1 /*	$NetBSD: snapshot_manip.c,v 1.1.1.3 2009/12/02 00:26:37 haad Exp $	*/
2 
3 /*
4  * Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
5  * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
6  *
7  * This file is part of LVM2.
8  *
9  * This copyrighted material is made available to anyone wishing to use,
10  * modify, copy, or redistribute it subject to the terms and conditions
11  * of the GNU Lesser General Public License v.2.1.
12  *
13  * You should have received a copy of the GNU Lesser General Public License
14  * along with this program; if not, write to the Free Software Foundation,
15  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
16  */
17 
18 #include "lib.h"
19 #include "metadata.h"
20 #include "toolcontext.h"
21 #include "lv_alloc.h"
22 
23 int lv_is_origin(const struct logical_volume *lv)
24 {
25 	return lv->origin_count ? 1 : 0;
26 }
27 
28 int lv_is_cow(const struct logical_volume *lv)
29 {
30 	return lv->snapshot ? 1 : 0;
31 }
32 
33 int lv_is_visible(const struct logical_volume *lv)
34 {
35 	if (lv->status & SNAPSHOT)
36 		return 0;
37 
38 	if (lv_is_cow(lv)) {
39 		if (lv_is_virtual_origin(origin_from_cow(lv)))
40 			return 1;
41 
42 		return lv_is_visible(origin_from_cow(lv));
43 	}
44 
45 	return lv->status & VISIBLE_LV ? 1 : 0;
46 }
47 
48 int lv_is_virtual_origin(const struct logical_volume *lv)
49 {
50 	return (lv->status & VIRTUAL_ORIGIN) ? 1 : 0;
51 }
52 
53 
54 /* Given a cow LV, return the snapshot lv_segment that uses it */
55 struct lv_segment *find_cow(const struct logical_volume *lv)
56 {
57 	return lv->snapshot;
58 }
59 
60 /* Given a cow LV, return its origin */
61 struct logical_volume *origin_from_cow(const struct logical_volume *lv)
62 {
63 	return lv->snapshot->origin;
64 }
65 
66 void init_snapshot_seg(struct lv_segment *seg, struct logical_volume *origin,
67 		       struct logical_volume *cow, uint32_t chunk_size)
68 {
69 	seg->chunk_size = chunk_size;
70 	seg->origin = origin;
71 	seg->cow = cow;
72 
73 	lv_set_hidden(cow);
74 
75 	cow->snapshot = seg;
76 
77 	origin->origin_count++;
78 
79 	/* FIXME Assumes an invisible origin belongs to a sparse device */
80 	if (!lv_is_visible(origin))
81 		origin->status |= VIRTUAL_ORIGIN;
82 
83 	seg->lv->status |= (SNAPSHOT | VIRTUAL);
84 
85 	dm_list_add(&origin->snapshot_segs, &seg->origin_list);
86 }
87 
88 int vg_add_snapshot(struct logical_volume *origin,
89 		    struct logical_volume *cow, union lvid *lvid,
90 		    uint32_t extent_count, uint32_t chunk_size)
91 {
92 	struct logical_volume *snap;
93 	struct lv_segment *seg;
94 
95 	/*
96 	 * Is the cow device already being used ?
97 	 */
98 	if (lv_is_cow(cow)) {
99 		log_error("'%s' is already in use as a snapshot.", cow->name);
100 		return 0;
101 	}
102 
103 	if (cow == origin) {
104 		log_error("Snapshot and origin LVs must differ.");
105 		return 0;
106 	}
107 
108 	if (!(snap = lv_create_empty("snapshot%d",
109 				     lvid, LVM_READ | LVM_WRITE | VISIBLE_LV,
110 				     ALLOC_INHERIT, origin->vg)))
111 		return_0;
112 
113 	snap->le_count = extent_count;
114 
115 	if (!(seg = alloc_snapshot_seg(snap, 0, 0)))
116 		return_0;
117 
118 	init_snapshot_seg(seg, origin, cow, chunk_size);
119 
120 	return 1;
121 }
122 
123 int vg_remove_snapshot(struct logical_volume *cow)
124 {
125 	dm_list_del(&cow->snapshot->origin_list);
126 	cow->snapshot->origin->origin_count--;
127 
128 	if (!lv_remove(cow->snapshot->lv)) {
129 		log_error("Failed to remove internal snapshot LV %s",
130 			  cow->snapshot->lv->name);
131 		return 0;
132 	}
133 
134 	cow->snapshot = NULL;
135 	lv_set_visible(cow);
136 
137 	return 1;
138 }
139