ceph: initialize client debugfs outside of monc->mutex (ab434b60) · Commits · 戴 / test

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>

net/ceph/ceph_common.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

net/ceph/mon_client.c

+12 −1

Original line number	Diff line number	Diff line
		@@ -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);
		}

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