bcachefs: Replace rcu_read_lock() with guards

The new guard(), scoped_guard() allow for more natural code.

Some of the uses with creative flow control have been left.

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

41 files changed, 344 insertions, 525 deletions

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index 2325a2699a89..e1231b20faec 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -1000,14 +1000,11 @@ int bch2_trigger_alloc(struct btree_trans *trans,
 		}
 
 		if (new_a->gen != old_a->gen) {
-			rcu_read_lock();
+			guard(rcu)();
 			u8 *gen = bucket_gen(ca, new.k->p.offset);
-			if (unlikely(!gen)) {
-				rcu_read_unlock();
+			if (unlikely(!gen))
 				goto invalid_bucket;
-			}
 			*gen = new_a->gen;
-			rcu_read_unlock();
 		}
 
 #define eval_state(_a, expr)		({ const struct bch_alloc_v4 *a = _a; expr; })
@@ -1033,15 +1030,12 @@ int bch2_trigger_alloc(struct btree_trans *trans,
 	}
 
 	if ((flags & BTREE_TRIGGER_gc) && (flags & BTREE_TRIGGER_insert)) {
-		rcu_read_lock();
+		guard(rcu)();
 		struct bucket *g = gc_bucket(ca, new.k->p.offset);
-		if (unlikely(!g)) {
-			rcu_read_unlock();
+		if (unlikely(!g))
 			goto invalid_bucket;
-		}
 		g->gen_valid	= 1;
 		g->gen		= new_a->gen;
-		rcu_read_unlock();
 	}
 err:
 fsck_err:
@@ -1117,13 +1111,12 @@ static bool next_bucket(struct bch_fs *c, struct bch_dev **ca, struct bpos *buck
 		bucket->offset = 0;
 	}
 
-	rcu_read_lock();
+	guard(rcu)();
 	*ca = __bch2_next_dev_idx(c, bucket->inode, NULL);
 	if (*ca) {
 		*bucket = POS((*ca)->dev_idx, (*ca)->mi.first_bucket);
 		bch2_dev_get(*ca);
 	}
-	rcu_read_unlock();
 
 	return *ca != NULL;
 }
@@ -2514,7 +2507,7 @@ void bch2_recalc_capacity(struct bch_fs *c)
 
 	lockdep_assert_held(&c->state_lock);
 
-	rcu_read_lock();
+	guard(rcu)();
 	for_each_member_device_rcu(c, ca, NULL) {
 		struct block_device *bdev = READ_ONCE(ca->disk_sb.bdev);
 		if (bdev)
@@ -2559,7 +2552,6 @@ void bch2_recalc_capacity(struct bch_fs *c)
 		bucket_size_max = max_t(unsigned, bucket_size_max,
 					ca->mi.bucket_size);
 	}
-	rcu_read_unlock();
 
 	bch2_set_ra_pages(c, ra_pages);
 
@@ -2584,10 +2576,9 @@ u64 bch2_min_rw_member_capacity(struct bch_fs *c)
 {
 	u64 ret = U64_MAX;
 
-	rcu_read_lock();
+	guard(rcu)();
 	for_each_rw_member_rcu(c, ca)
 		ret = min(ret, ca->mi.nbuckets * ca->mi.bucket_size);
-	rcu_read_unlock();
 	return ret;
 }
 
diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
index b97ae710219f..0cc5adc55b6f 100644
--- a/fs/bcachefs/alloc_background.h
+++ b/fs/bcachefs/alloc_background.h
@@ -13,11 +13,9 @@
 
 static inline bool bch2_dev_bucket_exists(struct bch_fs *c, struct bpos pos)
 {
-	rcu_read_lock();
+	guard(rcu)();
 	struct bch_dev *ca = bch2_dev_rcu_noerror(c, pos.inode);
-	bool ret = ca && bucket_valid(ca, pos.offset);
-	rcu_read_unlock();
-	return ret;
+	return ca && bucket_valid(ca, pos.offset);
 }
 
