drbd: Allow drbd_epoch_entries to use multiple bios.

This should allow for better performance if the lower level IO stack
of the peers differs in limits exposed either via the queue,
or via some merge_bvec_fn.
Signed-off-by: NPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: NLars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_int.h

@@ -740,18 +740,6 @@ enum epoch_event {
 	EV_CLEANUP = 32, /* used as flag */
 };
 
-struct drbd_epoch_entry {
-	struct drbd_work    w;
-	struct drbd_conf *mdev;
-	struct bio *private_bio;
-	struct hlist_node colision;
-	sector_t sector;
-	unsigned int size;
-	unsigned int flags;
-	struct drbd_epoch *epoch;
-	u64    block_id;
-};
-
 struct drbd_wq_barrier {
 	struct drbd_work w;
 	struct completion done;
@@ -762,17 +750,49 @@ struct digest_info {
 	void *digest;
 };
 
-/* ee flag bits */
+struct drbd_epoch_entry {
+	struct drbd_work w;
+	struct hlist_node colision;
+	struct drbd_epoch *epoch;
+	struct drbd_conf *mdev;
+	struct page *pages;
+	atomic_t pending_bios;
+	unsigned int size;
+	/* see comments on ee flag bits below */
+	unsigned long flags;
+	sector_t sector;
+	u64 block_id;
+};
+
+/* ee flag bits.
+ * While corresponding bios are in flight, the only modification will be
+ * set_bit WAS_ERROR, which has to be atomic.
+ * If no bios are in flight yet, or all have been completed,
+ * non-atomic modification to ee->flags is ok.
+ */
 enum {
 	__EE_CALL_AL_COMPLETE_IO,
-	__EE_CONFLICT_PENDING,
 	__EE_MAY_SET_IN_SYNC,
+
+	/* This epoch entry closes an epoch using a barrier.
+	 * On sucessful completion, the epoch is released,
+	 * and the P_BARRIER_ACK send. */
 	__EE_IS_BARRIER,
+
+	/* In case a barrier failed,
+	 * we need to resubmit without the barrier flag. */
+	__EE_RESUBMITTED,
+
+	/* we may have several bios per epoch entry.
+	 * if any of those fail, we set this flag atomically
+	 * from the endio callback */
+	__EE_WAS_ERROR,
 };
 #define EE_CALL_AL_COMPLETE_IO (1<<__EE_CALL_AL_COMPLETE_IO)
-#define EE_CONFLICT_PENDING    (1<<__EE_CONFLICT_PENDING)
 #define EE_MAY_SET_IN_SYNC     (1<<__EE_MAY_SET_IN_SYNC)
 #define EE_IS_BARRIER          (1<<__EE_IS_BARRIER)
+#define	EE_RESUBMITTED         (1<<__EE_RESUBMITTED)
+#define EE_WAS_ERROR           (1<<__EE_WAS_ERROR)
 
 /* global flag bits */
 enum {
@@ -1441,7 +1461,8 @@ static inline void ov_oos_print(struct drbd_conf *mdev)
 }
 
 
-extern void drbd_csum(struct drbd_conf *, struct crypto_hash *, struct bio *, void *);
+extern void drbd_csum_bio(struct drbd_conf *, struct crypto_hash *, struct bio *, void *);
+extern void drbd_csum_ee(struct drbd_conf *, struct crypto_hash *, struct drbd_epoch_entry *, void *);
 /* worker callbacks */
 extern int w_req_cancel_conflict(struct drbd_conf *, struct drbd_work *, int);
 extern int w_read_retry_remote(struct drbd_conf *, struct drbd_work *, int);
@@ -1465,6 +1486,8 @@ extern int w_e_reissue(struct drbd_conf *, struct drbd_work *, int);
 extern void resync_timer_fn(unsigned long data);
 
 /* drbd_receiver.c */
+extern int drbd_submit_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e,
+		const unsigned rw, const int fault_type);
 extern int drbd_release_ee(struct drbd_conf *mdev, struct list_head *list);
 extern struct drbd_epoch_entry *drbd_alloc_ee(struct drbd_conf *mdev,
 					    u64 id,
@@ -1620,6 +1643,41 @@ void drbd_bcast_ee(struct drbd_conf *mdev,
  * inline helper functions
  *************************/
 
