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attach_mnt(): expand in attach_recursive_mnt(), then lose the flag argument

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simpler that way - all but one caller pass false as 'beneath' argument,
and that one caller is actually happier with the call expanded - the
logics with choice of mountpoint is identical for 'moving' and 'attaching'
cases, and now that is no longer hidden.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2025-04-25 12:40:28 -04:00
parent d0b3b7b22d
commit 8c6ce8e86d
1 changed files with 12 additions and 25 deletions
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37
fs/namespace.c
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@ -1116,16 +1116,10 @@ static void __attach_mnt(struct mount *mnt, struct mount *parent)
* @parent: the parent
* @mnt: the new mount
* @mp: the new mountpoint
* @beneath: whether to mount @mnt beneath or on top of @parent
*
* If @beneath is false, mount @mnt at @mp on @parent. Then attach @mnt
* Mount @mnt at @mp on @parent. Then attach @mnt
* to @parent's child mount list and to @mount_hashtable.
*
* If @beneath is true, remove @mnt from its current parent and
* mountpoint and mount it on @mp on @parent, and mount @parent on the
* old parent and old mountpoint of @mnt. Finally, attach @parent to
* @mnt_hashtable and @parent->mnt_parent->mnt_mounts.
*
* Note, when __attach_mnt() is called @mnt->mnt_parent already points
* to the correct parent.
*
@ -1133,18 +1127,9 @@ static void __attach_mnt(struct mount *mnt, struct mount *parent)
* to have been acquired in that order.
*/
static void attach_mnt(struct mount *mnt, struct mount *parent,
struct mountpoint *mp, bool beneath)
struct mountpoint *mp)
{
if (beneath)
mnt_set_mountpoint_beneath(mnt, parent, mp);
else
mnt_set_mountpoint(parent, mp, mnt);
/*
* Note, @mnt->mnt_parent has to be used. If @mnt was mounted
* beneath @parent then @mnt will need to be attached to
* @parent's old parent, not @parent. IOW, @mnt->mnt_parent
* isn't the same mount as @parent.
*/
mnt_set_mountpoint(parent, mp, mnt);
__attach_mnt(mnt, mnt->mnt_parent);
}
@ -1157,7 +1142,7 @@ void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct m
hlist_del_init(&mnt->mnt_mp_list);
hlist_del_init_rcu(&mnt->mnt_hash);
attach_mnt(mnt, parent, mp, false);
attach_mnt(mnt, parent, mp);
put_mountpoint(old_mp);
mnt_add_count(old_parent, -1);
@ -2295,7 +2280,7 @@ struct mount *copy_tree(struct mount *src_root, struct dentry *dentry,
goto out;
lock_mount_hash();
list_add_tail(&dst_mnt->mnt_list, &res->mnt_list);
attach_mnt(dst_mnt, dst_parent, src_parent->mnt_mp, false);
attach_mnt(dst_mnt, dst_parent, src_parent->mnt_mp);
unlock_mount_hash();
}
}
@ -2743,10 +2728,12 @@ static int attach_recursive_mnt(struct mount *source_mnt,
}
if (moving) {
if (beneath)
dest_mp = smp;
unhash_mnt(source_mnt);
attach_mnt(source_mnt, top_mnt, dest_mp, beneath);
if (beneath)
mnt_set_mountpoint_beneath(source_mnt, top_mnt, smp);
else
mnt_set_mountpoint(top_mnt, dest_mp, source_mnt);
__attach_mnt(source_mnt, source_mnt->mnt_parent);
mnt_notify_add(source_mnt);
touch_mnt_namespace(source_mnt->mnt_ns);
} else {
@ -4827,9 +4814,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
root_mnt->mnt.mnt_flags &= ~MNT_LOCKED;
}
/* mount old root on put_old */
attach_mnt(root_mnt, old_mnt, old_mp, false);
attach_mnt(root_mnt, old_mnt, old_mp);
/* mount new_root on / */
attach_mnt(new_mnt, root_parent, root_mp, false);
attach_mnt(new_mnt, root_parent, root_mp);
mnt_add_count(root_parent, -1);
touch_mnt_namespace(current->nsproxy->mnt_ns);
/* A moved mount should not expire automatically */