bcachefs: Start moving debug info from sysfs to debugfs

In sysfs, files can only output at most PAGE_SIZE. This is a problem for
debug info that needs to list an arbitrary number of times, and because
of this limit some of our debug info has been terser and harder to read
than we'd like.

This patch moves info about journal pins and cached btree nodes to
debugfs, and greatly expands and improves the output we return.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

1 files changed, 163 insertions, 13 deletions

diff --git a/fs/bcachefs/debug.c b/fs/bcachefs/debug.c
index c3bfa7f1d77d..1fff03d301a9 100644
--- a/fs/bcachefs/debug.c
+++ b/fs/bcachefs/debug.c
@@ -185,9 +185,10 @@ out:
 /* XXX: bch_fs refcounting */
 
 struct dump_iter {
-	struct bpos		from;
-	struct bch_fs	*c;
+	struct bch_fs		*c;
 	enum btree_id		id;
+	struct bpos		from;
+	u64			iter;
 
 	struct printbuf		buf;
 
@@ -226,6 +227,7 @@ static int bch2_dump_open(struct inode *inode, struct file *file)
 
 	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;
@@ -420,10 +422,148 @@ static const struct file_operations bfloat_failed_debug_ops = {
 	.read		= bch2_read_bfloat_failed,
 };
 
+static void bch2_cached_btree_node_to_text(struct printbuf *out, struct bch_fs *c,
+					   struct btree *b)
+{
+	out->tabstops[0] = 32;
+
+	pr_buf(out, "%px btree=%s l=%u ",
+	       b,
+	       bch2_btree_ids[b->c.btree_id],
+	       b->c.level);
+	pr_newline(out);
+
+	pr_indent_push(out, 2);
+
+	bch2_bkey_val_to_text(out, c, bkey_i_to_s_c(&b->key));
+	pr_newline(out);
+
+	pr_buf(out, "flags: ");
+	pr_tab(out);
+	bch2_flags_to_text(out, bch2_btree_node_flags, b->flags);
+	pr_newline(out);
+
+	pr_buf(out, "written:");
+	pr_tab(out);
+	pr_buf(out, "%u", b->written);
+	pr_newline(out);
+
+	pr_buf(out, "writes blocked:");
+	pr_tab(out);
+	pr_buf(out, "%u", !list_empty_careful(&b->write_blocked));
+	pr_newline(out);
+
+	pr_buf(out, "will make reachable:");
+	pr_tab(out);
+	pr_buf(out, "%lx", b->will_make_reachable);
+	pr_newline(out);
+
+	pr_buf(out, "journal pin %px:", &b->writes[0].journal);
+	pr_tab(out);
+	pr_buf(out, "%llu", b->writes[0].journal.seq);
+	pr_newline(out);
+
+	pr_buf(out, "journal pin %px:", &b->writes[1].journal);
+	pr_tab(out);
+	pr_buf(out, "%llu", b->writes[1].journal.seq);
+	pr_newline(out);
+
+	pr_indent_pop(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;
+	int err;
+
+	i->ubuf = buf;
+	i->size	= size;
+	i->ret	= 0;
+
+	do {
+		struct bucket_table *tbl;
+		struct rhash_head *pos;
+		struct btree *b;
+
+		err = flush_buf(i);
+		if (err)
+			return err;
+
+		if (!i->size)
+			break;
+
+		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)
+		return -ENOMEM;
+
+	return 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,
+};
+
+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,
+};
+
 void bch2_fs_debug_exit(struct bch_fs *c)
 {
-	if (!IS_ERR_OR_NULL(c->debug))
-		debugfs_remove_recursive(c->debug);
+	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)
@@ -435,29 +575,39 @@ void bch2_fs_debug_init(struct bch_fs *c)
 		return;
 
 	snprintf(name, sizeof(name), "%pU", c->sb.user_uuid.b);
-	c->debug = debugfs_create_dir(name, bch_debug);
-	if (IS_ERR_OR_NULL(c->debug))
+	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);
+
+	debugfs_create_file("journal_pins", 0400, c->fs_debug_dir,
+			    c->btree_debug, &journal_pins_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;
-		bd->btree = debugfs_create_file(bch2_btree_ids[bd->id],
-						0400, c->debug, bd,
-						&btree_debug_ops);
+		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]);
 
-		bd->btree_format = debugfs_create_file(name, 0400, c->debug, bd,
-						       &btree_format_debug_ops);
+		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]);
 
-		bd->failed = debugfs_create_file(name, 0400, c->debug, bd,
-						 &bfloat_failed_debug_ops);
+		debugfs_create_file(name, 0400, c->btree_debug_dir, bd,
+				    &bfloat_failed_debug_ops);
 	}
 }