+/* see also page_chain_add and friends in drbd_receiver.c */
+static inline struct page *page_chain_next(struct page *page)
+{
+	return (struct page *)page_private(page);
+}
+#define page_chain_for_each(page) \
+	for (; page && ({ prefetch(page_chain_next(page)); 1; }); \
+			page = page_chain_next(page))
+#define page_chain_for_each_safe(page, n) \
+	for (; page && ({ n = page_chain_next(page); 1; }); page = n)
+
+static inline int drbd_bio_has_active_page(struct bio *bio)
+{
+	struct bio_vec *bvec;
+	int i;
+
+	__bio_for_each_segment(bvec, bio, i, 0) {
+		if (page_count(bvec->bv_page) > 1)
+			return 1;
+	}
+
+	return 0;
+}
+
+static inline int drbd_ee_has_active_page(struct drbd_epoch_entry *e)
+{
+	struct page *page = e->pages;
+	page_chain_for_each(page) {
+		if (page_count(page) > 1)
+			return 1;
+	}
+	return 0;
+}
+
+
 static inline void drbd_state_lock(struct drbd_conf *mdev)
 {
 	wait_event(mdev->misc_wait,

drivers/block/drbd/drbd_main.c

@@ -2354,6 +2354,19 @@ static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio)
 	return 1;
 }
 
+static int _drbd_send_zc_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e)
+{
+	struct page *page = e->pages;
+	unsigned len = e->size;
+	page_chain_for_each(page) {
+		unsigned l = min_t(unsigned, len, PAGE_SIZE);
+		if (!_drbd_send_page(mdev, page, 0, l))
+			return 0;
+		len -= l;
+	}
+	return 1;
+}
+
 static void consider_delay_probes(struct drbd_conf *mdev)
 {
 	if (mdev->state.conn != C_SYNC_SOURCE || mdev->agreed_pro_version < 93)
@@ -2430,7 +2443,7 @@ int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req)
 		drbd_send(mdev, mdev->data.socket, &p, sizeof(p), MSG_MORE));
 	if (ok && dgs) {
 		dgb = mdev->int_dig_out;
-		drbd_csum(mdev, mdev->integrity_w_tfm, req->master_bio, dgb);
+		drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, dgb);
 		ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, MSG_MORE);
 	}
 	if (ok) {
@@ -2483,11 +2496,11 @@ int drbd_send_block(struct drbd_conf *mdev, enum drbd_packets cmd,
 					sizeof(p), MSG_MORE);
 	if (ok && dgs) {
 		dgb = mdev->int_dig_out;
-		drbd_csum(mdev, mdev->integrity_w_tfm, e->private_bio, dgb);
+		drbd_csum_ee(mdev, mdev->integrity_w_tfm, e, dgb);
 		ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, MSG_MORE);
 	}
 	if (ok)
-		ok = _drbd_send_zc_bio(mdev, e->private_bio);
+		ok = _drbd_send_zc_ee(mdev, e);
 
 	drbd_put_data_sock(mdev);
 

drivers/block/drbd/drbd_nl.c

@@ -2215,9 +2215,9 @@ void drbd_bcast_ee(struct drbd_conf *mdev,
 {
 	struct cn_msg *cn_reply;
 	struct drbd_nl_cfg_reply *reply;
-	struct bio_vec *bvec;
 	unsigned short *tl;
-	int i;
+	struct page *page;
+	unsigned len;
 
 	if (!e)
 		return;
@@ -2255,11 +2255,15 @@ void drbd_bcast_ee(struct drbd_conf *mdev,
 	put_unaligned(T_ee_data, tl++);
 	put_unaligned(e->size, tl++);
 
