1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright (c) 2001 by Sun Microsystems, Inc. 24 * All rights reserved. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* 30 * Utility routines and top-level conflict detection code for NBMAND 31 * locks. 32 */ 33 34 #include <sys/nbmlock.h> 35 #include <sys/rwlock.h> 36 #include <sys/vnode.h> 37 #include <sys/cmn_err.h> 38 #include <sys/types.h> 39 #include <sys/fcntl.h> 40 #include <sys/vfs.h> 41 42 /* 43 * Enter the critical region for synchronizing I/O requests with lock/share 44 * requests. "mode" specifies whether the caller intends to update 45 * lock/share state (as opposed to just query it). 46 */ 47 48 void 49 nbl_start_crit(vnode_t *vp, krw_t mode) 50 { 51 rw_enter(&vp->v_nbllock, mode); 52 } 53 54 /* 55 * Leave the critical region. 56 */ 57 58 void 59 nbl_end_crit(vnode_t *vp) 60 { 61 rw_exit(&vp->v_nbllock); 62 } 63 64 /* 65 * Return non-zero if some thread is in the critical region. 66 * Note that this is appropriate for use in ASSERT()s only. 67 */ 68 69 int 70 nbl_in_crit(vnode_t *vp) 71 { 72 return (RW_LOCK_HELD(&vp->v_nbllock)); 73 } 74 75 /* 76 * Return the nbl_op_t that corresponds to the given lock type (read or 77 * write). 78 */ 79 80 nbl_op_t 81 nbl_lock_to_op(int lock_type) 82 { 83 int level; 84 85 switch (lock_type) { 86 case F_WRLCK: 87 return (NBL_READWRITE); 88 case F_RDLCK: 89 return (NBL_READ); 90 default: 91 #ifdef DEBUG 92 level = CE_PANIC; 93 #else 94 level = CE_WARN; 95 #endif 96 cmn_err(level, "unexpected lock type: %d\n", lock_type); 97 return (NBL_WRITE); /* pick something restrictive */ 98 } 99 /*NOTREACHED*/ 100 } 101 102 /* 103 * Returns non-zero if we need to look further for an NBMAND lock or 104 * share conflict. 105 */ 106 int 107 nbl_need_check(vnode_t *vp) 108 { 109 /* 110 * Currently we only check if NBMAND locks/shares are allowed on 111 * the filesystem. An option for the future would be to have a 112 * flag on the vnode, though the locking for that can get tricky. 113 */ 114 return ((vp->v_vfsp) && (vp->v_vfsp->vfs_flag & VFS_NBMAND)); 115 } 116 117 /* 118 * Top-level conflict detection routine. The arguments describe the 119 * operation that is being attempted. If the operation conflicts with an 120 * existing lock or share reservation, a non-zero value is returned. If 121 * the operation is allowed, zero is returned. Note that there is an 122 * implicit argument, which is the process ID of the requester. 123 * 124 * svmand indicates that the file has System V mandatory locking enabled, 125 * so we should look at all record locks, not just NBMAND record locks. 126 * (This is to avoid a deadlock between a process making an I/O request and 127 * a process trying to release a lock. Instead of letting the first 128 * process block in the filesystem code, we flag a conflict here.) 129 */ 130 131 int 132 nbl_conflict(vnode_t *vp, 133 nbl_op_t op, /* attempted operation */ 134 u_offset_t offset, /* ignore if not I/O */ 135 ssize_t length, /* ignore if not I/O */ 136 int svmand) /* System V mandatory locking */ 137 { 138 ASSERT(nbl_in_crit(vp)); 139 ASSERT(op == NBL_READ || op == NBL_WRITE || op == NBL_RENAME || 140 op == NBL_REMOVE || op == NBL_READWRITE); 141 142 if (nbl_share_conflict(vp, op)) { 143 return (1); 144 } 145 146 /* 147 * If this is not an I/O request, there's no need to check against 148 * the locks on the file. 149 */ 150 if (op == NBL_REMOVE || op == NBL_RENAME) 151 return (0); 152 153 return (nbl_lock_conflict(vp, op, offset, length, svmand)); 154 } 155 156 /* 157 * Determine if the given file has mode bits for System V mandatory locks. 158 * If there was an error, the errno value is returned. Otherwise, zero is 159 * returned and *svp is set appropriately (non-zero for mandatory locks, 160 * zero for no mandatory locks). 161 */ 162 163 int 164 nbl_svmand(vnode_t *vp, cred_t *cr, int *svp) 165 { 166 struct vattr va; 167 int error; 168 169 va.va_mask = AT_MODE; 170 error = VOP_GETATTR(vp, &va, 0, cr); 171 if (error != 0) 172 return (error); 173 174 *svp = MANDLOCK(vp, va.va_mode); 175 return (0); 176 } 177