From 230536ff6b06b199995687aa7fbf164970ebda85 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Fri, 29 Nov 2024 14:02:25 +0100 Subject: [PATCH] pidfs: support FS_IOC_GETVERSION This will allow 32 bit userspace to detect when a given inode number has been recycled and also to construct a unique 64 bit identifier. Link: https://lore.kernel.org/r/20241129-work-pidfs-v2-3-61043d66fbce@kernel.org Reviewed-by: Jeff Layton Reviewed-by: Amir Goldstein Reviewed-by: Jan Kara Signed-off-by: Christian Brauner --- fs/pidfs.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/pidfs.c b/fs/pidfs.c index 71af820eafa5b..8d62d900d20d3 100644 --- a/fs/pidfs.c +++ b/fs/pidfs.c @@ -271,6 +271,14 @@ static long pidfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg) struct ns_common *ns_common = NULL; struct pid_namespace *pid_ns; + if (cmd == FS_IOC_GETVERSION) { + if (!arg) + return -EINVAL; + + __u32 __user *argp = (__u32 __user *)arg; + return put_user(file_inode(file)->i_generation, argp); + } + task = get_pid_task(pid, PIDTYPE_PID); if (!task) return -ESRCH; -- 2.50.1