1/*
2 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
3 * All Rights Reserved.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17 */
18#include "xfs.h"
19
20/*
21 * Source file used to associate/disassociate behaviors with virtualized
22 * objects.  See xfs_behavior.h for more information about behaviors, etc.
23 *
24 * The implementation is split between functions in this file and macros
25 * in xfs_behavior.h.
26 */
27
28/*
29 * Insert a new behavior descriptor into a behavior chain.
30 *
31 * The behavior chain is ordered based on the 'position' number which
32 * lives in the first field of the ops vector (higher numbers first).
33 *
34 * Attempts to insert duplicate ops result in an EINVAL return code.
35 * Otherwise, return 0 to indicate success.
36 */
37int
38bhv_insert(bhv_head_t *bhp, bhv_desc_t *bdp)
39{
40	bhv_desc_t	*curdesc, *prev;
41	int		position;
42
43	/*
44	 * Validate the position value of the new behavior.
45	 */
46	position = BHV_POSITION(bdp);
47	ASSERT(position >= BHV_POSITION_BASE && position <= BHV_POSITION_TOP);
48
49	/*
50	 * Find location to insert behavior.  Check for duplicates.
51	 */
52	prev = NULL;
53	for (curdesc = bhp->bh_first;
54	     curdesc != NULL;
55	     curdesc = curdesc->bd_next) {
56
57		/* Check for duplication. */
58		if (curdesc->bd_ops == bdp->bd_ops) {
59			ASSERT(0);
60			return EINVAL;
61		}
62
63		/* Find correct position */
64		if (position >= BHV_POSITION(curdesc)) {
65			ASSERT(position != BHV_POSITION(curdesc));
66			break;		/* found it */
67		}
68
69		prev = curdesc;
70	}
71
72	if (prev == NULL) {
73		/* insert at front of chain */
74		bdp->bd_next = bhp->bh_first;
75		bhp->bh_first = bdp;
76	} else {
77		/* insert after prev */
78		bdp->bd_next = prev->bd_next;
79		prev->bd_next = bdp;
80	}
81
82	return 0;
83}
84
85/*
86 * Remove a behavior descriptor from a position in a behavior chain;
87 * the position is guaranteed not to be the first position.
88 * Should only be called by the bhv_remove() macro.
89 */
90void
91bhv_remove_not_first(bhv_head_t *bhp, bhv_desc_t *bdp)
92{
93	bhv_desc_t	*curdesc, *prev;
94
95	ASSERT(bhp->bh_first != NULL);
96	ASSERT(bhp->bh_first->bd_next != NULL);
97
98	prev = bhp->bh_first;
99	for (curdesc = bhp->bh_first->bd_next;
100	     curdesc != NULL;
101	     curdesc = curdesc->bd_next) {
102
103		if (curdesc == bdp)
104			break;		/* found it */
105		prev = curdesc;
106	}
107
108	ASSERT(curdesc == bdp);
109	prev->bd_next = bdp->bd_next;	/* remove from after prev */
110}
111
112/*
113 * Looks for the first behavior within a specified range of positions.
114 * Return the associated behavior descriptor.  Or NULL, if none found.
115 */
116bhv_desc_t *
117bhv_lookup_range(bhv_head_t *bhp, int low, int high)
118{
119	bhv_desc_t	*curdesc;
120
121	for (curdesc = bhp->bh_first;
122	     curdesc != NULL;
123	     curdesc = curdesc->bd_next) {
124
125		int	position = BHV_POSITION(curdesc);
126
127		if (position <= high) {
128			if (position >= low)
129				return curdesc;
130			return NULL;
131		}
132	}
133
134	return NULL;
135}
136
137/*
138 * Return the base behavior in the chain, or NULL if the chain
139 * is empty.
140 *
141 * The caller has not read locked the behavior chain, so acquire the
142 * lock before traversing the chain.
143 */
144bhv_desc_t *
145bhv_base(bhv_head_t *bhp)
146{
147	bhv_desc_t	*curdesc;
148
149	for (curdesc = bhp->bh_first;
150	     curdesc != NULL;
151	     curdesc = curdesc->bd_next) {
152
153		if (curdesc->bd_next == NULL) {
154			return curdesc;
155		}
156	}
157
158	return NULL;
159}
160
161void
162bhv_head_init(
163	bhv_head_t *bhp,
164	char *name)
165{
166	bhp->bh_first = NULL;
167}
168
169void
170bhv_insert_initial(
171	bhv_head_t *bhp,
172	bhv_desc_t *bdp)
173{
174	ASSERT(bhp->bh_first == NULL);
175	(bhp)->bh_first = bdp;
176}
177
178void
179bhv_head_destroy(
180	bhv_head_t *bhp)
181{
182	ASSERT(bhp->bh_first == NULL);
183}
184