On Fri, 9 Mar 2001, Mike Galbraith wrote:
> I think I've figured it out.. at least I've found a way to reproduce
> the exact errors to the last detail and some pretty nasty corruption
> to go with it. The operator must help though.. a lot ;-)
>
> If you do mount -o remount /dev/somedisk / thinking that that will get
> rid of your /dev/ram0 root, that isn't the case, and you will corrupt
> the device you remounted (I did it to a scratch monkey) very badly when
> you write to the still mounted ramdisk.
Ugh. mount -o remount ignores dev_name argument. It will change the
flags of fs mounted from /dev/ram0 and will not even touch a /dev/somedisk.
If you write to device you have mounted... Well, don't expect it to be pretty.
> You must exec a shell (or something) chrooted to your mounted harddisk
> to un-busy the old root and then pivot_root/unmount that old root. I
> tested this, and all is well.
>
> I think this is a consequence of the multiple mount changes.. not sure.
> (ergo cc to Al Viro.. he knows eeeeverything about mount points)
I _really_ doubt that it has anything to multiple mounts. mount -o remount
never unmounts anything. Never did. The rest is an obvious result - you
leave fs mounted, you do direct write to its device, you see it fucked.
The fact that it is a root doesn't matter. Relevant part of manpage:
remount
Attempt to remount an already-mounted file
system. This is commonly used to change the
mount flags for a file system, especially to
make a readonly file system writeable.
Hmm... Might be cleaner. IMO
Attempt to change the mount flags of
already-mounted file system. This is commonly
used to make a readonly file system writeable.
would be less confusing. Andries, your comments?
Cheers,
Al
(fully expecting a long rant from Richard declaring that -o remount had
_always_ been used to mount a different fs and both ANSI C standard and
X-files fan guide mention it somewhere ;-)
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This archive was generated by hypermail 2b29 : Thu Mar 15 2001 - 21:00:10 EST