Merge tag 'bcachefs-2025-03-13' of git://evilpiepirate.org/bcachefs

Pull bcachefs fixes from Kent Overstreet:
 "Roxana caught an unitialized value that might explain some of the
  rebalance weirdness we're still tracking down - cool.

  Otherwise pretty minor"

* tag 'bcachefs-2025-03-13' of git://evilpiepirate.org/bcachefs:
  bcachefs: bch2_get_random_u64_below()
  bcachefs: target_congested -> get_random_u32_below()
  bcachefs: fix tiny leak in bch2_dev_add()
  bcachefs: Make sure trans is unlocked when submitting read IO
  bcachefs: Initialize from_inode members for bch_io_opts
  bcachefs: Fix b->written overflow

Author: torvalds

fs/bcachefs/btree_io.c

@@ -1186,7 +1186,7 @@ int bch2_btree_node_read_done(struct bch_fs *c, struct bch_dev *ca,
 			     le64_to_cpu(i->journal_seq),
 			     b->written, b->written + sectors, ptr_written);
 
-		b->written += sectors;
+		b->written = min(b->written + sectors, btree_sectors(c));
 
 		if (blacklisted && !first)
 			continue;

fs/bcachefs/extents.c

@@ -99,7 +99,7 @@ static inline bool ptr_better(struct bch_fs *c,
 
 		/* Pick at random, biased in favor of the faster device: */
 
-		return bch2_rand_range(l1 + l2) > l1;
+		return bch2_get_random_u64_below(l1 + l2) > l1;
 	}
 
 	if (bch2_force_reconstruct_read)

fs/bcachefs/inode.c

@@ -1198,6 +1198,7 @@ void bch2_inode_opts_get(struct bch_io_opts *opts, struct bch_fs *c,
 		opts->_name##_from_inode = true;			\
 	} else {							\
 		opts->_name = c->opts._name;				\
+		opts->_name##_from_inode = false;			\
 	}
 	BCH_INODE_OPTS()
 #undef x

fs/bcachefs/io_read.c

@@ -59,7 +59,7 @@ static bool bch2_target_congested(struct bch_fs *c, u16 target)
 	}
 	rcu_read_unlock();
 
-	return bch2_rand_range(nr * CONGESTED_MAX) < total;
+	return get_random_u32_below(nr * CONGESTED_MAX) < total;
 }
 
 #else
@@ -951,12 +951,6 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
 		goto retry_pick;
 	}
 
-	/*
-	 * Unlock the iterator while the btree node's lock is still in
-	 * cache, before doing the IO:
-	 */
-	bch2_trans_unlock(trans);
-
 	if (flags & BCH_READ_NODECODE) {
 		/*
 		 * can happen if we retry, and the extent we were going to read
@@ -1113,6 +1107,15 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
 		trace_and_count(c, read_split, &orig->bio);
 	}
 
+	/*
+	 * Unlock the iterator while the btree node's lock is still in
+	 * cache, before doing the IO:
+	 */
+	if (!(flags & BCH_READ_IN_RETRY))
+		bch2_trans_unlock(trans);
+	else
+		bch2_trans_unlock_long(trans);
+
 	if (!rbio->pick.idx) {
 		if (unlikely(!rbio->have_ioref)) {
 			struct printbuf buf = PRINTBUF;
@@ -1160,6 +1163,8 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
 	if (likely(!(flags & BCH_READ_IN_RETRY))) {
 		return 0;
 	} else {
+		bch2_trans_unlock(trans);
+
 		int ret;
 
 		rbio->context = RBIO_CONTEXT_UNBOUND;

fs/bcachefs/super.c

@@ -1811,7 +1811,11 @@ int bch2_dev_add(struct bch_fs *c, const char *path)
 		goto err_late;
 
 	up_write(&c->state_lock);
-	return 0;
+out:
+	printbuf_exit(&label);
+	printbuf_exit(&errbuf);
+	bch_err_fn(c, ret);
+	return ret;
 
 err_unlock:
 	mutex_unlock(&c->sb_lock);
@@ -1820,10 +1824,7 @@ int bch2_dev_add(struct bch_fs *c, const char *path)
 	if (ca)
 		bch2_dev_free(ca);
 	bch2_free_super(&sb);
-	printbuf_exit(&label);
-	printbuf_exit(&errbuf);
-	bch_err_fn(c, ret);
-	return ret;
+	goto out;
 err_late:
 	up_write(&c->state_lock);
 	ca = NULL;

fs/bcachefs/util.c

@@ -653,19 +653,24 @@ int bch2_bio_alloc_pages(struct bio *bio, size_t size, gfp_t gfp_mask)
 	return 0;
 }
 
-size_t bch2_rand_range(size_t max)
+u64 bch2_get_random_u64_below(u64 ceil)
 {
-	size_t rand;
+	if (ceil <= U32_MAX)
+		return __get_random_u32_below(ceil);
 
-	if (!max)
-		return 0;
+	/* this is the same (clever) algorithm as in __get_random_u32_below() */
+	u64 rand = get_random_u64();
+	u64 mult = ceil * rand;
 
-	do {
-		rand = get_random_long();
-		rand &= roundup_pow_of_two(max) - 1;
-	} while (rand >= max);
+	if (unlikely(mult < ceil)) {
+		u64 bound = -ceil % ceil;
+		while (unlikely(mult < bound)) {
+			rand = get_random_u64();
+			mult = ceil * rand;
+		}
+	}
 
-	return rand;
+	return mul_u64_u64_shr(ceil, rand, 64);
 }
 
 void memcpy_to_bio(struct bio *dst, struct bvec_iter dst_iter, const void *src)

fs/bcachefs/util.h

@@ -401,7 +401,7 @@ do {									\
 	_ret;								\
 })
 
-size_t bch2_rand_range(size_t);
+u64 bch2_get_random_u64_below(u64);
 
 void memcpy_to_bio(struct bio *, struct bvec_iter, const void *);
 void memcpy_from_bio(void *, struct bio *, struct bvec_iter);