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authorAlasdair G Kergon <agk@redhat.com>2006-02-01 03:04:50 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-01 08:53:10 -0800
commitaa14edeb994f8f7e223d02ad14780bf2fa719f6d (patch)
tree07fb8ba39d619708bdc0a68a32d4a7296abd955c
parentcb82a6cdf994d6656ad0a25ed28395af3416a27c (diff)
[PATCH] device-mapper snapshot: load metadata on creation
Move snapshot metadata loading to happen when the table is created instead of when the device is resumed. Writes to the origin device don't trigger exceptions until each snapshot table becomes active when resume() is called on each snapshot. If you're using lvm2, for this patch to work properly you should update to lvm2 version 2.02.01 or later and device-mapper version 1.02.02 or later. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/md/dm-snap.c23
-rw-r--r--drivers/md/dm-snap.h4
2 files changed, 15 insertions, 12 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 87727d84dbb..ad9b61f16c5 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -373,16 +373,11 @@ static inline ulong round_up(ulong n, ulong size)
static void read_snapshot_metadata(struct dm_snapshot *s)
{
- if (s->have_metadata)
- return;
-
if (s->store.read_metadata(&s->store)) {
down_write(&s->lock);
s->valid = 0;
up_write(&s->lock);
}
-
- s->have_metadata = 1;
}
/*
@@ -471,7 +466,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
s->chunk_shift = ffs(chunk_size) - 1;
s->valid = 1;
- s->have_metadata = 0;
+ s->active = 0;
s->last_percent = 0;
init_rwsem(&s->lock);
s->table = ti->table;
@@ -506,7 +501,11 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto bad5;
}
+ /* Metadata must only be loaded into one table at once */
+ read_snapshot_metadata(s);
+
/* Add snapshot to the list of snapshots for this origin */
+ /* Exceptions aren't triggered till snapshot_resume() is called */
if (register_snapshot(s)) {
r = -EINVAL;
ti->error = "Cannot register snapshot origin";
@@ -862,7 +861,9 @@ static void snapshot_resume(struct dm_target *ti)
{
struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
- read_snapshot_metadata(s);
+ down_write(&s->lock);
+ s->active = 1;
+ up_write(&s->lock);
}
static int snapshot_status(struct dm_target *ti, status_type_t type,
@@ -932,8 +933,8 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
/* Do all the snapshots on this origin */
list_for_each_entry (snap, snapshots, list) {
- /* Only deal with valid snapshots */
- if (!snap->valid)
+ /* Only deal with valid and active snapshots */
+ if (!snap->valid || !snap->active)
continue;
/* Nothing to do if writing beyond end of snapshot */
@@ -1104,7 +1105,7 @@ static int origin_status(struct dm_target *ti, status_type_t type, char *result,
static struct target_type origin_target = {
.name = "snapshot-origin",
- .version = {1, 0, 1},
+ .version = {1, 1, 0},
.module = THIS_MODULE,
.ctr = origin_ctr,
.dtr = origin_dtr,
@@ -1115,7 +1116,7 @@ static struct target_type origin_target = {
static struct target_type snapshot_target = {
.name = "snapshot",
- .version = {1, 0, 1},
+ .version = {1, 1, 0},
.module = THIS_MODULE,
.ctr = snapshot_ctr,
.dtr = snapshot_dtr,
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h
index 375aa24d4d7..fdec1e2dc87 100644
--- a/drivers/md/dm-snap.h
+++ b/drivers/md/dm-snap.h
@@ -99,7 +99,9 @@ struct dm_snapshot {
/* You can't use a snapshot if this is 0 (e.g. if full) */
int valid;
- int have_metadata;
+
+ /* Origin writes don't trigger exceptions until this is set */
+ int active;
/* Used for display of table */
char type;