1 files changed, 954 insertions, 0 deletions

diff --git a/fs/bcachefs/debug.c b/fs/bcachefs/debug.c
new file mode 100644
index 000000000000..75a3dc7cbd47
--- /dev/null
+++ b/fs/bcachefs/debug.c
@@ -0,0 +1,954 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Assorted bcachefs debug code
+ *
+ * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcachefs.h"
+#include "bkey_methods.h"
+#include "btree_cache.h"
+#include "btree_io.h"
+#include "btree_iter.h"
+#include "btree_locking.h"
+#include "btree_update.h"
+#include "buckets.h"
+#include "debug.h"
+#include "error.h"
+#include "extents.h"
+#include "fsck.h"
+#include "inode.h"
+#include "super.h"
+
+#include <linux/console.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/seq_file.h>
+
+static struct dentry *bch_debug;
+
+static bool bch2_btree_verify_replica(struct bch_fs *c, struct btree *b,
+				      struct extent_ptr_decoded pick)
+{
+	struct btree *v = c->verify_data;
+	struct btree_node *n_ondisk = c->verify_ondisk;
+	struct btree_node *n_sorted = c->verify_data->data;
+	struct bset *sorted, *inmemory = &b->data->keys;
+	struct bch_dev *ca = bch_dev_bkey_exists(c, pick.ptr.dev);
+	struct bio *bio;
+	bool failed = false, saw_error = false;
+
+	if (!bch2_dev_get_ioref(ca, READ))
+		return false;
+
+	bio = bio_alloc_bioset(ca->disk_sb.bdev,
+			       buf_pages(n_sorted, btree_bytes(c)),
+			       REQ_OP_READ|REQ_META,
+			       GFP_NOFS,
+			       &c->btree_bio);
+	bio->bi_iter.bi_sector	= pick.ptr.offset;
+	bch2_bio_map(bio, n_sorted, btree_bytes(c));
+
+	submit_bio_wait(bio);
+
+	bio_put(bio);
+	percpu_ref_put(&ca->io_ref);
+
+	memcpy(n_ondisk, n_sorted, btree_bytes(c));
+
+	v->written = 0;
+	if (bch2_btree_node_read_done(c, ca, v, false, &saw_error) || saw_error)
+		return false;
+
+	n_sorted = c->verify_data->data;
+	sorted = &n_sorted->keys;
+
+	if (inmemory->u64s != sorted->u64s ||
+	    memcmp(inmemory->start,
+		   sorted->start,
+		   vstruct_end(inmemory) - (void *) inmemory->start)) {
+		unsigned offset = 0, sectors;
+		struct bset *i;
+		unsigned j;
+
+		console_lock();
+
+		printk(KERN_ERR "*** in memory:\n");
+		bch2_dump_bset(c, b, inmemory, 0);
+
+		printk(KERN_ERR "*** read back in:\n");
+		bch2_dump_bset(c, v, sorted, 0);
+
+		while (offset < v->written) {
+			if (!offset) {
+				i = &n_ondisk->keys;
+				sectors = vstruct_blocks(n_ondisk, c->block_bits) <<
+					c->block_bits;
+			} else {
+				struct btree_node_entry *bne =
+					(void *) n_ondisk + (offset << 9);
+				i = &bne->keys;
+
+				sectors = vstruct_blocks(bne, c->block_bits) <<
+					c->block_bits;
+			}
+
+			printk(KERN_ERR "*** on disk block %u:\n", offset);
+			bch2_dump_bset(c, b, i, offset);
+
+			offset += sectors;
+		}
+
+		for (j = 0; j < le16_to_cpu(inmemory->u64s); j++)
+			if (inmemory->_data[j] != sorted->_data[j])
+				break;
+
+		console_unlock();
+		bch_err(c, "verify failed at key %u", j);
+
+		failed = true;
+	}
+
+	if (v->written != b->written) {
+		bch_err(c, "written wrong: expected %u, got %u",
+			b->written, v->written);
+		failed = true;
+	}
+
+	return failed;
+}
+
+void __bch2_btree_verify(struct bch_fs *c, struct btree *b)
+{
+	struct bkey_ptrs_c ptrs;
