M_LOCKF); } /* * Return non-zero if locks 'x' and 'y' overlap. */ static int lf_overlaps(struct lockf_entry *x, struct lockf_entry *y) { return (x->lf_start <= y->lf_end && x->lf_end >= y->lf_start); } /* * Return non-zero if lock 'x' is blocked by lock 'y' (or vice versa). */ static int lf_blocks(struct lockf_entry *x, struct lockf_entry *y) { return x->lf_owner != y->lf_owner && (x->lf_type == F_WRLCK || y->lf_type == F_WRLCK) && lf_overlaps(x, y); } /* * Allocate a lock edge from the free list */ static struct lockf_edge * lf_alloc_edge(void) { return (malloc(sizeof(struct lockf_edge), M_LOCKF, M_WAITOK|M_ZERO)); } /* * Free a lock edge. */ static void lf_free_edge(struct lockf_edge *e) { free(e, M_LOCKF); } /* * Ensure that the lock's owner has a corresponding vertex in the * owner graph. */ static void lf_alloc_vertex(struct lockf_entry *lock) { struct owner_graph *g = &lf_owner_graph; if (!lock->lf_owner->lo_vertex) lock->lf_owner->lo_vertex = graph_alloc_vertex(g, lock->lf_owner); } /* * Attempt to record an edge from lock x to lock y. Return EDEADLK if * the new edge would cause a cycle in the owner graph. */ static int lf_add_edge(struct lockf_entry *x, struct lockf_entry *y) { struct owner_graph *g = &lf_owner_graph; struct lockf_edge *e; int error; #ifdef DIAGNOSTIC LIST_FOREACH(e, &x->lf_outedges, le_outlink) KASSERT(e->le_to != y, ("adding lock edge twice")); #endif /* * Make sure the two owners have entries in the owner graph. */ lf_alloc_vertex(x); lf_alloc_vertex(y); error = graph_add_edge(g, x->lf_owner->lo_vertex, y->lf_owner->lo_vertex); if (error) return (error); e = lf_alloc_edge(); LIST_INSERT_HEAD(&x->lf_outedges, e, le_outlink); LIST_INSERT_HEAD(&y->lf_inedges, e, le_inlink); e->le_from = x; e->le_to = y; return (0); } /* * Remove an edge from the lock graph. */ static void lf_remove_edge(struct lockf_edge *e) { struct owner_graph *g = &lf_owner_graph; struct lockf_entry *x = e->le_from; struct lockf_entry *y = e->le_to; graph_remove_edge(g, x->lf_owner->lo_vertex, y->lf_owner->lo_vertex); LIST_REMOVE(e, le_outlink); LIST_REMOVE(e, le_inlink); e->le_from = NULL; e->le_to = NULL; lf_free_edge(e); } /* * Remove all out-going edges from lock x. */ static void lf_remove_outgoing(struct lockf_entry *x) { struct lockf_edge *e; while ((e = LIST_FIRST(&x->lf_outedges)) != NULL) { lf_remove_edge(e); } } /* * Remove all in-coming edges from lock x. */ static void lf_remove_incoming(struct lockf_entry *x) { struct lockf_edge *e; while ((e = LIST_FIRST(&x->lf_inedges)) != NULL) { lf_remove_edge(e); } } /* * Walk the list of locks for the file and create an out-going edge * from lock to each blocking lock. */ static int lf_add_outgoing(struct lockf *state, struct lockf_entry *lock) { struct lockf_entry *overlap; int error; LIST_FOREACH(overlap, &state->ls_active, lf_link) { /* * We may assume that the active list is sorted by * lf_start. */ if (overlap->lf_start > lock->lf_end) break; if (!lf_blocks(lock, overlap)) continue; /* * We've found a blocking lock. Add the corresponding * edge to the graphs and see if it would cause a * deadlock. */ error = lf_add_edge(lock, overlap); /* * The only error that lf_add_edge returns is EDEADLK. * Remove any edges we added and return the error. */ if (error) { lf_remove_outgoing(lock); return (error); } } /* * We also need to add edges to sleeping locks that block * us. This ensures that lf_wakeup_lock cannot grant two * mutually blocking locks simultaneously and also enforces a * 'first come, first served' fairness model. Note that this * only happens if we are blocked by at least one active lock * due to the call to lf_getblock in lf_setlock below. */ LIST_FOREACH(overlap, &state->ls_pending, lf_link) { if (!lf_blocks(lock, overlap)) continue; /* * We've found a blocking lock. Add the corresponding * edge to the graphs and see if it would cause a * deadlock. */ error = lf_add_edge(lock, overlap); /* * The only error that lf_add_edge returns is EDEADLK. * Remove any edges we added and return the error. */ if (error) { lf_remove_outgoing(lock); return (error); } } return (0); } /* * Walk the list of pending locks for the file and create an in-coming * edge from lock to each blocking lock. */ static int lf_add_incoming(struct lockf *state, struct lockf_entry *lock) { struct lockf_entry *overlap; int error; sx_assert(&state->ls_lock, SX_XLOCKED); if (LIST_EMPTY(&state->ls_pending)) return (0); error = 0; sx_xlock(&lf_owner_graph_lock); LIST_FOREACH(overlap, &state->ls_pending, lf_link) { if (!lf_blocks(lock, overlap)) continue; /* * We've found a blocking lock. Add the corresponding * edge to the graphs and see if it would cause a * deadlock. */ error = lf_add_edge(overlap, lock); /* * The only error that lf_add_edge returns is EDEADLK. * Remove any edges we added and return the error. */ if (error) { lf_remove_incoming(lock); break; } } sx_xunlock(&lf_owner_graph_lock); return (error); } /* * Insert lock into the active list, keeping list entries ordered by * increasing values of lf_start. */ static void lf_insert_lock(struct lockf *state, struct lockf_entry *lock) { struct lockf_entry *lf, *lfprev; if (LIST_EMPTY(&state->ls_active)) { LIST_INSERT_HEAD(&state->ls_active, lock, lf_link); return; } lfprev = NULL; LIST_FOREACH(lf, &state->ls_active, lf_link) { if (lf->lf_start > lock->lf_start) { LIST_INSERT_BEFORE(lf, lock, lf_link); return; } lfprev = lf; } LIST_INSERT_AFTER(lfprev, lock, lf_link); } /* * Wake up a sleeping lock and remove it from the pending list now * that all its dependencies have been resolved. The caller should * arrange for the lock to be added to the active list, adjusting any * existing locks for the same owner as needed. */ static void lf_wakeup_lock(struct lockf *state, struct lockf_entry *wakelock) { /* * Remove from ls_pending list and wake up the caller * or start the async notification, as appropriate. */ LIST_REMOVE(wakelock, lf_link); #ifdef LOCKF_DEBUG if (lockf_debug & 1) lf_print("lf_wakeup_lock: awakening", wakelock); #endif /* LOCKF_DEBUG */ if (wakelock->lf_async_task) { taskqueue_enqueue(taskqueue_thread, wakelock->lf_async_task); } else { wakeup(wakelock); } } /* * Re-check all dependent locks and remove edges to locks that we no * longer block. If 'all' is non-zero, the lock has been removed and * we must remove all the dependencies, otherwise it has simply been * reduced but remains active. Any pending locks which have been been * unblocked are added to 'granted' */ static void lf_update_dependancies(struct lockf *state, struct lockf_entry *lock, int all, struct lockf_entry_list *granted) { struct lockf_edge *e, *ne; struct lockf_entry *deplock; LIST_FOREACH_SAFE(e, &lock->lf_inedges, le_inlink, ne) { deplock = e->le_from; if (all || !lf_blocks(lock, deplock)) { sx_xlock(&lf_owner_graph_lock); lf_remove_edge(e); sx_xunlock(&lf_owner_graph_lock); if (LIST_EMPTY(&deplock->lf_outedges)) { lf_wakeup_lock(state, deplock); LIST_INSERT_HEAD(granted, deplock, lf_link); } } } } /* * Set the start of an existing active lock, updating dependencies and * adding any newly woken locks to 'granted'. */ static void lf_set_start(struct lockf *state, struct lockf_entry *lock, off_t new_start, struct lockf_entry_list *granted) { KASSERT(new_start >= lock->lf_start, ("can't increase lock")); lock->lf_start = new_start; LIST_REMOVE(lock, lf_link); lf_insert_lock(state, lock); lf_update_dependancies(state, lock, FALSE, granted); } /* * Set the end of an existing active lock, updating dependencies and * adding any newly woken locks to 'granted'. */ static void lf_set_end(struct lockf *state, struct lockf_entry *lock, off_t new_end, struct lockf_entry_list *granted) { KASSERT(new_end <= lock->lf_end, ("can't increase lock")); lock->lf_end = new_end; lf_update_dependancies(state, lock, FALSE, granted); } /* * Add a lock to the active list, updating or removing any current * locks owned by the same owner and processing any pending locks that * become unblocked as a result. This code is also used for unlock * since the logic for updating existing locks is identical. * * As a result of processing the new lock, we may unblock existing * pending locks as a result of downgrading/unlocking. We simply * activate the newly granted locks by looping. * * Since the new lock already has its dependencies set up, we always * add it to the list (unless its an unlock request). This may * fragment the lock list in some pathological cases but its probably * not a real problem. */ static void lf_activate_lock(struct lockf *state, struct lockf_entry *lock) { struct lockf_entry *overlap, *lf; struct lockf_entry_list granted; int ovcase; LIST_INIT(&granted); LIST_INSERT_HEAD(&granted, lock, lf_link); while (!LIST_EMPTY(&granted)) { lock = LIST_FIRST(&granted); LIST_REMOVE(lock, lf_link); /* * Skip over locks owned by other processes. Handle * any locks that overlap and are owned by ourselves. */ overlap = LIST_FIRST(&state->ls_active); for (;;) { ovcase = lf_findoverlap(&overlap, lock, SELF); #ifdef LOCKF_DEBUG if (ovcase && (lockf_debug & 2)) { printf("lf_setlock: overlap %d", ovcase); lf_print("", overlap); } #endif /* * Six cases: * 0) no overlap * 1) overlap == lock * 2) overlap contains lock * 3) lock contains overlap * 4) overlap starts before lock * 5) overlap ends after lock */ switch (ovcase) { case 0: /* no overlap */ break; case 1: /* overlap == lock */ /* * We have already setup the * dependants for the new lock, taking * into account a possible downgrade * or unlock. Remove the old lock. */ LIST_REMOVE(overlap, lf_link); lf_update_dependancies(state, overlap, TRUE, &granted); lf_free_lock(overlap); break; case 2: /* overlap contains lock */ /* * Just split the existing lock. */ lf_split(state, overlap, lock, &granted); break; case 3: /* lock contains overlap */ /* * Delete the overlap and advance to * the next entry in the list. */ lf = LIST_NEXT(overlap, lf_link); LIST_REMOVE(overlap, lf_link); lf_update_dependancies(state, overlap, TRUE, &granted); lf_free_lock(overlap); overlap = lf; continue; case 4: /* overlap starts before lock */ /* * Just update the overlap end and * move on. */ lf_set_end(state, overlap, lock->lf_start - 1, &granted); overlap = LIST_NEXT(overlap, lf_link); continue; case 5: /* overlap