From: Eric Mei <eric.mei@oracle.com>
Date: Fri, 4 Jun 2010 23:21:14 +0000 (-0600)
Subject: b=22520 make sure cl_inode_fini() to destroy the cl_object.
X-Git-Tag: v1_10_0_44~28
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=4aae7fae328fbb395601a8d323b831a3f12c7206

b=22520 make sure cl_inode_fini() to destroy the cl_object.

r=rread
r=wangdi
---

diff --git a/lustre/lclient/lcommon_cl.c b/lustre/lclient/lcommon_cl.c
index a593621..580226f 100644
--- a/lustre/lclient/lcommon_cl.c
+++ b/lustre/lclient/lcommon_cl.c
@@ -1189,6 +1189,41 @@ int cl_inode_init(struct inode *inode, struct lustre_md *md)
         return result;
 }
 
+/**
+ * Wait for others drop their references of the object at first, then we drop
+ * the last one, which will lead to the object be destroyed immediately.
+ * Must be called after cl_object_kill() against this object.
+ *
+ * The reason we want to do this is: destroying top object will wait for sub
+ * objects being destroyed first, so we can't let bottom layer (e.g. from ASTs)
+ * to initiate top object destroying which may deadlock. See bz22520.
+ */
+static void cl_object_put_last(struct lu_env *env, struct cl_object *obj)
+{
+        struct lu_object_header *header = obj->co_lu.lo_header;
+        struct lu_site          *site;
+        cfs_waitlink_t           waiter;
+
+        if (unlikely(cfs_atomic_read(&header->loh_ref) != 1)) {
+                site = obj->co_lu.lo_dev->ld_site;
+
+                cfs_waitlink_init(&waiter);
+                cfs_waitq_add(&site->ls_marche_funebre, &waiter);
+
+                while (1) {
+                        cfs_set_current_state(CFS_TASK_UNINT);
+                        if (cfs_atomic_read(&header->loh_ref) == 1)
+                                break;
+                        cfs_waitq_wait(&waiter, CFS_TASK_UNINT);
+                }
+
+                cfs_set_current_state(CFS_TASK_RUNNING);
+                cfs_waitq_del(&site->ls_marche_funebre, &waiter);
+        }
+
+        cl_object_put(env, obj);
+}
+
 void cl_inode_fini(struct inode *inode)
 {
         struct lu_env           *env;
@@ -1216,7 +1251,7 @@ void cl_inode_fini(struct inode *inode)
                  */
                 cl_object_kill(env, clob);
                 lu_object_ref_del(&clob->co_lu, "inode", inode);
-                cl_object_put(env, clob);
+                cl_object_put_last(env, clob);
                 lli->lli_clob = NULL;
                 if (emergency) {
                         cl_env_unplant(ccc_inode_fini_env, &refcheck);
diff --git a/lustre/obdclass/lu_object.c b/lustre/obdclass/lu_object.c
index fe5ee83..a0f93ec 100644
--- a/lustre/obdclass/lu_object.c
+++ b/lustre/obdclass/lu_object.c
@@ -113,6 +113,12 @@ void lu_object_put(const struct lu_env *env, struct lu_object *o)
                         -- site->ls_total;
                         kill_it = 1;
                 }
+        } else if (lu_object_is_dying(top)) {
+                /*
+                 * somebody may be waiting for this, currently only used
+                 * for cl_object, see cl_object_put_last().
+                 */
+                cfs_waitq_broadcast(&site->ls_marche_funebre);
         }
         cfs_write_unlock(&site->ls_guard);
         if (kill_it)