+	struct extent_ptr_decoded p;
+	const union bch_extent_entry *entry;
+	struct btree *v;
+	struct bset *inmemory = &b->data->keys;
+	struct bkey_packed *k;
+	bool failed = false;
+
+	if (c->opts.nochanges)
+		return;
+
+	bch2_btree_node_io_lock(b);
+	mutex_lock(&c->verify_lock);
+
+	if (!c->verify_ondisk) {
+		c->verify_ondisk = kvpmalloc(btree_bytes(c), GFP_KERNEL);
+		if (!c->verify_ondisk)
+			goto out;
+	}
+
+	if (!c->verify_data) {
+		c->verify_data = __bch2_btree_node_mem_alloc(c);
+		if (!c->verify_data)
+			goto out;
+
+		list_del_init(&c->verify_data->list);
+	}
+
+	BUG_ON(b->nsets != 1);
+
+	for (k = inmemory->start; k != vstruct_last(inmemory); k = bkey_p_next(k))
+		if (k->type == KEY_TYPE_btree_ptr_v2)
+			((struct bch_btree_ptr_v2 *) bkeyp_val(&b->format, k))->mem_ptr = 0;
+
+	v = c->verify_data;
+	bkey_copy(&v->key, &b->key);
+	v->c.level	= b->c.level;
+	v->c.btree_id	= b->c.btree_id;
+	bch2_btree_keys_init(v);
+
+	ptrs = bch2_bkey_ptrs_c(bkey_i_to_s_c(&b->key));
+	bkey_for_each_ptr_decode(&b->key.k, ptrs, p, entry)
+		failed |= bch2_btree_verify_replica(c, b, p);
+
+	if (failed) {
+		struct printbuf buf = PRINTBUF;
+
+		bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&b->key));
+		bch2_fs_fatal_error(c, "btree node verify failed for : %s\n", buf.buf);
+		printbuf_exit(&buf);
+	}
+out:
+	mutex_unlock(&c->verify_lock);
+	bch2_btree_node_io_unlock(b);
+}
+
+void bch2_btree_node_ondisk_to_text(struct printbuf *out, struct bch_fs *c,
+				    const struct btree *b)
+{
+	struct btree_node *n_ondisk = NULL;
+	struct extent_ptr_decoded pick;
+	struct bch_dev *ca;
+	struct bio *bio = NULL;
+	unsigned offset = 0;
+	int ret;
+
+	if (bch2_bkey_pick_read_device(c, bkey_i_to_s_c(&b->key), NULL, &pick) <= 0) {
+		prt_printf(out, "error getting device to read from: invalid device\n");
+		return;
+	}
+
+	ca = bch_dev_bkey_exists(c, pick.ptr.dev);
+	if (!bch2_dev_get_ioref(ca, READ)) {
+		prt_printf(out, "error getting device to read from: not online\n");
+		return;
+	}
+
+	n_ondisk = kvpmalloc(btree_bytes(c), GFP_KERNEL);
+	if (!n_ondisk) {
+		prt_printf(out, "memory allocation failure\n");
+		goto out;
+	}
+
+	bio = bio_alloc_bioset(ca->disk_sb.bdev,
+			       buf_pages(n_ondisk, btree_bytes(c)),
+			       REQ_OP_READ|REQ_META,
+			       GFP_NOFS,
+			       &c->btree_bio);
+	bio->bi_iter.bi_sector	= pick.ptr.offset;
+	bch2_bio_map(bio, n_ondisk, btree_bytes(c));
+
+	ret = submit_bio_wait(bio);
+	if (ret) {
+		prt_printf(out, "IO error reading btree node: %s\n", bch2_err_str(ret));
+		goto out;
+	}
+
+	while (offset < btree_sectors(c)) {
+		struct bset *i;
+		struct nonce nonce;
+		struct bch_csum csum;
+		struct bkey_packed *k;
+		unsigned sectors;
+
+		if (!offset) {
+			i = &n_ondisk->keys;
+
+			if (!bch2_checksum_type_valid(c, BSET_CSUM_TYPE(i))) {
+				prt_printf(out, "unknown checksum type at offset %u: %llu\n",
+					   offset, BSET_CSUM_TYPE(i));
+				goto out;
+			}
+
+			nonce = btree_nonce(i, offset << 9);
+			csum = csum_vstruct(c, BSET_CSUM_TYPE(i), nonce, n_ondisk);
+
+			if (bch2_crc_cmp(csum, n_ondisk->csum)) {
+				prt_printf(out, "invalid checksum\n");
+				goto out;
+			}
+
+			bset_encrypt(c, i, offset << 9);
