Merge tag 'bcachefs-2025-04-03' of git://evilpiepirate.org/bcachefs

Pull more bcachefs updates from Kent Overstreet:
 "More notable fixes:

   - Fix for striping behaviour on tiering filesystems where replicas
     exceeds durability on destination target

   - Fix a race in device removal where deleting alloc info races with
     the discard worker

   - Some small stack usage improvements: this is just enough for KMSAN
     builds to not blow the stack, more is queued up for 6.16"

* tag 'bcachefs-2025-04-03' of git://evilpiepirate.org/bcachefs:
  bcachefs: Fix "journal stuck" during recovery
  bcachefs: backpointer_get_key: check for null from peek_slot()
  bcachefs: Fix null ptr deref in invalidate_one_bucket()
  bcachefs: Fix check_snapshot_exists() restart handling
  bcachefs: use nonblocking variant of print_string_as_lines in error path
  bcachefs: Fix scheduling while atomic from logging changes
  bcachefs: Add error handling for zlib_deflateInit2()
  bcachefs: add missing selection of XARRAY_MULTI
  bcachefs: bch_dev_usage_full
  bcachefs: Kill btree_iter.trans
  bcachefs: do_trace_key_cache_fill()
  bcachefs: Split up bch_dev.io_ref
  bcachefs: fix ref leak in btree_node_read_all_replicas
  bcachefs: Fix null ptr deref in bch2_write_endio()
  bcachefs: Fix field spanning write warning
  bcachefs: Fix striping behaviour

1 files changed, 18 insertions, 6 deletions

diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index 21d1d86d5008..ff26bb515150 100644
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -252,12 +252,24 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 				  0,
 				  bp.v->level,
 				  iter_flags);
-	struct bkey_s_c k = bch2_btree_iter_peek_slot(iter);
+	struct bkey_s_c k = bch2_btree_iter_peek_slot(trans, iter);
 	if (bkey_err(k)) {
 		bch2_trans_iter_exit(trans, iter);
 		return k;
 	}
 
+	/*
+	 * peek_slot() doesn't normally return NULL - except when we ask for a
+	 * key at a btree level that doesn't exist.
+	 *
+	 * We may want to revisit this and change peek_slot():
+	 */
+	if (!k.k) {
+		bkey_init(&iter->k);
+		iter->k.p = bp.v->pos;
+		k.k = &iter->k;
+	}
+
 	if (k.k &&
 	    extent_matches_bp(c, bp.v->btree_id, bp.v->level, k, bp))
 		return k;
@@ -293,7 +305,7 @@ struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 				  0,
 				  bp.v->level - 1,
 				  0);
-	struct btree *b = bch2_btree_iter_peek_node(iter);
+	struct btree *b = bch2_btree_iter_peek_node(trans, iter);
 	if (IS_ERR_OR_NULL(b))
 		goto err;
 
@@ -321,7 +333,7 @@ static int bch2_check_backpointer_has_valid_bucket(struct btree_trans *trans, st
 		return 0;
 
 	struct bch_fs *c = trans->c;
-	struct btree_iter alloc_iter = { NULL };
+	struct btree_iter alloc_iter = {};
 	struct bkey_s_c alloc_k;
 	struct printbuf buf = PRINTBUF;
 	int ret = 0;
@@ -462,7 +474,7 @@ err:
 	if (bio)
 		bio_put(bio);
 	kvfree(data_buf);
-	percpu_ref_put(&ca->io_ref);
+	percpu_ref_put(&ca->io_ref[READ]);
 	printbuf_exit(&buf);
 	return ret;
 }
@@ -650,7 +662,7 @@ static int check_btree_root_to_backpointers(struct btree_trans *trans,
 retry:
 	bch2_trans_node_iter_init(trans, &iter, btree_id, POS_MIN,
 				  0, bch2_btree_id_root(c, btree_id)->b->c.level, 0);
-	b = bch2_btree_iter_peek_node(&iter);
+	b = bch2_btree_iter_peek_node(trans, &iter);
 	ret = PTR_ERR_OR_ZERO(b);
 	if (ret)
 		goto err;
@@ -934,7 +946,7 @@ static int btree_node_get_and_pin(struct btree_trans *trans, struct bkey_i *k,
 {
 	struct btree_iter iter;
 	bch2_trans_node_iter_init(trans, &iter, btree, k->k.p, 0, level, 0);
-	struct btree *b = bch2_btree_iter_peek_node(&iter);
+	struct btree *b = bch2_btree_iter_peek_node(trans, &iter);
 	int ret = PTR_ERR_OR_ZERO(b);
 	if (ret)
 		goto err;