Changeset 840 for trunk/server/lib/tdb/common/io.c

Timestamp:

Feb 4, 2014, 4:58:40 PM (12 years ago)

Author:

Silvan Scherrer

Message:

Samba Server 3.6: adjust locking code

File:

• trunk/server/lib/tdb/common/io.c (modified) (1 diff)

trunk/server/lib/tdb/common/io.c

@@ -92 +92 @@
 
 #ifdef __OS2__
-        // YD we must upgrade read locks to write locks (exclusive), otherwise
+        // YD we must upgrade read locks to write locks (exclusive), as otherwise
         // the owner (us) is not allowed to write to the file (different from unix)
         // if a wider previous lock is in effect, we cannot write lock our segment
         // (e.g. a lock_upgrade locks all the file), so we hope the previous lock 
         // is a write lock: do not wait for lock.
-        int upgradeLockRC = tdb_brlock( tdb, F_WRLCK, off, len, F_SETLK);
+        // so this is what we try here:
+        // 1. add a write lock and see if it works
+        // 2. if the write lock wasn't set, we try to unlock the segment
+        //    first and add the write lock afterwards 
+        int upgradeLockRC = tdb_brlock(tdb, F_WRLCK, off, len, TDB_LOCK_NOWAIT);
+        if (upgradeLockRC != 0) {
+                tdb_brunlock(tdb, F_RDLCK, off, len);
+                int upgradeLockRC = tdb_brlock(tdb, F_WRLCK, off, len, TDB_LOCK_NOWAIT);
+        }
         TDB_LOG((tdb, TDB_DEBUG_TRACE,"upgrading lock at %d len=%d "
                 "before writing %s (rc=%d).\n", off, len,