rbd: udevadm settle before unmap

udev runs blkid on device close, and other such nonsense that can
make unmap fail with EBUSY.  Settle before we unmap to avoid this if
possible.  See #4183.

Closes: #4186
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

diff --git a/src/rbd.cc b/src/rbd.cc
index d4b2d8b911878c206e43f9998eab54c4d2da1317..02a793bf64ba03e680e22f84d82f92bf25b63ee7 100644 (file)
--- a/src/rbd.cc
+++ b/src/rbd.cc
@@ -1664,6 +1664,18 @@ static int do_kernel_rm(const char *dev)
   if (r < 0)
     return r;
 
+  // let udevadm do its job *before* we try to unmap
+  if (udevadm_settle) {
+    r = system("/sbin/udevadm settle");
+    if (r) {
+      if (r < 0)
+        cerr << "rbd: error executing udevadm as shell command!" << std::endl;
+      else
+        cerr << "rbd: '/sbin/udevadm settle' failed! (" << r << ")" <<std::endl;
+      // ignore the error, though.
+    }
+  }
+
   int fd = open("/sys/bus/rbd/remove", O_WRONLY);
   if (fd < 0) {
     return -errno;