libceph: no more kick_requests() race

Since we no longer drop the request mutex between registering and
mapping an osd request in ceph_osdc_start_request(), there is no
chance of a race with kick_requests().

We can now therefore map and send the new request unconditionally
(but we'll issue a warning should it ever occur).

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-off-by: Sage Weil <sage@inktank.com>

1 files changed, 15 insertions, 22 deletions

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index f9276cb26aa2..3723a7f16afd 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1779,31 +1779,24 @@ int ceph_osdc_start_request(struct ceph_osd_client *osdc,
 
         down_read(&osdc->map_sem);
         mutex_lock(&osdc->request_mutex);
-        /*
-         * a racing kick_requests() may have sent the message for us
-         * while we dropped request_mutex above, so only send now if
-         * the request still han't been touched yet.
-         */
         __register_request(osdc, req);
-        if (req->r_sent == 0) {
-                rc = __map_request(osdc, req, 0);
-                if (rc < 0) {
-                        if (nofail) {
-                                dout("osdc_start_request failed map, "
-                                     " will retry %lld\n", req->r_tid);
-                                rc = 0;
-                        }
-                        goto out_unlock;
-                }
-                if (req->r_osd == NULL) {
-                        dout("send_request %p no up osds in pg\n", req);
-                        ceph_monc_request_next_osdmap(&osdc->client->monc);
-                } else {
-                        __send_request(osdc, req);
+        WARN_ON(req->r_sent);
+        rc = __map_request(osdc, req, 0);
+        if (rc < 0) {
+                if (nofail) {
+                        dout("osdc_start_request failed map, "
+                                " will retry %lld\n", req->r_tid);
+                        rc = 0;
                 }
-                rc = 0;
+                goto out_unlock;
         }
-
+        if (req->r_osd == NULL) {
+                dout("send_request %p no up osds in pg\n", req);
+                ceph_monc_request_next_osdmap(&osdc->client->monc);
+        } else {
+                __send_request(osdc, req);
+        }
+        rc = 0;
 out_unlock:
         mutex_unlock(&osdc->request_mutex);
         up_read(&osdc->map_sem);