From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Conditionally adjust snapshot usage accounting if snapshot-merge is in
progress. Care is taken to preserve the established kernel<->userspace
interface.
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm-snap-persistent.c | 19 ++++++++++++++++++-
1 files changed, 18 insertions(+), 1 deletions(-)
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 2523056..005c60c 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -91,6 +91,7 @@ struct pstore {
struct dm_exception_store *store;
int version;
int valid;
+ int merging; /* 1 if there is merging going on */
uint32_t exceptions_per_area;
/*
@@ -502,7 +503,18 @@ static struct pstore *get_info(struct dm_exception_store *store)
static void persistent_fraction_full(struct dm_exception_store *store,
sector_t *numerator, sector_t *denominator)
{
- *numerator = get_info(store)->next_free * store->chunk_size;
+ struct pstore *ps = get_info(store);
+ /*
+ * Must maintain the fact that DM reports the first two chunks as used
+ * (externally) even though they should've been hidden (used internally).
+ * - this preserves the established (flawed) kernel<->userspace interface
+ * - snapshot-merge must add these two chunks into its usage reporting
+ */
+ if (!ps->merging)
+ *numerator = ps->next_free * store->chunk_size;
+ else
+ *numerator = (area_location(ps, ps->current_area) - 1 +
+ ps->current_committed + 2) * store->chunk_size;
*denominator = get_dev_size(dm_snap_get_cow(store->snap)->bdev);
}
@@ -598,6 +610,8 @@ static int persistent_prepare_exception(struct dm_exception_store *store,
chunk_t next_free;
sector_t size = get_dev_size(dm_snap_get_cow(store->snap)->bdev);
+ ps->merging = 0;
+
/* Is there enough room ? */
if (size < ((ps->next_free + 1) * store->chunk_size))
return -ENOSPC;
@@ -686,6 +700,8 @@ static int persistent_prepare_merge(struct dm_exception_store *store,
struct pstore *ps = get_info(store);
struct disk_exception de;
+ ps->merging = 1;
+
if (!ps->current_committed) {
if (!ps->current_area)
return 0;
@@ -757,6 +773,7 @@ static int persistent_ctr(struct dm_exception_store *store,
ps->store = store;
ps->valid = 1;
+ ps->merging = 0;
ps->version = SNAPSHOT_DISK_VERSION;
ps->area = NULL;
ps->zero_area = NULL;
--
1.6.2.5
--
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