 static inline u64 bucket_to_u64(struct bpos bucket)
diff --git a/fs/bcachefs/alloc_foreground.c b/fs/bcachefs/alloc_foreground.c
index 0e7eeb89299c..e157bc86b2f3 100644
--- a/fs/bcachefs/alloc_foreground.c
+++ b/fs/bcachefs/alloc_foreground.c
@@ -69,10 +69,9 @@ const char * const bch2_watermarks[] = {
 
 void bch2_reset_alloc_cursors(struct bch_fs *c)
 {
-	rcu_read_lock();
+	guard(rcu)();
 	for_each_member_device_rcu(c, ca, NULL)
 		memset(ca->alloc_cursor, 0, sizeof(ca->alloc_cursor));
-	rcu_read_unlock();
 }
 
 static void bch2_open_bucket_hash_add(struct bch_fs *c, struct open_bucket *ob)
@@ -166,9 +165,8 @@ static void open_bucket_free_unused(struct bch_fs *c, struct open_bucket *ob)
 	       ARRAY_SIZE(c->open_buckets_partial));
 
 	spin_lock(&c->freelist_lock);
-	rcu_read_lock();
-	bch2_dev_rcu(c, ob->dev)->nr_partial_buckets++;
-	rcu_read_unlock();
+	scoped_guard(rcu)
+		bch2_dev_rcu(c, ob->dev)->nr_partial_buckets++;
 
 	ob->on_partial_list = true;
 	c->open_buckets_partial[c->open_buckets_partial_nr++] =
@@ -873,9 +871,8 @@ static int bucket_alloc_set_partial(struct bch_fs *c,
 					  i);
 			ob->on_partial_list = false;
 
-			rcu_read_lock();
-			bch2_dev_rcu(c, ob->dev)->nr_partial_buckets--;
-			rcu_read_unlock();
+			scoped_guard(rcu)
+				bch2_dev_rcu(c, ob->dev)->nr_partial_buckets--;
 
 			ret = add_new_bucket(c, req, ob);
 			if (ret)
@@ -1057,9 +1054,8 @@ void bch2_open_buckets_stop(struct bch_fs *c, struct bch_dev *ca,
 
 			ob->on_partial_list = false;
 
-			rcu_read_lock();
-			bch2_dev_rcu(c, ob->dev)->nr_partial_buckets--;
-			rcu_read_unlock();
+			scoped_guard(rcu)
+				bch2_dev_rcu(c, ob->dev)->nr_partial_buckets--;
 
 			spin_unlock(&c->freelist_lock);
 			bch2_open_bucket_put(c, ob);
@@ -1087,14 +1083,11 @@ static struct write_point *__writepoint_find(struct hlist_head *head,
 {
 	struct write_point *wp;
 
-	rcu_read_lock();
+	guard(rcu)();
 	hlist_for_each_entry_rcu(wp, head, node)
 		if (wp->write_point == write_point)
-			goto out;
-	wp = NULL;
-out:
-	rcu_read_unlock();
-	return wp;
+			return wp;
+	return NULL;
 }
 
 static inline bool too_many_writepoints(struct bch_fs *c, unsigned factor)
@@ -1638,19 +1631,16 @@ static noinline void bch2_print_allocator_stuck(struct bch_fs *c)
 
 	bch2_printbuf_make_room(&buf, 4096);
 
-	rcu_read_lock();
 	buf.atomic++;
-
-	for_each_online_member_rcu(c, ca) {
-		prt_printf(&buf, "Dev %u:\n", ca->dev_idx);
-		printbuf_indent_add(&buf, 2);
-		bch2_dev_alloc_debug_to_text(&buf, ca);
-		printbuf_indent_sub(&buf, 2);
-		prt_newline(&buf);
-	}
-
+	scoped_guard(rcu)
+		for_each_online_member_rcu(c, ca) {
+			prt_printf(&buf, "Dev %u:\n", ca->dev_idx);
+			printbuf_indent_add(&buf, 2);
+			bch2_dev_alloc_debug_to_text(&buf, ca);
+			printbuf_indent_sub(&buf, 2);
+			prt_newline(&buf);
+		}
 	--buf.atomic;
-	rcu_read_unlock();
 
