Messages in this thread | | | Date | Wed, 11 Feb 1998 00:16:49 -0500 | From | "Theodore Y. Ts'o" <> | Subject | Re: FS size sanity check |
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Date: Wed, 11 Feb 1998 03:44:47 +0530 (IST) From: ganesh@cse.iitb.ernet.in
Shouldn't there be a sanity check somewhere to see that the filesystem size is <= device size before mounting ? It seems that this is not done, at least for msdos. We just had a case where a dos fs which thought it was 2GB was actually sitting in a 1 GB partition with the rest of the disk being linux, leading to a lot of grief when it overran into the linux partitions. Looks like someone had repartitioned the disk for installing linux without bothering to use fips or reformatting the dos side. Although the situation was definitely caused by user stupidity, I think there should at least be a warning somewhere while mounting such a "dangerous" fs. The question is, should it be in userspace (mount), or in the kernel ? If in the kernel, each fs should probably do the check in its read_super since there are some fs's like compressed fs's whose advertised size legitimately exceeds the block device size.
This check is already done by e2fsck; so if an ext2 filesystem is bigger than the partition, you will get a warning during the boot sequence.
It would probably be a good idea to put a check in the kernel for this sort of thing, though. Especially for filesystems like FAT and VFAT, where we don't have filesystem checkers which get run at boot time.
- Ted
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