From: Mikulas Patocka mpatocka@redhat.com
[ Upstream commit a2f83e8b0c82c9500421a26c49eb198b25fcdea3 ]
This simple refactoring moves code for modifying the semaphore cow_count into separate functions to prepare for changes that will extend these methods to provide for a more sophisticated mechanism for COW throttling.
Signed-off-by: Mikulas Patocka mpatocka@redhat.com Reviewed-by: Nikos Tsironis ntsironis@arrikto.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/dm-snap.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 36805b12661e1..d9216afbd490f 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1399,6 +1399,16 @@ static void snapshot_dtr(struct dm_target *ti) kfree(s); }
+static void account_start_copy(struct dm_snapshot *s) +{ + down(&s->cow_count); +} + +static void account_end_copy(struct dm_snapshot *s) +{ + up(&s->cow_count); +} + /* * Flush a list of buffers. */ @@ -1594,7 +1604,7 @@ static void copy_callback(int read_err, unsigned long write_err, void *context) rb_link_node(&pe->out_of_order_node, parent, p); rb_insert_color(&pe->out_of_order_node, &s->out_of_order_tree); } - up(&s->cow_count); + account_end_copy(s); }
/* @@ -1618,7 +1628,7 @@ static void start_copy(struct dm_snap_pending_exception *pe) dest.count = src.count;
/* Hand over to kcopyd */ - down(&s->cow_count); + account_start_copy(s); dm_kcopyd_copy(s->kcopyd_client, &src, 1, &dest, 0, copy_callback, pe); }
@@ -1638,7 +1648,7 @@ static void start_full_bio(struct dm_snap_pending_exception *pe, pe->full_bio = bio; pe->full_bio_end_io = bio->bi_end_io;
- down(&s->cow_count); + account_start_copy(s); callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, copy_callback, pe);