Commit 56392d2f authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Jens Axboe
Browse files

drbd: Clarify when activity log I/O is delegated to the worker thread 



Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c04ccaa6

drivers/block/drbd/drbd_actlog.c

+27 −22
Original line number Diff line number Diff line
@@ -104,7 +104,7 @@ struct update_al_work { 
	int err;

};



static int al_write_transaction(struct drbd_conf *mdev);

static int al_write_transaction(struct drbd_conf *mdev, bool delegate);



void *drbd_md_get_buffer(struct drbd_conf *mdev)

{
@@ -246,7 +246,10 @@ static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr) 
	return al_ext;

}



void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i)

/*

 * @delegate:   delegate activity log I/O to the worker thread

 */

void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i, bool delegate)

{

	/* for bios crossing activity log extent boundaries,

	 * we may need to activate two extents in one go */
@@ -255,6 +258,17 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i) 
	unsigned enr;

	bool locked = false;



	/* When called through generic_make_request(), we must delegate

	 * activity log I/O to the worker thread: a further request

	 * submitted via generic_make_request() within the same task

	 * would be queued on current->bio_list, and would only start

	 * after this function returns (see generic_make_request()).

	 *

	 * However, if we *are* the worker, we must not delegate to ourselves.

	 */



	if (delegate)

		BUG_ON(current == mdev->tconn->worker.task);



	D_ASSERT(first <= last);

	D_ASSERT(atomic_read(&mdev->local_cnt) > 0);
@@ -270,13 +284,6 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i) 
			(locked = lc_try_lock_for_transaction(mdev->act_log)));



	if (locked) {

		/* drbd_al_write_transaction(mdev,al_ext,enr);

		 * recurses into generic_make_request(), which

		 * disallows recursion, bios being serialized on the

		 * current->bio_tail list now.

		 * we have to delegate updates to the activity log

		 * to the worker thread. */



		/* Double check: it may have been committed by someone else,

		 * while we have been waiting for the lock. */

		if (mdev->act_log->pending_changes) {
@@ -287,7 +294,7 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i) 
			rcu_read_unlock();



			if (write_al_updates) {

				al_write_transaction(mdev);

				al_write_transaction(mdev, delegate);

				mdev->al_writ_cnt++;

			}
@@ -495,20 +502,18 @@ static int w_al_write_transaction(struct drbd_work *w, int unused) 
/* Calls from worker context (see w_restart_disk_io()) need to write the

   transaction directly. Others came through generic_make_request(),

   those need to delegate it to the worker. */

static int al_write_transaction(struct drbd_conf *mdev)

static int al_write_transaction(struct drbd_conf *mdev, bool delegate)

{

	if (delegate) {

		struct update_al_work al_work;



	if (current == mdev->tconn->worker.task)

		return _al_write_transaction(mdev);



		init_completion(&al_work.event);

		al_work.w.cb = w_al_write_transaction;

		al_work.w.mdev = mdev;

		drbd_queue_work_front(&mdev->tconn->sender_work, &al_work.w);

		wait_for_completion(&al_work.event);



		return al_work.err;

	} else

		return _al_write_transaction(mdev);

}



static int _try_lc_del(struct drbd_conf *mdev, struct lc_element *al_ext)

drivers/block/drbd/drbd_int.h

+1 −1
Original line number Diff line number Diff line
@@ -1598,7 +1598,7 @@ extern const char *drbd_conn_str(enum drbd_conns s); 
extern const char *drbd_role_str(enum drbd_role s);



/* drbd_actlog.c */

extern void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i);

extern void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i, bool delegate);

extern void drbd_al_complete_io(struct drbd_conf *mdev, struct drbd_interval *i);

extern void drbd_rs_complete_io(struct drbd_conf *mdev, sector_t sector);

extern int drbd_rs_begin_io(struct drbd_conf *mdev, sector_t sector);

drivers/block/drbd/drbd_receiver.c

+1 −1
Original line number Diff line number Diff line
@@ -2265,7 +2265,7 @@ static int receive_Data(struct drbd_tconn *tconn, struct packet_info *pi) 
		drbd_set_out_of_sync(mdev, peer_req->i.sector, peer_req->i.size);

		peer_req->flags |= EE_CALL_AL_COMPLETE_IO;

		peer_req->flags &= ~EE_MAY_SET_IN_SYNC;

		drbd_al_begin_io(mdev, &peer_req->i);

		drbd_al_begin_io(mdev, &peer_req->i, true);

	}



	err = drbd_submit_peer_request(mdev, peer_req, rw, DRBD_FAULT_DT_WR);

drivers/block/drbd/drbd_req.c

+1 −1
Original line number Diff line number Diff line
@@ -1054,7 +1054,7 @@ void __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long 
	if (rw == WRITE && req->private_bio && req->i.size

	&& !test_bit(AL_SUSPENDED, &mdev->flags)) {

		req->rq_state |= RQ_IN_ACT_LOG;

		drbd_al_begin_io(mdev, &req->i);

		drbd_al_begin_io(mdev, &req->i, true);

	}



	spin_lock_irq(&mdev->tconn->req_lock);

drivers/block/drbd/drbd_worker.c

+1 −1
Original line number Diff line number Diff line
@@ -1411,7 +1411,7 @@ int w_restart_disk_io(struct drbd_work *w, int cancel) 
	struct drbd_conf *mdev = w->mdev;



	if (bio_data_dir(req->master_bio) == WRITE && req->rq_state & RQ_IN_ACT_LOG)

		drbd_al_begin_io(mdev, &req->i);

		drbd_al_begin_io(mdev, &req->i, false);



	drbd_req_make_private_bio(req, req->master_bio);

	req->private_bio->bi_bdev = mdev->ldev->backing_bdev;