Messages in this thread | | | Date | Sat, 30 Mar 2002 00:11:00 +0100 | From | Pavel Machek <> | Subject | Re: [Q] FAT driver enhancement |
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Hi!
> A while ago I initiated a thread about mounting a NTFS partition as FAT > partition. The problem is that FAT partitions do not have a real > fingerprint, so the FAT driver mounts almost anything. > > The current 2.5 driver only tests if some values in the bootsector are > non-zero. IMHO, this is not strict enough. For example, the number of FATs > is always 1 or 2 (anyone ever seen more ?). Besides, when there are two > FATs, all entries in those FATs should be equal. If they are not, we deal > with a non-FAT or broken FAT partition, and we should not mount. > > It's not a real fingerprint, but what are the chances all sectors of what > we think is the FAT are equal on non-FAT filesystems ? Yes, when you just > did a > > dd if=/dev/zero of=/dev/partition; mkfs.somefs /dev/partition > > there is a chance, but that's an empty filesystem. Data corruption isn't > that bad on an empty disk. We know that a FAT is at the beginning of a > partition and I assume that any other filesystem will fill up those first > sectors very soon. > > Questions: > > 1) How do you think about the checking of the FAT tables ? It definitely > will slow down the mount.
Reading FATs is very fast, and they are probably going to be needed, anyway. I guess its okay.
> 2) If I implement it, where shoud it go ? At the moment, I hacked > fat_read_super, for there the FAT fs is validated, but I got the > feeling this is not the place to be. > 3) Anyone seen more than two FATs on a filesystem ? Can I assume there is > a limit ?
No. I think you can only have two.
Pavel -- (about SSSCA) "I don't say this lightly. However, I really think that the U.S. no longer is classifiable as a democracy, but rather as a plutocracy." --hpa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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