bcachefs: Rework allocating buckets for stripes

Allocating buckets for existing stripes was busted, in part because the
data structures were too contorted. This reworks new stripes so that we
have an array of open buckets that matches blocks in the stripe, and
it's sparse if we're reusing an existing stripe.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/alloc_foreground.c

@@ -489,16 +489,20 @@ bucket_alloc_from_stripe(struct bch_fs *c,
 	devs_sorted = bch2_dev_alloc_list(c, &wp->stripe, devs_may_alloc);
 
 	for (i = 0; i < devs_sorted.nr; i++)
-		open_bucket_for_each(c, &h->s->blocks, ob, ec_idx)
+		for (ec_idx = 0; ec_idx < h->s->nr_data; ec_idx++) {
+			if (!h->s->blocks[ec_idx])
+				continue;
+
+			ob = c->open_buckets + h->s->blocks[ec_idx];
 			if (ob->ptr.dev == devs_sorted.devs[i] &&
-			    !test_and_set_bit(h->s->data_block_idx[ec_idx],
-					      h->s->blocks_allocated))
+			    !test_and_set_bit(ec_idx, h->s->blocks_allocated))
 				goto got_bucket;
+		}
 	goto out_put_head;
 got_bucket:
 	ca = bch_dev_bkey_exists(c, ob->ptr.dev);
 
-	ob->ec_idx	= h->s->data_block_idx[ec_idx];
+	ob->ec_idx	= ec_idx;
 	ob->ec		= h->s;
 
 	add_new_bucket(c, ptrs, devs_may_alloc,
@@ -636,10 +640,13 @@ void bch2_open_buckets_stop_dev(struct bch_fs *c, struct bch_dev *ca,
 
 		if (!drop && ob->ec) {
 			mutex_lock(&ob->ec->lock);
-			open_bucket_for_each(c, &ob->ec->blocks, ob2, j)
-				drop |= ob2->ptr.dev == ca->dev_idx;
-			open_bucket_for_each(c, &ob->ec->parity, ob2, j)
+			for (j = 0; j < ob->ec->new_stripe.key.v.nr_blocks; j++) {
+				if (!ob->ec->blocks[j])
+					continue;
+
+				ob2 = c->open_buckets + ob->ec->blocks[j];
 				drop |= ob2->ptr.dev == ca->dev_idx;
+			}
 			mutex_unlock(&ob->ec->lock);
 		}
 

fs/bcachefs/ec.c

@@ -907,9 +907,6 @@ static void ec_stripe_create(struct ec_stripe_new *s)
 	if (!percpu_ref_tryget(&c->writes))
 		goto err;
 
-	BUG_ON(bitmap_weight(s->blocks_allocated,
-			     s->blocks.nr) != s->blocks.nr);
-
 	ec_generate_ec(&s->new_stripe);
 
 	ec_generate_checksums(&s->new_stripe);
@@ -952,12 +949,17 @@ static void ec_stripe_create(struct ec_stripe_new *s)
 err:
 	bch2_disk_reservation_put(c, &s->res);
 
-	open_bucket_for_each(c, &s->blocks, ob, i) {
+	for (i = 0; i < v->nr_blocks; i++)
+		if (s->blocks[i]) {
+			ob = c->open_buckets + s->blocks[i];
+
+			if (i < nr_data) {
 				ob->ec = NULL;
 				__bch2_open_bucket_put(c, ob);
+			} else {
+				bch2_open_bucket_put(c, ob);
+			}
 		}
-
-	bch2_open_buckets_put(c, &s->parity);
 
 	bch2_keylist_free(&s->keys, s->inline_keys);
 
@@ -1216,7 +1218,7 @@ void bch2_ec_stripe_head_put(struct bch_fs *c, struct ec_stripe_head *h)
 	if (h->s &&
 	    h->s->allocated &&
 	    bitmap_weight(h->s->blocks_allocated,
-			  h->s->blocks.nr) == h->s->blocks.nr)
+			  h->s->nr_data) == h->s->nr_data)
 		ec_stripe_set_pending(c, h);
 
 	mutex_unlock(&h->lock);
@@ -1253,64 +1255,82 @@ static enum bucket_alloc_ret
 new_stripe_alloc_buckets(struct bch_fs *c, struct ec_stripe_head *h,
 			 struct closure *cl)
 {
-	struct bch_devs_mask devs;
+	struct bch_devs_mask devs = h->devs;
 	struct open_bucket *ob;
-	unsigned i, nr_have, nr_data =
-		min_t(unsigned, h->nr_active_devs,
-		      BCH_BKEY_PTRS_MAX) - h->redundancy;
+	struct open_buckets buckets;
+	unsigned i, j, nr_have_parity = 0, nr_have_data = 0;
 	bool have_cache = true;
 	enum bucket_alloc_ret ret = ALLOC_SUCCESS;
 