+
+			sectors = vstruct_sectors(n_ondisk, c->block_bits);
+		} else {
+			struct btree_node_entry *bne = (void *) n_ondisk + (offset << 9);
+
+			i = &bne->keys;
+
+			if (i->seq != n_ondisk->keys.seq)
+				break;
+
+			if (!bch2_checksum_type_valid(c, BSET_CSUM_TYPE(i))) {
+				prt_printf(out, "unknown checksum type at offset %u: %llu\n",
+					   offset, BSET_CSUM_TYPE(i));
+				goto out;
+			}
+
+			nonce = btree_nonce(i, offset << 9);
+			csum = csum_vstruct(c, BSET_CSUM_TYPE(i), nonce, bne);
+
+			if (bch2_crc_cmp(csum, bne->csum)) {
+				prt_printf(out, "invalid checksum");
+				goto out;
+			}
+
+			bset_encrypt(c, i, offset << 9);
+
+			sectors = vstruct_sectors(bne, c->block_bits);
+		}
+
+		prt_printf(out, "  offset %u version %u, journal seq %llu\n",
+			   offset,
+			   le16_to_cpu(i->version),
+			   le64_to_cpu(i->journal_seq));
+		offset += sectors;
+
+		printbuf_indent_add(out, 4);
+
+		for (k = i->start; k != vstruct_last(i); k = bkey_p_next(k)) {
+			struct bkey u;
+
+			bch2_bkey_val_to_text(out, c, bkey_disassemble(b, k, &u));
+			prt_newline(out);
+		}
+
+		printbuf_indent_sub(out, 4);
+	}
+out:
+	if (bio)
+		bio_put(bio);
+	kvpfree(n_ondisk, btree_bytes(c));
+	percpu_ref_put(&ca->io_ref);
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+/* XXX: bch_fs refcounting */
+
+struct dump_iter {
+	struct bch_fs		*c;
+	enum btree_id		id;
+	struct bpos		from;
+	struct bpos		prev_node;
+	u64			iter;
+
+	struct printbuf		buf;
+
+	char __user		*ubuf;	/* destination user buffer */
+	size_t			size;	/* size of requested read */
+	ssize_t			ret;	/* bytes read so far */
+};
+
+static ssize_t flush_buf(struct dump_iter *i)
+{
+	if (i->buf.pos) {
+		size_t bytes = min_t(size_t, i->buf.pos, i->size);
+		int copied = bytes - copy_to_user(i->ubuf, i->buf.buf, bytes);
+
+		i->ret	 += copied;
+		i->ubuf	 += copied;
+		i->size	 -= copied;
+		i->buf.pos -= copied;
+		memmove(i->buf.buf, i->buf.buf + copied, i->buf.pos);
+
+		if (copied != bytes)
+			return -EFAULT;
+	}
+
+	return i->size ? 0 : i->ret;
+}
+
+static int bch2_dump_open(struct inode *inode, struct file *file)
+{
+	struct btree_debug *bd = inode->i_private;
+	struct dump_iter *i;
+
+	i = kzalloc(sizeof(struct dump_iter), GFP_KERNEL);
+	if (!i)
+		return -ENOMEM;
+
+	file->private_data = i;
+	i->from = POS_MIN;
+	i->iter	= 0;
+	i->c	= container_of(bd, struct bch_fs, btree_debug[bd->id]);
+	i->id	= bd->id;
+	i->buf	= PRINTBUF;
+
+	return 0;
+}
+
+static int bch2_dump_release(struct inode *inode, struct file *file)
+{
+	struct dump_iter *i = file->private_data;
+
+	printbuf_exit(&i->buf);
+	kfree(i);
+	return 0;
+}
+
+static ssize_t bch2_read_btree(struct file *file, char __user *buf,
+			       size_t size, loff_t *ppos)
+{
+	struct dump_iter *i = file->private_data;
+	struct btree_trans *trans;
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	ssize_t ret;
+
+	i->ubuf = buf;
+	i->size	= size;
+	i->ret	= 0;
+
+	ret = flush_buf(i);
+	if (ret)
+		return ret;
+
+	trans = bch2_trans_get(i->c);
+	ret = for_each_btree_key2(trans, iter, i->id, i->from,
+				  BTREE_ITER_PREFETCH|
+				  BTREE_ITER_ALL_SNAPSHOTS, k, ({
+		bch2_bkey_val_to_text(&i->buf, i->c, k);