ends after lock */ /* * Change the start of overlap and * re-insert. */ lf_set_start(state, overlap, lock->lf_end + 1, &granted); break; } break; } #ifdef LOCKF_DEBUG if (lockf_debug & 1) { if (lock->lf_type != F_UNLCK) lf_print("lf_activate_lock: activated", lock); else lf_print("lf_activate_lock: unlocked", lock); lf_printlist("lf_activate_lock", lock); } #endif /* LOCKF_DEBUG */ if (lock->lf_type != F_UNLCK) lf_insert_lock(state, lock); } } /* * Cancel a pending lock request, either as a result of a signal or a * cancel request for an async lock. */ static void lf_cancel_lock(struct lockf *state, struct lockf_entry *lock) { struct lockf_entry_list granted; /* * Note it is theoretically possible that cancelling this lock * may allow some other pending lock to become * active. Consider this case: * * Owner Action Result Dependencies * * A: lock [0..0] succeeds * B: lock [2..2] succeeds * C: lock [1..2] blocked C->B * D: lock [0..1] blocked C->B,D->A,D->C * A: unlock [0..0] C->B,D->C * C: cancel [1..2] */ LIST_REMOVE(lock, lf_link); /* * Removing out-going edges is simple. */ sx_xlock(&lf_owner_graph_lock); lf_remove_outgoing(lock); sx_xunlock(&lf_owner_graph_lock); /* * Removing in-coming edges may allow some other lock to * become active - we use lf_update_dependancies to figure * this out. */ LIST_INIT(&granted); lf_update_dependancies(state, lock, TRUE, &granted); lf_free_lock(lock); /* * Feed any newly active locks to lf_activate_lock. */ while (!LIST_EMPTY(&granted)) { lock = LIST_FIRST(&granted); LIST_REMOVE(lock, lf_link); lf_activate_lock(state, lock); } } /* * Set a byte-range lock. */ static int lf_setlock(struct lockf *state, struct lockf_entry *lock, struct vnode *vp, void **cookiep) { static char lockstr[] = "lockf"; int error, priority, stops_deferred; #ifdef LOCKF_DEBUG if (lockf_debug & 1) lf_print("lf_setlock", lock); #endif /* LOCKF_DEBUG */ /* * Set the priority */ priority = PLOCK; if (lock->lf_type == F_WRLCK) priority += 4; if (!(lock->lf_flags & F_NOINTR)) priority |= PCATCH; /* * Scan lock list for this file looking for locks that would block us. */ if (lf_getblock(state, lock)) { /* * Free the structure and return if nonblocking. */ if ((lock->lf_flags & F_WAIT) == 0 && lock->lf_async_task == NULL) { lf_free_lock(lock); error = EAGAIN; goto out; } /* * For flock type locks, we must first remove * any shared locks that we hold before we sleep * waiting for an exclusive lock. */ if ((lock->lf_flags & F_FLOCK) && lock->lf_type == F_WRLCK) { lock->lf_type = F_UNLCK; lf_activate_lock(state, lock); lock->lf_type = F_WRLCK; } /* * We are blocked. Create edges to each blocking lock, * checking for deadlock using the owner graph. For * simplicity, we run deadlock detection for all * locks, posix and otherwise. */ sx_xlock(&lf_owner_graph_lock); error = lf_add_outgoing(state, lock); sx_xunlock(&lf_owner_graph_lock); if (error) { #ifdef LOCKF_DEBUG if (lockf_debug & 1) lf_print("lf_setlock: deadlock", lock); #endif lf_free_lock(lock); goto out; } /* * We have added edges to everything that blocks * us. Sleep until they all go away. */ LIST_INSERT_HEAD(&state->ls_pending, lock, lf_link); #ifdef LOCKF_DEBUG if (lockf_debug & 1) { struct lockf_edge *e; LIST_FOREACH(e, &lock->lf_outedges, le_outlink) { lf_print("lf_setlock: blocking on", e->le_to); lf_printlist("lf_setlock", e->le_to); } } #endif /* LOCKF_DEBUG */ if ((lock->lf_flags & F_WAIT) == 0) { /* * The caller requested async notification - * this callback happens when the blocking * lock is released, allowing the caller to * make another attempt to take the lock. */ *cookiep = (void *) lock; error = EINPROGRESS; goto out; } lock->lf_refs++; stops_deferred = sigdeferstop(SIGDEFERSTOP_ERESTART); error = sx_sleep(lock, &state->ls_lock, priority, lockstr, 0); sigallowstop(stops_deferred); if (lf_free_lock(lock)) { error = EDOOFUS; goto out; } /* * We may have been awakened by a signal and/or by a * debugger continuing us (in which cases we must * remove our lock graph edges) and/or by another * process releasing a lock (in which case our edges * have already been removed and we have been moved to * the active list). We may also have been woken by * lf_purgelocks which we report to the caller as * EINTR. In that case, lf_purgelocks will have * removed our lock graph edges. * * Note that it is possible to receive a signal after * we were successfully woken (and moved to the active * list) but before we resumed execution. In this * case, our lf_outedges list will be clear. We * pretend there was no error. * * Note also, if we have been sleeping long enough, we * may now have incoming edges from some newer lock * which is waiting behind us in the queue. */ if (lock->lf_flags & F_INTR) { error = EINTR; lf_free_lock(lock); goto out; } if (LIST_EMPTY(&lock->lf_outedges)) { error = 0; } else { lf_cancel_lock(state, lock); goto out; } #ifdef LOCKF_DEBUG if (lockf_debug & 1) { lf_print("lf_setlock: granted", lock); } #endif goto out; } /* * It looks like we are going to grant the lock. First add * edges from any currently pending lock that the new lock * would block. */ error = lf_add_incoming(state, lock); if (error) { #ifdef LOCKF_DEBUG if (lockf_debug & 1) lf_print("lf_setlock: deadlock", lock); #endif lf_free_lock(lock); goto out; } /* * No blocks!! Add the lock. Note that we will * downgrade or upgrade any overlapping locks this * process already owns. */ lf_activate_lock(state, lock); error = 0; out: return (error); } /* * Remove a byte-range lock on an inode. * * Generally, find the lock (or an overlap to that lock) * and remove it (or shrink it), then wakeup anyone we can. */ static int lf_clearlock(struct lockf *state, struct lockf_entry *unlock) { struct lockf_entry *overlap; overlap = LIST_FIRST(&state->ls_active); if (overlap == NOLOCKF) return (0); #ifdef LOCKF_DEBUG if (unlock->lf_type != F_UNLCK) panic("lf_clearlock: bad type"); if (lockf_debug & 1) lf_print("lf_clearlock", unlock); #endif /* LOCKF_DEBUG */ lf_activate_lock(state, unlock); return (0); } /* * Check whether there is a blocking lock, and if so return its * details in '*fl'. */ static int lf_getlock(struct lockf *state, struct lockf_entry *lock, struct flock *fl) { struct lockf_entry *block; #ifdef LOCKF_DEBUG if (lockf_debug & 1) lf_print("lf_getlock", lock); #endif /* LOCKF_DEBUG */ if ((block = lf_getblock(state, lock))) { fl->l_type = block->lf_type; fl->l_whence = SEEK_SET; fl->l_start = block->lf_start; if (block->lf_end == OFF_MAX) fl->l_len = 0; else fl->l_len = block->lf_end - block->lf_start + 1; fl->l_pid = block->lf_owner->lo_pid; fl->l_sysid = block->lf_owner->lo_sysid; } else { fl->l_type = F_UNLCK; } return (0); } /* * Cancel an async lock request. */ static int lf_cancel(struct lockf *state, struct lockf_entry *lock, void *cookie) { struct lockf_entry *reallock; /* * We need to match this request with an existing lock * request. */ LIST_FOREACH(reallock, &state->ls_pending, lf_link) { if ((void *) reallock == cookie) { /* * Double-check that this lock looks right * (maybe use a rolling ID for the cancel * cookie instead?) */ if (!(reallock->lf_vnode == lock->lf_vnode && reallock->lf_start == lock->lf_start && reallock->lf_end == lock->lf_end)) { return (ENOENT); } /* * Make sure this lock was async and then just * remove it from its wait lists. */ if (!reallock->lf_async_task) { return (ENOENT); } /* * Note that since any other thread must take * state->ls_lock before it can possibly * trigger the async callback, we are safe * from a race with lf_wakeup_lock, i.e. we * can free the lock (actually our caller does * this). */ lf_cancel_lock(state, reallock); return (0); } } /* * We didn't find a matching lock - not much we can do here. */ return (ENOENT); } /* * Walk the list of locks for an inode and * return the first blocking lock. */ static struct lockf_entry * lf_getblock(struct lockf *state, struct lockf_entry *lock) { struct lockf_entry *overlap; LIST_FOREACH(overlap, &state->ls_active, lf_link) { /* * We may assume that the active list is sorted by * lf_start. */ if (overlap->lf_start > lock->lf_end) break; if (!lf_blocks(lock, overlap)) continue; return (overlap); } return (NOLOCKF); } /* * Walk the list of locks for an inode to find an overlapping lock (if * any) and return a classification of that overlap. * * Arguments: * *overlap The place in the lock list to start looking * lock The lock which is being tested * type Pass 'SELF' to test only locks with the same * owner as lock, or 'OTHER' to test only locks * with a different owner * * Returns one of six values: * 0) no overlap * 1) overlap == lock * 2) overlap contains lock * 3) lock contains overlap * 4) overlap starts before lock * 5) overlap ends after lock * * If there is an overlapping lock, '*overlap' is set to point at the * overlapping lock. * * NOTE: this returns only the FIRST overlapping lock. There * may be more than one. */ static int lf_findoverlap(struct lockf_entry **overlap, struct lockf_entry *lock, int type) { struct lockf_entry *lf; off_t start, end; int res; if ((*overlap) == NOLOCKF) { return (0); } #ifdef LOCKF_DEBUG if (lockf_debug & 2) lf_print("lf_findoverlap: looking for overlap in", lock); #endif /* LOCKF_DEBUG */ start = lock->lf_start; end = lock->lf_end; res = 0; while (*overlap) { lf = *overlap; if (lf->lf_start > end) break; if (((type & SELF) && lf->lf_owner != lock->lf_owner) || ((type & OTHERS) && lf->lf_owner == lock->lf_owner)) { *overlap = LIST_NEXT(lf, lf_link); continue; } #ifdef LOCKF_DEBUG if (lockf_debug & 2) lf_print("\tchecking", lf); #endif /* LOCKF_DEBUG */ /* * OK, check for overlap * * Six cases: * 0) no overlap * 1) overlap == lock * 2) overlap contains lock * 3) lock contains overlap * 4) overlap starts before lock * 5) overlap ends after lock */ if (start > lf->lf_end) { /* Case 0 */ #ifdef LOCKF_DEBUG if (lockf_debug & 2) printf("no overlap\n"); #endif /* LOCKF_DEBUG */ *overlap = LIST_NEXT(lf, lf_link); continue; } if (lf->lf_start == start && lf->lf_end == end) { /* Case 1 */ #ifdef LOCKF_DEBUG if (lockf_debug & 2) printf("overlap == lock\n"); #endif /* LOCKF_DEBUG */ res = 1; break; } if (lf->lf_start <= start && lf->lf_end >= end) { /* Case 2 */ #ifdef LOCKF_DEBUG if (lockf_debug & 2) printf("overlap