-	devs = h->devs;
-
-	for_each_set_bit(i, h->s->blocks_allocated, BCH_BKEY_PTRS_MAX) {
+	for (i = 0; i < h->s->new_stripe.key.v.nr_blocks; i++) {
+		if (test_bit(i, h->s->blocks_gotten)) {
 			__clear_bit(h->s->new_stripe.key.v.ptrs[i].dev, devs.d);
-		--nr_data;
+			if (i < h->s->nr_data)
+				nr_have_data++;
+			else
+				nr_have_parity++;
+		}
 	}
 
-	BUG_ON(h->s->blocks.nr > nr_data);
-	BUG_ON(h->s->parity.nr > h->redundancy);
-
-	open_bucket_for_each(c, &h->s->parity, ob, i)
-		__clear_bit(ob->ptr.dev, devs.d);
-	open_bucket_for_each(c, &h->s->blocks, ob, i)
-		__clear_bit(ob->ptr.dev, devs.d);
+	BUG_ON(nr_have_data	> h->s->nr_data);
+	BUG_ON(nr_have_parity	> h->s->nr_parity);
 
 	percpu_down_read(&c->mark_lock);
 	rcu_read_lock();
 
-	if (h->s->parity.nr < h->redundancy) {
-		nr_have = h->s->parity.nr;
-
-		ret = bch2_bucket_alloc_set(c, &h->s->parity,
+	buckets.nr = 0;
+	if (nr_have_parity < h->s->nr_parity) {
+		ret = bch2_bucket_alloc_set(c, &buckets,
 					    &h->parity_stripe,
 					    &devs,
-					    h->redundancy,
-					    &nr_have,
+					    h->s->nr_parity,
+					    &nr_have_parity,
 					    &have_cache,
 					    h->copygc
 					    ? RESERVE_MOVINGGC
 					    : RESERVE_NONE,
 					    0,
 					    cl);
+
+		open_bucket_for_each(c, &buckets, ob, i) {
+			j = find_next_zero_bit(h->s->blocks_gotten,
+					       h->s->nr_data + h->s->nr_parity,
+					       h->s->nr_data);
+			BUG_ON(j >= h->s->nr_data + h->s->nr_parity);
+
+			h->s->blocks[j] = buckets.v[i];
+			h->s->new_stripe.key.v.ptrs[j] = ob->ptr;
+			__set_bit(j, h->s->blocks_gotten);
+		}
+
 		if (ret)
 			goto err;
 	}
 
-	if (h->s->blocks.nr < nr_data) {
-		nr_have = h->s->blocks.nr;
-
-		ret = bch2_bucket_alloc_set(c, &h->s->blocks,
+	buckets.nr = 0;
+	if (nr_have_data < h->s->nr_data) {
+		ret = bch2_bucket_alloc_set(c, &buckets,
 					    &h->block_stripe,
 					    &devs,
-					    nr_data,
-					    &nr_have,
+					    h->s->nr_data,
+					    &nr_have_data,
 					    &have_cache,
 					    h->copygc
 					    ? RESERVE_MOVINGGC
 					    : RESERVE_NONE,
 					    0,
 					    cl);
+
+		open_bucket_for_each(c, &buckets, ob, i) {
+			j = find_next_zero_bit(h->s->blocks_gotten,
+					       h->s->nr_data, 0);
+			BUG_ON(j >= h->s->nr_data);
+
+			h->s->blocks[j] = buckets.v[i];
+			h->s->new_stripe.key.v.ptrs[j] = ob->ptr;
+			__set_bit(j, h->s->blocks_gotten);
+		}
+
 		if (ret)
 			goto err;
 	}
@@ -1362,8 +1382,7 @@ struct ec_stripe_head *bch2_ec_stripe_head_get(struct bch_fs *c,
 					       struct closure *cl)
 {
 	struct ec_stripe_head *h;
-	struct open_bucket *ob;
-	unsigned i, data_idx = 0;
+	unsigned i;
 	s64 idx;
 	int ret;
 
@@ -1398,9 +1417,14 @@ struct ec_stripe_head *bch2_ec_stripe_head_get(struct bch_fs *c,
 				BUG();
 			}
 
