LU-1187 mdd: a few missing stuff in MD stack for DNE.

[fs/lustre-release.git] / lustre / lmv / lmv_obd.c

diff --git a/lustre/lmv/lmv_obd.c b/lustre/lmv/lmv_obd.c
index fa3e183..52055c6 100644 (file)
--- a/lustre/lmv/lmv_obd.c
+++ b/lustre/lmv/lmv_obd.c
@@ -1989,7 +1989,7 @@ static int lmv_unlink(struct obd_export *exp, struct md_op_data *op_data,
        struct lmv_obd          *lmv = &obd->u.lmv;
        struct lmv_tgt_desc     *tgt = NULL;
        struct mdt_body         *body;
-       int                      rc;
+       int                     rc;
        ENTRY;
 
        rc = lmv_check_connect(obd);
@@ -2036,14 +2036,37 @@ retry:
        body = req_capsule_server_get(&(*request)->rq_pill, &RMF_MDT_BODY);
        if (body == NULL)
                RETURN(-EPROTO);
-       /*
-        * Not cross-ref case, just get out of here.
-        */
+
+       /* Not cross-ref case, just get out of here. */
        if (likely(!(body->valid & OBD_MD_MDS)))
                RETURN(0);
 
-       /* Clearly this is a remote object, try remote MDT */
+       CDEBUG(D_INODE, "%s: try unlink to another MDT for "DFID"\n",
+              exp->exp_obd->obd_name, PFID(&body->fid1));
+
+       /* This is a remote object, try remote MDT, Note: it may
+        * try more than 1 time here, Considering following case
+        * /mnt/lustre is root on MDT0, remote1 is on MDT1
+        * 1. Initially A does not know where remote1 is, it send
+        *    unlink RPC to MDT0, MDT0 return -EREMOTE, it will
+        *    resend unlink RPC to MDT1 (retry 1st time).
+        *
+        * 2. During the unlink RPC in flight,
+        *    client B mv /mnt/lustre/remote1 /mnt/lustre/remote2
+        *    and create new remote1, but on MDT0
+        *
+        * 3. MDT1 get unlink RPC(from A), then do remote lock on
+        *    /mnt/lustre, then lookup get fid of remote1, and find
+        *    it is remote dir again, and replay -EREMOTE again.
+        *
+        * 4. Then A will resend unlink RPC to MDT0. (retry 2nd times).
+        *
+        * In theory, it might try unlimited time here, but it should
+        * be very rare case.  */
        op_data->op_fid2 = body->fid1;
+       ptlrpc_req_finished(*request);
+       *request = NULL;
+
        goto retry;
 }