 	prt_printf(&buf, "Copygc debug:\n");
 	printbuf_indent_add(&buf, 2);
diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index cde7dd115267..ebc8ee2cd33e 100644
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -48,17 +48,19 @@ void bch2_backpointer_to_text(struct printbuf *out, struct bch_fs *c, struct bke
 {
 	struct bkey_s_c_backpointer bp = bkey_s_c_to_backpointer(k);
 
-	rcu_read_lock();
-	struct bch_dev *ca = bch2_dev_rcu_noerror(c, bp.k->p.inode);
-	if (ca) {
-		u32 bucket_offset;
-		struct bpos bucket = bp_pos_to_bucket_and_offset(ca, bp.k->p, &bucket_offset);
-		rcu_read_unlock();
+	struct bch_dev *ca;
+	u32 bucket_offset;
+	struct bpos bucket;
+	scoped_guard(rcu) {
+		ca = bch2_dev_rcu_noerror(c, bp.k->p.inode);
+		if (ca)
+			bucket = bp_pos_to_bucket_and_offset(ca, bp.k->p, &bucket_offset);
+	}
+
+	if (ca)
 		prt_printf(out, "bucket=%llu:%llu:%u ", bucket.inode, bucket.offset, bucket_offset);
-	} else {
-		rcu_read_unlock();
+	else
 		prt_printf(out, "sector=%llu:%llu ", bp.k->p.inode, bp.k->p.offset >> MAX_EXTENT_COMPRESS_RATIO_SHIFT);
-	}
 
 	bch2_btree_id_level_to_text(out, bp.v->btree_id, bp.v->level);
 	prt_str(out, " data_type=");
@@ -591,6 +593,7 @@ check_existing_bp:
 		bkey_for_each_ptr(other_extent_ptrs, ptr)
 			if (ptr->dev == bp->k.p.inode &&
 			    dev_ptr_stale_rcu(ca, ptr)) {
+				rcu_read_unlock();
 				ret = drop_dev_and_update(trans, other_bp.v->btree_id,
 							  other_extent, bp->k.p.inode);
 				if (ret)
@@ -679,26 +682,23 @@ static int check_extent_to_backpointers(struct btree_trans *trans,
 		if (p.ptr.dev == BCH_SB_MEMBER_INVALID)
 			continue;
 
-		rcu_read_lock();
-		struct bch_dev *ca = bch2_dev_rcu_noerror(c, p.ptr.dev);
-		if (!ca) {
-			rcu_read_unlock();
-			continue;
-		}
+		bool empty;
+		{
+			/* scoped_guard() is a loop, so it breaks continue */
+			guard(rcu)();
+			struct bch_dev *ca = bch2_dev_rcu_noerror(c, p.ptr.dev);
+			if (!ca)
+				continue;
 
-		if (p.ptr.cached && dev_ptr_stale_rcu(ca, &p.ptr)) {
-			rcu_read_unlock();
-			continue;
-		}
+			if (p.ptr.cached && dev_ptr_stale_rcu(ca, &p.ptr))
+				continue;
 
-		u64 b = PTR_BUCKET_NR(ca, &p.ptr);
-		if (!bch2_bucket_bitmap_test(&ca->bucket_backpointer_mismatch, b)) {
-			rcu_read_unlock();
-			continue;
-		}
+			u64 b = PTR_BUCKET_NR(ca, &p.ptr);
+			if (!bch2_bucket_bitmap_test(&ca->bucket_backpointer_mismatch, b))
+				continue;
 
