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 2008 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 * 25 * Copyright 2013 Nexenta Systems, Inc. All rights reserved. 26 */ 27 28 /* 29 * Utility routines and top-level conflict detection code for NBMAND 30 * locks. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/cmn_err.h> 35 #include <sys/debug.h> 36 #include <sys/fcntl.h> 37 #include <sys/rwlock.h> 38 #include <sys/vnode.h> 39 #include <sys/vfs.h> 40 #include <sys/nbmlock.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 * Returns non-zero if we need to look further for an NBMAND lock or 77 * share conflict. 78 */ 79 /* ARGSUSED */ 80 int 81 nbl_need_check(vnode_t *vp) 82 { 83 /* 84 * Currently we only check if NBMAND locks/shares are allowed on 85 * the filesystem. An option for the future would be to have a 86 * flag on the vnode, though the locking for that can get tricky. 87 */ 88 /* (vp->v_vfsp) && (vp->v_vfsp->vfs_flag & VFS_NBMAND)) */ 89 return (0); 90 } 91 92 /* 93 * Top-level conflict detection routine. The arguments describe the 94 * operation that is being attempted. If the operation conflicts with an 95 * existing lock or share reservation, a non-zero value is returned. If 96 * the operation is allowed, zero is returned. Note that there is an 97 * implicit argument, which is the process ID of the requester. 98 * 99 * svmand indicates that the file has System V mandatory locking enabled, 100 * so we should look at all record locks, not just NBMAND record locks. 101 * (This is to avoid a deadlock between a process making an I/O request and 102 * a process trying to release a lock. Instead of letting the first 103 * process block in the filesystem code, we flag a conflict here.) 104 */ 105 106 int 107 nbl_conflict(vnode_t *vp, 108 nbl_op_t op, /* attempted operation */ 109 u_offset_t offset, /* ignore if not I/O */ 110 ssize_t length, /* ignore if not I/O */ 111 int svmand, /* System V mandatory locking */ 112 caller_context_t *ct) /* caller context */ 113 { 114 ASSERT(nbl_in_crit(vp)); 115 ASSERT(op == NBL_READ || op == NBL_WRITE || op == NBL_RENAME || 116 op == NBL_REMOVE || op == NBL_READWRITE); 117 118 if (nbl_share_conflict(vp, op, ct)) { 119 return (1); 120 } 121 122 /* 123 * If this is not an I/O request, there's no need to check against 124 * the locks on the file. 125 */ 126 if (op == NBL_REMOVE || op == NBL_RENAME) 127 return (0); 128 129 return (nbl_lock_conflict(vp, op, offset, length, svmand, ct)); 130 } 131 132 /* 133 * Determine if the given file has mode bits for System V mandatory locks. 134 * If there was an error, the errno value is returned. Otherwise, zero is 135 * returned and *svp is set appropriately (non-zero for mandatory locks, 136 * zero for no mandatory locks). 137 */ 138 139 int 140 nbl_svmand(vnode_t *vp, cred_t *cr, int *svp) 141 { 142 struct vattr va; 143 int error; 144 145 va.va_mask = AT_MODE; 146 error = VOP_GETATTR(vp, &va, 0, cr, NULL); 147 if (error != 0) 148 return (error); 149 150 *svp = MANDLOCK(vp, va.va_mode); 151 return (0); 152 } 153 154 /* 155 * The kernel handles this for us when we actually try I/O. 156 */ 157 /* ARGSUSED */ 158 int 159 nbl_share_conflict(vnode_t *vp, nbl_op_t op, caller_context_t *ct) 160 { 161 return (0); 162 } 163 164 /* 165 * The kernel handles this for us when we actually try I/O. 166 */ 167 /* ARGSUSED */ 168 int 169 nbl_lock_conflict(vnode_t *vp, nbl_op_t op, u_offset_t offset, 170 ssize_t length, int svmand, caller_context_t *ct) 171 { 172 return (0); 173 } 174