dm space maps: improve performance with inc/dec on ranges of blocks

When we break sharing on btree nodes we typically need to increment
the reference counts to every value held in the node.  This can
cause a lot of repeated calls to the space maps.  Fix this by changing
the interface to the space map inc/dec methods to take ranges of
adjacent blocks to be operated on.

For installations that are using a lot of snapshots this will reduce
cpu overhead of fundamental operations such as provisioning a new block,
or deleting a snapshot, by as much as 10 times.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c
index 4353e1146d73..16643fc974e8 100644
--- a/drivers/md/persistent-data/dm-transaction-manager.c
+++ b/drivers/md/persistent-data/dm-transaction-manager.c
@@ -359,6 +359,17 @@ void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b)
 }
 EXPORT_SYMBOL_GPL(dm_tm_inc);
 
+void dm_tm_inc_range(struct dm_transaction_manager *tm, dm_block_t b, dm_block_t e)
+{
+	/*
+	 * The non-blocking clone doesn't support this.
+	 */
+	BUG_ON(tm->is_clone);
+
+	dm_sm_inc_blocks(tm->sm, b, e);
+}
+EXPORT_SYMBOL_GPL(dm_tm_inc_range);
+
 void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b)
 {
 	/*
@@ -370,6 +381,47 @@ void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b)
 }
 EXPORT_SYMBOL_GPL(dm_tm_dec);
 
+void dm_tm_dec_range(struct dm_transaction_manager *tm, dm_block_t b, dm_block_t e)
+{
+	/*
+	 * The non-blocking clone doesn't support this.
+	 */
+	BUG_ON(tm->is_clone);
+
+	dm_sm_dec_blocks(tm->sm, b, e);
+}
+EXPORT_SYMBOL_GPL(dm_tm_dec_range);
+
+void dm_tm_with_runs(struct dm_transaction_manager *tm,
+		     const __le64 *value_le, unsigned count, dm_tm_run_fn fn)
+{
+	uint64_t b, begin, end;
+	bool in_run = false;
+	unsigned i;
+
+	for (i = 0; i < count; i++, value_le++) {
+		b = le64_to_cpu(*value_le);
+
+		if (in_run) {
+			if (b == end)
+				end++;
+			else {
+				fn(tm, begin, end);
+				begin = b;
+				end = b + 1;
+			}
+		} else {
+			in_run = true;
+			begin = b;
+			end = b + 1;
+		}
+	}
+
+	if (in_run)
+		fn(tm, begin, end);
+}
+EXPORT_SYMBOL_GPL(dm_tm_with_runs);
+
 int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
 	      uint32_t *result)
 {