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Commit f4aa4c7b authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: loop: convert to per-device workqueue 



Documentation/workqueue.txt:
	If there is dependency among multiple work items used
	during memory reclaim, they should be queued to separate
	wq each with WQ_MEM_RECLAIM.

Loop devices can be stacked, so we have to convert to per-device
workqueue. One example is Fedora live CD.

Fixes: b5dd2f60
Cc: stable@vger.kernel.org (v4.0)
Cc: Justin M. Forbes <jforbes@fedoraproject.org>
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 9dc6c806

drivers/block/loop.c

+14 −16
Original line number Diff line number Diff line
@@ -86,8 +86,6 @@ static DEFINE_MUTEX(loop_index_mutex); 
static int max_part;

static int part_shift;



static struct workqueue_struct *loop_wq;



static int transfer_xor(struct loop_device *lo, int cmd,

			struct page *raw_page, unsigned raw_off,

			struct page *loop_page, unsigned loop_off,
@@ -725,6 +723,12 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode, 
	size = get_loop_size(lo, file);

	if ((loff_t)(sector_t)size != size)

		goto out_putf;

	error = -ENOMEM;

	lo->wq = alloc_workqueue("kloopd%d",

			WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0,

			lo->lo_number);

	if (!lo->wq)

		goto out_putf;



	error = 0;
@@ -872,6 +876,8 @@ static int loop_clr_fd(struct loop_device *lo) 
	lo->lo_flags = 0;

	if (!part_shift)

		lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;

	destroy_workqueue(lo->wq);

	lo->wq = NULL;

	mutex_unlock(&lo->lo_ctl_mutex);

	/*

	 * Need not hold lo_ctl_mutex to fput backing file.
@@ -1425,9 +1431,13 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx, 
		const struct blk_mq_queue_data *bd)

{

	struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);

	struct loop_device *lo = cmd->rq->q->queuedata;



	blk_mq_start_request(bd->rq);



	if (lo->lo_state != Lo_bound)

		return -EIO;



	if (cmd->rq->cmd_flags & REQ_WRITE) {

		struct loop_device *lo = cmd->rq->q->queuedata;

		bool need_sched = true;
@@ -1441,9 +1451,9 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx, 
		spin_unlock_irq(&lo->lo_lock);



		if (need_sched)

			queue_work(loop_wq, &lo->write_work);

			queue_work(lo->wq, &lo->write_work);

	} else {

		queue_work(loop_wq, &cmd->read_work);

		queue_work(lo->wq, &cmd->read_work);

	}



	return BLK_MQ_RQ_QUEUE_OK;
@@ -1455,9 +1465,6 @@ static void loop_handle_cmd(struct loop_cmd *cmd) 
	struct loop_device *lo = cmd->rq->q->queuedata;

	int ret = -EIO;



	if (lo->lo_state != Lo_bound)

		goto failed;



	if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY))

		goto failed;
@@ -1806,13 +1813,6 @@ static int __init loop_init(void) 
		goto misc_out;

	}



	loop_wq = alloc_workqueue("kloopd",

			WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0);

	if (!loop_wq) {

		err = -ENOMEM;

		goto misc_out;

	}



	blk_register_region(MKDEV(LOOP_MAJOR, 0), range,

				  THIS_MODULE, loop_probe, NULL, NULL);
@@ -1850,8 +1850,6 @@ static void __exit loop_exit(void) 
	blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);

	unregister_blkdev(LOOP_MAJOR, "loop");



	destroy_workqueue(loop_wq);



	misc_deregister(&loop_misc);

}

drivers/block/loop.h

+1 −0
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ struct loop_device { 
	gfp_t		old_gfp_mask;



	spinlock_t		lo_lock;

	struct workqueue_struct *wq;

	struct list_head	write_cmd_head;

	struct work_struct	write_work;

	bool			write_started;