[dm-devel] [PATCH 2/3] libmutipath: don't close fd on dm_lib_release

[Benjamin Marzinski]

If dm_hold_control_open() isn't set, when dm_lib_release() is called, it
will close the control fd. The control fd will get re-opened on the next
dm_task_run() call, but if there is a dm_task_run() call already
in progress in another thread, it can fail. Since many of the
device-mapper callouts happen with the vecs lock held, this wasn't too
noticeable, but there is code that calls dm_task_run() without the
vecs lock held, notably the dmevent waiter code.

Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
---
 libmultipath/devmapper.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index bed8ddc6..d96472fe 100644
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -254,6 +254,7 @@ void libmp_dm_init(void)
 	memcpy(conf->version, version, sizeof(version));
 	put_multipath_config(conf);
 	dm_init(verbosity);
+	dm_hold_control_dev(1);
 	dm_udev_set_sync_support(libmp_dm_udev_sync);
 }
 
-- 
2.17.2