-		bool empty = bch2_bucket_bitmap_test(&ca->bucket_backpointer_empty, b);
-		rcu_read_unlock();
+			empty = bch2_bucket_bitmap_test(&ca->bucket_backpointer_empty, b);
+		}
 
 		struct bkey_i_backpointer bp;
 		bch2_extent_ptr_to_bp(c, btree, level, k, p, entry, &bp);
@@ -981,7 +981,7 @@ static bool backpointer_node_has_missing(struct bch_fs *c, struct bkey_s_c k)
 	case KEY_TYPE_btree_ptr_v2: {
 		bool ret = false;
 
-		rcu_read_lock();
+		guard(rcu)();
 		struct bpos pos = bkey_s_c_to_btree_ptr_v2(k).v->min_key;
 		while (pos.inode <= k.k->p.inode) {
 			if (pos.inode >= c->sb.nr_devices)
@@ -1009,7 +1009,6 @@ static bool backpointer_node_has_missing(struct bch_fs *c, struct bkey_s_c k)
 next:
 			pos = SPOS(pos.inode + 1, 0, 0);
 		}
-		rcu_read_unlock();
 
 		return ret;
 	}
diff --git a/fs/bcachefs/backpointers.h b/fs/bcachefs/backpointers.h
index 6840561084ce..fac05948da1c 100644
--- a/fs/bcachefs/backpointers.h
+++ b/fs/bcachefs/backpointers.h
@@ -53,11 +53,10 @@ static inline struct bpos bp_pos_to_bucket_and_offset(const struct bch_dev *ca,
 
 static inline bool bp_pos_to_bucket_nodev_noerror(struct bch_fs *c, struct bpos bp_pos, struct bpos *bucket)
 {
-	rcu_read_lock();
+	guard(rcu)();
 	struct bch_dev *ca = bch2_dev_rcu_noerror(c, bp_pos.inode);
 	if (ca)
 		*bucket = bp_pos_to_bucket(ca, bp_pos);
-	rcu_read_unlock();
 	return ca != NULL;
 }
 
diff --git a/fs/bcachefs/btree_gc.c b/fs/bcachefs/btree_gc.c
index 91b6395421df..f95486729ba5 100644
--- a/fs/bcachefs/btree_gc.c
+++ b/fs/bcachefs/btree_gc.c
@@ -1093,42 +1093,41 @@ static int gc_btree_gens_key(struct btree_trans *trans,
 {
 	struct bch_fs *c = trans->c;
 	struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
-	struct bkey_i *u;
-	int ret;
 
 	if (unlikely(test_bit(BCH_FS_going_ro, &c->flags)))
 		return -EROFS;
 
-	rcu_read_lock();
-	bkey_for_each_ptr(ptrs, ptr) {
-		struct bch_dev *ca = bch2_dev_rcu(c, ptr->dev);
-		if (!ca)
-			continue;
+	bool too_stale = false;
+	scoped_guard(rcu) {
+		bkey_for_each_ptr(ptrs, ptr) {
+			struct bch_dev *ca = bch2_dev_rcu(c, ptr->dev);
+			if (!ca)
+				continue;
 
-		if (dev_ptr_stale(ca, ptr) > 16) {
-			rcu_read_unlock();
-			goto update;
+			too_stale |= dev_ptr_stale(ca, ptr) > 16;
 		}
+
+		if (!too_stale)
+			bkey_for_each_ptr(ptrs, ptr) {
+				struct bch_dev *ca = bch2_dev_rcu(c, ptr->dev);
+				if (!ca)
+					continue;
+
+				u8 *gen = &ca->oldest_gen[PTR_BUCKET_NR(ca, ptr)];
+				if (gen_after(*gen, ptr->gen))
+					*gen = ptr->gen;
+			}
 	}
 
-	bkey_for_each_ptr(ptrs, ptr) {
-		struct bch_dev *ca = bch2_dev_rcu(c, ptr->dev);
-		if (!ca)
-			continue;
+	if (too_stale) {
+		struct bkey_i *u = bch2_bkey_make_mut(trans, iter, &k, 0);
+		int ret = PTR_ERR_OR_ZERO(u);
+		if (ret)
+			return ret;
 
