(lock_superlock): Synchronize NFS cache.

1 files changed, 25 insertions, 0 deletions

diff --git a/src/filelock.c b/src/filelock.c
index 52349ffa872..48d1f0f758b 100644
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -37,6 +37,23 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #include <paths.h>
 #include "buffer.h"
 
+#ifdef SYSV_SYSTEM_DIR
+#include <dirent.h>
+#else /* not SYSV_SYSTEM_DIR */
+#ifdef NONSYSTEM_DIR_LIBRARY
+#include "ndir.h"
+#else /* not NONSYSTEM_DIR_LIBRARY */
+#ifdef MSDOS
+#include <dirent.h>
+#else
+#include <sys/dir.h>
+#endif
+#endif /* not NONSYSTEM_DIR_LIBRARY */
+#ifndef MSDOS
+extern DIR *opendir ();
+#endif /* not MSDOS */
+#endif /* not SYSV_SYSTEM_DIR */
+
 extern int errno;
 
 extern char *egetenv ();
@@ -325,6 +342,7 @@ lock_superlock (lfname)
      char *lfname;
 {
   register int i, fd;
+  DIR *lockdir;
 
   for (i = -20; i < 0 && (fd = open (superlock_path,
                                      O_WRONLY | O_EXCL | O_CREAT, 0666)) < 0;
@@ -332,6 +350,13 @@ lock_superlock (lfname)
     {
       if (errno != EEXIST)
         return;
+
+      /* This seems to be necessary to prevent Emacs from hanging when the
+         competing process has already deleted the superlock, but it's still
+         in the NFS cache.  So we force NFS to synchronize the cache.  */
+      if (lockdir = opendir (lock_path))
+        closedir (lockdir);
+
       sleep (1);
     }
   if (fd >= 0)