contains lock\n"); #endif /* LOCKF_DEBUG */ res = 2; break; } if (start <= lf->lf_start && end >= lf->lf_end) { /* Case 3 */ #ifdef LOCKF_DEBUG if (lockf_debug & 2) printf("lock contains overlap\n"); #endif /* LOCKF_DEBUG */ res = 3; break; } if (lf->lf_start < start && lf->lf_end >= start) { /* Case 4 */ #ifdef LOCKF_DEBUG if (lockf_debug & 2) printf("overlap starts before lock\n"); #endif /* LOCKF_DEBUG */ res = 4; break; } if (lf->lf_start > start && lf->lf_end > end) { /* Case 5 */ #ifdef LOCKF_DEBUG if (lockf_debug & 2) printf("overlap ends after lock\n"); #endif /* LOCKF_DEBUG */ res = 5; break; } panic("lf_findoverlap: default"); } return (res); } /* * Split an the existing 'lock1', based on the extent of the lock * described by 'lock2'. The existing lock should cover 'lock2' * entirely. * * Any pending locks which have been been unblocked are added to * 'granted' */ static void lf_split(struct lockf *state, struct lockf_entry *lock1, struct lockf_entry *lock2, struct lockf_entry_list *granted) { struct lockf_entry *splitlock; #ifdef LOCKF_DEBUG if (lockf_debug & 2) { lf_print("lf_split", lock1); lf_print("splitting from", lock2); } #endif /* LOCKF_DEBUG */ /* * Check to see if we don't need to split at all. */ if (lock1->lf_start == lock2->lf_start) { lf_set_start(state, lock1, lock2->lf_end + 1, granted); return; } if (lock1->lf_end == lock2->lf_end) { lf_set_end(state, lock1, lock2->lf_start - 1, granted); return; } /* * Make a new lock consisting of the last part of * the encompassing lock. */ splitlock = lf_alloc_lock(lock1->lf_owner); memcpy(splitlock, lock1, sizeof *splitlock); splitlock->lf_refs = 1; if (splitlock->lf_flags & F_REMOTE) vref(splitlock->lf_vnode); /* * This cannot cause a deadlock since any edges we would add * to splitlock already exist in lock1. We must be sure to add * necessary dependencies to splitlock before we reduce lock1 * otherwise we may accidentally grant a pending lock that * was blocked by the tail end of lock1. */ splitlock->lf_start = lock2->lf_end + 1; LIST_INIT(&splitlock->lf_outedges); LIST_INIT(&splitlock->lf_inedges); lf_add_incoming(state, splitlock); lf_set_end(state, lock1, lock2->lf_start - 1, granted); /* * OK, now link it in */ lf_insert_lock(state, splitlock); } struct lockdesc { STAILQ_ENTRY(lockdesc) link; struct vnode *vp; struct flock fl; }; STAILQ_HEAD(lockdesclist, lockdesc); int lf_iteratelocks_sysid(int sysid, lf_iterator *fn, void *arg) { struct lockf *ls; struct lockf_entry *lf; struct lockdesc *ldesc; struct lockdesclist locks; int error; /* * In order to keep the locking simple, we iterate over the * active lock lists to build a list of locks that need * releasing. We then call the iterator for each one in turn. * * We take an extra reference to the vnode for the duration to * make sure it doesn't go away before we are finished. */ STAILQ_INIT(&locks); sx_xlock(&lf_lock_states_lock); LIST_FOREACH(ls, &lf_lock_states, ls_link) { sx_xlock(&ls->ls_lock); LIST_FOREACH(lf, &ls->ls_active, lf_link) { if (lf->lf_owner->lo_sysid != sysid) continue; ldesc = malloc(sizeof(struct lockdesc), M_LOCKF, M_WAITOK); ldesc->vp = lf->lf_vnode; vref(ldesc->vp); ldesc->fl.l_start = lf->lf_start; if (lf->lf_end == OFF_MAX) ldesc->fl.l_len = 0; else ldesc->fl.l_len = lf->lf_end - lf->lf_start + 1; ldesc->fl.l_whence = SEEK_SET; ldesc->fl.l_type = F_UNLCK; ldesc->fl.l_pid = lf->lf_owner->lo_pid; ldesc->fl.l_sysid = sysid; STAILQ_INSERT_TAIL(&locks, ldesc, link); } sx_xunlock(&ls->ls_lock); } sx_xunlock(&lf_lock_states_lock); /* * Call the iterator function for each lock in turn. If the * iterator returns an error code, just free the rest of the * lockdesc structures. */ error = 0; while ((ldesc = STAILQ_FIRST(&locks)) != NULL) { STAILQ_REMOVE_HEAD(&locks, link); if (!error) error = fn(ldesc->vp, &ldesc->fl, arg); vrele(ldesc->vp); free(ldesc, M_LOCKF); } return (error); } int lf_iteratelocks_vnode(struct vnode *vp, lf_iterator *fn, void *arg) { struct lockf *ls; struct lockf_entry *lf; struct lockdesc *ldesc; struct lockdesclist locks; int error; /* * In order to keep the locking simple, we iterate over the * active lock lists to build a list of locks that need * releasing. We then call the iterator for each one in turn. * * We take an extra reference to the vnode for the duration to * make sure it doesn't go away before we are finished. */ STAILQ_INIT(&locks); VI_LOCK(vp); ls = vp->v_lockf; if (!ls) { VI_UNLOCK(vp); return (0); } MPASS(ls->ls_threads >= 0); ls->ls_threads++; VI_UNLOCK(vp); sx_xlock(&ls->ls_lock); LIST_FOREACH(lf, &ls->ls_active, lf_link) { ldesc = malloc(sizeof(struct lockdesc), M_LOCKF, M_WAITOK); ldesc->vp = lf->lf_vnode; vref(ldesc->vp); ldesc->fl.l_start = lf->lf_start; if (lf->lf_end == OFF_MAX) ldesc->fl.l_len = 0; else ldesc->fl.l_len = lf->lf_end - lf->lf_start + 1; ldesc->fl.l_whence = SEEK_SET; ldesc->fl.l_type = F_UNLCK; ldesc->fl.l_pid = lf->lf_owner->lo_pid; ldesc->fl.l_sysid = lf->lf_owner->lo_sysid; STAILQ_INSERT_TAIL(&locks, ldesc, link); } sx_xunlock(&ls->ls_lock); VI_LOCK(vp); MPASS(ls->ls_threads > 0); ls->ls_threads--; wakeup(ls); VI_UNLOCK(vp); /* * Call