diff options
| -rw-r--r-- | fs/btrfs/super.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index d41d5960ef4a..170baef49fae 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2304,11 +2304,18 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root) struct list_head *head; struct rcu_string *name; - mutex_lock(&fs_info->fs_devices->device_list_mutex); + /* + * Lightweight locking of the devices. We should not need + * device_list_mutex here as we only read the device data and the list + * is protected by RCU. Even if a device is deleted during the list + * traversals, we'll get valid data, the freeing callback will wait at + * least until until the rcu_read_unlock. + */ + rcu_read_lock(); cur_devices = fs_info->fs_devices; while (cur_devices) { head = &cur_devices->devices; - list_for_each_entry(dev, head, dev_list) { + list_for_each_entry_rcu(dev, head, dev_list) { if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state)) continue; if (!dev->name) @@ -2320,14 +2327,12 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root) } if (first_dev) { - rcu_read_lock(); name = rcu_dereference(first_dev->name); seq_escape(m, name->str, " \t\n\\"); - rcu_read_unlock(); } else { WARN_ON(1); } - mutex_unlock(&fs_info->fs_devices->device_list_mutex); + rcu_read_unlock(); return 0; } |