[Bug 439784] Re: invalid: environment block

[Jordan]

I have not confirmed this yet by looking at any code, but the reason
that grubenv is ending up zero bytes is likely that some code is writing
to grubenv ( from linux, not grub itself ) by doing something like:
write file "grubenv.tmp"; unlink file "grubenv"; rename "grubenv.tmp" ,
"grubenv". The reason this is likely being done is that
/boot/grub/grubenv is read only. The problem is that unless in
data=ordered mode ext* ( this affects ext3 also now that ordered mode is
not default ) will sometimes write metadata before data. The work around
to prevent zero byte files was to implicitly fsync when renaming over an
existing file; because the code is unlinking grubenv first this implicit
fsync is not triggered.

To fix this you could either temporarily make grubenv writable and do
the standard write new file then rename over old or do: write
/boot/grub/grubenv.tmp; fdatasync /boot/grub/grubenv.tmp; unlink
/boot/grub/grubenv; rename /boot/grub/grubenv.tmp to /boot/grub/grubenv;
fsync /boot/grub/ .

Even if that is not the cause of the problem I don't see how checking
for a zero byte file during init is a fix since this bug will prevent
users from getting to init in the first place, but I am likely just not
understanding something.

-- 
invalid: environment block
https://bugs.launchpad.net/bugs/439784
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