bcachefs fixes for 6.16-rc7

- two small syzbot fixes
 - fix discard behaviour regression; we no longer wait until the number
   of buckets needing discard is greater than the number of buckets
   available before kicking off discards
 - fix a fast_list leak when async object debugging is enabled
 - fixes for casefolding when CONFIG_UTF8 != y
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Merge tag 'bcachefs-2025-07-17' of git://evilpiepirate.org/bcachefs

Pull bcachefs fixes from Kent Overstreet:

 - two small syzbot fixes

 - fix discard behaviour regression; we no longer wait until the number
   of buckets needing discard is greater than the number of buckets
   available before kicking off discards

 - fix a fast_list leak when async object debugging is enabled

 - fixes for casefolding when CONFIG_UTF8 != y

* tag 'bcachefs-2025-07-17' of git://evilpiepirate.org/bcachefs:
  bcachefs: Fix bch2_maybe_casefold() when CONFIG_UTF8=n
  bcachefs: Fix build when CONFIG_UNICODE=n
  bcachefs: Fix reference to invalid bucket in copygc
  bcachefs: Don't build aux search tree when still repairing node
  bcachefs: Tweak threshold for allocator triggering discards
  bcachefs: Fix triggering of discard by the journal path
  bcachefs: io_read: remove from async obj list in rbio_done()

fs/bcachefs/alloc_foreground.c

@@ -511,7 +511,8 @@ again:
 	bch2_dev_usage_read_fast(ca, &req->usage);
 	avail = dev_buckets_free(ca, req->usage, req->watermark);
 
-	if (req->usage.buckets[BCH_DATA_need_discard] > avail)
+	if (req->usage.buckets[BCH_DATA_need_discard] >
+	    min(avail, ca->mi.nbuckets >> 7))
 		bch2_dev_do_discards(ca);
 
 	if (req->usage.buckets[BCH_DATA_need_gc_gens] > avail)

fs/bcachefs/btree_io.c

@@ -1295,9 +1295,6 @@ int bch2_btree_node_read_done(struct bch_fs *c, struct bch_dev *ca,
 
 	btree_bounce_free(c, btree_buf_bytes(b), used_mempool, sorted);
 
-	if (updated_range)
-		bch2_btree_node_drop_keys_outside_node(b);
-
 	i = &b->data->keys;
 	for (k = i->start; k != vstruct_last(i);) {
 		struct bkey tmp;
@@ -1335,6 +1332,9 @@ int bch2_btree_node_read_done(struct bch_fs *c, struct bch_dev *ca,
 
 	btree_node_reset_sib_u64s(b);
 
+	if (updated_range)
+		bch2_btree_node_drop_keys_outside_node(b);
+
 	/*
 	 * XXX:
 	 *

fs/bcachefs/dirent.c

@@ -13,6 +13,7 @@
 
 #include <linux/dcache.h>
 
+#ifdef CONFIG_UNICODE
 int bch2_casefold(struct btree_trans *trans, const struct bch_hash_info *info,
 		  const struct qstr *str, struct qstr *out_cf)
 {
@@ -33,6 +34,7 @@ int bch2_casefold(struct btree_trans *trans, const struct bch_hash_info *info,
 	*out_cf = (struct qstr) QSTR_INIT(buf, ret);
 	return 0;
 }
+#endif
 
 static unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
 {
@@ -254,6 +256,7 @@ int bch2_dirent_init_name(struct bch_fs *c,
 		if (!bch2_fs_casefold_enabled(c))
 			return -EOPNOTSUPP;
 
+#ifdef CONFIG_UNICODE
 		memcpy(&dirent->v.d_cf_name_block.d_names[0], name->name, name->len);
 
 		char *cf_out = &dirent->v.d_cf_name_block.d_names[name->len];
@@ -279,6 +282,7 @@ int bch2_dirent_init_name(struct bch_fs *c,
 		dirent->v.d_cf_name_block.d_cf_name_len = cpu_to_le16(cf_len);
 
 		EBUG_ON(bch2_dirent_get_casefold_name(dirent_i_to_s_c(dirent)).len != cf_len);
+#endif
 	}
 
 	unsigned u64s = dirent_val_u64s(name->len, cf_len);

fs/bcachefs/dirent.h

@@ -23,8 +23,16 @@ struct bch_fs;
 struct bch_hash_info;
 struct bch_inode_info;
 
+#ifdef CONFIG_UNICODE
 int bch2_casefold(struct btree_trans *, const struct bch_hash_info *,
 		  const struct qstr *, struct qstr *);
+#else
+static inline int bch2_casefold(struct btree_trans *trans, const struct bch_hash_info *info,
+				const struct qstr *str, struct qstr *out_cf)
+{
+	return -EOPNOTSUPP;
+}
+#endif
 
 static inline int bch2_maybe_casefold(struct btree_trans *trans,
 				      const struct bch_hash_info *info,

fs/bcachefs/io_read.c

@@ -166,6 +166,7 @@ static noinline void promote_free(struct bch_read_bio *rbio)
 	BUG_ON(ret);
 
 	async_object_list_del(c, promote, op->list_idx);
+	async_object_list_del(c, rbio, rbio->list_idx);
 
 	bch2_data_update_exit(&op->write);
 
@@ -456,6 +457,10 @@ static void bch2_rbio_done(struct bch_read_bio *rbio)
 	if (rbio->start_time)
 		bch2_time_stats_update(&rbio->c->times[BCH_TIME_data_read],
 				       rbio->start_time);
+#ifdef CONFIG_BCACHEFS_ASYNC_OBJECT_LISTS
+	if (rbio->list_idx)
+		async_object_list_del(rbio->c, rbio, rbio->list_idx);
+#endif
 	bio_endio(&rbio->bio);
 }
 

fs/bcachefs/journal_io.c

@@ -1767,6 +1767,7 @@ static CLOSURE_CALLBACK(journal_write_done)
 
 			closure_wake_up(&c->freelist_wait);
 			bch2_reset_alloc_cursors(c);
+			do_discards = true;
 		}
 
 		j->seq_ondisk = seq;

fs/bcachefs/movinggc.c

@@ -71,7 +71,7 @@ static int bch2_bucket_is_movable(struct btree_trans *trans,
 	if (ret)
 		return ret;
 
-	struct bch_dev *ca = bch2_dev_tryget(c, k.k->p.inode);
+	struct bch_dev *ca = bch2_dev_bucket_tryget(c, k.k->p);
 	if (!ca)
 		goto out;