Re: [dm-devel] [PATCH v5 12/12] block: Only clone bio vecs that are in use

[Kent Overstreet <koverstreet google com>]

On Thu, Aug 09, 2012 at 10:37:00AM -0700, Tejun Heo wrote:
> Hello,
> 
> On Mon, Aug 06, 2012 at 03:08:41PM -0700, Kent Overstreet wrote:
> > bcache creates large bios internally, and then splits them according to
> > the device requirements before it sends them down. If a lower level
> > device tries to clone the bio, and the original bio had more than
> > BIO_MAX_PAGES, the clone will fail unecessarily.
> > 
> > We can fix this by only cloning the bio vecs that are actually in use.
> 
> How was this tested?

This code has been in the bcache tree for months, and I added it to fix
a real bug (think I saw it with bcache on top of dm) - and since then
it's been tested in probably just about all the relevant configurations,
certainly both dm and md.