bcachefs: Kill allocator threads & freelists

Now that we have new persistent data structures for the allocator, this
patch converts the allocator to use them.

Now, foreground bucket allocation uses the freespace btree to find
buckets to allocate, instead of popping buckets off the freelist.

The background allocator threads are no longer needed and are deleted,
as well as the allocator freelists. Now we only need background tasks
for invalidating buckets containing cached data (when we are low on
empty buckets), and for issuing discards.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 28 insertions, 34 deletions

diff --git a/fs/bcachefs/buckets.h b/fs/bcachefs/buckets.h
index 757919d5e20f..bcb40f15f82e 100644
--- a/fs/bcachefs/buckets.h
+++ b/fs/bcachefs/buckets.h
@@ -58,11 +58,6 @@ static inline struct bucket *gc_bucket(struct bch_dev *ca, size_t b)
 	return __bucket(ca, b, true);
 }
 
-static inline struct bucket *bucket(struct bch_dev *ca, size_t b)
-{
-	return __bucket(ca, b, false);
-}
-
 static inline struct bucket_gens *bucket_gens(struct bch_dev *ca)
 {
 	return rcu_dereference_check(ca->bucket_gens,
@@ -151,50 +146,50 @@ static inline bool is_available_bucket(struct bucket_mark mark)
 struct bch_dev_usage bch2_dev_usage_read(struct bch_dev *);
 
 static inline u64 __dev_buckets_available(struct bch_dev *ca,
-					  struct bch_dev_usage stats)
+					  struct bch_dev_usage stats,
+					  enum alloc_reserve reserve)
 {
-	u64 total = ca->mi.nbuckets - ca->mi.first_bucket;
+	s64 total = ca->mi.nbuckets - ca->mi.first_bucket;
+	s64 reserved = 0;
+
+	switch (reserve) {
+	case RESERVE_none:
+		reserved += ca->mi.nbuckets >> 6;
+		fallthrough;
+	case RESERVE_movinggc:
+		reserved += ca->nr_btree_reserve;
+		fallthrough;
+	case RESERVE_btree:
+		reserved += ca->nr_btree_reserve;
+		fallthrough;
+	case RESERVE_btree_movinggc:
+		break;
+	default:
+		BUG();
+	}
 
 	if (WARN_ONCE(stats.buckets_unavailable > total,
 		      "buckets_unavailable overflow (%llu > %llu)\n",
 		      stats.buckets_unavailable, total))
 		return 0;
 
-	return total - stats.buckets_unavailable;
+	return max_t(s64, 0,
+		     total -
+		     stats.buckets_unavailable -
+		     ca->nr_open_buckets -
+		     reserved);
 }
 
-static inline u64 dev_buckets_available(struct bch_dev *ca)
+static inline u64 dev_buckets_available(struct bch_dev *ca,
+					enum alloc_reserve reserve)
 {
-	return __dev_buckets_available(ca, bch2_dev_usage_read(ca));
-}
-
-static inline u64 __dev_buckets_reclaimable(struct bch_dev *ca,
-					    struct bch_dev_usage stats)
-{
-	struct bch_fs *c = ca->fs;
-	s64 available = __dev_buckets_available(ca, stats);
-	unsigned i;
-
-	spin_lock(&c->freelist_lock);
-	for (i = 0; i < RESERVE_NR; i++)
-		available -= fifo_used(&ca->free[i]);
-	available -= fifo_used(&ca->free_inc);
-	available -= ca->nr_open_buckets;
-	spin_unlock(&c->freelist_lock);
-
-	return max(available, 0LL);
-}
-
-static inline u64 dev_buckets_reclaimable(struct bch_dev *ca)
-{
-	return __dev_buckets_reclaimable(ca, bch2_dev_usage_read(ca));
+	return __dev_buckets_available(ca, bch2_dev_usage_read(ca), reserve);
 }
 
 /* Filesystem usage: */
 
 static inline unsigned fs_usage_u64s(struct bch_fs *c)
 {
-
 	return sizeof(struct bch_fs_usage) / sizeof(u64) +
 		READ_ONCE(c->replicas.nr);
 }
@@ -222,7 +217,6 @@ bch2_fs_usage_read_short(struct bch_fs *);
 
 void bch2_fs_usage_initialize(struct bch_fs *);
 
-void bch2_mark_alloc_bucket(struct bch_fs *, struct bch_dev *, size_t, bool);
 void bch2_mark_metadata_bucket(struct bch_fs *, struct bch_dev *,
 			       size_t, enum bch_data_type, unsigned,
 			       struct gc_pos, unsigned);