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Subject[PATCH v4] fs: umount on symlink leaks mnt count
v4: description corrected
v3: patch inline

Currently umount on symlink blocks following umount:

/vz is separate mount

# ls /vz/ -al | grep test
drwxr-xr-x. 2 root root 4096 Jul 19 01:14 testdir
lrwxrwxrwx. 1 root root 11 Jul 19 01:16 testlink -> /vz/testdir
# umount -l /vz/testlink
umount: /vz/testlink: not mounted (expected)

# lsof /vz
# umount /vz
umount: /vz: device is busy. (unexpected)

In this case mountpoint_last() gets an extra refcount on path->mnt

Signed-off-by: Vasily Averin <vvs@openvz.org>
---
fs/namei.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 985c6f3..9eb787e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2256,9 +2256,10 @@ done:
goto out;
}
path->dentry = dentry;
- path->mnt = mntget(nd->path.mnt);
+ path->mnt = nd->path.mnt;
if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW))
return 1;
+ mntget(path->mnt);
follow_mount(path);
error = 0;
out:
--
1.7.5.4


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