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 (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #pragma ident "%Z%%M% %I% %E% SMI" 27 28 /* 29 * Utility routines and top-level conflict detection code for NBMAND 30 * locks. 31 */ 32 33 #include <sys/nbmlock.h> 34 #include <sys/rwlock.h> 35 #include <sys/vnode.h> 36 #include <sys/cmn_err.h> 37 #include <sys/types.h> 38 #include <sys/fcntl.h> 39 #include <sys/vfs.h> 40 41 /* 42 * Enter the critical region for synchronizing I/O requests with lock/share 43 * requests. "mode" specifies whether the caller intends to update 44 * lock/share state (as opposed to just query it). 45 */ 46 47 void 48 nbl_start_crit(vnode_t *vp, krw_t mode) 49 { 50 rw_enter(&vp->v_nbllock, mode); 51 } 52 53 /* 54 * Leave the critical region. 55 */ 56 57 void 58 nbl_end_crit(vnode_t *vp) 59 { 60 rw_exit(&vp->v_nbllock); 61 } 62 63 /* 64 * Return non-zero if some thread is in the critical region. 65 * Note that this is appropriate for use in ASSERT()s only. 66 */ 67 68 int 69 nbl_in_crit(vnode_t *vp) 70 { 71 return (RW_LOCK_HELD(&vp->v_nbllock)); 72 } 73 74 /* 75 * Return the nbl_op_t that corresponds to the given lock type (read or 76 * write). 77 */ 78 79 nbl_op_t 80 nbl_lock_to_op(int lock_type) 81 { 82 int level; 83 84 switch (lock_type) { 85 case F_WRLCK: 86 return (NBL_READWRITE); 87 case F_RDLCK: 88 return (NBL_READ); 89 default: 90 #ifdef DEBUG 91 level = CE_PANIC; 92 #else 93 level = CE_WARN; 94 #endif 95 cmn_err(level, "unexpected lock type: %d\n", lock_type); 96 return (NBL_WRITE); /* pick something restrictive */ 97 } 98 /*NOTREACHED*/ 99 } 100 101 /* 102 * Returns non-zero if we need to look further for an NBMAND lock or 103 * share conflict. 104 */ 105 int 106 nbl_need_check(vnode_t *vp) 107 { 108 /* 109 * Currently we only check if NBMAND locks/shares are allowed on 110 * the filesystem. An option for the future would be to have a 111 * flag on the vnode, though the locking for that can get tricky. 112 */ 113 return ((vp->v_vfsp) && (vp->v_vfsp->vfs_flag & VFS_NBMAND)); 114 } 115 116 /* 117 * Top-level conflict detection routine. The arguments describe the 118 * operation that is being attempted. If the operation conflicts with an 119 * existing lock or share reservation, a non-zero value is returned. If 120 * the operation is allowed, zero is returned. Note that there is an 121 * implicit argument, which is the process ID of the requester. 122 * 123 * svmand indicates that the file has System V mandatory locking enabled, 124 * so we should look at all record locks, not just NBMAND record locks. 125 * (This is to avoid a deadlock between a process making an I/O request and 126 * a process trying to release a lock. Instead of letting the first 127 * process block in the filesystem code, we flag a conflict here.) 128 */ 129 130 int 131 nbl_conflict(vnode_t *vp, 132 nbl_op_t op, /* attempted operation */ 133 u_offset_t offset, /* ignore if not I/O */ 134 ssize_t length, /* ignore if not I/O */ 135 int svmand, /* System V mandatory locking */ 136 caller_context_t *ct) /* caller context */ 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, ct)) { 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, ct)); 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, NULL); 171 if (error != 0) 172 return (error); 173 174 *svp = MANDLOCK(vp, va.va_mode); 175 return (0); 176 } 177