[PATCH] blk: light iocontext ops (fb3cc432) · Commits · 戴 / test

drivers/block/ll_rw_blk.c

+25 −31

Original line number	Diff line number	Diff line
		@@ -1876,7 +1876,7 @@ static struct request get_request(request_queue_t q, int rw, struct bio *bio,
		{
		struct request *rq = NULL;
		struct request_list *rl = &q->rq;
		struct io_context *ioc = get_io_context(GFP_ATOMIC);
		struct io_context *ioc = current_io_context(GFP_ATOMIC);

		if (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)))
		goto out;
		@@ -1959,7 +1959,6 @@ rq_starved:
		rq_init(q, rq);
		rq->rl = rl;
		out:
		put_io_context(ioc);
		return rq;
		}

		@@ -1997,9 +1996,8 @@ static struct request get_request_wait(request_queue_t q, int rw,
		* up to a big batch of them for a small period time.
		* See ioc_batching, ioc_set_batching
		*/
		ioc = get_io_context(GFP_NOIO);
		ioc = current_io_context(GFP_NOIO);
		ioc_set_batching(q, ioc);
		put_io_context(ioc);

		spin_lock_irq(q->queue_lock);
		}
		@@ -3282,24 +3280,20 @@ void exit_io_context(void)

		/*
		* If the current task has no IO context then create one and initialise it.
		* If it does have a context, take a ref on it.
		* Otherwise, return its existing IO context.
		*
		* This is always called in the context of the task which submitted the I/O.
		* But weird things happen, so we disable local interrupts to ensure exclusive
		* access to *current.
		* This returned IO context doesn't have a specifically elevated refcount,
		* but since the current task itself holds a reference, the context can be
		* used in general code, so long as it stays within `current` context.
		*/
		struct io_context *get_io_context(int gfp_flags)
		struct io_context *current_io_context(int gfp_flags)
		{
		struct task_struct *tsk = current;
		unsigned long flags;
		struct io_context *ret;

		local_irq_save(flags);
		ret = tsk->io_context;
		if (ret)
		goto out;

		local_irq_restore(flags);
		if (likely(ret))
		return ret;

		ret = kmem_cache_alloc(iocontext_cachep, gfp_flags);
		if (ret) {
		@@ -3310,25 +3304,25 @@ struct io_context *get_io_context(int gfp_flags)
		ret->nr_batch_requests = 0; /* because this is 0 */
		ret->aic = NULL;
		ret->cic = NULL;

		local_irq_save(flags);

		/*
		* very unlikely, someone raced with us in setting up the task
		* io context. free new context and just grab a reference.
		*/
		if (!tsk->io_context)
		tsk->io_context = ret;
		else {
		kmem_cache_free(iocontext_cachep, ret);
		ret = tsk->io_context;
		}

		out:
		atomic_inc(&ret->refcount);
		local_irq_restore(flags);
		return ret;
		}
		EXPORT_SYMBOL(current_io_context);

		/*
		* If the current task has no IO context then create one and initialise it.
		* If it does have a context, take a ref on it.
		*
		* This is always called in the context of the task which submitted the I/O.
		*/
		struct io_context *get_io_context(int gfp_flags)
		{
		struct io_context *ret;
		ret = current_io_context(gfp_flags);
		if (likely(ret))
		atomic_inc(&ret->refcount);
		return ret;
		}
		EXPORT_SYMBOL(get_io_context);

include/linux/blkdev.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -96,6 +96,7 @@ struct io_context {

		void put_io_context(struct io_context *ioc);
		void exit_io_context(void);
		struct io_context *current_io_context(int gfp_flags);
		struct io_context *get_io_context(int gfp_flags);
		void copy_io_context(struct io_context pdst, struct io_context psrc);
		void swap_io_context(struct io_context ioc1, struct io_context ioc2);

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