status: rmdirfd: try harder to remove mount points

The previous patch left a mount point in /run/crun which could not be
removed, we should try harder to remove directories failing with EBUSY
as we do in create_missing_devs().

This patch also fixes the issue described in the previous commit
("status: rmdirfd: try harder to remove mount points").

Fixes: 523eed3 ("linux: add new fallback when mount fails with EBUSY")
Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>

src/libcrun/status.c

@@ -24,6 +24,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <yajl/yajl_tree.h>
+#include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <dirent.h>
@@ -485,7 +486,20 @@ rmdirfd (const char *namedir, int fd, libcrun_error_t *err)
       ret = unlinkat (dirfd (d), de->d_name, 0);
       if (ret < 0)
         {
+        retry_unlink:
           ret = unlinkat (dirfd (d), de->d_name, AT_REMOVEDIR);
+          if (ret < 0 && errno == EBUSY)
+            {
+              cleanup_close int tfd = openat (dirfd (d), de->d_name, O_CLOEXEC | O_PATH | O_NOFOLLOW);
+              if (tfd >= 0)
+                {
+                  proc_fd_path_t procpath;
+
+                  get_proc_self_fd_path (procpath, tfd);
+                  if (umount2 (procpath, MNT_DETACH) == 0)
+                    goto retry_unlink;
+                }
+            }
           if (ret < 0 && errno == ENOTEMPTY)
             {
               cleanup_close int cfd = -1;