drbd: register peer requests on read_ee early

This change “drbd: register peer requests on read_ee early” (commit c5a2c15) in Linux kernel is authored by Lars Ellenberg <lars.ellenberg [at] linbit.com> on Thu May 8 10:08:05 2014 +0200.

Description of "drbd: register peer requests on read_ee early"

The change “drbd: register peer requests on read_ee early” introduces changes as follows.

drbd: register peer requests on read_ee early

Initialize peer_request with timestamp and proper empty list head.
Add peer_request to list early, so debugfs can find this request and
report it as "preparing", even if we sleep before we actually submit it.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

Linux kernel releases containing commit c5a2c15

The Linux kernel releases containing this commit are as follows.

Linux kernel code changes from "drbd: register peer requests on read_ee early"

There are 25 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/block/drbd/drbd_receiver.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)
 
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 2f67dc03d403..42e383513bfc 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -362,17 +362,14 @@ drbd_alloc_peer_req(struct drbd_peer_device *peer_device, u64 id, sector_t secto
 			goto fail;
 	}
 
+	memset(peer_req, 0, sizeof(*peer_req));
+	INIT_LIST_HEAD(&peer_req->w.list);
 	drbd_clear_interval(&peer_req->i);
 	peer_req->i.size = data_size;
 	peer_req->i.sector = sector;
-	peer_req->i.local = false;
-	peer_req->i.waiting = false;
-
-	peer_req->epoch = NULL;
+	peer_req->submit_jif = jiffies;
 	peer_req->peer_device = peer_device;
 	peer_req->pages = page;
-	atomic_set(&peer_req->pending_bios, 0);
-	peer_req->flags = 0;
 	/*
 	 * The block_id is opaque to the receiver.  It is not endianness
 	 * converted, and sent back to the sender unchanged.
@@ -2668,6 +2665,15 @@ static int receive_DataRequest(struct drbd_connection *connection, struct packet
 	 * we would also throttle its application reads.
 	 * In that case, throttling is done on the SyncTarget only.
 	 */
+
+	/* Even though this may be a resync request, we do add to "read_ee";
+	 * "sync_ee" is only used for resync WRITEs.
+	 * Add to list early, so debugfs can find this request
+	 * even if we have to sleep below. */
+	spin_lock_irq(&device->resource->req_lock);
+	list_add_tail(&peer_req->w.list, &device->read_ee);
+	spin_unlock_irq(&device->resource->req_lock);
+
 	if (device->state.peer != R_PRIMARY
 	&& drbd_rs_should_slow_down(device, sector, false))
 		schedule_timeout_uninterruptible(HZ/10);
@@ -2679,21 +2685,18 @@ static int receive_DataRequest(struct drbd_connection *connection, struct packet
 
 submit:
 	inc_unacked(device);
-	spin_lock_irq(&device->resource->req_lock);
-	list_add_tail(&peer_req->w.list, &device->read_ee);
-	spin_unlock_irq(&device->resource->req_lock);
-
 	if (drbd_submit_peer_request(device, peer_req, READ, fault_type) == 0)
 		return 0;
 
 	/* don't care for the reason here */
 	drbd_err(device, "submit failed, triggering re-connect\n");
+
+out_free_e:
 	spin_lock_irq(&device->resource->req_lock);
 	list_del(&peer_req->w.list);
 	spin_unlock_irq(&device->resource->req_lock);
 	/* no drbd_rs_complete_io(), we are dropping the connection anyways */
 
-out_free_e:
 	put_ldev(device);
 	drbd_free_peer_req(device, peer_req);
 	return -EIO;

The commit for this change in Linux stable tree is c5a2c15 (patch).

Last modified: 2020/02/10