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 26 /* 27 * Utility routines and top-level conflict detection code for NBMAND 28 * locks. 29 */ 30 31 #include <sys/nbmlock.h> 32 #include <sys/rwlock.h> 33 #include <sys/vnode.h> 34 #include <sys/cmn_err.h> 35 #include <sys/types.h> 36 #include <sys/fcntl.h> 37 #include <sys/vfs.h> 38 39 /* 40 * Enter the critical region for synchronizing I/O requests with lock/share 41 * requests. "mode" specifies whether the caller intends to update 42 * lock/share state (as opposed to just query it). 43 */ 44 45 void 46 nbl_start_crit(vnode_t *vp, krw_t mode) 47 { 48 rw_enter(&vp->v_nbllock, mode); 49 } 50 51 /* 52 * Leave the critical region. 53 */ 54 55 void 56 nbl_end_crit(vnode_t *vp) 57 { 58 rw_exit(&vp->v_nbllock); 59 } 60 61 /* 62 * Return non-zero if some thread is in the critical region. 63 * Note that this is appropriate for use in ASSERT()s only. 64 */ 65 66 int 67 nbl_in_crit(vnode_t *vp) 68 { 69 return (RW_LOCK_HELD(&vp->v_nbllock)); 70 } 71 72 /* 73 * Returns non-zero if we need to look further for an NBMAND lock or 74 * share conflict. 75 */ 76 int 77 nbl_need_check(vnode_t *vp) 78 { 79 /* 80 * Currently we only check if NBMAND locks/shares are allowed on 81 * the filesystem. An option for the future would be to have a 82 * flag on the vnode, though the locking for that can get tricky. 83 */ 84 return ((vp->v_vfsp) && (vp->v_vfsp->vfs_flag & VFS_NBMAND)); 85 } 86 87 /* 88 * Top-level conflict detection routine. The arguments describe the 89 * operation that is being attempted. If the operation conflicts with an 90 * existing lock or share reservation, a non-zero value is returned. If 91 * the operation is allowed, zero is returned. Note that there is an 92 * implicit argument, which is the process ID of the requester. 93 * 94 * svmand indicates that the file has System V mandatory locking enabled, 95 * so we should look at all record locks, not just NBMAND record locks. 96 * (This is to avoid a deadlock between a process making an I/O request and 97 * a process trying to release a lock. Instead of letting the first 98 * process block in the filesystem code, we flag a conflict here.) 99 */ 100 101 int 102 nbl_conflict(vnode_t *vp, 103 nbl_op_t op, /* attempted operation */ 104 u_offset_t offset, /* ignore if not I/O */ 105 ssize_t length, /* ignore if not I/O */ 106 int svmand, /* System V mandatory locking */ 107 caller_context_t *ct) /* caller context */ 108 { 109 ASSERT(nbl_in_crit(vp)); 110 ASSERT(op == NBL_READ || op == NBL_WRITE || op == NBL_RENAME || 111 op == NBL_REMOVE || op == NBL_READWRITE); 112 113 if (nbl_share_conflict(vp, op, ct)) { 114 return (1); 115 } 116 117 /* 118 * If this is not an I/O request, there's no need to check against 119 * the locks on the file. 120 */ 121 if (op == NBL_REMOVE || op == NBL_RENAME) 122 return (0); 123 124 return (nbl_lock_conflict(vp, op, offset, length, svmand, ct)); 125 } 126 127 /* 128 * Determine if the given file has mode bits for System V mandatory locks. 129 * If there was an error, the errno value is returned. Otherwise, zero is 130 * returned and *svp is set appropriately (non-zero for mandatory locks, 131 * zero for no mandatory locks). 132 */ 133 134 int 135 nbl_svmand(vnode_t *vp, cred_t *cr, int *svp) 136 { 137 struct vattr va; 138 int error; 139 140 va.va_mask = AT_MODE; 141 error = VOP_GETATTR(vp, &va, 0, cr, NULL); 142 if (error != 0) 143 return (error); 144 145 *svp = MANDLOCK(vp, va.va_mode); 146 return (0); 147 } 148