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Diffstat (limited to 'block/blk-core.c')
-rw-r--r-- | block/blk-core.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 684d7eb33d4..97e9e5405b8 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2595,6 +2595,20 @@ EXPORT_SYMBOL(kblockd_schedule_delayed_work); #define PLUG_MAGIC 0x91827364 +/** + * blk_start_plug - initialize blk_plug and track it inside the task_struct + * @plug: The &struct blk_plug that needs to be initialized + * + * Description: + * 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. + */ void blk_start_plug(struct blk_plug *plug) { struct task_struct *tsk = current; |