bcachefs: ob_dev()

Wrapper around bch2_dev_have_ref() for open_buckets; we do guarantee
that the device an open_bucket points to exists.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/alloc_foreground.c

@@ -100,7 +100,7 @@ static void bch2_open_bucket_hash_remove(struct bch_fs *c, struct open_bucket *o
 
 void __bch2_open_bucket_put(struct bch_fs *c, struct open_bucket *ob)
 {
-	struct bch_dev *ca = bch2_dev_bkey_exists(c, ob->dev);
+	struct bch_dev *ca = ob_dev(c, ob);
 
 	if (ob->ec) {
 		ec_stripe_new_put(c, ob->ec, STRIPE_REF_io);
@@ -684,8 +684,7 @@ static int add_new_bucket(struct bch_fs *c,
 			   unsigned flags,
 			   struct open_bucket *ob)
 {
-	unsigned durability =
-		bch2_dev_bkey_exists(c, ob->dev)->mi.durability;
+	unsigned durability = ob_dev(c, ob)->mi.durability;
 
 	BUG_ON(*nr_effective >= nr_replicas);
 
@@ -831,7 +830,7 @@ static bool want_bucket(struct bch_fs *c,
 			bool *have_cache, bool ec,
 			struct open_bucket *ob)
 {
-	struct bch_dev *ca = bch2_dev_bkey_exists(c, ob->dev);
+	struct bch_dev *ca = ob_dev(c, ob);
 
 	if (!test_bit(ob->dev, devs_may_alloc->d))
 		return false;
@@ -901,7 +900,7 @@ static int bucket_alloc_set_partial(struct bch_fs *c,
 		struct open_bucket *ob = c->open_buckets + c->open_buckets_partial[i];
 
 		if (want_bucket(c, wp, devs_may_alloc, have_cache, ec, ob)) {
-			struct bch_dev *ca = bch2_dev_bkey_exists(c, ob->dev);
+			struct bch_dev *ca = ob_dev(c, ob);
 			struct bch_dev_usage usage;
 			u64 avail;
 
@@ -1286,7 +1285,7 @@ deallocate_extra_replicas(struct bch_fs *c,
 	unsigned i;
 
 	open_bucket_for_each(c, ptrs, ob, i) {
-		unsigned d = bch2_dev_bkey_exists(c, ob->dev)->mi.durability;
+		unsigned d = ob_dev(c, ob)->mi.durability;
 
 		if (d && d <= extra_replicas) {
 			extra_replicas -= d;
@@ -1443,7 +1442,7 @@ int bch2_alloc_sectors_start_trans(struct btree_trans *trans,
 
 struct bch_extent_ptr bch2_ob_ptr(struct bch_fs *c, struct open_bucket *ob)
 {
-	struct bch_dev *ca = bch2_dev_bkey_exists(c, ob->dev);
+	struct bch_dev *ca = ob_dev(c, ob);
 
 	return (struct bch_extent_ptr) {
 		.type	= 1 << BCH_EXTENT_ENTRY_ptr,
@@ -1519,7 +1518,7 @@ void bch2_fs_allocator_foreground_init(struct bch_fs *c)
 
 static void bch2_open_bucket_to_text(struct printbuf *out, struct bch_fs *c, struct open_bucket *ob)
 {
-	struct bch_dev *ca = bch2_dev_bkey_exists(c, ob->dev);
+	struct bch_dev *ca = ob_dev(c, ob);
 	unsigned data_type = ob->data_type;
 	barrier(); /* READ_ONCE() doesn't work on bitfields */
 

fs/bcachefs/alloc_foreground.h

@@ -30,6 +30,11 @@ void bch2_dev_stripe_increment(struct bch_dev *, struct dev_stripe_state *);
 
 long bch2_bucket_alloc_new_fs(struct bch_dev *);
 
+static inline struct bch_dev *ob_dev(struct bch_fs *c, struct open_bucket *ob)
+{
+	return bch2_dev_have_ref(c, ob->dev);
+}
+
 struct open_bucket *bch2_bucket_alloc(struct bch_fs *, struct bch_dev *,
 				      enum bch_watermark, enum bch_data_type,
 				      struct closure *);
@@ -185,7 +190,7 @@ bch2_alloc_sectors_append_ptrs_inlined(struct bch_fs *c, struct write_point *wp,
 	wp->sectors_allocated	+= sectors;
 
 	open_bucket_for_each(c, &wp->ptrs, ob, i) {
-		struct bch_dev *ca = bch2_dev_bkey_exists(c, ob->dev);
+		struct bch_dev *ca = ob_dev(c, ob);
 		struct bch_extent_ptr ptr = bch2_ob_ptr(c, ob);
 
 		ptr.cached = cached ||

fs/bcachefs/ec.c

@@ -1550,16 +1550,13 @@ void bch2_ec_bucket_cancel(struct bch_fs *c, struct open_bucket *ob)
 void *bch2_writepoint_ec_buf(struct bch_fs *c, struct write_point *wp)
 {
 	struct open_bucket *ob = ec_open_bucket(c, &wp->ptrs);
-	struct bch_dev *ca;
-	unsigned offset;
-
 	if (!ob)
 		return NULL;
 
 	BUG_ON(!ob->ec->new_stripe.data[ob->ec_idx]);
 
-	ca	= bch2_dev_bkey_exists(c, ob->dev);
-	offset	= ca->mi.bucket_size - ob->sectors_free;
+	struct bch_dev *ca	= ob_dev(c, ob);
+	unsigned offset		= ca->mi.bucket_size - ob->sectors_free;
 
 	return ob->ec->new_stripe.data[ob->ec_idx] + (offset << 9);
 }

fs/bcachefs/sb-members.h

@@ -195,6 +195,13 @@ static inline bool bucket_valid(const struct bch_dev *ca, u64 b)
 	return b - ca->mi.first_bucket < ca->mi.nbuckets_minus_first;
 }
 
+static inline struct bch_dev *bch2_dev_have_ref(const struct bch_fs *c, unsigned dev)
+{
+	EBUG_ON(!bch2_dev_exists(c, dev));
+
+	return rcu_dereference_check(c->devs[dev], 1);
+}
+
 /*
  * If a key exists that references a device, the device won't be going away and
  * we can omit rcu_read_lock():