-		u8 *gen = &ca->oldest_gen[PTR_BUCKET_NR(ca, ptr)];
-		if (gen_after(*gen, ptr->gen))
-			*gen = ptr->gen;
+		bch2_extent_normalize(c, bkey_i_to_s(u));
 	}
-	rcu_read_unlock();
-	return 0;
-update:
-	u = bch2_bkey_make_mut(trans, iter, &k, 0);
-	ret = PTR_ERR_OR_ZERO(u);
-	if (ret)
-		return ret;
 
-	bch2_extent_normalize(c, bkey_i_to_s(u));
 	return 0;
 }
 
diff --git a/fs/bcachefs/btree_io.c b/fs/bcachefs/btree_io.c
index c19a4b44162a..2e191561d578 100644
--- a/fs/bcachefs/btree_io.c
+++ b/fs/bcachefs/btree_io.c
@@ -1325,14 +1325,13 @@ int bch2_btree_node_read_done(struct bch_fs *c, struct bch_dev *ca,
 
 	btree_node_reset_sib_u64s(b);
 
-	rcu_read_lock();
-	bkey_for_each_ptr(bch2_bkey_ptrs(bkey_i_to_s(&b->key)), ptr) {
-		struct bch_dev *ca2 = bch2_dev_rcu(c, ptr->dev);
+	scoped_guard(rcu)
+		bkey_for_each_ptr(bch2_bkey_ptrs(bkey_i_to_s(&b->key)), ptr) {
+			struct bch_dev *ca2 = bch2_dev_rcu(c, ptr->dev);
 
-		if (!ca2 || ca2->mi.state != BCH_MEMBER_STATE_rw)
-			set_btree_node_need_rewrite(b);
-	}
-	rcu_read_unlock();
+			if (!ca2 || ca2->mi.state != BCH_MEMBER_STATE_rw)
+				set_btree_node_need_rewrite(b);
+		}
 
 	if (!ptr_written)
 		set_btree_node_need_rewrite(b);
diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 5affa5fc22f4..c7606e0b113d 100644
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -3568,13 +3568,12 @@ bch2_btree_bkey_cached_common_to_text(struct printbuf *out,
 				      struct btree_bkey_cached_common *b)
 {
 	struct six_lock_count c = six_lock_counts(&b->lock);
-	struct task_struct *owner;
 	pid_t pid;
 
-	rcu_read_lock();
-	owner = READ_ONCE(b->lock.owner);
-	pid = owner ? owner->pid : 0;
-	rcu_read_unlock();
+	scoped_guard(rcu) {
+		struct task_struct *owner = READ_ONCE(b->lock.owner);
+		pid = owner ? owner->pid : 0;
+	}
 
 	prt_printf(out, "\t%px %c ", b, b->cached ? 'c' : 'b');
 	bch2_btree_id_to_text(out, b->btree_id);
@@ -3603,7 +3602,7 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
 	prt_printf(out, "%i %s\n", task ? task->pid : 0, trans->fn);
 
 	/* trans->paths is rcu protected vs. freeing */
-	rcu_read_lock();
+	guard(rcu)();
 	out->atomic++;
 
 	struct btree_path *paths = rcu_dereference(trans->paths);
@@ -3646,7 +3645,6 @@ void bch2_btree_trans_to_text(struct printbuf *out, struct btree_trans *trans)
 	}
 out:
 	--out->atomic;
-	rcu_read_unlock();
 }
 
 void bch2_fs_btree_iter_exit(struct bch_fs *c)
diff --git a/fs/bcachefs/btree_journal_iter.c b/fs/bcachefs/btree_journal_iter.c
index ade3b5addd75..48863e6925e0 100644
--- a/fs/bcachefs/btree_journal_iter.c
+++ b/fs/bcachefs/btree_journal_iter.c
@@ -457,11 +457,9 @@ static void bch2_journal_iter_advance(struct journal_iter *iter)
 
 static struct bkey_s_c bch2_journal_iter_peek(struct journal_iter *iter)
 {
-	struct bkey_s_c ret = bkey_s_c_null;
-
 	journal_iter_verify(iter);
 
