loop: scale loop device by introducing per device lock

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.

Signed-off-by: Pavel Tatashin <[email protected]>
Reviewed-by: Tyler Hicks <[email protected]>
Reviewed-by: Petr Vorel <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions