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Commit 844a6ae7 authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Philipp Reisner
Browse files

drbd: add lists to find oldest pending requests 



Adding requests to per-device fifo lists as soon as possible after
allocating them leaves a simple list_first_entry_or_null() to find the
oldest request, regardless what it is still waiting for.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent e5f891b2

drivers/block/drbd/drbd_int.h

+10 −1
Original line number Diff line number Diff line
@@ -318,6 +318,10 @@ struct drbd_request { 
	struct list_head tl_requests; /* ring list in the transfer log */

	struct bio *master_bio;       /* master bio pointer */



	/* see struct drbd_device */

	struct list_head req_pending_master_completion;

	struct list_head req_pending_local;



	/* for generic IO accounting */

	unsigned long start_jif;
@@ -738,7 +742,7 @@ struct submit_worker { 
	struct workqueue_struct *wq;

	struct work_struct worker;



	spinlock_t lock;

	/* protected by ..->resource->req_lock */

	struct list_head writes;

};
@@ -795,6 +799,11 @@ struct drbd_device { 
	struct rb_root read_requests;

	struct rb_root write_requests;



	/* for statistics and timeouts */

	/* [0] read, [1] write */

	struct list_head pending_master_completion[2];

	struct list_head pending_completion[2];



	/* use checksums for *this* resync */

	bool use_csums;

	/* blocks to resync in this run [unit BM_BLOCK_SIZE] */

drivers/block/drbd/drbd_main.c

+6 −1
Original line number Diff line number Diff line
@@ -1934,6 +1934,10 @@ void drbd_init_set_defaults(struct drbd_device *device) 
	INIT_LIST_HEAD(&device->resync_work.list);

	INIT_LIST_HEAD(&device->unplug_work.list);

	INIT_LIST_HEAD(&device->bm_io_work.w.list);

	INIT_LIST_HEAD(&device->pending_master_completion[0]);

	INIT_LIST_HEAD(&device->pending_master_completion[1]);

	INIT_LIST_HEAD(&device->pending_completion[0]);

	INIT_LIST_HEAD(&device->pending_completion[1]);



	device->resync_work.cb  = w_resync_timer;

	device->unplug_work.cb  = w_send_write_hint;
@@ -2268,6 +2272,8 @@ static void do_retry(struct work_struct *ws) 
	}

}



/* called via drbd_req_put_completion_ref(),

 * holds resource->req_lock */

void drbd_restart_request(struct drbd_request *req)

{

	unsigned long flags;
@@ -2687,7 +2693,6 @@ static int init_submitter(struct drbd_device *device) 
		return -ENOMEM;



	INIT_WORK(&device->submit.worker, do_submit);

	spin_lock_init(&device->submit.lock);

	INIT_LIST_HEAD(&device->submit.writes);

	return 0;

}

drivers/block/drbd/drbd_req.c

+33 −12
Original line number Diff line number Diff line
@@ -84,6 +84,8 @@ static struct drbd_request *drbd_req_new(struct drbd_device *device, 


	INIT_LIST_HEAD(&req->tl_requests);

	INIT_LIST_HEAD(&req->w.list);

	INIT_LIST_HEAD(&req->req_pending_master_completion);

	INIT_LIST_HEAD(&req->req_pending_local);



	/* one reference to be put by __drbd_make_request */

	atomic_set(&req->completion_ref, 1);
@@ -120,12 +122,14 @@ void drbd_req_destroy(struct kref *kref) 
		return;

	}



	/* remove it from the transfer log.

	 * well, only if it had been there in the first

	 * place... if it had not (local only or conflicting

	 * and never sent), it should still be "empty" as

	 * initialized in drbd_req_new(), so we can list_del() it

	 * here unconditionally */

	/* If called from mod_rq_state (expected normal case) or

	 * drbd_send_and_submit (the less likely normal path), this holds the

	 * req_lock, and req->tl_requests will typicaly be on ->transfer_log,

	 * though it may be still empty (never added to the transfer log).

	 *

	 * If called from do_retry(), we do NOT hold the req_lock, but we are

	 * still allowed to unconditionally list_del(&req->tl_requests),

	 * because it will be on a local on-stack list only. */

	list_del_init(&req->tl_requests);



	/* finally remove the request from the conflict detection
@@ -312,8 +316,15 @@ void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m) 


	if (req->i.waiting)

		wake_up(&device->misc_wait);



	/* Either we are about to complete to upper layers,

	 * or we will restart this request.

	 * In either case, the request object will be destroyed soon,

	 * so better remove it from all lists. */

	list_del_init(&req->req_pending_master_completion);

}



/* still holds resource->req_lock */

static int drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put)

{

	struct drbd_device *device = req->device;
@@ -400,6 +411,7 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, 
			++k_put;

		else

			++c_put;

		list_del_init(&req->req_pending_local);

	}



	if ((s & RQ_NET_PENDING) && (clear & RQ_NET_PENDING)) {
@@ -1070,9 +1082,11 @@ drbd_submit_req_private_bio(struct drbd_request *req) 


static void drbd_queue_write(struct drbd_device *device, struct drbd_request *req)

{

	spin_lock(&device->submit.lock);

	spin_lock_irq(&device->resource->req_lock);

	list_add_tail(&req->tl_requests, &device->submit.writes);

	spin_unlock(&device->submit.lock);

	list_add_tail(&req->req_pending_master_completion,

			&device->pending_master_completion[1 /* WRITE */]);

	spin_unlock_irq(&device->resource->req_lock);

	queue_work(device->submit.wq, &device->submit.worker);

}
@@ -1186,8 +1200,15 @@ static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request 
			no_remote = true;

	}



	/* If it took the fast path in drbd_request_prepare, add it here.

	 * The slow path has added it already. */

	if (list_empty(&req->req_pending_master_completion))

		list_add_tail(&req->req_pending_master_completion,

			&device->pending_master_completion[rw == WRITE]);

	if (req->private_bio) {

		/* needs to be marked within the same spinlock */

		list_add_tail(&req->req_pending_local,

			&device->pending_completion[rw == WRITE]);

		_req_mod(req, TO_BE_SUBMITTED);

		/* but we need to give up the spinlock to submit */

		submit_private_bio = true;
@@ -1278,9 +1299,9 @@ void do_submit(struct work_struct *ws) 
	struct drbd_request *req, *tmp;



	for (;;) {

		spin_lock(&device->submit.lock);

		spin_lock_irq(&device->resource->req_lock);

		list_splice_tail_init(&device->submit.writes, &incoming);

		spin_unlock(&device->submit.lock);

		spin_unlock_irq(&device->resource->req_lock);



		submit_fast_path(device, &incoming);

		if (list_empty(&incoming))
@@ -1304,9 +1325,9 @@ void do_submit(struct work_struct *ws) 
			if (list_empty(&device->submit.writes))

				break;



			spin_lock(&device->submit.lock);

			spin_lock_irq(&device->resource->req_lock);

			list_splice_tail_init(&device->submit.writes, &more_incoming);

			spin_unlock(&device->submit.lock);

			spin_unlock_irq(&device->resource->req_lock);



			if (list_empty(&more_incoming))

				break;