On 16.12.2017 04:13, Anand Jain wrote:
>
>
> On 12/15/2017 11:06 PM, Nikolay Borisov wrote:
>>
>>
>> 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.
>
> I remembered your earlier similar comments and I thought of adding
> lockdep here, but as such I am also working on cleaning up uuid_mutext
> and device_list_mutex I would like to include such lockdep assert in
> those patches.
Makes sense so long as this change lands
>
> Thanks, Anand
>>> ---
>>> 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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