+			BUG_ON(h->s->existing_stripe.size != h->blocksize);
+			BUG_ON(h->s->existing_stripe.size != h->s->existing_stripe.key.v.sectors);
+
 			for (i = 0; i < h->s->existing_stripe.key.v.nr_blocks; i++) {
-				if (stripe_blockcount_get(&h->s->existing_stripe.key.v, i))
+				if (stripe_blockcount_get(&h->s->existing_stripe.key.v, i)) {
+					__set_bit(i, h->s->blocks_gotten);
 					__set_bit(i, h->s->blocks_allocated);
+				}
 
 				ec_block_io(c, &h->s->existing_stripe, READ, i, &h->s->iodone);
 			}
@@ -1438,20 +1462,6 @@ struct ec_stripe_head *bch2_ec_stripe_head_get(struct bch_fs *c,
 			goto out;
 		}
 
-		open_bucket_for_each(c, &h->s->blocks, ob, i) {
-			data_idx = find_next_zero_bit(h->s->blocks_allocated,
-						      h->s->nr_data, data_idx);
-			BUG_ON(data_idx >= h->s->nr_data);
-
-			h->s->new_stripe.key.v.ptrs[data_idx] = ob->ptr;
-			h->s->data_block_idx[i] = data_idx;
-			data_idx++;
-		}
-
-		open_bucket_for_each(c, &h->s->parity, ob, i)
-			h->s->new_stripe.key.v.ptrs[h->s->nr_data + i] = ob->ptr;
-
-		//pr_info("new stripe, blocks_allocated %lx", h->s->blocks_allocated[0]);
 		h->s->allocated = true;
 	}
 out:
@@ -1471,12 +1481,14 @@ void bch2_ec_stop_dev(struct bch_fs *c, struct bch_dev *ca)
 		if (!h->s)
 			goto unlock;
 
-		open_bucket_for_each(c, &h->s->blocks, ob, i)
-			if (ob->ptr.dev == ca->dev_idx)
-				goto found;
-		open_bucket_for_each(c, &h->s->parity, ob, i)
+		for (i = 0; i < h->s->new_stripe.key.v.nr_blocks; i++) {
+			if (!h->s->blocks[i])
+				continue;
+
+			ob = c->open_buckets + h->s->blocks[i];
 			if (ob->ptr.dev == ca->dev_idx)
 				goto found;
+		}
 		goto unlock;
 found:
 		h->s->err = -EROFS;
@@ -1662,19 +1674,17 @@ void bch2_new_stripes_to_text(struct printbuf *out, struct bch_fs *c)
 		       h->target, h->algo, h->redundancy);
 
 		if (h->s)
-			pr_buf(out, "\tpending: blocks %u allocated %u\n",
-			       h->s->blocks.nr,
+			pr_buf(out, "\tpending: blocks %u+%u allocated %u\n",
+			       h->s->nr_data, h->s->nr_parity,
 			       bitmap_weight(h->s->blocks_allocated,
-					     h->s->blocks.nr));
+					     h->s->nr_data));
 	}
 	mutex_unlock(&c->ec_stripe_head_lock);
 
 	mutex_lock(&c->ec_stripe_new_lock);
 	list_for_each_entry(s, &c->ec_stripe_new_list, list) {
-		pr_buf(out, "\tin flight: blocks %u allocated %u pin %u\n",
-		       s->blocks.nr,
-		       bitmap_weight(s->blocks_allocated,
-				     s->blocks.nr),
+		pr_buf(out, "\tin flight: blocks %u+%u pin %u\n",
+		       s->nr_data, s->nr_parity,
 		       atomic_read(&s->pin));
 	}
 	mutex_unlock(&c->ec_stripe_new_lock);

fs/bcachefs/ec.h

@@ -143,11 +143,9 @@ struct ec_stripe_new {
 	bool			pending;
 	bool			have_existing_stripe;
 
+	unsigned long		blocks_gotten[BITS_TO_LONGS(BCH_BKEY_PTRS_MAX)];
 	unsigned long		blocks_allocated[BITS_TO_LONGS(BCH_BKEY_PTRS_MAX)];
-
-	struct open_buckets	blocks;
-	u8			data_block_idx[BCH_BKEY_PTRS_MAX];
-	struct open_buckets	parity;
+	open_bucket_idx_t	blocks[BCH_BKEY_PTRS_MAX];
 	struct disk_reservation	res;
 
 	struct keylist		keys;