-	__bio_for_each_segment(bvec, e->private_bio, i, 0) {
-		void *d = kmap(bvec->bv_page);
-		memcpy(tl, d + bvec->bv_offset, bvec->bv_len);
-		kunmap(bvec->bv_page);
-		tl=(unsigned short*)((char*)tl + bvec->bv_len);
+	len = e->size;
+	page = e->pages;
+	page_chain_for_each(page) {
+		void *d = kmap_atomic(page, KM_USER0);
+		unsigned l = min_t(unsigned, len, PAGE_SIZE);
+		memcpy(tl, d, l);
+		kunmap_atomic(d, KM_USER0);
+		tl = (unsigned short*)((char*)tl + l);
+		len -= l;
 	}
 	put_unaligned(TT_END, tl++); /* Close the tag list */
 

drivers/block/drbd/drbd_worker.c

@@ -47,8 +47,7 @@ static int w_make_ov_request(struct drbd_conf *mdev, struct drbd_work *w, int ca
 
 /* defined here:
    drbd_md_io_complete
-   drbd_endio_write_sec
-   drbd_endio_read_sec
+   drbd_endio_sec
    drbd_endio_pri
 
  * more endio handlers:
@@ -85,27 +84,10 @@ void drbd_md_io_complete(struct bio *bio, int error)
 /* reads on behalf of the partner,
  * "submitted" by the receiver
  */
-void drbd_endio_read_sec(struct bio *bio, int error) __releases(local)
+void drbd_endio_read_sec_final(struct drbd_epoch_entry *e) __releases(local)
 {
 	unsigned long flags = 0;
-	struct drbd_epoch_entry *e = NULL;
-	struct drbd_conf *mdev;
-	int uptodate = bio_flagged(bio, BIO_UPTODATE);
-
-	e = bio->bi_private;
-	mdev = e->mdev;
-
-	if (error)
-		dev_warn(DEV, "read: error=%d s=%llus\n", error,
-				(unsigned long long)e->sector);
-	if (!error && !uptodate) {
-		dev_warn(DEV, "read: setting error to -EIO s=%llus\n",
-				(unsigned long long)e->sector);
-		/* strange behavior of some lower level drivers...
-		 * fail the request by clearing the uptodate flag,
-		 * but do not return any error?! */
-		error = -EIO;
-	}
+	struct drbd_conf *mdev = e->mdev;
 
 	D_ASSERT(e->block_id != ID_VACANT);
 
@@ -114,49 +96,38 @@ void drbd_endio_read_sec(struct bio *bio, int error) __releases(local)
 	list_del(&e->w.list);
 	if (list_empty(&mdev->read_ee))
 		wake_up(&mdev->ee_wait);
+	if (test_bit(__EE_WAS_ERROR, &e->flags))
+		__drbd_chk_io_error(mdev, FALSE);
 	spin_unlock_irqrestore(&mdev->req_lock, flags);
 
-	drbd_chk_io_error(mdev, error, FALSE);
 	drbd_queue_work(&mdev->data.work, &e->w);
 	put_ldev(mdev);
 }
 
+static int is_failed_barrier(int ee_flags)
+{
+	return (ee_flags & (EE_IS_BARRIER|EE_WAS_ERROR|EE_RESUBMITTED))
+			== (EE_IS_BARRIER|EE_WAS_ERROR);
+}
+
 /* writes on behalf of the partner, or resync writes,
- * "submitted" by the receiver.
- */
-void drbd_endio_write_sec(struct bio *bio, int error) __releases(local)
+ * "submitted" by the receiver, final stage.  */
+static void drbd_endio_write_sec_final(struct drbd_epoch_entry *e) __releases(local)
 {
 	unsigned long flags = 0;
-	struct drbd_epoch_entry *e = NULL;
-	struct drbd_conf *mdev;
+	struct drbd_conf *mdev = e->mdev;
 	sector_t e_sector;
 	int do_wake;
 	int is_syncer_req;
 	int do_al_complete_io;
-	int uptodate = bio_flagged(bio, BIO_UPTODATE);
-	int is_barrier = bio_rw_flagged(bio, BIO_RW_BARRIER);
 
