external/gpl2/lvm2/dist/lib/metadata/snapshot_manip.c

   1 /*      $NetBSD$        */
   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 }