bcachefs: fix copygc so it doesn't spin when no work to do

3 files changed, 38 insertions, 7 deletions

diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c
index 4ea89a97c45c..864de940f1e7 100644
--- a/fs/bcachefs/buckets.c
+++ b/fs/bcachefs/buckets.c
@@ -285,6 +285,17 @@ static inline int is_unavailable_bucket(struct bucket_mark m)
 	return !is_available_bucket(m);
 }
 
+static inline int is_fragmented_bucket(struct bucket_mark m,
+				       struct bch_dev *ca)
+{
+	if (!m.owned_by_allocator &&
+	    m.data_type == BCH_DATA_USER &&
+	    bucket_sectors_used(m))
+		return max_t(int, 0, (int) ca->mi.bucket_size -
+			     bucket_sectors_used(m));
+	return 0;
+}
+
 static inline enum bch_data_type bucket_type(struct bucket_mark m)
 {
 	return m.cached_sectors && !m.dirty_sectors
@@ -361,6 +372,8 @@ static void bch2_dev_usage_update(struct bch_fs *c, struct bch_dev *ca,
 	dev_usage->sectors[new.data_type] += new.dirty_sectors;
 	dev_usage->sectors[BCH_DATA_CACHED] +=
 		(int) new.cached_sectors - (int) old.cached_sectors;
+	dev_usage->sectors_fragmented +=
+		is_fragmented_bucket(new, ca) - is_fragmented_bucket(old, ca);
 
 	if (!is_available_bucket(old) && is_available_bucket(new))
 		bch2_wake_allocator(ca);
diff --git a/fs/bcachefs/buckets_types.h b/fs/bcachefs/buckets_types.h
index 6f52a109d102..a0256e13618c 100644
--- a/fs/bcachefs/buckets_types.h
+++ b/fs/bcachefs/buckets_types.h
@@ -53,6 +53,7 @@ struct bch_dev_usage {
 
 	/* _compressed_ sectors: */
 	u64			sectors[BCH_DATA_NR];
+	u64			sectors_fragmented;
 };
 
 /* kill, switch to bch_data_type? */
diff --git a/fs/bcachefs/movinggc.c b/fs/bcachefs/movinggc.c
index 2aa58b557794..ea7f591e18b1 100644
--- a/fs/bcachefs/movinggc.c
+++ b/fs/bcachefs/movinggc.c
@@ -213,8 +213,9 @@ static int bch2_copygc_thread(void *arg)
 	struct bch_dev *ca = arg;
 	struct bch_fs *c = ca->fs;
 	struct io_clock *clock = &c->io_clock[WRITE];
+	struct bch_dev_usage usage;
 	unsigned long last;
-	u64 available, want, next;
+	u64 available, fragmented, reserve, next;
 
 	set_freezable();
 
@@ -223,16 +224,32 @@ static int bch2_copygc_thread(void *arg)
 			break;
 
 		last = atomic_long_read(&clock->now);
+
+		reserve = div64_u64((ca->mi.nbuckets - ca->mi.first_bucket) *
+				 ca->mi.bucket_size *
+				 c->opts.gc_reserve_percent, 200);
+
+		usage = bch2_dev_usage_read(c, ca);
+
 		/*
 		 * don't start copygc until less than half the gc reserve is
 		 * available:
 		 */
-		available = dev_buckets_available(c, ca);
-		want = div64_u64((ca->mi.nbuckets - ca->mi.first_bucket) *
-				 c->opts.gc_reserve_percent, 200);
-		if (available > want) {
-			next = last + (available - want) *
-				ca->mi.bucket_size;
+		available = __dev_buckets_available(ca, usage) *
+			ca->mi.bucket_size;
+		if (available > reserve) {
+			next = last + available - reserve;
+			bch2_kthread_io_clock_wait(clock, next);
+			continue;
+		}
+
+		/*
+		 * don't start copygc until there's more than half the copygc
+		 * reserve of fragmented space:
+		 */
+		fragmented = usage.sectors_fragmented;
+		if (fragmented < reserve) {
+			next = last + reserve - fragmented;
 			bch2_kthread_io_clock_wait(clock, next);
 			continue;
 		}