r24642: prevent recursion with fetch_locked

add a note about server_id exists checking
(This used to be commit dd951b983c0cde2dd54c5370dc8d6440509b0559)

diff --git a/source4/ntvfs/common/brlock_tdb.c b/source4/ntvfs/common/brlock_tdb.c
index 25a0a040a58ac2df46ed79e66e0ecc0d7a74068a..0bca9d2590a8cd83e8e718418e1130ea950deaee 100644 (file)
--- a/source4/ntvfs/common/brlock_tdb.c
+++ b/source4/ntvfs/common/brlock_tdb.c
@@ -135,9 +135,12 @@ static BOOL brl_tdb_same_context(struct lock_context *ctx1, struct lock_context
 
 /*
   see if lck1 and lck2 overlap
+
+  lck1 is the existing lock. lck2 is the new lock we are 
+  looking at adding
 */
 static BOOL brl_tdb_overlap(struct lock_struct *lck1, 
-                       struct lock_struct *lck2)
+                           struct lock_struct *lck2)
 {
        /* this extra check is not redundent - it copes with locks
           that go beyond the end of 64 bit file space */
@@ -151,6 +154,15 @@ static BOOL brl_tdb_overlap(struct lock_struct *lck1,
            lck2->start >= (lck1->start+lck1->size)) {
                return False;
        }
+
+       /* we have a conflict. Now check to see if lck1 really still
+        * exists, which involves checking if the process still
+        * exists. We leave this test to last as its the most
+        * expensive test, especially when we are clustered */
+       /* TODO: need to do this via a server_id_exists() call, which
+        * hasn't been written yet. When clustered this will need to
+        * call into ctdb */
+
        return True;
 } 
 
@@ -283,14 +295,6 @@ static NTSTATUS brl_tdb_lock(struct brl_context *brl,
        NTSTATUS status;
        struct db_record *rec = NULL;
 
-       kbuf.dptr = brlh->key.data;
-       kbuf.dsize = brlh->key.length;
-
-       rec = brl->db->fetch_locked(brl->db, brl, kbuf);
-       if (rec == NULL) {
-               return NT_STATUS_INTERNAL_DB_CORRUPTION;
-       }
-
        /* if this is a pending lock, then with the chainlock held we
           try to get the real lock. If we succeed then we don't need
           to make it pending. This prevents a possible race condition
@@ -305,11 +309,19 @@ static NTSTATUS brl_tdb_lock(struct brl_context *brl,
                brlh->last_lock = lock;
 
                if (NT_STATUS_IS_OK(status)) {
-                       talloc_free(rec);
                        return NT_STATUS_OK;
                }
        }
 
+       kbuf.dptr = brlh->key.data;
+       kbuf.dsize = brlh->key.length;
+
+       rec = brl->db->fetch_locked(brl->db, brl, kbuf);
+       if (rec == NULL) {
+               return NT_STATUS_INTERNAL_DB_CORRUPTION;
+       }
+
+
        dbuf = rec->value;
 
        lock.context.smbpid = smbpid;