blob: 16088e175ecc3dd5f99811e8408a0febb3135fcf [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (c) 2000-2003 Silicon Graphics, Inc. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of version 2 of the GNU General Public License as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it would be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
11 *
12 * Further, this software is distributed without any warranty that it is
13 * free of the rightful claim of any third person regarding infringement
14 * or the like. Any license provided herein, whether implied or
15 * otherwise, applies only to this software file. Patent licenses, if
16 * any, provided herein do not apply to combinations of this program with
17 * other software, or any other product whatsoever.
18 *
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write the Free Software Foundation, Inc., 59
21 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
22 *
23 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
24 * Mountain View, CA 94043, or:
25 *
26 * http://www.sgi.com
27 *
28 * For further information regarding this notice, see:
29 *
30 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
31 *
32 */
33#include "xfs.h"
34
35/*
36 * Source file used to associate/disassociate behaviors with virtualized
37 * objects. See xfs_behavior.h for more information about behaviors, etc.
38 *
39 * The implementation is split between functions in this file and macros
40 * in xfs_behavior.h.
41 */
42
43/*
44 * Insert a new behavior descriptor into a behavior chain.
45 *
46 * The behavior chain is ordered based on the 'position' number which
47 * lives in the first field of the ops vector (higher numbers first).
48 *
49 * Attemps to insert duplicate ops result in an EINVAL return code.
50 * Otherwise, return 0 to indicate success.
51 */
52int
53bhv_insert(bhv_head_t *bhp, bhv_desc_t *bdp)
54{
55 bhv_desc_t *curdesc, *prev;
56 int position;
57
58 /*
59 * Validate the position value of the new behavior.
60 */
61 position = BHV_POSITION(bdp);
62 ASSERT(position >= BHV_POSITION_BASE && position <= BHV_POSITION_TOP);
63
64 /*
65 * Find location to insert behavior. Check for duplicates.
66 */
67 prev = NULL;
68 for (curdesc = bhp->bh_first;
69 curdesc != NULL;
70 curdesc = curdesc->bd_next) {
71
72 /* Check for duplication. */
73 if (curdesc->bd_ops == bdp->bd_ops) {
74 ASSERT(0);
75 return EINVAL;
76 }
77
78 /* Find correct position */
79 if (position >= BHV_POSITION(curdesc)) {
80 ASSERT(position != BHV_POSITION(curdesc));
81 break; /* found it */
82 }
83
84 prev = curdesc;
85 }
86
87 if (prev == NULL) {
88 /* insert at front of chain */
89 bdp->bd_next = bhp->bh_first;
90 bhp->bh_first = bdp;
91 } else {
92 /* insert after prev */
93 bdp->bd_next = prev->bd_next;
94 prev->bd_next = bdp;
95 }
96
97 return 0;
98}
99
100/*
101 * Remove a behavior descriptor from a position in a behavior chain;
102 * the postition is guaranteed not to be the first position.
103 * Should only be called by the bhv_remove() macro.
104 */
105void
106bhv_remove_not_first(bhv_head_t *bhp, bhv_desc_t *bdp)
107{
108 bhv_desc_t *curdesc, *prev;
109
110 ASSERT(bhp->bh_first != NULL);
111 ASSERT(bhp->bh_first->bd_next != NULL);
112
113 prev = bhp->bh_first;
114 for (curdesc = bhp->bh_first->bd_next;
115 curdesc != NULL;
116 curdesc = curdesc->bd_next) {
117
118 if (curdesc == bdp)
119 break; /* found it */
120 prev = curdesc;
121 }
122
123 ASSERT(curdesc == bdp);
124 prev->bd_next = bdp->bd_next; /* remove from after prev */
125}
126
127/*
128 * Look for a specific ops vector on the specified behavior chain.
129 * Return the associated behavior descriptor. Or NULL, if not found.
130 */
131bhv_desc_t *
132bhv_lookup(bhv_head_t *bhp, void *ops)
133{
134 bhv_desc_t *curdesc;
135
136 for (curdesc = bhp->bh_first;
137 curdesc != NULL;
138 curdesc = curdesc->bd_next) {
139
140 if (curdesc->bd_ops == ops)
141 return curdesc;
142 }
143
144 return NULL;
145}
146
147/*
148 * Looks for the first behavior within a specified range of positions.
149 * Return the associated behavior descriptor. Or NULL, if none found.
150 */
151bhv_desc_t *
152bhv_lookup_range(bhv_head_t *bhp, int low, int high)
153{
154 bhv_desc_t *curdesc;
155
156 for (curdesc = bhp->bh_first;
157 curdesc != NULL;
158 curdesc = curdesc->bd_next) {
159
160 int position = BHV_POSITION(curdesc);
161
162 if (position <= high) {
163 if (position >= low)
164 return curdesc;
165 return NULL;
166 }
167 }
168
169 return NULL;
170}
171
172/*
173 * Return the base behavior in the chain, or NULL if the chain
174 * is empty.
175 *
176 * The caller has not read locked the behavior chain, so acquire the
177 * lock before traversing the chain.
178 */
179bhv_desc_t *
180bhv_base(bhv_head_t *bhp)
181{
182 bhv_desc_t *curdesc;
183
184 for (curdesc = bhp->bh_first;
185 curdesc != NULL;
186 curdesc = curdesc->bd_next) {
187
188 if (curdesc->bd_next == NULL) {
189 return curdesc;
190 }
191 }
192
193 return NULL;
194}
195
196void
197bhv_head_init(
198 bhv_head_t *bhp,
199 char *name)
200{
201 bhp->bh_first = NULL;
202}
203
204void
205bhv_insert_initial(
206 bhv_head_t *bhp,
207 bhv_desc_t *bdp)
208{
209 ASSERT(bhp->bh_first == NULL);
210 (bhp)->bh_first = bdp;
211}
212
213void
214bhv_head_destroy(
215 bhv_head_t *bhp)
216{
217 ASSERT(bhp->bh_first == NULL);
218}