the iterator function for each lock in turn. If the * iterator returns an error code, just free the rest of the * lockdesc structures. */ error = 0; while ((ldesc = STAILQ_FIRST(&locks)) != NULL) { STAILQ_REMOVE_HEAD(&locks, link); if (!error) error = fn(ldesc->vp, &ldesc->fl, arg); vrele(ldesc->vp); free(ldesc, M_LOCKF); } return (error); } static int lf_clearremotesys_iterator(struct vnode *vp, struct flock *fl, void *arg) { VOP_ADVLOCK(vp, 0, F_UNLCK, fl, F_REMOTE); return (0); } void lf_clearremotesys(int sysid) { KASSERT(sysid != 0, ("Can't clear local locks with F_UNLCKSYS")); lf_iteratelocks_sysid(sysid, lf_clearremotesys_iterator, NULL); } int lf_countlocks(int sysid) { int i; struct lock_owner *lo; int count; count = 0; for (i = 0; i < LOCK_OWNER_HASH_SIZE; i++) { sx_xlock(&lf_lock_owners[i].lock); LIST_FOREACH(lo, &lf_lock_owners[i].list, lo_link) if (lo->lo_sysid == sysid) count += lo->lo_refs; sx_xunlock(&lf_lock_owners[i].lock); } return (count); } #ifdef LOCKF_DEBUG /* * Return non-zero if y is reachable from x using a brute force * search. If reachable and path is non-null, return the route taken * in path. */ static int graph_reaches(struct owner_vertex *x, struct owner_vertex *y, struct owner_vertex_list *path) { struct owner_edge *e; if (x == y) { if (path) TAILQ_INSERT_HEAD(path, x, v_link); return 1; } LIST_FOREACH(e, &x->v_outedges, e_outlink) { if (graph_reaches(e->e_to, y, path)) { if (path) TAILQ_INSERT_HEAD(path, x, v_link); return 1; } } return 0; } /* * Perform consistency checks on the graph. Make sure the values of * v_order are correct. If checkorder is non-zero, check no vertex can * reach any other vertex with a smaller order. */ static void graph_check(struct owner_graph *g, int checkorder) { int i, j; for (i = 0; i < g->g_size; i++) { if (!g->g_vertices[i]->v_owner) continue; KASSERT(g->g_vertices[i]->v_order == i, ("lock graph vertices disordered")); if (checkorder) { for (j = 0; j < i; j++) { if (!g->g_vertices[j]->v_owner) continue; KASSERT(!graph_reaches(g->g_vertices[i], g->g_vertices[j], NULL), ("lock graph vertices disordered")); } } } } static void graph_print_vertices(struct owner_vertex_list *set) { struct owner_vertex *v; printf("{ "); TAILQ_FOREACH(v, set, v_link) { printf("%d:", v->v_order); lf_print_owner(v->v_owner); if (TAILQ_NEXT(v, v_link)) printf(", "); } printf(" }\n"); } #endif /* * Calculate the sub-set of vertices v from the affected region [y..x] * where v is reachable from y. Return -1 if a loop was detected * (i.e. x is reachable from y, otherwise the number of vertices in * this subset. */ static int graph_delta_forward(struct owner_graph *g, struct owner_vertex *x, struct owner_vertex *y, struct owner_vertex_list *delta) { uint32_t gen; struct owner_vertex *v; struct owner_edge *e; int n; /* * We start with a set containing just y. Then for each vertex * v in the set so far unprocessed, we add each vertex that v * has an out-edge to and that is within the affected region * [y..x]. If we see the vertex x on our travels, stop * immediately. */ TAILQ_INIT(delta); TAILQ_INSERT_TAIL(delta, y, v_link); v = y; n = 1; gen = g->g_gen; while (v) { LIST_FOREACH(e, &v->v_outedges, e_outlink) { if (e->e_to == x) return -1; if (e->e_to->v_order < x->v_order && e->e_to->v_gen != gen) { e->e_to->v_gen = gen; TAILQ_INSERT_TAIL(delta, e->e_to, v_link); n++; } } v = TAILQ_NEXT(v, v_link); } return (n); } /* * Calculate the sub-set of vertices v from the affected region [y..x] * where v reaches x. Return the number of vertices in this subset. */ static int graph_delta_backward(struct owner_graph *g, struct owner_vertex *x, struct owner_vertex *y, struct owner_vertex_list *delta) { uint32_t gen; struct owner_vertex *v; struct owner_edge *e; int n; /* * We start with a set containing just x. Then for each vertex * v in the set so far unprocessed, we add each vertex that v * has an in-edge from and that is within the affected region * [y..x]. */ TAILQ_INIT(delta); TAILQ_INSERT_TAIL(delta, x, v_link); v = x; n = 1; gen = g->g_gen; while (v) { LIST_FOREACH(e, &v->v_inedges, e_inlink) { if (e->e_from->v_order > y->v_order && e->e_from->v_gen != gen) { e->e_from->v_gen = gen; TAILQ_INSERT_HEAD(delta, e->e_from, v_link); n++; } } v = TAILQ_PREV(v, owner_vertex_list, v_link); } return (n); } static int graph_add_indices(int *indices, int n, struct owner_vertex_list *set) { struct owner_vertex *v; int i, j; TAILQ_FOREACH(v, set, v_link) { for (i = n; i > 0 && indices[i - 1] > v->v_order; i--) ; for (j = n - 1; j >= i; j--) indices[j + 1] = indices[j]; indices[i] = v->v_order; n++; } return (n); } static int graph_assign_indices(struct owner_graph *g, int *indices, int nextunused, struct owner_vertex_list *set) { struct owner_vertex *v, *vlowest; while (!TAILQ_EMPTY(set)) { vlowest = NULL; TAILQ_FOREACH(v, set, v_link) { if (!vlowest || v->v_order < vlowest->v_order) vlowest = v; } TAILQ_REMOVE(set, vlowest, v_link); vlowest->v_order = indices[nextunused]; g->g_vertices[vlowest->v_order] = vlowest; nextunused++; } return (nextunused); } static int graph_add_edge(struct owner_graph *g, struct owner_vertex *x, struct owner_vertex *y) { struct owner_edge *e; struct owner_vertex_list deltaF, deltaB; int nF, n, vi, i; int *indices; int nB __unused; sx_assert(&lf_owner_graph_lock, SX_XLOCKED); LIST_FOREACH(e, &x->v_outedges, e_outlink) { if (e->e_to == y) { e->e_refs++; return (0); } } #ifdef LOCKF_DEBUG if (lockf_debug & 8) { printf("adding edge %d:", x->v_order); lf_print_owner(x->v_owner); printf(" -> %d:", y->v_order); lf_print_owner(y->v_owner); printf("\n"); } #endif if (y->v_order < x->v_order) { /* * The new edge violates the order. First find the set * of affected vertices reachable from y (deltaF) and * the set of affect vertices affected that reach x * (deltaB), using the graph generation number to * detect whether we have visited a given vertex * already. We re-order the graph so that each vertex * in deltaB appears before each vertex in deltaF. * * If x is a member of deltaF, then the new edge would * create a cycle. Otherwise, we may assume that * deltaF and deltaB are disjoint. */ g->g_gen++; if (g->g_gen == 0) { /* * Generation wrap. */ for (vi = 0; vi < g->g_size; vi++) { g->g_vertices[vi]->v_gen = 0; } g->g_gen++; } nF = graph_delta_forward(g, x, y, &deltaF); if (nF < 0) { #ifdef LOCKF_DEBUG if (lockf_debug & 8) { struct owner_vertex_list path; printf("deadlock: "); TAILQ_INIT(&path); graph_reaches(y, x, &path); graph_print_vertices(&path); } #endif return (EDEADLK); } #ifdef LOCKF_DEBUG if (lockf_debug & 8) { printf("re-ordering graph vertices\n"); printf("deltaF = "); graph_print_vertices(&deltaF); } #endif nB = graph_delta_backward(g, x, y, &deltaB); #ifdef LOCKF_DEBUG if (lockf_debug & 8) { printf("deltaB = "); graph_print_vertices(&deltaB); } #endif /* * We first build a set of vertex indices (vertex * order values) that we may use, then we re-assign * orders first to those vertices in deltaB, then to * deltaF. Note that the contents of deltaF and deltaB * may be partially disordered - we perform an * insertion sort while building our index set. */ indices = g->g_indexbuf; n = graph_add_indices(indices, 0, &deltaF); graph_add_indices(indices, n, &deltaB); /* * We must also be sure to maintain the relative * ordering of deltaF and deltaB when re-assigning * vertices. We do this by iteratively removing the * lowest ordered element from the set and assigning * it the next value from our new ordering. */ i = graph_assign_indices(g, indices, 0, &deltaB); graph_assign_indices(g, indices, i, &deltaF); #ifdef LOCKF_DEBUG if (lockf_debug & 8) { struct owner_vertex_list set; TAILQ_INIT(&set); for (i = 0; i < nB + nF; i++) TAILQ_INSERT_TAIL(&set, g->g_vertices[indices[i]], v_link); printf("new ordering = "); graph_print_vertices(&set); } #endif } KASSERT(x->v_order < y->v_order, ("Failed to re-order graph")); #ifdef LOCKF_DEBUG if (lockf_debug & 8) { graph_check(g, TRUE); } #endif e = malloc(sizeof(struct owner_edge), M_LOCKF, M_WAITOK); LIST_INSERT_HEAD(&x->v_outedges, e, e_outlink); LIST_INSERT_HEAD(&y->v_inedges, e, e_inlink); e->e_refs = 1; e->e_from = x; e->e_to = y; return (0); } /* * Remove an edge x->y from the graph. */ static void graph_remove_edge(struct owner_graph *g, struct owner_vertex *x, struct owner_vertex *y) { struct owner_edge *e; sx_assert(&lf_owner_graph_lock, SX_XLOCKED); LIST_FOREACH(e, &x->v_outedges, e_outlink) { if (e->e_to == y) break; } KASSERT(e, ("Removing non-existent edge from deadlock graph")); e->e_refs--; if (e->e_refs == 0) { #ifdef LOCKF_DEBUG if (lockf_debug & 8) { printf("removing edge %d:", x->v_order); lf_print_owner(x->v_owner); printf(" -> %d:", y->v_order); lf_print_owner(y->v_owner); printf("\n"); } #endif LIST_REMOVE(e, e_outlink); LIST_REMOVE(e, e_inlink); free(e, M_LOCKF); } } /* * Allocate a vertex from the free list. Return ENOMEM if there are * none. */ static struct owner_vertex * graph_alloc_vertex(struct owner_graph *g, struct lock_owner *lo) { struct owner_vertex *v; sx_assert(&lf_owner_graph_lock, SX_XLOCKED); v = malloc(sizeof(struct owner_vertex), M_LOCKF, M_WAITOK); if (g->g_size == g->g_space) { g->g_vertices = realloc(g->g_vertices, 2 * g->g_space * sizeof(struct owner_vertex *), M_LOCKF, M_WAITOK); free(g->g_indexbuf, M_LOCKF); g->g_indexbuf = malloc(2 * g->g_space * sizeof(int), M_LOCKF, M_WAITOK); g->g_space = 2 * g->g_space; } v->v_order = g->g_size; v->v_gen = g->g_gen; g->g_vertices[g->g_size] = v; g->g_size++; LIST_INIT(&v->v_outedges); LIST_INIT(&v->v_inedges); v->v_owner = lo; return (v); } static void graph_free_vertex(struct owner_graph *g, struct owner_vertex *v) { struct owner_vertex *w; int i; sx_assert(&lf_owner_graph_lock, SX_XLOCKED); KASSERT(LIST_EMPTY(&v->v_outedges), ("Freeing vertex with edges")); KASSERT(LIST_EMPTY(&v->v_inedges), ("Freeing vertex with edges")); /* * Remove from the graph's array and close up the gap, * renumbering the other vertices. */ for (i = v->v_order + 1; i < g->g_size; i++) { w = g->g_vertices[i]; w->v_order--; g->g_vertices[i - 1] = w; } g->g_size--; free(v, M_LOCKF); } static struct owner_graph * graph_init(struct owner_graph *g) { g->g_vertices = malloc(10 * sizeof(struct owner_vertex *), M_LOCKF, M_WAITOK); g->g_size = 