From: Rafał Miłecki <rafal@milecki.pl>
Date: Wed, 21 Feb 2018 12:32:16 +0000 (+0100)
Subject: mount: try lazy unmount if normal one fails
X-Git-Url: http://git.openwrt.org/?p=project%2Fmountd.git;a=commitdiff_plain;h=97da4edeb9eb3b26c9843d3a5ab605e7bcf2573f

mount: try lazy unmount if normal one fails

If umount call fails (e.g. because of some application accessing old
path) the only chance of getting mount entry cleaned is receiving autofs
expire packet. This isn't fully reliable:
1) Sometimes expire can happen before closing all handles. In such case
   a second unmount try will fail as well and there won't be a next one.
2) Expire happens after specified timeout. If device reappears quickly
   (e.g. due to being replugged or USB controller restart) it may be
   worth having old mount cleaned up earlier for better user experience.

This problem can be easily handled by using MNT_DETACH (lazy) umount as
a fallback.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---

diff --git a/mount.c b/mount.c
index ddcd5b3..3994149 100644
--- a/mount.c
+++ b/mount.c
@@ -604,6 +604,7 @@ static int mount_dev_del(struct mount *mount)
 		log_printf("device %s has disappeared ... unmounting %s\n", mount->dev, tmp);
 		if (umount(tmp)) {
 			err = -errno;
+			umount2(tmp, MNT_DETACH);
 		}
 		rmdir(tmp);
 		mount_dump_uci_state();