When a file is open and being written to by a client, executing the stat command on this file (by the same or a different client) results in the modified time reported by stat remaining unchanged from when the file was first opened. This could potentially be a bug or an intentional behavior, and further insights are needed to understand the cause.

Steps to Reproduce:

Setup:
    - Deploy an SMB server on an Ubuntu machine (this issue has been observed on Ubuntu but may also be reproducible on Windows).
    - Expose a share from the SMB server.
    - Mount the share using cifs on another Linux machine.
    - Use the following Python script to keep the file open and write to it:
    import time
   
    file_name = "/mnt/<location>/a.txt"
    char_to_write = "a"
   
    with open(file_name, "a") as file:
        while True:
            file.write(char_to_write)
            file.flush()
            print(".")
            time.sleep(1)

    - While the above script is running, execute stat on the file from the same client or any other client that has the share mounted:
   stat /mnt/<location>/a.txt        
    - Observe that even though the file is being written to, its modified time does not get updated.