From 18d39ba3ba872581e0f9498eb7ddb902cda53685 Mon Sep 17 00:00:00 2001
From: alex <alex>
Date: Sat, 31 Jul 2004 14:35:46 +0000
Subject: [PATCH] b=4044 r=adilger

- few clients connecting simultaneously might race in mds_lmv_connect().
  just take a sem around code that connects to LMV
---
 lustre/include/linux/obd.h |  1 +
 lustre/mds/handler.c       |  1 +
 lustre/mds/mds_lmv.c       | 15 +++++++++++++--
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/lustre/include/linux/obd.h b/lustre/include/linux/obd.h
index 0279d97..dbcbd69 100644
--- a/lustre/include/linux/obd.h
+++ b/lustre/include/linux/obd.h
@@ -342,6 +342,7 @@ struct mds_obd {
         struct obd_device               *mds_lmv_obd; /* XXX lmv_obd */
         struct obd_export               *mds_lmv_exp; /* XXX lov_exp */
         struct ptlrpc_service           *mds_create_service;
+        struct semaphore                 mds_lmv_sem;
         atomic_t                         mds_real_clients;
         struct obd_uuid                  mds_lmv_uuid;
         struct dentry                   *mds_fids_dir;
diff --git a/lustre/mds/handler.c b/lustre/mds/handler.c
index 035b9fc..a52583b 100644
--- a/lustre/mds/handler.c
+++ b/lustre/mds/handler.c
@@ -2014,6 +2014,7 @@ static int mds_setup(struct obd_device *obd, obd_count len, void *buf)
                         lcfg->lcfg_inlbuf4);
 
         /* we have to know mdsnum before touching underlying fs -bzzz */
+        sema_init(&mds->mds_lmv_sem, 1);
         if (lcfg->lcfg_inllen5 > 0 && lcfg->lcfg_inlbuf5 && 
             strcmp(lcfg->lcfg_inlbuf5, "dumb")) {
                 class_uuid_t uuid;
diff --git a/lustre/mds/mds_lmv.c b/lustre/mds/mds_lmv.c
index 225d55a..da60695 100644
--- a/lustre/mds/mds_lmv.c
+++ b/lustre/mds/mds_lmv.c
@@ -57,12 +57,18 @@ int mds_lmv_connect(struct obd_device *obd, char * lmv_name)
         if (mds->mds_lmv_obd)
                 RETURN(0);
 
+        down(&mds->mds_lmv_sem);
+        if (mds->mds_lmv_obd) {
+                up(&mds->mds_lmv_sem);
+                RETURN(0);
+        }
+
         mds->mds_lmv_obd = class_name2obd(lmv_name);
         if (!mds->mds_lmv_obd) {
                 CERROR("MDS cannot locate LMV %s\n",
                        lmv_name);
                 mds->mds_lmv_obd = ERR_PTR(-ENOTCONN);
-                RETURN(-ENOTCONN);
+                GOTO(err_last, rc = -ENOTCONN);
         }
 
         rc = obd_connect(&conn, mds->mds_lmv_obd, &obd->obd_uuid, OBD_OPT_MDS_CONNECTION);
@@ -70,7 +76,7 @@ int mds_lmv_connect(struct obd_device *obd, char * lmv_name)
                 CERROR("MDS cannot connect to LMV %s (%d)\n",
                        lmv_name, rc);
                 mds->mds_lmv_obd = ERR_PTR(rc);
-                RETURN(rc);
+                GOTO(err_last, rc);
         }
         mds->mds_lmv_exp = class_conn2export(&conn);
         if (mds->mds_lmv_exp == NULL)
@@ -105,6 +111,7 @@ int mds_lmv_connect(struct obd_device *obd, char * lmv_name)
         if (rc)
                 GOTO(err_reg, rc);
 
+        up(&mds->mds_lmv_sem);
 	RETURN(0);
 
 err_reg:
@@ -113,6 +120,8 @@ err_discon:
         obd_disconnect(mds->mds_lmv_exp, 0);
         mds->mds_lmv_exp = NULL;
         mds->mds_lmv_obd = ERR_PTR(rc);
+err_last:
+        up(&mds->mds_lmv_sem);
         RETURN(rc);
 }
 
@@ -135,6 +144,7 @@ int mds_lmv_disconnect(struct obd_device *obd, int flags)
         int rc = 0;
         ENTRY;
 
+        down(&mds->mds_lmv_sem);
         if (!IS_ERR(mds->mds_lmv_obd) && mds->mds_lmv_exp != NULL) {
                 obd_register_observer(mds->mds_lmv_obd, NULL);
 
@@ -148,6 +158,7 @@ int mds_lmv_disconnect(struct obd_device *obd, int flags)
                 mds->mds_lmv_exp = NULL;
                 mds->mds_lmv_obd = NULL;
         }
+        up(&mds->mds_lmv_sem);
 
         RETURN(rc);
 }
-- 
1.8.3.1