Btrfs: fix race between readahead and device replace/removal

[cascardo/linux.git] / fs / btrfs / reada.c

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 298631e..8428db7 100644 (file)
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -761,12 +761,14 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info)
 
        do {
                enqueued = 0;
+               mutex_lock(&fs_devices->device_list_mutex);
                list_for_each_entry(device, &fs_devices->devices, dev_list) {
                        if (atomic_read(&device->reada_in_flight) <
                            MAX_IN_FLIGHT)
                                enqueued += reada_start_machine_dev(fs_info,
                                                                    device);
                }
+               mutex_unlock(&fs_devices->device_list_mutex);
                total += enqueued;
        } while (enqueued && total < 10000);