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Commit 959b1c04 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: close devices without offloading to a temporary list 



Since commit 88c14590 ("btrfs: use RCU in btrfs_show_devname for
device list traversal") btrfs_show_devname no longer takes
device_list_mutex. As such the deadlock that 0ccd0528 ("btrfs: fix a
possible umount deadlock") aimed to fix no longer exists, we can free
the devices immediatelly and remove the code that does the pending work.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 621567a2

fs/btrfs/volumes.c

+6 −20
Original line number Diff line number Diff line
@@ -1001,7 +1001,7 @@ static void btrfs_close_bdev(struct btrfs_device *device) 
	blkdev_put(device->bdev, device->mode);

}



static void btrfs_prepare_close_one_device(struct btrfs_device *device)

static void btrfs_close_one_device(struct btrfs_device *device)

{

	struct btrfs_fs_devices *fs_devices = device->fs_devices;

	struct btrfs_device *new_device;
@@ -1019,6 +1019,8 @@ static void btrfs_prepare_close_one_device(struct btrfs_device *device) 
	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))

		fs_devices->missing_devices--;



	btrfs_close_bdev(device);



	new_device = btrfs_alloc_device(NULL, &device->devid,

					device->uuid);

	BUG_ON(IS_ERR(new_device)); /* -ENOMEM */
@@ -1032,39 +1034,23 @@ static void btrfs_prepare_close_one_device(struct btrfs_device *device) 


	list_replace_rcu(&device->dev_list, &new_device->dev_list);

	new_device->fs_devices = device->fs_devices;



	call_rcu(&device->rcu, free_device_rcu);

}



static int close_fs_devices(struct btrfs_fs_devices *fs_devices)

{

	struct btrfs_device *device, *tmp;

	struct list_head pending_put;



	INIT_LIST_HEAD(&pending_put);



	if (--fs_devices->opened > 0)

		return 0;



	mutex_lock(&fs_devices->device_list_mutex);

	list_for_each_entry_safe(device, tmp, &fs_devices->devices, dev_list) {

		btrfs_prepare_close_one_device(device);

		list_add(&device->dev_list, &pending_put);

		btrfs_close_one_device(device);

	}

	mutex_unlock(&fs_devices->device_list_mutex);



	/*

	 * btrfs_show_devname() is using the device_list_mutex,

	 * sometimes call to blkdev_put() leads vfs calling

	 * into this func. So do put outside of device_list_mutex,

	 * as of now.

	 */

	while (!list_empty(&pending_put)) {

		device = list_first_entry(&pending_put,

				struct btrfs_device, dev_list);

		list_del(&device->dev_list);

		btrfs_close_bdev(device);

		call_rcu(&device->rcu, free_device_rcu);

	}



	WARN_ON(fs_devices->open_devices);

	WARN_ON(fs_devices->rw_devices);

	fs_devices->opened = 0;