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o First changes to add snapshot support.

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I'm taking a different route from LVM1 here in that snapshots are a
seperate entity from the logical volumes, I think of them as an
application of an LV (or two lvs rather).  As such there is a list of
snapshots held against the vg, and there is *not* a SNAPSHOT, or
SHAPSHOT_ORG flag in lv->status.
This commit is contained in:
Joe Thornber 2002-02-12 16:31:31 +00:00
parent f09d2b350f
commit 7d68b08028
6 changed files with 141 additions and 11 deletions
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3
lib/Makefile.in
View File

@ -40,13 +40,14 @@ SOURCES=\
format_text/import.c \
label/label.c \
label/uuid-map.c \
locking/locking.c \
locking/file_locking.c \
locking/locking.c \
log/log.c \
metadata/lv_manip.c \
metadata/merge.c \
metadata/metadata.c \
metadata/pv_map.c \
metadata/snapshot_manip.c \
misc/lvm-file.c \
mm/dbg_malloc.c \
mm/pool.c \

33
lib/metadata/metadata.h
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@ -94,6 +94,10 @@ struct volume_group {
/* logical volumes */
uint32_t lv_count;
struct list lvs;
/* snapshots */
uint32_t snapshot_count;
struct list snapshots;
};
struct stripe_segment {
@ -128,6 +132,14 @@ struct logical_volume {
struct list segments;
};
struct snapshot {
int persistent; /* boolean */
uint32_t chunk_size; /* in 512 byte sectors */
struct logical_volume *origin;
struct logical_volume *cow;
};
struct name_list {
struct list list;
char *name;
@ -143,6 +155,12 @@ struct lv_list {
struct logical_volume *lv;
};
struct snapshot_list {
struct list list;
struct snapshot *snapshot;
};
struct format_instance {
struct cmd_context *cmd;
struct format_handler *ops;
@ -315,4 +333,19 @@ int lv_check_segments(struct logical_volume *lv);
int lv_merge_segments(struct logical_volume *lv);
/*
* Useful functions for managing snapshots.
*/
int lv_is_origin(struct volume_group *vg, struct logical_volume *lv);
int lv_is_cow(struct volume_group *vg, struct logical_volume *lv);
int vg_add_snapshot(struct volume_group *vg,
struct logical_volume *origin,
struct logical_volume *cow,
int persistent,
uint32_t chunk_size);
int vg_remove_snapshot(struct volume_group *vg, struct logical_volume *cow);
#endif

96
lib/metadata/snapshot_manip.c Normal file
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@ -0,0 +1,96 @@
/*
* Copyright (C) 2002 Sistina Software (UK) Limited.
*
* This file is released under the LGPL.
*/
#include "log.h"
#include "metadata.h"
#include "toolcontext.h"
int lv_is_origin(struct volume_group *vg, struct logical_volume *lv)
{
struct list *slh;
struct snapshot *s;
list_iterate (slh, &vg->snapshots) {
s = list_item(slh, struct snapshot_list)->snapshot;
if (s->origin == lv)
return 1;
}
return 0;
}
int lv_is_cow(struct volume_group *vg, struct logical_volume *lv)
{
struct list *slh;
struct snapshot *s;
list_iterate (slh, &vg->snapshots) {
s = list_item(slh, struct snapshot_list)->snapshot;
if (s->cow == lv)
return 1;
}
return 0;
}
int vg_add_snapshot(struct volume_group *vg,
struct logical_volume *origin,
struct logical_volume *cow,
int persistent,
uint32_t chunk_size)
{
struct snapshot *s;
struct snapshot_list *sl;
struct pool *mem = vg->cmd->mem;
/*
* Is the cow device already being used ?
*/
if (lv_is_cow(vg, cow)) {
log_err("'%s' is already in use as a snapshot.", cow->name);
return 0;
}
if (!(s = pool_alloc(mem, sizeof(*s)))) {
stack;
return 0;
}
s->persistent = persistent;
s->chunk_size = chunk_size;
s->origin = origin;
s->cow = cow;
if (!(sl = pool_alloc(mem, sizeof(*sl)))) {
stack;
pool_free(mem, s);
return 0;
}
sl->snapshot = s;
list_add(&vg->snapshots, &sl->list);
return 1;
}
int vg_remove_snapshot(struct volume_group *vg, struct logical_volume *cow)
{
struct list *slh;
struct snapshot_list *sl;
list_iterate (slh, &vg->snapshots) {
sl = list_item(slh, struct snapshot_list);
if (sl->snapshot->cow == cow) {
list_del(slh);
return 1;
}
}
/* fail */
log_err("Asked to remove an unknow snapshot.");
return 0;
}