SMB3: Honor 'posix' flag for multiuser mounts

The flag from the primary tcon needs to be copied into the volume info
so that cifs_get_tcon will try to enable extensions on the per-user
tcon. At that point, since posix extensions must have already been
enabled on the superblock, don't try to needlessly adjust the mount
flags.

Fixes: ce558b0 ("smb3: Add posix create context for smb3.11 posix mounts")
Fixes: b326614 ("smb3: allow "posix" mount option to enable new SMB311 protocol extensions")
Signed-off-by: Paul Aurich <paul@darkrain42.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>

fs/cifs/connect.c

@@ -5311,6 +5311,7 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 	vol_info->persistent = master_tcon->use_persistent;
 	vol_info->handle_timeout = master_tcon->handle_timeout;
 	vol_info->no_linux_ext = !master_tcon->unix_ext;
+	vol_info->linux_ext = master_tcon->posix_extensions;
 	vol_info->sectype = master_tcon->ses->sectype;
 	vol_info->sign = master_tcon->ses->sign;
 	vol_info->seal = master_tcon->seal;
@@ -5339,10 +5340,6 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 		goto out;
 	}
 
-	/* if new SMB3.11 POSIX extensions are supported do not remap / and \ */
-	if (tcon->posix_extensions)
-		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_POSIX_PATHS;
-
 	if (cap_unix(ses))
 		reset_cifs_unix_caps(0, tcon, NULL, vol_info);