From a2f83e8b0c82c9500421a26c49eb198b25fcdea3 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 2 Oct 2019 06:14:17 -0400 Subject: 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 Reviewed-by: Nikos Tsironis Signed-off-by: Mike Snitzer --- drivers/md/dm-snap.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) (limited to 'drivers/md/dm-snap.c') diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index f150f5c5492b..da3bd1794ee0 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1512,6 +1512,16 @@ 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. */ @@ -1732,7 +1742,7 @@ 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); } /* @@ -1756,7 +1766,7 @@ 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); } @@ -1776,7 +1786,7 @@ 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); @@ -1866,7 +1876,7 @@ static void zero_callback(int read_err, unsigned long write_err, void *context) struct bio *bio = context; struct dm_snapshot *s = bio->bi_private; - up(&s->cow_count); + account_end_copy(s); bio->bi_status = write_err ? BLK_STS_IOERR : 0; bio_endio(bio); } @@ -1880,7 +1890,7 @@ static void zero_exception(struct dm_snapshot *s, struct dm_exception *e, dest.sector = bio->bi_iter.bi_sector; dest.count = s->store->chunk_size; - down(&s->cow_count); + account_start_copy(s); WARN_ON_ONCE(bio->bi_private); bio->bi_private = s; dm_kcopyd_zero(s->kcopyd_client, 1, &dest, 0, zero_callback, bio); -- cgit v1.2.3