+		prt_newline(&i->buf);
+		drop_locks_do(trans, flush_buf(i));
+	}));
+	i->from = iter.pos;
+
+	bch2_trans_put(trans);
+
+	if (!ret)
+		ret = flush_buf(i);
+
+	return ret ?: i->ret;
+}
+
+static const struct file_operations btree_debug_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch2_dump_open,
+	.release	= bch2_dump_release,
+	.read		= bch2_read_btree,
+};
+
+static ssize_t bch2_read_btree_formats(struct file *file, char __user *buf,
+				       size_t size, loff_t *ppos)
+{
+	struct dump_iter *i = file->private_data;
+	struct btree_trans *trans;
+	struct btree_iter iter;
+	struct btree *b;
+	ssize_t ret;
+
+	i->ubuf = buf;
+	i->size	= size;
+	i->ret	= 0;
+
+	ret = flush_buf(i);
+	if (ret)
+		return ret;
+
+	if (bpos_eq(SPOS_MAX, i->from))
+		return i->ret;
+
+	trans = bch2_trans_get(i->c);
+retry:
+	bch2_trans_begin(trans);
+
+	for_each_btree_node(trans, iter, i->id, i->from, 0, b, ret) {
+		bch2_btree_node_to_text(&i->buf, i->c, b);
+		i->from = !bpos_eq(SPOS_MAX, b->key.k.p)
+			? bpos_successor(b->key.k.p)
+			: b->key.k.p;
+
+		ret = drop_locks_do(trans, flush_buf(i));
+		if (ret)
+			break;
+	}
+	bch2_trans_iter_exit(trans, &iter);
+
+	if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+		goto retry;
+
+	bch2_trans_put(trans);
+
+	if (!ret)
+		ret = flush_buf(i);
+
+	return ret ?: i->ret;
+}
+
+static const struct file_operations btree_format_debug_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch2_dump_open,
+	.release	= bch2_dump_release,
+	.read		= bch2_read_btree_formats,
+};
+
+static ssize_t bch2_read_bfloat_failed(struct file *file, char __user *buf,
+				       size_t size, loff_t *ppos)
+{
+	struct dump_iter *i = file->private_data;
+	struct btree_trans *trans;
+	struct btree_iter iter;
+	struct bkey_s_c k;
+	ssize_t ret;
+
+	i->ubuf = buf;
+	i->size	= size;
+	i->ret	= 0;
+
+	ret = flush_buf(i);
+	if (ret)
+		return ret;
+
+	trans = bch2_trans_get(i->c);
+
+	ret = for_each_btree_key2(trans, iter, i->id, i->from,
+				  BTREE_ITER_PREFETCH|
+				  BTREE_ITER_ALL_SNAPSHOTS, k, ({
+		struct btree_path_level *l = &iter.path->l[0];
+		struct bkey_packed *_k =
+			bch2_btree_node_iter_peek(&l->iter, l->b);
+
+		if (bpos_gt(l->b->key.k.p, i->prev_node)) {
+			bch2_btree_node_to_text(&i->buf, i->c, l->b);
+			i->prev_node = l->b->key.k.p;
+		}
+
+		bch2_bfloat_to_text(&i->buf, l->b, _k);
+		drop_locks_do(trans, flush_buf(i));
+	}));
+	i->from = iter.pos;
+
+	bch2_trans_put(trans);
+
+	if (!ret)
+		ret = flush_buf(i);
+
+	return ret ?: i->ret;
+}
+
+static const struct file_operations bfloat_failed_debug_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch2_dump_open,
+	.release	= bch2_dump_release,
+	.read		= bch2_read_bfloat_failed,
+};
+
+static void bch2_cached_btree_node_to_text(struct printbuf *out, struct bch_fs *c,
+					   struct btree *b)
+{
+	if (!out->nr_tabstops)
+		printbuf_tabstop_push(out, 32);
+
+	prt_printf(out, "%px btree=%s l=%u ",
+	       b,
+	       bch2_btree_ids[b->c.btree_id],
+	       b->c.level);
+	prt_newline(out);
+
+	printbuf_indent_add(out, 2);
+
+	bch2_bkey_val_to_text(out, c, bkey_i_to_s_c(&b->key));
+	prt_newline(out);
+
+	prt_printf(out, "flags: ");
+	prt_tab(out);
