From fe4b2c9dce0636641462799cf8a846894aa79647 Mon Sep 17 00:00:00 2001
From: yury <yury>
Date: Mon, 16 Aug 2004 08:49:49 +0000
Subject: [PATCH] - fixes, comments in mds_lock_mode_for_dir() about protecting
 against possible splitting.

---
 lustre/mds/handler.c   | 18 +++++++++++++-----
 lustre/mds/mds_reint.c |  2 +-
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/lustre/mds/handler.c b/lustre/mds/handler.c
index 819acf5..cdde8cf 100644
--- a/lustre/mds/handler.c
+++ b/lustre/mds/handler.c
@@ -161,7 +161,7 @@ static int mds_sendpage(struct ptlrpc_request *req, struct file *file,
 }
 
 int mds_lock_mode_for_dir(struct obd_device *obd,
-                              struct dentry *dentry, int mode)
+                          struct dentry *dentry, int mode)
 {
         int ret_mode, split;
 
@@ -180,13 +180,24 @@ int mds_lock_mode_for_dir(struct obd_device *obd,
          *    type of access (lookup/modify/split) - LCK_EX -bzzz */
 
         split = mds_splitting_expected(obd, dentry);
-        if (split == MDS_NO_SPLITTABLE || split == MDS_NO_SPLIT_EXPECTED) {
+        
+        /* it is important to check here only for MDS_NO_SPLITTABLE.
+         * The reason is that MDS_NO_SPLITTABLE means dir is not splittable
+         * in principle and another thread will not split it on the quiet. 
+         * But if we have MDS_NO_SPLIT_EXPECTED, this means, that dir may be 
+         * splitted anytime, but not now (forcurrent thread) and we should 
+         * consider that it can  happen soon and go that branch which can yield 
+         * LCK_EX to protect from possible splitting. */
+        if (split == MDS_NO_SPLITTABLE) {
                 /* this inode won't be splitted. so we need not to protect from
                  * just flush client's cache on modification */
                 ret_mode = 0;
                 if (mode == LCK_PW)
                         ret_mode = LCK_CW;
         } else {
+                if (mode == LCK_EX)
+                        return LCK_EX;
+                
                 if (mode == LCK_PR) {
                         ret_mode = LCK_CR;
                 } else if (mode == LCK_PW) {
@@ -206,9 +217,6 @@ int mds_lock_mode_for_dir(struct obd_device *obd,
                                        (unsigned) dentry->d_inode->i_generation);
                                 ret_mode = LCK_EX;
                         }
-                } else {
-                        CWARN("unexpected lock mode %d\n", mode);
-                        ret_mode = LCK_EX;
                 }
         }
         return ret_mode;
diff --git a/lustre/mds/mds_reint.c b/lustre/mds/mds_reint.c
index cb7524f..1b88793 100644
--- a/lustre/mds/mds_reint.c
+++ b/lustre/mds/mds_reint.c
@@ -2153,7 +2153,7 @@ static int mds_reint_link(struct mds_update_record *rec, int offset,
 #ifdef S_PDIROPS
         if (IS_PDIROPS(de_tgt_dir->d_inode)) {
                 int flags = 0;
-                update_mode = mds_lock_mode_for_dir(obd, de_tgt_dir, LCK_PW);
+                update_mode = mds_lock_mode_for_dir(obd, de_tgt_dir, LCK_EX);
                 if (update_mode) {
                         rc = ldlm_cli_enqueue(NULL, NULL, obd->obd_namespace,
                                               tgt_dir_res_id, LDLM_IBITS,
-- 
1.8.3.1