bcachefs: bch2_dev_rcu_noerror()

bch2_dev_rcu() now properly errors if the device is invalid

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

Author: Kent Overstreet

fs/bcachefs/alloc_background.h

@@ -16,7 +16,7 @@ enum bch_validate_flags;
 static inline bool bch2_dev_bucket_exists(struct bch_fs *c, struct bpos pos)
 {
 	rcu_read_lock();
-	struct bch_dev *ca = bch2_dev_rcu(c, pos.inode);
+	struct bch_dev *ca = bch2_dev_rcu_noerror(c, pos.inode);
 	bool ret = ca && bucket_valid(ca, pos.offset);
 	rcu_read_unlock();
 	return ret;

fs/bcachefs/backpointers.c

@@ -55,7 +55,7 @@ int bch2_backpointer_validate(struct bch_fs *c, struct bkey_s_c k,
 	struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
 
 	rcu_read_lock();
-	struct bch_dev *ca = bch2_dev_rcu(c, bp.k->p.inode);
+	struct bch_dev *ca = bch2_dev_rcu_noerror(c, bp.k->p.inode);
 	if (!ca) {
 		/* these will be caught by fsck */
 		rcu_read_unlock();
@@ -89,7 +89,7 @@ void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer
 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
 {
 	rcu_read_lock();
-	struct bch_dev *ca = bch2_dev_rcu(c, k.k->p.inode);
+	struct bch_dev *ca = bch2_dev_rcu_noerror(c, k.k->p.inode);
 	if (ca) {
 		struct bpos bucket = bp_pos_to_bucket(ca, k.k->p);
 		rcu_read_unlock();
@@ -673,7 +673,7 @@ static int check_extent_to_backpointers(struct btree_trans *trans,
 			continue;
 
 		rcu_read_lock();
-		struct bch_dev *ca = bch2_dev_rcu(c, p.ptr.dev);
+		struct bch_dev *ca = bch2_dev_rcu_noerror(c, p.ptr.dev);
 		if (ca)
 			bch2_extent_ptr_to_bp(c, ca, btree, level, k, p, entry, &bucket_pos, &bp);
 		rcu_read_unlock();

fs/bcachefs/buckets.c

@@ -281,7 +281,7 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			goto err;
 
 		rcu_read_lock();
-		bch2_bkey_drop_ptrs(bkey_i_to_s(new), ptr, !bch2_dev_rcu(c, ptr->dev));
+		bch2_bkey_drop_ptrs(bkey_i_to_s(new), ptr, !bch2_dev_exists(c, ptr->dev));
 		rcu_read_unlock();
 
 		if (level) {

fs/bcachefs/extents.c

@@ -1021,7 +1021,7 @@ void bch2_extent_ptr_to_text(struct printbuf *out, struct bch_fs *c, const struc
 {
 	out->atomic++;
 	rcu_read_lock();
-	struct bch_dev *ca = bch2_dev_rcu(c, ptr->dev);
+	struct bch_dev *ca = bch2_dev_rcu_noerror(c, ptr->dev);
 	if (!ca) {
 		prt_printf(out, "ptr: %u:%llu gen %u%s", ptr->dev,
 			   (u64) ptr->offset, ptr->gen,
@@ -1125,8 +1125,9 @@ static int extent_ptr_validate(struct bch_fs *c,
 {
 	int ret = 0;
 
+	/* bad pointers are repaired by check_fix_ptrs(): */
 	rcu_read_lock();
-	struct bch_dev *ca = bch2_dev_rcu(c, ptr->dev);
+	struct bch_dev *ca = bch2_dev_rcu_noerror(c, ptr->dev);
 	if (!ca) {
 		rcu_read_unlock();
 		return 0;

fs/bcachefs/replicas.c

@@ -795,7 +795,7 @@ bool bch2_have_enough_devs(struct bch_fs *c, struct bch_devs_mask devs,
 		for (unsigned i = 0; i < e->nr_devs; i++) {
 			nr_online += test_bit(e->devs[i], devs.d);
 
-			struct bch_dev *ca = bch2_dev_rcu(c, e->devs[i]);
+			struct bch_dev *ca = bch2_dev_rcu_noerror(c, e->devs[i]);
 			nr_failed += !ca || ca->mi.state == BCH_MEMBER_STATE_failed;
 		}
 		rcu_read_unlock();

fs/bcachefs/sb-members.h

@@ -198,29 +198,37 @@ static inline struct bch_dev *bch2_dev_locked(struct bch_fs *c, unsigned dev)
 					 lockdep_is_held(&c->state_lock));
 }
 
-static inline struct bch_dev *bch2_dev_rcu(struct bch_fs *c, unsigned dev)
+static inline struct bch_dev *bch2_dev_rcu_noerror(struct bch_fs *c, unsigned dev)
 {
 	return c && dev < c->sb.nr_devices
 		? rcu_dereference(c->devs[dev])
 		: NULL;
 }
 
+void bch2_dev_missing(struct bch_fs *, unsigned);
+
+static inline struct bch_dev *bch2_dev_rcu(struct bch_fs *c, unsigned dev)
+{
+	struct bch_dev *ca = bch2_dev_rcu_noerror(c, dev);
+	if (unlikely(!ca))
+		bch2_dev_missing(c, dev);
+	return ca;
+}
+
 static inline struct bch_dev *bch2_dev_tryget_noerror(struct bch_fs *c, unsigned dev)
 {
 	rcu_read_lock();
-	struct bch_dev *ca = bch2_dev_rcu(c, dev);
+	struct bch_dev *ca = bch2_dev_rcu_noerror(c, dev);
 	if (ca)
 		bch2_dev_get(ca);
 	rcu_read_unlock();
 	return ca;
 }
 
-void bch2_dev_missing(struct bch_fs *, unsigned);
-
 static inline struct bch_dev *bch2_dev_tryget(struct bch_fs *c, unsigned dev)
 {
 	struct bch_dev *ca = bch2_dev_tryget_noerror(c, dev);
-	if (!ca)
+	if (unlikely(!ca))
 		bch2_dev_missing(c, dev);
 	return ca;
 }