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d1ddc6f1d9
propagate_mnt() does not attach anything to mounts created during
propagate_mnt() itself. What's more, anything on ->mnt_slave_list
of such new mount must also be new, so we don't need to even look
there.
When move_mount() had been introduced, we've got an additional
class of mounts to skip - if we are moving from anon namespace,
we do not want to propagate to mounts we are moving (i.e. all
mounts in that anon namespace).
Unfortunately, the part about "everything on their ->mnt_slave_list
will also be ignorable" is not true - if we have propagation graph
A -> B -> C
and do OPEN_TREE_CLONE open_tree() of B, we get
A -> [B <-> B'] -> C
as propagation graph, where B' is a clone of B in our detached tree.
Making B private will result in
A -> B' -> C
C still gets propagation from A, as it would after making B private
if we hadn't done that open_tree(), but now the propagation goes
through B'. Trying to move_mount() our detached tree on subdirectory
in A should have
* moved B' on that subdirectory in A
* skipped the corresponding subdirectory in B' itself
* copied B' on the corresponding subdirectory in C.
As it is, the logics in propagation_next() and friends ends up
skipping propagation into C, since it doesn't consider anything
downstream of B'.
IOW, walking the propagation graph should only skip the ->mnt_slave_list
of new mounts; the only places where the check for "in that one
anon namespace" are applicable are propagate_one() (where we should
treat that as the same kind of thing as "mountpoint we are looking
at is not visible in the mount we are looking at") and
propagation_would_overmount(). The latter is better dealt with
in the caller (can_move_mount_beneath()); on the first call of
propagation_would_overmount() the test is always false, on the
second it is always true in "move from anon namespace" case and
always false in "move within our namespace" one, so it's easier
to just use check_mnt() before bothering with the second call and
be done with that.
Fixes: 064fe6e233 ("mount: handle mount propagation for detached mount trees")
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
60 lines
2.0 KiB
C
60 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* linux/fs/pnode.h
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*
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* (C) Copyright IBM Corporation 2005.
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*/
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#ifndef _LINUX_PNODE_H
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#define _LINUX_PNODE_H
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#include <linux/list.h>
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#include "mount.h"
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#define IS_MNT_SHARED(m) ((m)->mnt.mnt_flags & MNT_SHARED)
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#define IS_MNT_SLAVE(m) ((m)->mnt_master)
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#define IS_MNT_NEW(m) (!(m)->mnt_ns)
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#define CLEAR_MNT_SHARED(m) ((m)->mnt.mnt_flags &= ~MNT_SHARED)
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#define IS_MNT_UNBINDABLE(m) ((m)->mnt.mnt_flags & MNT_UNBINDABLE)
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#define IS_MNT_MARKED(m) ((m)->mnt.mnt_flags & MNT_MARKED)
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#define SET_MNT_MARK(m) ((m)->mnt.mnt_flags |= MNT_MARKED)
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#define CLEAR_MNT_MARK(m) ((m)->mnt.mnt_flags &= ~MNT_MARKED)
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#define IS_MNT_LOCKED(m) ((m)->mnt.mnt_flags & MNT_LOCKED)
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#define CL_EXPIRE 0x01
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#define CL_SLAVE 0x02
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#define CL_COPY_UNBINDABLE 0x04
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#define CL_MAKE_SHARED 0x08
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#define CL_PRIVATE 0x10
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#define CL_SHARED_TO_SLAVE 0x20
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#define CL_COPY_MNT_NS_FILE 0x40
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#define CL_COPY_ALL (CL_COPY_UNBINDABLE | CL_COPY_MNT_NS_FILE)
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static inline void set_mnt_shared(struct mount *mnt)
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{
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mnt->mnt.mnt_flags &= ~MNT_SHARED_MASK;
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mnt->mnt.mnt_flags |= MNT_SHARED;
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}
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void change_mnt_propagation(struct mount *, int);
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int propagate_mnt(struct mount *, struct mountpoint *, struct mount *,
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struct hlist_head *);
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int propagate_umount(struct list_head *);
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int propagate_mount_busy(struct mount *, int);
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void propagate_mount_unlock(struct mount *);
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void mnt_release_group_id(struct mount *);
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int get_dominating_id(struct mount *mnt, const struct path *root);
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int mnt_get_count(struct mount *mnt);
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void mnt_set_mountpoint(struct mount *, struct mountpoint *,
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struct mount *);
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void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp,
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struct mount *mnt);
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struct mount *copy_tree(struct mount *, struct dentry *, int);
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bool is_path_reachable(struct mount *, struct dentry *,
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const struct path *root);
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int count_mounts(struct mnt_namespace *ns, struct mount *mnt);
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bool propagation_would_overmount(const struct mount *from,
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const struct mount *to,
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const struct mountpoint *mp);
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#endif /* _LINUX_PNODE_H */
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