On Sat, Sep 10, 2016 at 07:03:38AM +0800, Anand Jain wrote:
> static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
> {
> struct btrfs_device *device, *tmp;
> + LIST_HEAD(pending_put);
> + INIT_LIST_HEAD(&pending_put);
LIST_HEAD declares and initializes the list to an empty one, not
necessary to call INIT_LIST_HEAD.
>
> if (--fs_devices->opened > 0)
> return 0;
> @@ -906,9 +904,24 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
> mutex_lock(&fs_devices->device_list_mutex);
> list_for_each_entry_safe(device, tmp, &fs_devices->devices, dev_list) {
> btrfs_close_one_device(device);
> + list_add(&device->dev_list, &pending_put);
> }
> mutex_unlock(&fs_devices->device_list_mutex);
>
> + /*
> + * btrfs_show_devname() is using the device_list_mutex,
> + * sometimes a 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_entry(pending_put.next,
Could be list_first_entry
> + struct btrfs_device, dev_list);
> + list_del(&device->dev_list);
> + btrfs_close_bdev(device);
> + call_rcu(&device->rcu, free_device);
> + }
> +
> WARN_ON(fs_devices->open_devices);
> WARN_ON(fs_devices->rw_devices);
> fs_devices->opened = 0;
After this patch, the function btrfs_close_one_device no longer does
what it says, ie. it does not close the device. I'd have to look closer
why it allocates a new structure and replaces it in the list, but this
looks weird.
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