-	rcu_read_lock();
+	guard(rcu)();
 	while (iter->idx < iter->keys->size) {
 		struct journal_key *k = iter->keys->data + iter->idx;
 
@@ -470,19 +468,16 @@ static struct bkey_s_c bch2_journal_iter_peek(struct journal_iter *iter)
 			break;
 		BUG_ON(cmp);
 
-		if (!k->overwritten) {
-			ret = bkey_i_to_s_c(k->k);
-			break;
-		}
+		if (!k->overwritten)
+			return bkey_i_to_s_c(k->k);
 
 		if (k->overwritten_range)
 			iter->idx = idx_to_pos(iter->keys, rcu_dereference(k->overwritten_range)->end);
 		else
 			bch2_journal_iter_advance(iter);
 	}
-	rcu_read_unlock();
 
-	return ret;
+	return bkey_s_c_null;
 }
 
 static void bch2_journal_iter_exit(struct journal_iter *iter)
diff --git a/fs/bcachefs/btree_key_cache.c b/fs/bcachefs/btree_key_cache.c
index 9da950e7eb7d..e954b19756c0 100644
--- a/fs/bcachefs/btree_key_cache.c
+++ b/fs/bcachefs/btree_key_cache.c
@@ -187,27 +187,23 @@ lock:
 static struct bkey_cached *
 bkey_cached_reuse(struct btree_key_cache *c)
 {
-	struct bucket_table *tbl;
+
+	guard(rcu)();
+	struct bucket_table *tbl = rht_dereference_rcu(c->table.tbl, &c->table);
 	struct rhash_head *pos;
 	struct bkey_cached *ck;
-	unsigned i;
 
-	rcu_read_lock();
-	tbl = rht_dereference_rcu(c->table.tbl, &c->table);
-	for (i = 0; i < tbl->size; i++)
+	for (unsigned i = 0; i < tbl->size; i++)
 		rht_for_each_entry_rcu(ck, pos, tbl, i, hash) {
 			if (!test_bit(BKEY_CACHED_DIRTY, &ck->flags) &&
 			    bkey_cached_lock_for_evict(ck)) {
 				if (bkey_cached_evict(c, ck))
-					goto out;
+					return ck;
 				six_unlock_write(&ck->c.lock);
 				six_unlock_intent(&ck->c.lock);
 			}
 		}
-	ck = NULL;
-out:
-	rcu_read_unlock();
-	return ck;
+	return NULL;
 }
 
 static int btree_key_cache_create(struct btree_trans *trans,
diff --git a/fs/bcachefs/btree_locking.c b/fs/bcachefs/btree_locking.c
index 09ae5a8c6874..47035aae232e 100644
--- a/fs/bcachefs/btree_locking.c
+++ b/fs/bcachefs/btree_locking.c
@@ -311,7 +311,7 @@ int bch2_check_for_deadlock(struct btree_trans *trans, struct printbuf *cycle)
 	lock_graph_down(&g, trans);
 
 	/* trans->paths is rcu protected vs. freeing */
-	rcu_read_lock();
+	guard(rcu)();
 	if (cycle)
 		cycle->atomic++;
 next:
@@ -409,7 +409,6 @@ up:
 out:
 	if (cycle)
 		--cycle->atomic;
-	rcu_read_unlock();
 	return ret;
 }
 
diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c
index 410e0116917f..56bd8f66295c 100644
--- a/fs/bcachefs/buckets.c
+++ b/fs/bcachefs/buckets.c
@@ -299,9 +299,8 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 		if (ret)
 			goto err;
 
