Commit 0619317f authored by Jens Axboe's avatar Jens Axboe
Browse files

block: add polled wakeup task helper 



If we're polling for IO on a device that doesn't use interrupts, then
IO completion loop (and wake of task) is done by submitting task itself.
If that is the case, then we don't need to enter the wake_up_process()
function, we can simply mark ourselves as TASK_RUNNING.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e5045454

fs/block_dev.c

+2 −2
Original line number Diff line number Diff line
@@ -181,7 +181,7 @@ static void blkdev_bio_end_io_simple(struct bio *bio) 
	struct task_struct *waiter = bio->bi_private;



	WRITE_ONCE(bio->bi_private, NULL);

	wake_up_process(waiter);

	blk_wake_io_task(waiter);

}



static ssize_t
@@ -305,7 +305,7 @@ static void blkdev_bio_end_io(struct bio *bio) 
			struct task_struct *waiter = dio->waiter;



			WRITE_ONCE(dio->waiter, NULL);

			wake_up_process(waiter);

			blk_wake_io_task(waiter);

		}

	}

fs/iomap.c

+1 −1
Original line number Diff line number Diff line
@@ -1525,7 +1525,7 @@ static void iomap_dio_bio_end_io(struct bio *bio) 
		if (dio->wait_for_completion) {

			struct task_struct *waiter = dio->submit.waiter;

			WRITE_ONCE(dio->submit.waiter, NULL);

			wake_up_process(waiter);

			blk_wake_io_task(waiter);

		} else if (dio->flags & IOMAP_DIO_WRITE) {

			struct inode *inode = file_inode(dio->iocb->ki_filp);

include/linux/blkdev.h

+13 −0
Original line number Diff line number Diff line
@@ -1772,4 +1772,17 @@ static inline int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask, 


#endif /* CONFIG_BLOCK */



static inline void blk_wake_io_task(struct task_struct *waiter)

{

	/*

	 * If we're polling, the task itself is doing the completions. For

	 * that case, we don't need to signal a wakeup, it's enough to just

	 * mark us as RUNNING.

	 */

	if (waiter == current)

		__set_current_state(TASK_RUNNING);

	else

		wake_up_process(waiter);

}



#endif

mm/page_io.c

+1 −1
Original line number Diff line number Diff line
@@ -140,7 +140,7 @@ out: 
	unlock_page(page);

	WRITE_ONCE(bio->bi_private, NULL);

	bio_put(bio);

	wake_up_process(waiter);

	blk_wake_io_task(waiter);

	put_task_struct(waiter);

}

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