[dm-crypt] cryptsetup manpage: misleading/imprecise description of --size for resize

Milan Broz gmazyland at gmail.com
Wed Feb 15 20:30:53 CET 2017

On 02/15/2017 07:14 PM, G.raud wrote:
> Incriminated part of the cryptsetup manpage:
> " If --size (in sectors) is not specified, the size of the
>   underlying block device is used. "
> In fact the size of the underlying block device is used _to compute_ the
> _maximum_ size that can be made available, which in case of LUKS is not
> the whole block device space.  The manpage can be misleading to someone
> who doesn't know dmcrypt well and wants to resize a LUKS container.  At
> least append something like "to compute the maximum available size" or
> change to "the whole available space is used" for example.
> The maximum size in the case of LUKS is, I think, the size of the block
> device minus the offset; this could be additionaly stated in the
> manpage.

I think part of this sentence in man page predates the LUKS extension :)

Yes, in LUKS it is the size of the device without the area reserved for header
(visible in luksDump as payload offset).

I changed the man page to mention that.


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