diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2025-04-25 16:53:01 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2025-06-29 18:13:42 -0400 |
| commit | e30da2a20e31ab958d41e5a2c764968d95f17b61 (patch) | |
| tree | 8f8bb9b880ce1b1b0eb4892b310a5fe8d1a05425 | |
| parent | ec3265a245b22f8b8a0b20e04dd1d3f4f4a9ce09 (diff) | |
pivot_root(): reorder tree surgeries, collapse unhash_mnt() and put_mountpoint()
attach new_mnt *before* detaching root_mnt; that way we don't need to keep hold
on the mountpoint and one more pair of unhash_mnt()/put_mountpoint() gets
folded together into umount_mnt().
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/namespace.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index ff2281f780dc..eee73e945a54 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4685,7 +4685,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, { struct path new, old, root; struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent; - struct mountpoint *old_mp, *root_mp; + struct mountpoint *old_mp; int error; if (!may_mount()) @@ -4748,20 +4748,19 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, goto out4; lock_mount_hash(); umount_mnt(new_mnt); - root_mp = unhash_mnt(root_mnt); /* we'll need its mountpoint */ if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { new_mnt->mnt.mnt_flags |= MNT_LOCKED; root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; } - /* mount old root on put_old */ - attach_mnt(root_mnt, old_mnt, old_mp); /* mount new_root on / */ - attach_mnt(new_mnt, root_parent, root_mp); + attach_mnt(new_mnt, root_parent, root_mnt->mnt_mp); + umount_mnt(root_mnt); mnt_add_count(root_parent, -1); + /* mount old root on put_old */ + attach_mnt(root_mnt, old_mnt, old_mp); touch_mnt_namespace(current->nsproxy->mnt_ns); /* A moved mount should not expire automatically */ list_del_init(&new_mnt->mnt_expire); - put_mountpoint(root_mp); unlock_mount_hash(); mnt_notify_add(root_mnt); mnt_notify_add(new_mnt); |