Commit 18e92841 authored by Kent Overstreet's avatar Kent Overstreet
Browse files

bcachefs: Make btree_deadlock_to_text() clearer 



btree_deadlock_to_text() searches the list of btree transactions to find
a deadlock - when it finds one it's done; it's not like other *_read()
functions that's printing each object.

Factor out btree_deadlock_to_text() to make this clearer.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent f44cc269

fs/bcachefs/debug.c

+29 −23
Original line number Diff line number Diff line
@@ -802,48 +802,54 @@ static const struct file_operations btree_transaction_stats_op = { 
	.read		= btree_transaction_stats_read,

};



static ssize_t bch2_btree_deadlock_read(struct file *file, char __user *buf,

					    size_t size, loff_t *ppos)

/* walk btree transactions until we find a deadlock and print it */

static void btree_deadlock_to_text(struct printbuf *out, struct bch_fs *c)

{

	struct dump_iter *i = file->private_data;

	struct bch_fs *c = i->c;

	struct btree_trans *trans;

	ssize_t ret = 0;



	i->ubuf = buf;

	i->size	= size;

	i->ret	= 0;



	if (i->iter)

		goto out;

	pid_t iter = 0;

restart:

	seqmutex_lock(&c->btree_trans_lock);

	list_for_each_entry(trans, &c->btree_trans_list, list) {

		struct task_struct *task = READ_ONCE(trans->locking_wait.task);



		if (!task || task->pid <= i->iter)

		if (!task || task->pid <= iter)

			continue;



		closure_get(&trans->ref);

		u32 seq = seqmutex_unlock(&c->btree_trans_lock);

		iter = task->pid;



		ret = flush_buf(i);

		if (ret) {

			closure_put(&trans->ref);

			goto out;

		}

		closure_get(&trans->ref);



		bch2_check_for_deadlock(trans, &i->buf);

		u32 seq = seqmutex_unlock(&c->btree_trans_lock);



		i->iter = task->pid;

		bool found = bch2_check_for_deadlock(trans, out) != 0;



		closure_put(&trans->ref);



		if (found)

			return;



		if (!seqmutex_relock(&c->btree_trans_lock, seq))

			goto restart;

	}

	seqmutex_unlock(&c->btree_trans_lock);

out:

}



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;

	ssize_t ret = 0;



	i->ubuf = buf;

	i->size	= size;

	i->ret	= 0;



	if (!i->iter) {

		btree_deadlock_to_text(&i->buf, c);

		i->iter++;

	}



	if (i->buf.allocation_failure)

		ret = -ENOMEM;