[dm-crypt] luks header on initramfs img fails due to no O_DIRECT support in tmpfs

Milan Broz gmazyland at gmail.com
Fri Aug 8 13:20:13 CEST 2014

On 08/08/2014 09:22 AM, Natanael Copa wrote:
> I found this posting while looking at an issue with cryptsetup-1.6.5 in initramfs:
> http://www.saout.de/pipermail/dm-crypt/2014-August/004227.html
> I believe this is same thing as reported here:
> http://bugs.alpinelinux.org/issues/3281
> Seems like the problem is that open(2) does not support O_DIRECT when on tmpfs.

Yes, I expected something like that.

In cryptsetup 1.6.4 this was not happening because it was hidden by temporary dmcrypt
device in the middle of stack.

It is kernel bug, O_DIRECT should work on tmpfs and similar devices.

Anyway, it should also work on older kernels, so I'll think about implementing
some workaround here.


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