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mnt: Update detach_mounts to leave mounts connected 

Now that it is possible to lazily unmount an entire mount tree and
leave the individual mounts connected to each other add a new flag
UMOUNT_CONNECTED to umount_tree to force this behavior and use
this flag in detach_mounts.

This closes a bug where the deletion of a file or directory could
trigger an unmount and reveal data under a mount point.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2015-04-01 18:30:06 -05:00
parent f53e579751
commit e0c9c0afd2
1 changed files with 6 additions and 2 deletions
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8
fs/namespace.c
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@ -1348,6 +1348,7 @@ static inline void namespace_lock(void)
enum umount_tree_flags {
UMOUNT_SYNC = 1,
UMOUNT_PROPAGATE = 2,
UMOUNT_CONNECTED = 4,
};
/*
* mount_lock must be held
@ -1386,7 +1387,10 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
if (how & UMOUNT_SYNC)
p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
disconnect = !IS_MNT_LOCKED_AND_LAZY(p);
disconnect = !(((how & UMOUNT_CONNECTED) &&
mnt_has_parent(p) &&
(p->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) ||
IS_MNT_LOCKED_AND_LAZY(p));
pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt,
disconnect ? &unmounted : NULL);
@ -1529,7 +1533,7 @@ void __detach_mounts(struct dentry *dentry)
umount_mnt(p);
}
}
else umount_tree(mnt, 0);
else umount_tree(mnt, UMOUNT_CONNECTED);
}
unlock_mount_hash();
put_mountpoint(mp);