-	e = bio->bi_private;
-	mdev = e->mdev;
-
-	if (error)
-		dev_warn(DEV, "write: error=%d s=%llus\n", error,
-				(unsigned long long)e->sector);
-	if (!error && !uptodate) {
-		dev_warn(DEV, "write: setting error to -EIO s=%llus\n",
-				(unsigned long long)e->sector);
-		/* strange behavior of some lower level drivers...
-		 * fail the request by clearing the uptodate flag,
-		 * but do not return any error?! */
-		error = -EIO;
-	}
-
-	/* error == -ENOTSUPP would be a better test,
-	 * alas it is not reliable */
-	if (error && is_barrier && e->flags & EE_IS_BARRIER) {
+	/* if this is a failed barrier request, disable use of barriers,
+	 * and schedule for resubmission */
+	if (is_failed_barrier(e->flags)) {
 		drbd_bump_write_ordering(mdev, WO_bdev_flush);
 		spin_lock_irqsave(&mdev->req_lock, flags);
 		list_del(&e->w.list);
+		e->flags |= EE_RESUBMITTED;
 		e->w.cb = w_e_reissue;
 		/* put_ldev actually happens below, once we come here again. */
 		__release(local);
@@ -167,17 +138,16 @@ void drbd_endio_write_sec(struct bio *bio, int error) __releases(local)
 
 	D_ASSERT(e->block_id != ID_VACANT);
 
-	spin_lock_irqsave(&mdev->req_lock, flags);
-	mdev->writ_cnt += e->size >> 9;
-	is_syncer_req = is_syncer_block_id(e->block_id);
-
 	/* after we moved e to done_ee,
 	 * we may no longer access it,
 	 * it may be freed/reused already!
 	 * (as soon as we release the req_lock) */
 	e_sector = e->sector;
 	do_al_complete_io = e->flags & EE_CALL_AL_COMPLETE_IO;
+	is_syncer_req = is_syncer_block_id(e->block_id);
 
+	spin_lock_irqsave(&mdev->req_lock, flags);
+	mdev->writ_cnt += e->size >> 9;
 	list_del(&e->w.list); /* has been on active_ee or sync_ee */
 	list_add_tail(&e->w.list, &mdev->done_ee);
 
@@ -190,7 +160,7 @@ void drbd_endio_write_sec(struct bio *bio, int error) __releases(local)
 		? list_empty(&mdev->sync_ee)
 		: list_empty(&mdev->active_ee);
 
-	if (error)
+	if (test_bit(__EE_WAS_ERROR, &e->flags))
 		__drbd_chk_io_error(mdev, FALSE);
 	spin_unlock_irqrestore(&mdev->req_lock, flags);
 
@@ -205,7 +175,42 @@ void drbd_endio_write_sec(struct bio *bio, int error) __releases(local)
 
 	wake_asender(mdev);
 	put_ldev(mdev);
+}
 
+/* writes on behalf of the partner, or resync writes,
+ * "submitted" by the receiver.
+ */
+void drbd_endio_sec(struct bio *bio, int error)
+{
+	struct drbd_epoch_entry *e = bio->bi_private;
+	struct drbd_conf *mdev = e->mdev;
+	int uptodate = bio_flagged(bio, BIO_UPTODATE);
+	int is_write = bio_data_dir(bio) == WRITE;
+
+	if (error)
+		dev_warn(DEV, "%s: error=%d s=%llus\n",
+				is_write ? "write" : "read", error,
+				(unsigned long long)e->sector);
+	if (!error && !uptodate) {
+		dev_warn(DEV, "%s: setting error to -EIO s=%llus\n",
+				is_write ? "write" : "read",
+				(unsigned long long)e->sector);
+		/* strange behavior of some lower level drivers...
+		 * fail the request by clearing the uptodate flag,
+		 * but do not return any error?! */
+		error = -EIO;
+	}
+
+	if (error)
+		set_bit(__EE_WAS_ERROR, &e->flags);
+
+	bio_put(bio); /* no need for the bio anymore */
+	if (atomic_dec_and_test(&e->pending_bios)) {
+		if (is_write)
+			drbd_endio_write_sec_final(e);
+		else
+			drbd_endio_read_sec_final(e);
+	}
 }
 
 /* read, readA or write requests on R_PRIMARY coming from drbd_make_request
@@ -295,7 +300,34 @@ int w_resync_inactive(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 	return 1; /* Simply ignore this! */
 }
 
