On Tue, Jan 26, 2021 at 3:09 PM Jens Axboe [off-list ref] wrote:

On 1/26/21 7:46 AM, Pavel Tatashin wrote:

quoted

Currently, loop device has only one global lock: loop_ctl_mutex.

This becomes hot in scenarios where many loop devices are used.

Scale it by introducing per-device lock: lo_mutex that protects
modifications of all fields in struct loop_device.

Keep loop_ctl_mutex to protect global data: loop_index_idr, loop_lookup,
loop_add.

The new lock ordering requirement is that loop_ctl_mutex must be taken
before lo_mutex.

Applied, thanks.

Great, thank you!

Pasha

--
Jens Axboe