-		rcu_read_lock();
-		bch2_bkey_drop_ptrs(bkey_i_to_s(new), ptr, !bch2_dev_exists(c, ptr->dev));
-		rcu_read_unlock();
+		scoped_guard(rcu)
+			bch2_bkey_drop_ptrs(bkey_i_to_s(new), ptr, !bch2_dev_exists(c, ptr->dev));
 
 		if (level) {
 			/*
@@ -310,14 +309,11 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			 * sort it out:
 			 */
 			struct bkey_ptrs ptrs = bch2_bkey_ptrs(bkey_i_to_s(new));
-			rcu_read_lock();
-			bkey_for_each_ptr(ptrs, ptr) {
-				struct bch_dev *ca = bch2_dev_rcu(c, ptr->dev);
-				struct bucket *g = PTR_GC_BUCKET(ca, ptr);
-
-				ptr->gen = g->gen;
-			}
-			rcu_read_unlock();
+			scoped_guard(rcu)
+				bkey_for_each_ptr(ptrs, ptr) {
+					struct bch_dev *ca = bch2_dev_rcu(c, ptr->dev);
+					ptr->gen = PTR_GC_BUCKET(ca, ptr)->gen;
+				}
 		} else {
 			struct bkey_ptrs ptrs;
 			union bch_extent_entry *entry;
diff --git a/fs/bcachefs/buckets.h b/fs/bcachefs/buckets.h
index af1532de4a37..49a3807a5eab 100644
--- a/fs/bcachefs/buckets.h
+++ b/fs/bcachefs/buckets.h
@@ -84,10 +84,8 @@ static inline int bucket_gen_get_rcu(struct bch_dev *ca, size_t b)
 
 static inline int bucket_gen_get(struct bch_dev *ca, size_t b)
 {
-	rcu_read_lock();
-	int ret = bucket_gen_get_rcu(ca, b);
-	rcu_read_unlock();
-	return ret;
+	guard(rcu)();
+	return bucket_gen_get_rcu(ca, b);
 }
 
 static inline size_t PTR_BUCKET_NR(const struct bch_dev *ca,
@@ -156,10 +154,8 @@ static inline int dev_ptr_stale_rcu(struct bch_dev *ca, const struct bch_extent_
  */
 static inline int dev_ptr_stale(struct bch_dev *ca, const struct bch_extent_ptr *ptr)
 {
-	rcu_read_lock();
-	int ret = dev_ptr_stale_rcu(ca, ptr);
-	rcu_read_unlock();
-	return ret;
+	guard(rcu)();
+	return dev_ptr_stale_rcu(ca, ptr);
 }
 
 /* Device usage: */
diff --git a/fs/bcachefs/chardev.c b/fs/bcachefs/chardev.c
index 4066946b26bc..2db30eb134f3 100644
--- a/fs/bcachefs/chardev.c
+++ b/fs/bcachefs/chardev.c
@@ -613,13 +613,10 @@ static long bch2_ioctl_disk_get_idx(struct bch_fs *c,
 	if (!dev)
 		return -EINVAL;
 
-	rcu_read_lock();
+	guard(rcu)();
 	for_each_online_member_rcu(c, ca)
-		if (ca->dev == dev) {
-			rcu_read_unlock();
+		if (ca->dev == dev)
 			return ca->dev_idx;
-		}
-	rcu_read_unlock();
 
 	return -BCH_ERR_ENOENT_dev_idx_not_found;
 }
diff --git a/fs/bcachefs/data_update.c b/fs/bcachefs/data_update.c
index fafe7a57ea41..5c687ed1bcb2 100644
--- a/fs/bcachefs/data_update.c
+++ b/fs/bcachefs/data_update.c
@@ -376,21 +376,21 @@ restart_drop_conflicting_replicas:
 			bch2_bkey_durability(c, bkey_i_to_s_c(&new->k_i));
 
 		/* Now, drop excess replicas: */
-		rcu_read_lock();
+		scoped_guard(rcu) {
 restart_drop_extra_replicas:
-		bkey_for_each_ptr_decode(old.k, bch2_bkey_ptrs(bkey_i_to_s(insert)), p, entry) {
-			unsigned ptr_durability = bch2_extent_ptr_durability(c, &p);
+			bkey_for_each_ptr_decode(old.k, bch2_bkey_ptrs(bkey_i_to_s(insert)), p, entry) {
+				unsigned ptr_durability = bch2_extent_ptr_durability(c, &p);
 
