blk_start_plug — initialize blk_plug and track it inside the task_struct


void blk_start_plug (struct blk_plug * plug);


struct blk_plug * plug

The struct blk_plug that needs to be initialized


Tracking blk_plug inside the task_struct will help with auto-flushing the pending I/O should the task end up blocking between blk_start_plug and blk_finish_plug. This is important from a performance perspective, but also ensures that we don't deadlock. For instance, if the task is blocking for a memory allocation, memory reclaim could end up wanting to free a page belonging to that request that is currently residing in our private plug. By flushing the pending I/O when the process goes to sleep, we avoid this kind of deadlock.