+	prt_bitflags(out, bch2_btree_node_flags, b->flags);
+	prt_newline(out);
+
+	prt_printf(out, "pcpu read locks: ");
+	prt_tab(out);
+	prt_printf(out, "%u", b->c.lock.readers != NULL);
+	prt_newline(out);
+
+	prt_printf(out, "written:");
+	prt_tab(out);
+	prt_printf(out, "%u", b->written);
+	prt_newline(out);
+
+	prt_printf(out, "writes blocked:");
+	prt_tab(out);
+	prt_printf(out, "%u", !list_empty_careful(&b->write_blocked));
+	prt_newline(out);
+
+	prt_printf(out, "will make reachable:");
+	prt_tab(out);
+	prt_printf(out, "%lx", b->will_make_reachable);
+	prt_newline(out);
+
+	prt_printf(out, "journal pin %px:", &b->writes[0].journal);
+	prt_tab(out);
+	prt_printf(out, "%llu", b->writes[0].journal.seq);
+	prt_newline(out);
+
+	prt_printf(out, "journal pin %px:", &b->writes[1].journal);
+	prt_tab(out);
+	prt_printf(out, "%llu", b->writes[1].journal.seq);
+	prt_newline(out);
+
+	printbuf_indent_sub(out, 2);
+}
+
+static ssize_t bch2_cached_btree_nodes_read(struct file *file, char __user *buf,
+					    size_t size, loff_t *ppos)
+{
+	struct dump_iter *i = file->private_data;
+	struct bch_fs *c = i->c;
+	bool done = false;
+	ssize_t ret = 0;
+
+	i->ubuf = buf;
+	i->size	= size;
+	i->ret	= 0;
+
+	do {
+		struct bucket_table *tbl;
+		struct rhash_head *pos;
+		struct btree *b;
+
+		ret = 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;
+		}
+		--i->buf.atomic;
+		rcu_read_unlock();
+	} while (!done);
+
+	if (i->buf.allocation_failure)
+		ret = -ENOMEM;
+
+	if (!ret)
+		ret = flush_buf(i);
+
+	return ret ?: i->ret;
+}
+
+static const struct file_operations cached_btree_nodes_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch2_dump_open,
+	.release	= bch2_dump_release,
+	.read		= bch2_cached_btree_nodes_read,
+};
+
+#ifdef CONFIG_BCACHEFS_DEBUG_TRANSACTIONS
+static ssize_t bch2_btree_transactions_read(struct file *file, char __user *buf,
+					    size_t size, loff_t *ppos)
+{
+	struct dump_iter *i = file->private_data;
+	struct bch_fs *c = i->c;
+	struct btree_trans *trans;
+	ssize_t ret = 0;
+	u32 seq;
+
+	i->ubuf = buf;
+	i->size	= size;
+	i->ret	= 0;
+restart:
+	seqmutex_lock(&c->btree_trans_lock);
+	list_for_each_entry(trans, &c->btree_trans_list, list) {
+		if (trans->locking_wait.task->pid <= i->iter)
+			continue;
+
+		closure_get(&trans->ref);
+		seq = seqmutex_seq(&c->btree_trans_lock);
+		seqmutex_unlock(&c->btree_trans_lock);
+
+		ret = flush_buf(i);
+		if (ret) {
+			closure_put(&trans->ref);
+			goto unlocked;
+		}
+
+		bch2_btree_trans_to_text(&i->buf, trans);
+
+		prt_printf(&i->buf, "backtrace:");
+		prt_newline(&i->buf);
+		printbuf_indent_add(&i->buf, 2);
+		bch2_prt_task_backtrace(&i->buf, trans->locking_wait.task);
+		printbuf_indent_sub(&i->buf, 2);
+		prt_newline(&i->buf);
+
+		i->iter = trans->locking_wait.task->pid;
+
+		closure_put(&trans->ref);
+
+		if (!seqmutex_relock(&c->btree_trans_lock, seq))
+			goto restart;
+	}
+	seqmutex_unlock(&c->btree_trans_lock);
+unlocked:
+	if (i->buf.allocation_failure)
+		ret = -ENOMEM;
+
+	if (!ret)
+		ret = flush_buf(i);
+
+	return ret ?: i->ret;
+}
+
+static const struct file_operations btree_transactions_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch2_dump_open,
