From 5b1ae3cfc07e53e6e6e37f9f40b074dd7a8536b9 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 2 Oct 2019 06:14:17 -0400 Subject: [PATCH 1/2] dm snapshot: introduce account_start_copy() and account_end_copy() 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 Signed-off-by: Mike Snitzer --- 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 5d3797728b9c..a9c82fd036c6 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1398,6 +1398,16 @@ 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. */ @@ -1582,7 +1592,7 @@ static void copy_callback(int read_err, unsigned long write_err, void *context) } list_add(&pe->out_of_order_entry, lh); } - up(&s->cow_count); + account_end_copy(s); } /* @@ -1606,7 +1616,7 @@ 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); } @@ -1627,7 +1637,7 @@ static void start_full_bio(struct dm_snap_pending_exception *pe, pe->full_bio_end_io = bio->bi_end_io; pe->full_bio_private = bio->bi_private; - down(&s->cow_count); + account_start_copy(s); callback_data = dm_kcopyd_prepare_callback(s->kcopyd_client, copy_callback, pe); -- 2.11.0