On 15.12.2017 05:47, Anand Jain wrote:
> Let the list iterator iterate further and find other stale
> devices and delete it. This is in preparation to add support
> for user land request-able stale devices cleanup.
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
What is the lock protection of this function - uuid_mutex, it's not
really obvious. Perhaps adding a lockdep_assert_held for the correct
lock ? I guess David's earlier patch to document the locking in
volumes.c might shed some light on this one.
> ---
> fs/btrfs/volumes.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 0e89409112d5..70db6a1d5658 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -610,19 +610,20 @@ static void pending_bios_fn(struct btrfs_work *work)
>
> static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
> {
> - struct btrfs_fs_devices *fs_devs;
> - struct btrfs_device *dev;
> + struct btrfs_fs_devices *fs_devs, *tmp_fs_devs;
> + struct btrfs_device *dev, *tmp_dev;
>
> if (!cur_dev->name)
> return;
>
> - list_for_each_entry(fs_devs, &fs_uuids, list) {
> - int del = 1;
> + list_for_each_entry_safe(fs_devs, tmp_fs_devs, &fs_uuids, list) {
>
> if (fs_devs->opened)
> continue;
>
> - list_for_each_entry(dev, &fs_devs->devices, dev_list) {
> + list_for_each_entry_safe(dev, tmp_dev,
> + &fs_devs->devices, dev_list) {
> + int not_found;
>
> if (dev == cur_dev)
> continue;
> @@ -636,14 +637,12 @@ static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
> * either use mapper or non mapper path throughout.
> */
> rcu_read_lock();
> - del = strcmp(rcu_str_deref(dev->name),
> + not_found = strcmp(rcu_str_deref(dev->name),
> rcu_str_deref(cur_dev->name));
> rcu_read_unlock();
> - if (!del)
> - break;
> - }
> + if (not_found)
> + continue;
>
> - if (!del) {
> /* delete the stale device */
> if (fs_devs->num_devices == 1) {
> btrfs_sysfs_remove_fsid(fs_devs);
> @@ -654,7 +653,6 @@ static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
> list_del(&dev->dev_list);
> free_device(dev);
> }
> - break;
> }
> }
> }
>
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