-			if (!p.ptr.cached &&
-			    durability - ptr_durability >= m->op.opts.data_replicas) {
-				durability -= ptr_durability;
+				if (!p.ptr.cached &&
+				    durability - ptr_durability >= m->op.opts.data_replicas) {
+					durability -= ptr_durability;
 
-				bch2_extent_ptr_set_cached(c, &m->op.opts,
-							   bkey_i_to_s(insert), &entry->ptr);
-				goto restart_drop_extra_replicas;
+					bch2_extent_ptr_set_cached(c, &m->op.opts,
+								   bkey_i_to_s(insert), &entry->ptr);
+					goto restart_drop_extra_replicas;
+				}
 			}
 		}
-		rcu_read_unlock();
 
 		/* Finally, add the pointers we just wrote: */
 		extent_for_each_ptr_decode(extent_i_to_s(new), p, entry)
@@ -782,7 +782,8 @@ static int can_write_extent(struct bch_fs *c, struct data_update *m)
 	darray_for_each(m->op.devs_have, i)
 		__clear_bit(*i, devs.d);
 
-	rcu_read_lock();
+	guard(rcu)();
+
 	unsigned nr_replicas = 0, i;
 	for_each_set_bit(i, devs.d, BCH_SB_MEMBERS_MAX) {
 		struct bch_dev *ca = bch2_dev_rcu_noerror(c, i);
@@ -799,7 +800,6 @@ static int can_write_extent(struct bch_fs *c, struct data_update *m)
 		if (nr_replicas >= m->op.nr_replicas)
 			break;
 	}
-	rcu_read_unlock();
 
 	if (!nr_replicas)
 		return -BCH_ERR_data_update_done_no_rw_devs;
@@ -876,7 +876,7 @@ int bch2_data_update_init(struct btree_trans *trans,
 	unsigned ptr_bit = 1;
 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
 		if (!p.ptr.cached) {
-			rcu_read_lock();
+			guard(rcu)();
 			if (ptr_bit & m->data_opts.rewrite_ptrs) {
 				if (crc_is_compressed(p.crc))
 					reserve_sectors += k.k->size;
@@ -887,7 +887,6 @@ int bch2_data_update_init(struct btree_trans *trans,
 				bch2_dev_list_add_dev(&m->op.devs_have, p.ptr.dev);
 				durability_have += bch2_extent_ptr_durability(c, &p);
 			}
-			rcu_read_unlock();
 		}
 
 		/*
diff --git a/fs/bcachefs/debug.c b/fs/bcachefs/debug.c
index 04db3e0ed82b..901f643ead83 100644
--- a/fs/bcachefs/debug.c
+++ b/fs/bcachefs/debug.c
@@ -510,27 +510,27 @@ static ssize_t bch2_cached_btree_nodes_read(struct file *file, char __user *buf,
 	i->ret	= 0;
 
 	do {
-		struct bucket_table *tbl;
-		struct rhash_head *pos;
-		struct btree *b;
-
 		ret = bch2_debugfs_flush_buf(i);
 		if (ret)
 			return ret;
 
-		rcu_read_lock();
 		i->buf.atomic++;
-		tbl = rht_dereference_rcu(c->btree_cache.table.tbl,
-					  &c->btree_cache.table);
-		if (i->iter < tbl->size) {
-			rht_for_each_entry_rcu(b, pos, tbl, i->iter, hash)
-				bch2_cached_btree_node_to_text(&i->buf, c, b);
-			i->iter++;
-		} else {
-			done = true;
+		scoped_guard(rcu) {
+			struct bucket_table *tbl =
+				rht_dereference_rcu(c->btree_cache.table.tbl,
+						    &c->btree_cache.table);
+			if (i->iter &