ceph: initialize client debugfs outside of monc->mutex

Initializing debufs under monc->mutex introduces a lock dependency for
sb->s_type->i_mutex_key, which (combined with several other dependencies)
leads to an annoying lockdep warning.  There's no particular reason to do
the debugfs setup under this lock, so move it out.

It used to be the case that our first monmap could come from the OSD; that
is no longer the case with recent servers, so we will reliably set up the
client entry during the initial authentication.

We don't have to worry about racing with debugfs teardown by
ceph_debugfs_client_cleanup() because ceph_destroy_client() calls
ceph_msgr_flush() first, which will wait for the message dispatch work
to complete (and the debugfs init to complete).

Fixes: #1940
Signed-off-by: Sage Weil <sage@newdream.net>

diff --git a/net/ceph/ceph_common.c b/net/ceph/ceph_common.c
index 97f70e50ad3bb4ed806534fbc74d8a5230000acf..761ad9d6cc3b12fc4d6d8c10022e4c877559f5c8 100644 (file)
--- a/net/ceph/ceph_common.c
+++ b/net/ceph/ceph_common.c
@@ -85,8 +85,6 @@ int ceph_check_fsid(struct ceph_client *client, struct ceph_fsid *fsid)
        } else {
                pr_info("client%lld fsid %pU\n", ceph_client_id(client), fsid);
                memcpy(&client->fsid, fsid, sizeof(*fsid));
-               ceph_debugfs_client_init(client);
-               client->have_fsid = true;
        }
        return 0;
 }

diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index 0b62deae42bd88930f408e0473f13c11b0c252bd..1845cde2622740162fdb5e42a7663072d072ebf8 100644 (file)
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -8,8 +8,8 @@
 
 #include <linux/ceph/mon_client.h>
 #include <linux/ceph/libceph.h>
+#include <linux/ceph/debugfs.h>
 #include <linux/ceph/decode.h>
-
 #include <linux/ceph/auth.h>
 
 /*
@@ -340,8 +340,19 @@ static void ceph_monc_handle_map(struct ceph_mon_client *monc,
        client->monc.monmap = monmap;
        kfree(old);
 
+       if (!client->have_fsid) {
+               client->have_fsid = true;
+               mutex_unlock(&monc->mutex);
+               /*
+                * do debugfs initialization without mutex to avoid
+                * creating a locking dependency
+                */
+               ceph_debugfs_client_init(client);
+               goto out_unlocked;
+       }
 out:
        mutex_unlock(&monc->mutex);
+out_unlocked:
        wake_up_all(&client->auth_wq);
 }