+	.release	= bch2_dump_release,
+	.read		= bch2_btree_transactions_read,
+};
+#endif /* CONFIG_BCACHEFS_DEBUG_TRANSACTIONS */
+
+static ssize_t bch2_journal_pins_read(struct file *file, char __user *buf,
+				      size_t size, loff_t *ppos)
+{
+	struct dump_iter *i = file->private_data;
+	struct bch_fs *c = i->c;
+	bool done = false;
+	int err;
+
+	i->ubuf = buf;
+	i->size	= size;
+	i->ret	= 0;
+
+	do {
+		err = flush_buf(i);
+		if (err)
+			return err;
+
+		if (!i->size)
+			break;
+
+		done = bch2_journal_seq_pins_to_text(&i->buf, &c->journal, &i->iter);
+		i->iter++;
+	} while (!done);
+
+	if (i->buf.allocation_failure)
+		return -ENOMEM;
+
+	return i->ret;
+}
+
+static const struct file_operations journal_pins_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch2_dump_open,
+	.release	= bch2_dump_release,
+	.read		= bch2_journal_pins_read,
+};
+
+static int lock_held_stats_open(struct inode *inode, struct file *file)
+{
+	struct bch_fs *c = inode->i_private;
+	struct dump_iter *i;
+
+	i = kzalloc(sizeof(struct dump_iter), GFP_KERNEL);
+
+	if (!i)
+		return -ENOMEM;
+
+	i->iter = 0;
+	i->c    = c;
+	i->buf  = PRINTBUF;
+	file->private_data = i;
+
+	return 0;
+}
+
+static int lock_held_stats_release(struct inode *inode, struct file *file)
+{
+	struct dump_iter *i = file->private_data;
+
+	printbuf_exit(&i->buf);
+	kfree(i);
+
+	return 0;
+}
+
+static ssize_t lock_held_stats_read(struct file *file, char __user *buf,
+				      size_t size, loff_t *ppos)
+{
+	struct dump_iter        *i = file->private_data;
+	struct bch_fs *c = i->c;
+	int err;
+
+	i->ubuf = buf;
+	i->size = size;
+	i->ret  = 0;
+
+	while (1) {
+		struct btree_transaction_stats *s = &c->btree_transaction_stats[i->iter];
+
+		err = flush_buf(i);
+		if (err)
+			return err;
+
+		if (!i->size)
+			break;
+
+		if (i->iter == ARRAY_SIZE(bch2_btree_transaction_fns) ||
+		    !bch2_btree_transaction_fns[i->iter])
+			break;
+
+		prt_printf(&i->buf, "%s: ", bch2_btree_transaction_fns[i->iter]);
+		prt_newline(&i->buf);
+		printbuf_indent_add(&i->buf, 2);
+
+		mutex_lock(&s->lock);
+
+		prt_printf(&i->buf, "Max mem used: %u", s->max_mem);
+		prt_newline(&i->buf);
+
+		if (IS_ENABLED(CONFIG_BCACHEFS_LOCK_TIME_STATS)) {
+			prt_printf(&i->buf, "Lock hold times:");
+			prt_newline(&i->buf);
+
+			printbuf_indent_add(&i->buf, 2);
+			bch2_time_stats_to_text(&i->buf, &s->lock_hold_times);
+			printbuf_indent_sub(&i->buf, 2);
+		}
+
+		if (s->max_paths_text) {
+			prt_printf(&i->buf, "Maximum allocated btree paths (%u):", s->nr_max_paths);
+			prt_newline(&i->buf);
+
+			printbuf_indent_add(&i->buf, 2);
+			prt_str_indented(&i->buf, s->max_paths_text);
+			printbuf_indent_sub(&i->buf, 2);
+		}
+
+		mutex_unlock(&s->lock);
+
+		printbuf_indent_sub(&i->buf, 2);
+		prt_newline(&i->buf);
+		i->iter++;
+	}
+
+	if (i->buf.allocation_failure)
+		return -ENOMEM;
+
+	return i->ret;
+}
+
+static const struct file_operations lock_held_stats_op = {
+	.owner = THIS_MODULE,
+	.open = lock_held_stats_open,
+	.release = lock_held_stats_release,
+	.read = lock_held_stats_read,
+};
+
+static ssize_t bch2_btree_deadlock_read(struct file *file, char __user *buf,
+					    size_t size, loff_t *ppos)
