From af7c5463396c0073f1ebbf7f07d039e221703a69 Mon Sep 17 00:00:00 2001
From: huanghua <huanghua>
Date: Fri, 13 Oct 2006 09:43:28 +0000
Subject: [PATCH] follow {parent, child} lock order

---
 lustre/mdt/mdt_reint.c | 48 ++++++++++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/lustre/mdt/mdt_reint.c b/lustre/mdt/mdt_reint.c
index f3ff4f4..d089d36 100644
--- a/lustre/mdt/mdt_reint.c
+++ b/lustre/mdt/mdt_reint.c
@@ -468,33 +468,41 @@ static int mdt_reint_link(struct mdt_thread_info *info,
         if (MDT_FAIL_CHECK(OBD_FAIL_MDS_REINT_LINK))
                 RETURN(err_serious(-ENOENT));
 
-        /* step 1: lock the source */
-        lhs = &info->mti_lh[MDT_LH_PARENT];
-        lhs->mlh_mode = LCK_EX;
-        ms = mdt_object_find(info->mti_env, info->mti_mdt, rr->rr_fid1);
-        if (IS_ERR(ms))
-                RETURN(PTR_ERR(ms));
-
-        rc = mdt_object_cr_lock(info, ms, lhs, MDS_INODELOCK_UPDATE);
-        if (rc != 0)
-                GOTO(out_unlock_source, rc);
+        if (rr->rr_name[0] == 0) {
+                /* MDT holding name ask us to add ref. */
+                lhs = &info->mti_lh[MDT_LH_CHILD];
+                lhs->mlh_mode = LCK_EX;
+                ms = mdt_object_find_lock(info, rr->rr_fid2, lhs,
+                                          MDS_INODELOCK_UPDATE);
+                if (IS_ERR(ms))
+                        RETURN(PTR_ERR(ms));
 
-        if (strlen(rr->rr_name) == 0) {
-                /* MDT holding name ask to add ref. */
                 mdt_set_capainfo(info, 0, rr->rr_fid1, BYPASS_CAPA);
                 rc = mo_ref_add(info->mti_env, mdt_object_child(ms));
-                GOTO(out_unlock_source, rc);
+                mdt_object_unlock_put(info, ms, lhs, rc);
+                RETURN(rc);
         }
-        
-        /*step 2: find & lock the target parent dir*/
-        lhp = &info->mti_lh[MDT_LH_CHILD];
+
+        /* step 1: find & lock the target parent dir */
+        lhp = &info->mti_lh[MDT_LH_PARENT];
         lhp->mlh_mode = LCK_EX;
         mp = mdt_object_find_lock(info, rr->rr_fid2, lhp,
                                   MDS_INODELOCK_UPDATE);
         if (IS_ERR(mp))
-                GOTO(out_unlock_source, rc = PTR_ERR(mp));
+                RETURN(PTR_ERR(mp));
 
-        /* step 4: link it */
+        /* step 2: find & lock the source */
+        lhs = &info->mti_lh[MDT_LH_CHILD];
+        lhs->mlh_mode = LCK_EX;
+        ms = mdt_object_find(info->mti_env, info->mti_mdt, rr->rr_fid1);
+        if (IS_ERR(ms))
+                GOTO(out_unlock_parent, rc = PTR_ERR(ms));
+
+        rc = mdt_object_cr_lock(info, ms, lhs, MDS_INODELOCK_UPDATE);
+        if (rc != 0)
+                GOTO(out_unlock_source, rc);
+
+        /* step 3: link it */
         mdt_fail_write(info->mti_env, info->mti_mdt->mdt_bottom,
                        OBD_FAIL_MDS_REINT_LINK_WRITE);
 
@@ -502,10 +510,10 @@ static int mdt_reint_link(struct mdt_thread_info *info,
                       mdt_object_child(ms), rr->rr_name, ma);
 
         EXIT;
-
-        mdt_object_unlock_put(info, mp, lhp, rc);
 out_unlock_source:
         mdt_object_unlock_put(info, ms, lhs, rc);
+out_unlock_parent:
+        mdt_object_unlock_put(info, mp, lhp, rc);
         return rc;
 }
 
-- 
1.8.3.1