bcachefs: Fix potential sleeping during mount

dblueman · Kent Overstreet · commit b783fc4d1366 · 2023-11-14T23:44:43.000-05:00
During mount, bcachefs mount option processing may sleep while allocating a string buffer.

Fix this by reference counting in order to take the atomic path.

Signed-off-by: Daniel J Blueman &lt;daniel@quora.org&gt;
Signed-off-by: Kent Overstreet &lt;kent.overstreet@linux.dev&gt;
diff --git a/fs/bcachefs/disk_groups.c b/fs/bcachefs/disk_groups.c
@@ -555,6 +555,7 @@ void bch2_target_to_text(struct printbuf *out, struct bch_fs *c, unsigned v)
 	case TARGET_DEV: {
 		struct bch_dev *ca;
 
+		out->atomic++;
 		rcu_read_lock();
 		ca = t.dev < c->sb.nr_devices
 			? rcu_dereference(c->devs[t.dev])
@@ -570,6 +571,7 @@ void bch2_target_to_text(struct printbuf *out, struct bch_fs *c, unsigned v)
 		}
 
 		rcu_read_unlock();
+		out->atomic--;
 		break;
 	}
 	case TARGET_GROUP:

Original file line number	Diff line number	Diff line change
`@@ -555,6 +555,7 @@ void bch2_target_to_text(struct printbuf out, struct bch_fs c, unsigned v)`
`555`	`555`	`case TARGET_DEV: {`
`556`	`556`	`struct bch_dev *ca;`
`557`	`557`
	`558`	`+ out->atomic++;`
`558`	`559`	`rcu_read_lock();`
`559`	`560`	`ca = t.dev < c->sb.nr_devices`
`560`	`561`	`? rcu_dereference(c->devs[t.dev])`
`@@ -570,6 +571,7 @@ void bch2_target_to_text(struct printbuf out, struct bch_fs c, unsigned v)`
`570`	`571`	`}`
`571`	`572`
`572`	`573`	`rcu_read_unlock();`
	`574`	`+ out->atomic--;`
`573`	`575`	`break;`
`574`	`576`	`}`
`575`	`577`	`case TARGET_GROUP:`