btrfs: add missing device::flush_bio puts

This fixes potential bio leaks, in several error paths. Unfortunatelly
the device structure freeing is opencoded in many places and I missed
them when introducing the flush_bio.

Most of the time, devices get freed through call_rcu(..., free_device),
so it at least it's not that easy to hit the leak, but it's still
possible through the path that frees stale devices.

Fixes: e0ae99941423 ("btrfs: preallocate device flush bio")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -189,6 +189,7 @@ static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
 				    struct btrfs_device, dev_list);
 		list_del(&device->dev_list);
 		rcu_string_free(device->name);
+		bio_put(device->flush_bio);
 		kfree(device);
 	}
 	kfree(fs_devices);
@@ -578,6 +579,7 @@ static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
 				fs_devs->num_devices--;
 				list_del(&dev->dev_list);
 				rcu_string_free(dev->name);
+				bio_put(dev->flush_bio);
 				kfree(dev);
 			}
 			break;
@@ -630,6 +632,7 @@ static noinline int device_list_add(const char *path,
 
 		name = rcu_string_strdup(path, GFP_NOFS);
 		if (!name) {
+			bio_put(device->flush_bio);
 			kfree(device);
 			return -ENOMEM;
 		}
@@ -742,6 +745,7 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
 			name = rcu_string_strdup(orig_dev->name->str,
 					GFP_KERNEL);
 			if (!name) {
+				bio_put(device->flush_bio);
 				kfree(device);
 				goto error;
 			}
@@ -807,6 +811,7 @@ again:
 		list_del_init(&device->dev_list);
 		fs_devices->num_devices--;
 		rcu_string_free(device->name);
+		bio_put(device->flush_bio);
 		kfree(device);
 	}
 
@@ -2353,6 +2358,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 
 	name = rcu_string_strdup(device_path, GFP_KERNEL);
 	if (!name) {
+		bio_put(device->flush_bio);
 		kfree(device);
 		ret = -ENOMEM;
 		goto error;
@@ -2362,6 +2368,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 	trans = btrfs_start_transaction(root, 0);
 	if (IS_ERR(trans)) {
 		rcu_string_free(device->name);
+		bio_put(device->flush_bio);
 		kfree(device);
 		ret = PTR_ERR(trans);
 		goto error;
@@ -2505,6 +2512,7 @@ error_trans:
 	if (trans)
 		btrfs_end_transaction(trans);
 	rcu_string_free(device->name);
+	bio_put(device->flush_bio);
 	kfree(device);
 error:
 	blkdev_put(bdev, FMODE_EXCL);
@@ -2571,6 +2579,7 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 
 	name = rcu_string_strdup(device_path, GFP_KERNEL);
 	if (!name) {
+		bio_put(device->flush_bio);
 		kfree(device);
 		ret = -ENOMEM;
 		goto error;
@@ -6288,6 +6297,7 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
 
 		ret = find_next_devid(fs_info, &tmp);
 		if (ret) {
+			bio_put(dev->flush_bio);
 			kfree(dev);
 			return ERR_PTR(ret);
 		}