From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
This saves memory (without the patch, the exception store would consume twice
more memory while doing handover).
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Reviewed-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
---
drivers/md/dm-exception-store.h | 6 +++++-
drivers/md/dm-snap-persistent.c | 5 +++--
drivers/md/dm-snap-transient.c | 2 +-
drivers/md/dm-snap.c | 2 +-
4 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index bb88746..a96a40a 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -54,11 +54,15 @@ struct dm_exception_store_type {
* The target shouldn't read the COW device until this is
* called. As exceptions are read from the COW, they are
* reported back via the callback.
+ *
+ * will_handover means that there is another snapshot active;
+ * chunk size must be setup but no exceptions need to be read
+ * because they will be handed over from the active snapshot.
*/
int (*read_metadata) (struct dm_exception_store *store,
int (*callback)(void *callback_context,
chunk_t old, chunk_t new),
- void *callback_context);
+ void *callback_context, int will_handover);
/*
* Find somewhere to store the next exception.
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 157999e..e0f526a 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -529,7 +529,7 @@ static void persistent_dtr(struct dm_exception_store *store)
static int persistent_read_metadata(struct dm_exception_store *store,
int (*callback)(void *callback_context,
chunk_t old, chunk_t new),
- void *callback_context)
+ void *callback_context, int will_handover)
{
int r, uninitialized_var(new_snapshot);
struct pstore *ps = get_info(store);
@@ -586,7 +586,8 @@ static int persistent_read_metadata(struct dm_exception_store *store,
/*
* Read the metadata.
*/
- r = read_exceptions(ps, callback, callback_context);
+ if (!will_handover)
+ r = read_exceptions(ps, callback, callback_context);
return r;
}
diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c
index a0898a6..341231a 100644
--- a/drivers/md/dm-snap-transient.c
+++ b/drivers/md/dm-snap-transient.c
@@ -30,7 +30,7 @@ static void transient_dtr(struct dm_exception_store *store)
static int transient_read_metadata(struct dm_exception_store *store,
int (*callback)(void *callback_context,
chunk_t old, chunk_t new),
- void *callback_context)
+ void *callback_context, int will_handover)
{
return 0;
}
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 5414e66..1f0a57c 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -739,7 +739,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
/* Metadata must only be loaded into one table at once */
r = s->store->type->read_metadata(s->store, dm_add_exception,
- (void *)s);
+ (void *)s, s->handover);
if (r < 0) {
ti->error = "Failed to read snapshot metadata";
goto bad_load_and_register;
--
1.6.5.rc2
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