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
nbl_start_crit(vnode_t * vp,krw_t mode)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
nbl_end_crit(vnode_t * vp)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
nbl_in_crit(vnode_t * vp)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
nbl_need_check(vnode_t * vp)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
nbl_conflict(vnode_t * vp,nbl_op_t op,u_offset_t offset,ssize_t length,int svmand,caller_context_t * ct)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
nbl_svmand(vnode_t * vp,cred_t * cr,int * svp)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
nbl_share_conflict(vnode_t * vp,nbl_op_t op,caller_context_t * ct)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
nbl_lock_conflict(vnode_t * vp,nbl_op_t op,u_offset_t offset,ssize_t length,int svmand,caller_context_t * ct)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