-void drbd_csum(struct drbd_conf *mdev, struct crypto_hash *tfm, struct bio *bio, void *digest)
+void drbd_csum_ee(struct drbd_conf *mdev, struct crypto_hash *tfm, struct drbd_epoch_entry *e, void *digest)
+{
+	struct hash_desc desc;
+	struct scatterlist sg;
+	struct page *page = e->pages;
+	struct page *tmp;
+	unsigned len;
+
+	desc.tfm = tfm;
+	desc.flags = 0;
+
+	sg_init_table(&sg, 1);
+	crypto_hash_init(&desc);
+
+	while ((tmp = page_chain_next(page))) {
+		/* all but the last page will be fully used */
+		sg_set_page(&sg, page, PAGE_SIZE, 0);
+		crypto_hash_update(&desc, &sg, sg.length);
+		page = tmp;
+	}
+	/* and now the last, possibly only partially used page */
+	len = e->size & (PAGE_SIZE - 1);
+	sg_set_page(&sg, page, len ?: PAGE_SIZE, 0);
+	crypto_hash_update(&desc, &sg, sg.length);
+	crypto_hash_final(&desc, digest);
+}
+
+void drbd_csum_bio(struct drbd_conf *mdev, struct crypto_hash *tfm, struct bio *bio, void *digest)
 {
 	struct hash_desc desc;
 	struct scatterlist sg;
@@ -329,11 +361,11 @@ static int w_e_send_csum(struct drbd_conf *mdev, struct drbd_work *w, int cancel
 		return 1;
 	}
 
-	if (likely(drbd_bio_uptodate(e->private_bio))) {
+	if (likely((e->flags & EE_WAS_ERROR) == 0)) {
 		digest_size = crypto_hash_digestsize(mdev->csums_tfm);
 		digest = kmalloc(digest_size, GFP_NOIO);
 		if (digest) {
-			drbd_csum(mdev, mdev->csums_tfm, e->private_bio, digest);
+			drbd_csum_ee(mdev, mdev->csums_tfm, e, digest);
 
 			inc_rs_pending(mdev);
 			ok = drbd_send_drequest_csum(mdev,
@@ -369,23 +401,21 @@ static int read_for_csum(struct drbd_conf *mdev, sector_t sector, int size)
 	/* GFP_TRY, because if there is no memory available right now, this may
 	 * be rescheduled for later. It is "only" background resync, after all. */
 	e = drbd_alloc_ee(mdev, DRBD_MAGIC+0xbeef, sector, size, GFP_TRY);
-	if (!e) {
-		put_ldev(mdev);
-		return 2;
-	}
+	if (!e)
+		goto fail;
 
 	spin_lock_irq(&mdev->req_lock);
 	list_add(&e->w.list, &mdev->read_ee);
 	spin_unlock_irq(&mdev->req_lock);
 
-	e->private_bio->bi_end_io = drbd_endio_read_sec;
-	e->private_bio->bi_rw = READ;
 	e->w.cb = w_e_send_csum;
+	if (drbd_submit_ee(mdev, e, READ, DRBD_FAULT_RS_RD) == 0)
+		return 1;
 
-	mdev->read_cnt += size >> 9;
-	drbd_generic_make_request(mdev, DRBD_FAULT_RS_RD, e->private_bio);
-
-	return 1;
+	drbd_free_ee(mdev, e);
+fail:
+	put_ldev(mdev);
+	return 2;
 }
 
 void resync_timer_fn(unsigned long data)
@@ -819,7 +849,7 @@ int drbd_resync_finished(struct drbd_conf *mdev)
 /* helper */
 static void move_to_net_ee_or_free(struct drbd_conf *mdev, struct drbd_epoch_entry *e)
 {
-	if (drbd_bio_has_active_page(e->private_bio)) {
+	if (drbd_ee_has_active_page(e)) {
 		/* This might happen if sendpage() has not finished */
 		spin_lock_irq(&mdev->req_lock);
 		list_add_tail(&e->w.list, &mdev->net_ee);
@@ -845,7 +875,7 @@ int w_e_end_data_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 		return 1;
 	}
 
-	if (likely(drbd_bio_uptodate(e->private_bio))) {
+	if (likely((e->flags & EE_WAS_ERROR) == 0)) {
 		ok = drbd_send_block(mdev, P_DATA_REPLY, e);
 	} else {
 		if (__ratelimit(&drbd_ratelimit_state))
@@ -886,7 +916,7 @@ int w_e_end_rsdata_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 		put_ldev(mdev);
 	}
 
