Re: [PATCH] bio: ensure __bio_clone_fast copies bi_partno

[Michael Lyle <mlyle@lyle.org>]

Jens & everyone-- thanks for the speedy review and handling.  I've
updated my test cases to ensure that volumes from old releases work,
even when I "don't think" there's been a disk format change.

Bart--

On 11/17/2017 08:50 AM, Bart Van Assche wrote:
> Have you considered to use bio_copy_dev() instead of open-coding it?

One could... Right now almost all the uses of bio_copy_dev are in bcache
and they need to change for other reasons.  (e.g. macro uses parameter
more than once, function is passed in as parameter).  There's a whole
lot of places to change if it's desired to make bio_copy_dev universally
used to copy device information.

> Additionally, there is more code that copies these fields, e.g. the code in
> bio_clone_bioset(). Shouldn't that code be modified such that it also copies
> bi_partno?

Yes, when I was grepping around there were other things that looked
possibly unsafe.  I don't have test environments for all of these other
subsystems.

I wanted to get the minimal fix for this in, though, because people are
actively losing data to the problem it triggers with bcache.

Mike