cifs: To match file servers, make sure the server hostname matches

cifs: To match file servers, make sure the server hostname matches

BugLink: https://bugs.launchpad.net/bugs/1954926
commit 7be3248f313930ff3d3436d4e9ddbe9fccc1f541 upstream.

We generally rely on a bunch of factors to differentiate between servers.
For example, IP address, port etc.

For certain server types (like Azure), it is important to make sure
that the server hostname matches too, even if the both hostnames currently
resolve to the same IP address.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
[rtg - backported by the Microsoft team. They dropped changes to
fs/cifs/fs_connect.[ch], added a structure tag to fs/cifs/cifsglob.h: struct smb_vol,
misc changes to fs/cifs/connect.c to reflect the intent of the original upstream patch]
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>