>From: Theodore Ts'o <[EMAIL PROTECTED]>
> On Tue, Mar 07, 2006 at 06:12:25PM -0800, Elliott Mitchell wrote:
> > That isn't what I have a problem with in this case. Problem is `mount`
> > would have to understand the target filesystem in order to find out the
> > journal UUID is. `mount` doesn't have that sort of understanding of any
> > filesystem.
>
> Actually mount does already, in order to support mount-by-label, but
> what I would do is put that understanding into the blkid library,
> which would is already being called by mount.
In that situation mount has the UUID, and searches for a matching
filesystem. For this situation, it would have to look at the target
filesystem, and extract the journal UUID. That would require dwelving
fairly deeply into the filesystem. You're expecting libblkid to start
understanding filesystems? You planning to reimplement VFS in userspace?
(okay, perhaps not that deeply, but it is quite distinct from libblkid's
stated purpose)
> > In the case of a read-only mount, sure. In the case of a read-write
> > mount, it already is required if the filesystem is unclean.
>
> But if you know the filesystem is clean, why should you run e2fsck?
> Just to set the superblock hint? That's broken, it should be
> automatically done by mount. Anyway, that's the long-term direction
> but it will requre getting the new blkid library functionality
> released first, so I won't worry about it right away.
How much are block devices expected to change on every boot? For
automatically mounted filesystems, this could be done as part of
`fsck -a`. I'm unsure of the hint format, one solution would be to use 0
as a pseudo-major indicating to open the device of the same major but the
indicated minor. That would cover the common situation for removalable
storage that wasn't available at boot time. Know of anyone using external
journals on devices where the journal isn't on the same physical device?
I suspect not, as that really sounds like Russian Roulette.
Perhaps I was wrong earlier, it might in fact be best for the kernel to
know how to search for filesystems by UUID.
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