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Commit 4fde46f0 authored by Anand Jain's avatar Anand Jain Committed by David Sterba
Browse files

Btrfs: free the stale device 



When btrfs on a device is overwritten with a new btrfs (mkfs),
the old btrfs instance in the kernel becomes stale. So with this
patch, if kernel finds device is overwritten then delete the stale
fsid/uuid.

Signed-off-by: default avatarAnand Jain <anand.jain@oracle.com>
parent 2421a8cd

fs/btrfs/volumes.c

+61 −0
Original line number Original line Diff line number Diff line
@@ -445,6 +445,61 @@ static void pending_bios_fn(struct btrfs_work *work) 
	run_scheduled_bios(device);

	run_scheduled_bios(device);

}

}







void btrfs_free_stale_device(struct btrfs_device *cur_dev)

{

	struct btrfs_fs_devices *fs_devs;

	struct btrfs_device *dev;



	if (!cur_dev->name)

		return;



	list_for_each_entry(fs_devs, &fs_uuids, list) {

		int del = 1;



		if (fs_devs->opened)

			continue;

		if (fs_devs->seeding)

			continue;



		list_for_each_entry(dev, &fs_devs->devices, dev_list) {



			if (dev == cur_dev)

				continue;

			if (!dev->name)

				continue;



			/*

			 * Todo: This won't be enough. What if the same device

			 * comes back (with new uuid and) with its mapper path?

			 * But for now, this does help as mostly an admin will

			 * either use mapper or non mapper path throughout.

			 */

			rcu_read_lock();

			del = strcmp(rcu_str_deref(dev->name),

						rcu_str_deref(cur_dev->name));

			rcu_read_unlock();

			if (!del)

				break;

		}



		if (!del) {

			/* delete the stale device */

			if (fs_devs->num_devices == 1) {

				btrfs_sysfs_remove_fsid(fs_devs);

				list_del(&fs_devs->list);

				free_fs_devices(fs_devs);

			} else {

				fs_devs->num_devices--;

				list_del(&dev->dev_list);

				rcu_string_free(dev->name);

				kfree(dev);

			}

			break;

		}

	}

}



/*

/*

 * Add new device to list of registered devices

 * Add new device to list of registered devices

 *

 *
@@ -560,6 +615,12 @@ static noinline int device_list_add(const char *path, 
	if (!fs_devices->opened)

	if (!fs_devices->opened)

		device->generation = found_transid;

		device->generation = found_transid;





	/*

	 * if there is new btrfs on an already registered device,

	 * then remove the stale device entry.

	 */

	btrfs_free_stale_device(device);



	*fs_devices_ret = fs_devices;

	*fs_devices_ret = fs_devices;





	return ret;

	return ret;