+{
+	struct dump_iter *i = file->private_data;
+	struct bch_fs *c = i->c;
+	struct btree_trans *trans;
+	ssize_t ret = 0;
+	u32 seq;
+
+	i->ubuf = buf;
+	i->size	= size;
+	i->ret	= 0;
+
+	if (i->iter)
+		goto out;
+restart:
+	seqmutex_lock(&c->btree_trans_lock);
+	list_for_each_entry(trans, &c->btree_trans_list, list) {
+		if (trans->locking_wait.task->pid <= i->iter)
+			continue;
+
+		closure_get(&trans->ref);
+		seq = seqmutex_seq(&c->btree_trans_lock);
+		seqmutex_unlock(&c->btree_trans_lock);
+
+		ret = flush_buf(i);
+		if (ret) {
+			closure_put(&trans->ref);
+			goto out;
+		}
+
+		bch2_check_for_deadlock(trans, &i->buf);
+
+		i->iter = trans->locking_wait.task->pid;
+
+		closure_put(&trans->ref);
+
+		if (!seqmutex_relock(&c->btree_trans_lock, seq))
+			goto restart;
+	}
+	seqmutex_unlock(&c->btree_trans_lock);
+out:
+	if (i->buf.allocation_failure)
+		ret = -ENOMEM;
+
+	if (!ret)
+		ret = flush_buf(i);
+
+	return ret ?: i->ret;
+}
+
+static const struct file_operations btree_deadlock_ops = {
+	.owner		= THIS_MODULE,
+	.open		= bch2_dump_open,
+	.release	= bch2_dump_release,
+	.read		= bch2_btree_deadlock_read,
+};
+
+void bch2_fs_debug_exit(struct bch_fs *c)
+{
+	if (!IS_ERR_OR_NULL(c->fs_debug_dir))
+		debugfs_remove_recursive(c->fs_debug_dir);
+}
+
+void bch2_fs_debug_init(struct bch_fs *c)
+{
+	struct btree_debug *bd;
+	char name[100];
+
+	if (IS_ERR_OR_NULL(bch_debug))
+		return;
+
+	snprintf(name, sizeof(name), "%pU", c->sb.user_uuid.b);
+	c->fs_debug_dir = debugfs_create_dir(name, bch_debug);
+	if (IS_ERR_OR_NULL(c->fs_debug_dir))
+		return;
+
+	debugfs_create_file("cached_btree_nodes", 0400, c->fs_debug_dir,
+			    c->btree_debug, &cached_btree_nodes_ops);
+
+#ifdef CONFIG_BCACHEFS_DEBUG_TRANSACTIONS
+	debugfs_create_file("btree_transactions", 0400, c->fs_debug_dir,
+			    c->btree_debug, &btree_transactions_ops);
+#endif
+
+	debugfs_create_file("journal_pins", 0400, c->fs_debug_dir,
+			    c->btree_debug, &journal_pins_ops);
+
+	debugfs_create_file("btree_transaction_stats", 0400, c->fs_debug_dir,
+			    c, &lock_held_stats_op);
+
+	debugfs_create_file("btree_deadlock", 0400, c->fs_debug_dir,
+			    c->btree_debug, &btree_deadlock_ops);
+
+	c->btree_debug_dir = debugfs_create_dir("btrees", c->fs_debug_dir);
+	if (IS_ERR_OR_NULL(c->btree_debug_dir))
+		return;
+
+	for (bd = c->btree_debug;
+	     bd < c->btree_debug + ARRAY_SIZE(c->btree_debug);
+	     bd++) {
+		bd->id = bd - c->btree_debug;
+		debugfs_create_file(bch2_btree_ids[bd->id],
+				    0400, c->btree_debug_dir, bd,
+				    &btree_debug_ops);
+
+		snprintf(name, sizeof(name), "%s-formats",
+			 bch2_btree_ids[bd->id]);
+
+		debugfs_create_file(name, 0400, c->btree_debug_dir, bd,
+				    &btree_format_debug_ops);
+
+		snprintf(name, sizeof(name), "%s-bfloat-failed",
+			 bch2_btree_ids[bd->id]);
+
+		debugfs_create_file(name, 0400, c->btree_debug_dir, bd,
+				    &bfloat_failed_debug_ops);
+	}
+}
+
+#endif
+
+void bch2_debug_exit(void)
+{
+	if (!IS_ERR_OR_NULL(bch_debug))
+		debugfs_remove_recursive(bch_debug);
+}
+
+int __init bch2_debug_init(void)
+{
+	int ret = 0;
+
+	bch_debug = debugfs_create_dir("bcachefs", NULL);
+	return ret;
+}