btrfs: zoned: initialize device's zone info for seeding

When performing seeding on a zoned filesystem it is necessary to
initialize each zoned device's btrfs_zoned_device_info structure,
otherwise mounting the filesystem will cause a NULL pointer dereference.

This was uncovered by fstests' testcase btrfs/163.

CC: stable@vger.kernel.org # 5.15+
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -2551,7 +2551,9 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
 		fs_info->dev_root = root;
 	}
 	/* Initialize fs_info for all devices in any case */
-	btrfs_init_devices_late(fs_info);
+	ret = btrfs_init_devices_late(fs_info);
+	if (ret)
+		goto out;
 
 	/*
 	 * This tree can share blocks with some other fs tree during relocation

fs/btrfs/volumes.c

@@ -7756,10 +7756,11 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
 	return ret;
 }
 
-void btrfs_init_devices_late(struct btrfs_fs_info *fs_info)
+int btrfs_init_devices_late(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices, *seed_devs;
 	struct btrfs_device *device;
+	int ret = 0;
 
 	fs_devices->fs_info = fs_info;
 
@@ -7768,12 +7769,18 @@ void btrfs_init_devices_late(struct btrfs_fs_info *fs_info)
 		device->fs_info = fs_info;
 
 	list_for_each_entry(seed_devs, &fs_devices->seed_list, seed_list) {
-		list_for_each_entry(device, &seed_devs->devices, dev_list)
+		list_for_each_entry(device, &seed_devs->devices, dev_list) {
 			device->fs_info = fs_info;
+			ret = btrfs_get_dev_zone_info(device, false);
+			if (ret)
+				break;
+		}
 
 		seed_devs->fs_info = fs_info;
 	}
 	mutex_unlock(&fs_devices->device_list_mutex);
+
+	return ret;
 }
 
 static u64 btrfs_dev_stats_value(const struct extent_buffer *eb,

fs/btrfs/volumes.h

@@ -671,7 +671,7 @@ int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes,
 void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index);
 int btrfs_get_dev_stats(struct btrfs_fs_info *fs_info,
 			struct btrfs_ioctl_get_dev_stats *stats);
-void btrfs_init_devices_late(struct btrfs_fs_info *fs_info);
+int btrfs_init_devices_late(struct btrfs_fs_info *fs_info);
 int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info);
 int btrfs_run_dev_stats(struct btrfs_trans_handle *trans);
 void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_device *srcdev);