btrfs-progs: print errno string when /dev/btrfs-control open fails

Of recently and intermittently I am seeing open fail
for /dev/btrfs-control (btrfs is loaded), and there are no
dmesg errors, this may not be a complete help in digging
this issue but something which is necessary.
Thanks

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/utils.c b/utils.c
index cfb6116..7b028a7 100644 (file)
--- a/utils.c
+++ b/utils.c
@@ -1024,7 +1024,8 @@ void btrfs_register_one_device(char *fname)
        fd = open("/dev/btrfs-control", O_RDONLY);
        if (fd < 0) {
                fprintf(stderr, "failed to open /dev/btrfs-control "
-                       "skipping device registration\n");
+                       "skipping device registration: %s\n",
+                       strerror(errno));
                return;
        }
        strncpy(args.name, fname, BTRFS_PATH_NAME_MAX);