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
lv_is_origin(const struct logical_volume * lv)23 int lv_is_origin(const struct logical_volume *lv)
24 {
25 return lv->origin_count ? 1 : 0;
26 }
27
lv_is_cow(const struct logical_volume * lv)28 int lv_is_cow(const struct logical_volume *lv)
29 {
30 return lv->snapshot ? 1 : 0;
31 }
32
lv_is_visible(const struct logical_volume * lv)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
lv_is_virtual_origin(const struct logical_volume * lv)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 */
find_cow(const struct logical_volume * lv)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 */
origin_from_cow(const struct logical_volume * lv)61 struct logical_volume *origin_from_cow(const struct logical_volume *lv)
62 {
63 return lv->snapshot->origin;
64 }
65
init_snapshot_seg(struct lv_segment * seg,struct logical_volume * origin,struct logical_volume * cow,uint32_t chunk_size)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
vg_add_snapshot(struct logical_volume * origin,struct logical_volume * cow,union lvid * lvid,uint32_t extent_count,uint32_t chunk_size)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
vg_remove_snapshot(struct logical_volume * cow)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