isofs: support full length file names (255 instead of 253)

Linux file names are in principle limited only to PATH_MAX (which is
4096) but the code in get_rock_ridge_filename() limits them to 253
characters.

As mentioned by Jan Kara, the Rockridge standard to ECMA119/ISO9660 has
no limit of file name length, but this limits file names to the
traditional 255 NAME_MAX value.

Signed-off-by: Shawn Landden <slandden@gmail.com>
Link: https://patch.msgid.link/CA+49okq0ouJvAx0=txR_gyNKtZj55p3Zw4MB8jXZsGr4bEGjRA@mail.gmail.com
Signed-off-by: Jan Kara <jack@suse.cz>

Author: shawnl

fs/isofs/rock.c

@@ -271,7 +271,7 @@ int get_rock_ridge_filename(struct iso_directory_record *de,
 				break;
 			}
 			len = rr->len - 5;
-			if (retnamlen + len >= 254) {
+			if (retnamlen + len > NAME_MAX) {
 				truncate = 1;
 				break;
 			}