[lxc-devel] [RFC] rootfs pinning

[Michael H. Warfield]

On Tue, 2013-09-24 at 17:19 -0500, Serge Hallyn wrote: 
> Quoting Michael H. Warfield (mhw at WittsEnd.com):
> > No.  There's a change there, all right, and thank you for reminding me
> > of that, but (afaik) it's NOT in the kernel itself.  It's a mount
> > option.  It's that bloody MS_SHARED option and, to a lessor extent,
> 
> There *is* a kernel change which dhansen was telling me about last
> week - I believe it's commit 4ed5e82fe77f4147cf386327c9a63a2dd7eff518.
> It allows you to now do

> 	sudo mount -t tmpfs tmpfs /tmp/a
> 	sudo mount -o bind,remount,ro /tmp/a /tmp/b

> In the past you had to first create a bind mount before you could
> mark it readonly, i.e.

> 	sudo mount -t tmpfs tmpfs /tmp/a
> 	sudo mount --bind /tmp/a /tmp/b
> 	sudo mount -o remount,ro /tmp/b /tmp/b

Interesting point.  Very interesting.  I guess I can dig into it an look
it up but, what rev did that commit show up in and does it impact the
way we handle things dependent on kernel version?

> In either case first making sure there is a bind-mount for us to mark
> read-write seems to work.  (We'll have to, of course, make sure it
> was actually read-write to begin with, and that the user *wants* it
> read-write.  That'll be the only painful part of this patch)

Yeah...  That sounds about right.

> -serge

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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