0; g->g_space = 10; g->g_indexbuf = malloc(g->g_space * sizeof(int), M_LOCKF, M_WAITOK); g->g_gen = 0; return (g); } struct kinfo_lockf_linked { struct kinfo_lockf kl; struct vnode *vp; STAILQ_ENTRY(kinfo_lockf_linked) link; }; int vfs_report_lockf(struct mount *mp, struct sbuf *sb) { struct lockf *ls; struct lockf_entry *lf; struct kinfo_lockf_linked *klf; struct vnode *vp; struct ucred *ucred; char *fullpath, *freepath; struct stat stt; STAILQ_HEAD(, kinfo_lockf_linked) locks; int error, gerror; STAILQ_INIT(&locks); sx_slock(&lf_lock_states_lock); LIST_FOREACH(ls, &lf_lock_states, ls_link) { sx_slock(&ls->ls_lock); LIST_FOREACH(lf, &ls->ls_active, lf_link) { vp = lf->lf_vnode; if (VN_IS_DOOMED(vp) || vp->v_mount != mp) continue; vhold(vp); klf = malloc(sizeof(struct kinfo_lockf_linked), M_LOCKF, M_WAITOK | M_ZERO); klf->vp = vp; klf->kl.kl_structsize = sizeof(struct kinfo_lockf); klf->kl.kl_start = lf->lf_start; klf->kl.kl_len = lf->lf_end == OFF_MAX ? 0 : lf->lf_end - lf->lf_start + 1; klf->kl.kl_rw = lf->lf_type == F_RDLCK ? KLOCKF_RW_READ : KLOCKF_RW_WRITE; if (lf->lf_owner->lo_sysid != 0) { klf->kl.kl_pid = lf->lf_owner->lo_pid; klf->kl.kl_sysid = lf->lf_owner->lo_sysid; klf->kl.kl_type = KLOCKF_TYPE_REMOTE; } else if (lf->lf_owner->lo_pid == -1) { klf->kl.kl_pid = -1; klf->kl.kl_sysid = 0; klf->kl.kl_type = KLOCKF_TYPE_FLOCK; } else { klf->kl.kl_pid = lf->lf_owner->lo_pid; klf->kl.kl_sysid = 0; klf->kl.kl_type = KLOCKF_TYPE_PID; } STAILQ_INSERT_TAIL(&locks, klf, link); } sx_sunlock(&ls->ls_lock); } sx_sunlock(&lf_lock_states_lock); gerror = 0; ucred = curthread->td_ucred; while ((klf = STAILQ_FIRST(&locks)) != NULL) { STAILQ_REMOVE_HEAD(&locks, link); vp = klf->vp; if (gerror == 0 && vn_lock(vp, LK_SHARED) == 0) { error = prison_canseemount(ucred, vp->v_mount); if (error == 0) error = VOP_STAT(vp, &stt, ucred, NOCRED); VOP_UNLOCK(vp); if (error == 0) { klf->kl.kl_file_fsid = stt.st_dev; klf->kl.kl_file_rdev = stt.st_rdev; klf->kl.kl_file_fileid = stt.st_ino; freepath = NULL; fullpath = "-"; error = vn_fullpath(vp, &fullpath, &freepath); if (error == 0) strlcpy(klf->kl.kl_path, fullpath, sizeof(klf->kl.kl_path)); free(freepath, M_TEMP); if (sbuf_bcat(sb, &klf->kl, klf->kl.kl_structsize) != 0) { gerror = sbuf_error(sb); } } } vdrop(vp); free(klf, M_LOCKF); } return (gerror); } static int sysctl_kern_lockf_run(struct sbuf *sb) { struct mount *mp; int error; error = 0; mtx_lock(&mountlist_mtx); TAILQ_FOREACH(mp, &mountlist, mnt_list) { error = vfs_busy(mp, MBF_MNTLSTLOCK); if (error != 0) continue; error = mp->mnt_op->vfs_report_lockf(mp, sb); mtx_lock(&mountlist_mtx); vfs_unbusy(mp); if (error != 0) break; } mtx_unlock(&mountlist_mtx); return (error); } static int sysctl_kern_lockf(SYSCTL_HANDLER_ARGS) { struct sbuf sb; int error, error2; sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_lockf) * 5, req); sbuf_clear_flags(&sb, SBUF_INCLUDENUL); error = sysctl_kern_lockf_run(&sb); error2 = sbuf_finish(&sb); sbuf_delete(&sb); return (error != 0 ? error : error2); } SYSCTL_PROC(_kern, KERN_LOCKF, lockf, CTLTYPE_OPAQUE | CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 0, sysctl_kern_lockf, "S,lockf", "Advisory locks table"); #ifdef LOCKF_DEBUG /* * Print description of a lock owner */ static void lf_print_owner(struct lock_owner *lo) { if (lo->lo_flags & F_REMOTE) { printf("remote pid %d, system %d", lo->lo_pid, lo->lo_sysid); } else if (lo->lo_flags & F_FLOCK) { printf("file %p", lo->lo_id); } else { printf("local pid %d", lo->lo_pid); } } /* * Print out a lock. */ static void lf_print(char *tag, struct lockf_entry *lock) { printf("%s: lock %p for ", tag, (void *)lock); lf_print_owner(lock->lf_owner); printf("\nvnode %p", lock->lf_vnode); VOP_PRINT(lock->lf_vnode); printf(" %s, start %jd, end ", lock->lf_type == F_RDLCK ? "shared" : lock->lf_type == F_WRLCK ? "exclusive" : lock->lf_type == F_UNLCK ? "unlock" : "unknown", (intmax_t)lock->lf_start); if (lock->lf_end == OFF_MAX) printf("EOF"); else printf("%jd", (intmax_t)lock->lf_end); if (!LIST_EMPTY(&lock->lf_outedges)) printf(" block %p\n", (void *)LIST_FIRST(&lock->lf_outedges)->le_to); else printf("\n"); } static void lf_printlist(char *tag, struct lockf_entry *lock) { struct lockf_entry *lf, *blk; struct lockf_edge *e; printf("%s: Lock list for vnode %p:\n", tag, lock->lf_vnode); LIST_FOREACH(lf, &lock->lf_vnode->v_lockf->ls_active, lf_link) { printf("\tlock %p for ",(void *)lf); lf_print_owner(lock->lf_owner); printf(", %s, start %jd, end %jd", lf->lf_type == F_RDLCK ? "shared" : lf->lf_type == F_WRLCK ? "exclusive" : lf->lf_type == F_UNLCK ? "unlock" : "unknown", (intmax_t)lf->lf_start, (intmax_t)lf->lf_end); LIST_FOREACH(e, &lf->lf_outedges, le_outlink) { blk = e->le_to; printf("\n\t\tlock request %p for ", (void *)blk); lf_print_owner(blk->lf_owner); printf(", %s, start %jd, end %jd", blk->lf_type == F_RDLCK ? "shared" : blk->lf_type == F_WRLCK ? "exclusive" : blk->lf_type == F_UNLCK ? "unlock" : "unknown", (intmax_t)blk->lf_start, (intmax_t)blk->lf_end); if (!LIST_EMPTY(&blk->lf_inedges)) panic("lf_printlist: bad list"); } printf("\n"); } } #endif /* LOCKF_DEBUG */