On Fri, Jun 11, 2021 at 10:47 AM Tetsuo Handa
[off-list ref] wrote:

On 2021/06/10 1:46, Tyler Hicks wrote:

quoted

Thanks for doing this. I haven't had a chance to retry this commit with
lockdep but I did re-review it and didn't think that it would be the
cause of this lockdep report since it strictly reduced the usage of the
loop_ctl_mutex.

Well, I made commit 310ca162d779efee ("block/loop: Use global lock for ioctl() operation.")
because per device lock was not sufficient. Did commit 6cc8e7430801fa23 ("loop: scale loop
device by introducing per device lock") take this problem into account?

This was my intention when I wrote 6cc8e7430801fa23 ("loop: scale loop
device by introducing per device lock"). This is why this change does
not simply revert 310ca162d779efee ("block/loop: Use global lock for
ioctl() operation."), but keeps loop_ctl_mutex to protect the global
accesses.  loop_control_ioctl() is still locked by global
loop_ctl_mutex.