From 8c6ce8e86dd75db8e6c6a3e5a870e8d52dbab2d0 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 25 Apr 2025 12:40:28 -0400 Subject: [PATCH] attach_mnt(): expand in attach_recursive_mnt(), then lose the flag argument 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 Signed-off-by: Al Viro --- fs/namespace.c | 37 ++++++++++++------------------------- 1 file changed, 12 insertions(+), 25 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 54c59e091919b..1761d2c2fdae6 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -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 */ -- 2.47.2