Re: [Qemu-devel] [PATCH 1/2] vmdk: support vmfsSparse files

[Fam Zheng <famz@redhat.com>]

On Mon, 08/12 03:40, Paolo Bonzini wrote:
> 
> 
> ----- Original Message -----
> > From: "Fam Zheng" <famz@redhat.com>
> > To: "Paolo Bonzini" <pbonzini@redhat.com>
> > Cc: qemu-devel@nongnu.org, kwolf@redhat.com
> > Sent: Monday, August 12, 2013 3:31:44 AM
> > Subject: Re: [PATCH 1/2] vmdk: support vmfsSparse files
> > 
> > On Sun, 08/11 18:13, Paolo Bonzini wrote:
> > > VMware ESX hosts use a variant of the VMDK3 format, identified by the
> > > vmfsSparse create type ad the VMFSSPARSE extent type.
> > > 
> > > It has 16 KB grain tables (L2) and a variable-size grain directory (L1).
> > > In addition, the grain size is always 512, but that is not a problem
> > > because it is included in the header.
> > > 
> > > The format of the extents is documented in the VMDK spec.  The format
> > > of the descriptor file is not documented precisely, but it can be
> > > found at http://kb.vmware.com/kb/10026353 (Recreating a missing virtual
> > > machine disk (VMDK) descriptor file for delta disks).
> > > 
> > I don't have access to this link
> 
> It only works from Google.  Try Googling for "vmfssparse delta".
> 
> > , could you include some documents to
> > this descriptor format in comment or commit message? IIRC, it's only the
> > type be "VMFSSPARSE", right?
> 
> Yes.  And "VMFS" for the base (patch 2).
> 
> > What version of ESX has this format?
> 
> At least 4.0 and newer.
> 
> > This needs to be rebased, vmdk_add_extent() signature has been changed
> > in:
> > 
> >     commit 8aa1331c09a9b899f48d97f097bb49b7d458be1c
> >     Author: Fam Zheng <famz@redhat.com>
> >     Date:   Tue Aug 6 15:44:51 2013 +0800
> > 
> >         vmdk: check granularity field in opening
> > 
> >         Granularity is used to calculate the cluster size and allocate r/w
> >         buffer. Check the value from image before using it, so we don't
> >         abort()
> >         for unbounded memory allocation.
> > 
> >         Signed-off-by: Fam Zheng <famz@redhat.com>
> >         Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > 
> > Since the new function is a variant of vmdk_open_vmdk3(), would you
> > consider doing a tiny refactor and reduce duplication? And l1dir_size
> > and granularity need to be checked, as in vmdk_open_vmdk4().
> 
> I am not sure how to refactor it... in fact, since I'm on vacation I
> wouldn't mind if somebody else fixes the patch.  I can test it either
> tomorrow or next week.
> 
OK, I'll take it for your happy vocation. :)

-- 
Fam