1 files changed, 14 insertions, 6 deletions

diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 09803d0d5207..4c7fee1a5a85 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1086,11 +1086,13 @@ drbd_request_prepare(struct drbd_device *device, struct bio *bio, unsigned long
 
 static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request *req)
 {
+        struct drbd_resource *resource = device->resource;
         const int rw = bio_rw(req->master_bio);
         struct bio_and_error m = { NULL, };
         bool no_remote = false;
+        bool submit_private_bio = false;
 
-        spin_lock_irq(&device->resource->req_lock);
+        spin_lock_irq(&resource->req_lock);
         if (rw == WRITE) {
                 /* This may temporarily give up the req_lock,
                  * but will re-aquire it before it returns here.
@@ -1152,9 +1154,7 @@ static void drbd_send_and_submit(struct drbd_device *device, struct drbd_request
                 /* needs to be marked within the same spinlock */
                 _req_mod(req, TO_BE_SUBMITTED);
                 /* but we need to give up the spinlock to submit */
-                spin_unlock_irq(&device->resource->req_lock);
-                drbd_submit_req_private_bio(req);
-                spin_lock_irq(&device->resource->req_lock);
+                submit_private_bio = true;
         } else if (no_remote) {
 nodata:
                 if (__ratelimit(&drbd_ratelimit_state))
@@ -1167,8 +1167,16 @@ nodata:
 out:
         if (drbd_req_put_completion_ref(req, &m, 1))
                 kref_put(&req->kref, drbd_req_destroy);
-        spin_unlock_irq(&device->resource->req_lock);
-
+        spin_unlock_irq(&resource->req_lock);
+
+        /* Even though above is a kref_put(), this is safe.
+         * As long as we still need to submit our private bio,
+         * we hold a completion ref, and the request cannot disappear.
+         * If however this request did not even have a private bio to submit
+         * (e.g. remote read), req may already be invalid now.
+         * That's why we cannot check on req->private_bio. */
+        if (submit_private_bio)
+                drbd_submit_req_private_bio(req);
         if (m.bio)
                 complete_master_bio(device, &m);
 }