-	if (likely(drbd_bio_uptodate(e->private_bio))) {
+	if (likely((e->flags & EE_WAS_ERROR) == 0)) {
 		if (likely(mdev->state.pdsk >= D_INCONSISTENT)) {
 			inc_rs_pending(mdev);
 			ok = drbd_send_block(mdev, P_RS_DATA_REPLY, e);
@@ -934,7 +964,7 @@ int w_e_end_csum_rs_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 
 	di = (struct digest_info *)(unsigned long)e->block_id;
 
-	if (likely(drbd_bio_uptodate(e->private_bio))) {
+	if (likely((e->flags & EE_WAS_ERROR) == 0)) {
 		/* quick hack to try to avoid a race against reconfiguration.
 		 * a real fix would be much more involved,
 		 * introducing more locking mechanisms */
@@ -944,7 +974,7 @@ int w_e_end_csum_rs_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 			digest = kmalloc(digest_size, GFP_NOIO);
 		}
 		if (digest) {
-			drbd_csum(mdev, mdev->csums_tfm, e->private_bio, digest);
+			drbd_csum_ee(mdev, mdev->csums_tfm, e, digest);
 			eq = !memcmp(digest, di->digest, digest_size);
 			kfree(digest);
 		}
@@ -986,14 +1016,14 @@ int w_e_end_ov_req(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 	if (unlikely(cancel))
 		goto out;
 
-	if (unlikely(!drbd_bio_uptodate(e->private_bio)))
+	if (unlikely((e->flags & EE_WAS_ERROR) != 0))
 		goto out;
 
 	digest_size = crypto_hash_digestsize(mdev->verify_tfm);
 	/* FIXME if this allocation fails, online verify will not terminate! */
 	digest = kmalloc(digest_size, GFP_NOIO);
 	if (digest) {
-		drbd_csum(mdev, mdev->verify_tfm, e->private_bio, digest);
+		drbd_csum_ee(mdev, mdev->verify_tfm, e, digest);
 		inc_rs_pending(mdev);
 		ok = drbd_send_drequest_csum(mdev, e->sector, e->size,
 					     digest, digest_size, P_OV_REPLY);
@@ -1042,11 +1072,11 @@ int w_e_end_ov_reply(struct drbd_conf *mdev, struct drbd_work *w, int cancel)
 
 	di = (struct digest_info *)(unsigned long)e->block_id;
 
-	if (likely(drbd_bio_uptodate(e->private_bio))) {
+	if (likely((e->flags & EE_WAS_ERROR) == 0)) {
 		digest_size = crypto_hash_digestsize(mdev->verify_tfm);
 		digest = kmalloc(digest_size, GFP_NOIO);
 		if (digest) {
-			drbd_csum(mdev, mdev->verify_tfm, e->private_bio, digest);
+			drbd_csum_ee(mdev, mdev->verify_tfm, e, digest);
 
 			D_ASSERT(digest_size == di->digest_size);
 			eq = !memcmp(digest, di->digest, digest_size);

drivers/block/drbd/drbd_wrappers.h

@@ -18,23 +18,9 @@ static inline void drbd_set_my_capacity(struct drbd_conf *mdev,
 
 #define drbd_bio_uptodate(bio) bio_flagged(bio, BIO_UPTODATE)
 
-static inline int drbd_bio_has_active_page(struct bio *bio)
-{
-	struct bio_vec *bvec;
-	int i;
-
-	__bio_for_each_segment(bvec, bio, i, 0) {
-		if (page_count(bvec->bv_page) > 1)
-			return 1;
-	}
-
-	return 0;
-}
-
 /* bi_end_io handlers */
 extern void drbd_md_io_complete(struct bio *bio, int error);
-extern void drbd_endio_read_sec(struct bio *bio, int error);
-extern void drbd_endio_write_sec(struct bio *bio, int error);
+extern void drbd_endio_sec(struct bio *bio, int error);
 extern void drbd_endio_pri(struct bio *bio, int error);
 
 /*