libceph: protect osdc->osd_lru list with a spinlock

OSD client is getting moved from the big per-client lock to a set of
per-session locks.  The big rwlock would only be held for read most of
the time, so a global osdc->osd_lru needs additional protection.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

2 files changed, 19 insertions, 11 deletions

diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 2415dc0cb008..486d681694c4 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -224,6 +224,7 @@ struct ceph_osd_client {
         struct mutex           request_mutex;
         struct rb_root         osds;          /* osds */
         struct list_head       osd_lru;       /* idle osds */
+        spinlock_t             osd_lru_lock;
         u64                    last_tid;      /* tid of last request */
         struct rb_root         requests;      /* pending requests */
         struct list_head       req_lru;       /* in-flight lru */
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index b6950c2c6cc4..d1c8e06f1261 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1101,31 +1101,37 @@ static void remove_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd)
         }
 }
 
-static void __move_osd_to_lru(struct ceph_osd_client *osdc,
-                              struct ceph_osd *osd)
+static void __move_osd_to_lru(struct ceph_osd *osd)
 {
-        dout("%s %p\n", __func__, osd);
+        struct ceph_osd_client *osdc = osd->o_osdc;
+
+        dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);
         BUG_ON(!list_empty(&osd->o_osd_lru));
 
+        spin_lock(&osdc->osd_lru_lock);
         list_add_tail(&osd->o_osd_lru, &osdc->osd_lru);
+        spin_unlock(&osdc->osd_lru_lock);
+
         osd->lru_ttl = jiffies + osdc->client->options->osd_idle_ttl;
 }
 
-static void maybe_move_osd_to_lru(struct ceph_osd_client *osdc,
-                                  struct ceph_osd *osd)
+static void maybe_move_osd_to_lru(struct ceph_osd *osd)
 {
-        dout("%s %p\n", __func__, osd);
-
         if (list_empty(&osd->o_requests) &&
             list_empty(&osd->o_linger_requests))
-                __move_osd_to_lru(osdc, osd);
+                __move_osd_to_lru(osd);
 }
 
 static void __remove_osd_from_lru(struct ceph_osd *osd)
 {
-        dout("__remove_osd_from_lru %p\n", osd);
+        struct ceph_osd_client *osdc = osd->o_osdc;
+
+        dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);
+
+        spin_lock(&osdc->osd_lru_lock);
         if (!list_empty(&osd->o_osd_lru))
                 list_del_init(&osd->o_osd_lru);
+        spin_unlock(&osdc->osd_lru_lock);
 }
 
 /*
@@ -1199,7 +1205,7 @@ static void __unregister_request(struct ceph_osd_client *osdc,
                 ceph_msg_revoke(req->r_request);
 
                 list_del_init(&req->r_osd_item);
-                maybe_move_osd_to_lru(osdc, req->r_osd);
+                maybe_move_osd_to_lru(req->r_osd);
                 if (list_empty(&req->r_linger_osd_item))
                         req->r_osd = NULL;
         }
@@ -1248,7 +1254,7 @@ static void __unregister_linger_request(struct ceph_osd_client *osdc,
 
         if (req->r_osd) {
                 list_del_init(&req->r_linger_osd_item);
-                maybe_move_osd_to_lru(osdc, req->r_osd);
+                maybe_move_osd_to_lru(req->r_osd);
                 if (list_empty(&req->r_osd_item))
                         req->r_osd = NULL;
         }
@@ -2792,6 +2798,7 @@ int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
         osdc->last_tid = 0;
         osdc->osds = RB_ROOT;
         INIT_LIST_HEAD(&osdc->osd_lru);
+        spin_lock_init(&osdc->osd_lru_lock);
         osdc->requests = RB_ROOT;
         INIT_LIST_HEAD(&osdc->req_lru);
         INIT_LIST_HEAD(&osdc->req_unsent);