[PATCH] net/socket: set socket inode times to current_time

Socket creation time are sometimes useful but not available becasue the
socket inode times are not set when initializing the inode.  This patch
sets the socket inode times to current_time().

Before the fix, the socket inode times are at epoch, for example:

    $ stat -L /proc/383/fd/3
      File: /proc/383/fd/3
      Size: 0               Blocks: 0          IO Block: 4096   socket
    Device: 0,8     Inode: 15996       Links: 1
    Access: (0777/srwxrwxrwx)  Uid: ( 1000/    arch)   Gid: ( 1000/    arch)
    Access: 1970-01-01 00:00:00.000000000 +0000
    Modify: 1970-01-01 00:00:00.000000000 +0000
    Change: 1970-01-01 00:00:00.000000000 +0000

After the fix, the inode times are the socket creation time:

    $ stat -L /proc/254/fd/3
      File: /proc/254/fd/3
      Size: 0               Blocks: 0          IO Block: 4096   socket
    Device: 0,7     Inode: 13170       Links: 1
    Access: (0777/srwxrwxrwx)  Uid: ( 1000/    arch)   Gid: ( 1000/    arch)
    Access: 2023-02-01 03:27:50.094731201 +0000
    Modify: 2023-02-01 03:27:50.094731201 +0000
    Change: 2023-02-01 03:27:50.094731201 +0000

Signed-off-by: Wenhua Zhao <redacted>
---
 net/socket.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/socket.c b/net/socket.c
index 888cd618a968..c656c9599a92 100644
--- a/net/socket.c
+++ b/net/socket.c

@@ -635,6 +635,7 @@ struct socket *sock_alloc(void)
 	inode->i_uid = current_fsuid();
 	inode->i_gid = current_fsgid();
 	inode->i_op = &sockfs_inode_ops;
+	inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 
 	return sock;
 }

-- 
2.39.1

From:   Wenhua Zhao <redacted>
Date:   Tue, 31 Jan 2023 20:30:19 -0800

Socket creation time are sometimes useful but not available becasue the
socket inode times are not set when initializing the inode.  This patch
sets the socket inode times to current_time().

Before the fix, the socket inode times are at epoch, for example:

    $ stat -L /proc/383/fd/3
      File: /proc/383/fd/3
      Size: 0               Blocks: 0          IO Block: 4096   socket
    Device: 0,8     Inode: 15996       Links: 1
    Access: (0777/srwxrwxrwx)  Uid: ( 1000/    arch)   Gid: ( 1000/    arch)
    Access: 1970-01-01 00:00:00.000000000 +0000
    Modify: 1970-01-01 00:00:00.000000000 +0000
    Change: 1970-01-01 00:00:00.000000000 +0000

After the fix, the inode times are the socket creation time:

    $ stat -L /proc/254/fd/3
      File: /proc/254/fd/3
      Size: 0               Blocks: 0          IO Block: 4096   socket
    Device: 0,7     Inode: 13170       Links: 1
    Access: (0777/srwxrwxrwx)  Uid: ( 1000/    arch)   Gid: ( 1000/    arch)
    Access: 2023-02-01 03:27:50.094731201 +0000
    Modify: 2023-02-01 03:27:50.094731201 +0000
    Change: 2023-02-01 03:27:50.094731201 +0000

Signed-off-by: Wenhua Zhao <redacted>

Looks good, but we may want to use another example in changelog
because you can get almost the same time without the -L option
and the use case is bit confusing at least for me.

I guess you will use it in your application, not from the outside
world by stat.

  $ python3
  >>> from socket import socket
  >>> from os import fstat
  >>> 
  >>> sk = socket()
  >>> fstat(sk.fileno())
  os.stat_result(..., st_atime=0, st_mtime=0, st_ctime=0)