may_umount() needs namespace_sem

otherwise it races with clone_mnt() changing mnt_share/mnt_slaves

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2010-01-16 12:56:08 -05:00
parent 9b6e310211
commit 8ad08d8a0c
1 changed files with 2 additions and 0 deletions

View File

@ -965,10 +965,12 @@ EXPORT_SYMBOL(may_umount_tree);
int may_umount(struct vfsmount *mnt)
{
int ret = 1;
down_read(&namespace_sem);
spin_lock(&vfsmount_lock);
if (propagate_mount_busy(mnt, 2))
ret = 0;
spin_unlock(&vfsmount_lock);
up_read(&namespace_sem);
return ret;
}