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Commit 9a25a04c authored by Philipp Reisner's avatar Philipp Reisner
Browse files

drbd: If we detect late that IO got frozen, retry after we thawed. 



If we detect late (= after grabing mdev->req_lock) that IO got frozen, we
return 1 to generic_make_request(), which simply will retry to make a
request for that bio.

In the subsequent call of generic_make_request() into drbd_make_request_26()
we sleep in inc_ap_bio().

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent a1c88d0d

drivers/block/drbd/drbd_int.h

+2 −2
Original line number Diff line number Diff line
@@ -2223,7 +2223,7 @@ static inline int __inc_ap_bio_cond(struct drbd_conf *mdev) 
/* I'd like to use wait_event_lock_irq,

 * but I'm not sure when it got introduced,

 * and not sure when it has 3 or 4 arguments */

static inline void inc_ap_bio(struct drbd_conf *mdev, int one_or_two)

static inline void inc_ap_bio(struct drbd_conf *mdev, int count)

{

	/* compare with after_state_ch,

	 * os.conn != C_WF_BITMAP_S && ns.conn == C_WF_BITMAP_S */
@@ -2245,7 +2245,7 @@ static inline void inc_ap_bio(struct drbd_conf *mdev, int one_or_two) 
		finish_wait(&mdev->misc_wait, &wait);

		spin_lock_irq(&mdev->req_lock);

	}

	atomic_add(one_or_two, &mdev->ap_bio_cnt);

	atomic_add(count, &mdev->ap_bio_cnt);

	spin_unlock_irq(&mdev->req_lock);

}

drivers/block/drbd/drbd_req.c

+26 −7
Original line number Diff line number Diff line
@@ -722,6 +722,7 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio) 
	struct drbd_request *req;

	int local, remote;

	int err = -EIO;

	int ret = 0;



	/* allocate outside of all locks; */

	req = drbd_req_new(mdev, bio);
@@ -784,7 +785,7 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio) 
			    (mdev->state.pdsk == D_INCONSISTENT &&

			     mdev->state.conn >= C_CONNECTED));



	if (!(local || remote)) {

	if (!(local || remote) && !mdev->state.susp) {

		dev_err(DEV, "IO ERROR: neither local nor remote disk\n");

		goto fail_free_complete;

	}
@@ -810,6 +811,16 @@ allocate_barrier: 
	/* GOOD, everything prepared, grab the spin_lock */

	spin_lock_irq(&mdev->req_lock);



	if (mdev->state.susp) {

		/* If we got suspended, use the retry mechanism of

		   generic_make_request() to restart processing of this

		   bio. In the next call to drbd_make_request_26

		   we sleep in inc_ap_bio() */

		ret = 1;

		spin_unlock_irq(&mdev->req_lock);

		goto fail_free_complete;

	}



	if (remote) {

		remote = (mdev->state.pdsk == D_UP_TO_DATE ||

			    (mdev->state.pdsk == D_INCONSISTENT &&
@@ -947,12 +958,14 @@ fail_and_free_req: 
		req->private_bio = NULL;

		put_ldev(mdev);

	}

	if (!ret)

		bio_endio(bio, err);



	drbd_req_free(req);

	dec_ap_bio(mdev);

	kfree(b);



	return 0;

	return ret;

}



/* helper function for drbd_make_request
@@ -1065,15 +1078,21 @@ int drbd_make_request_26(struct request_queue *q, struct bio *bio) 


		/* we need to get a "reference count" (ap_bio_cnt)

		 * to avoid races with the disconnect/reconnect/suspend code.

		 * In case we need to split the bio here, we need to get two references

		 * In case we need to split the bio here, we need to get three references

		 * atomically, otherwise we might deadlock when trying to submit the

		 * second one! */

		inc_ap_bio(mdev, 2);

		inc_ap_bio(mdev, 3);



		D_ASSERT(e_enr == s_enr + 1);



		drbd_make_request_common(mdev, &bp->bio1);

		drbd_make_request_common(mdev, &bp->bio2);

		while (drbd_make_request_common(mdev, &bp->bio1))

			inc_ap_bio(mdev, 1);



		while (drbd_make_request_common(mdev, &bp->bio2))

			inc_ap_bio(mdev, 1);



		dec_ap_bio(mdev);



		bio_pair_release(bp);

	}

	return 0;