Make volume labels distinguishable from files

[unterwulf]

So they could be easily filtered out by a parser if needed.

(This is required to make a fatcat extfs helper for Midnight Commander.)

[Gregwar]

Hello,
Disk label is in the fat headers, can you provide examples of command to generate an image with such volume file ?

[unterwulf]

In fact FAT has two places to store disk label.

You are talking about Partition Volume Label:
https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system#EBPB_OFS_20h
The commit is about directory volume label:
https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system#DIR_OFS_0Bh

IIRC, any MS-DOS format command would "generate" an image having both labels. If you happen to have an image of original MS-DOS 3.30 or 4.01 distribution floppy you can list it with fatcat and then mount it via loopback and you'll see that Linux will have one entry shorter listing of the root directory than fatcat. (Of course MS-DOS itself or Windows won't list it as a file as well.)

The problem this commit fixes is that on ancient images fatcat shows directory volume labels as fake zero-sized files.