Re: [Qemu-block] [Qemu-devel] [PATCH v4 2/4] block: remove bdrv_media_changed

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 07/11/2017 11:37 AM, Manos Pitsidianakis wrote:
>> This function is not used anywhere, so remove it.
>> 
>
> Might be interesting to figure out when it WAS last used.

Yes.  When I see "remove X because it's unused" during patch review, I
immediately ask "why is it unused now, and what was it used for
previously?"  Ideally, the commit message answers these questions
preemptively.

>                                                            If I grepped
> correctly, it was commit 21fcf360 back in May 2012?

Yes.  "fdc: simplify media change handling".  I suspect that commit
broke media change for passed-through host floppy.

Its only implementation went away in commit f709623 "block: Remove host
floppy support".

Suggest

    block: bdrv_media_changed() is unused, remove

    The i82078 floppy device model used to call bdrv_media_changed() to
    implement its media change bit when backed by a host floppy.  This
    went away in 21fcf36 "fdc: simplify media change handling".
    Probably broke host floppy media change.  Host floppy pass-through
    was dropped in commit f709623.  bdrv_media_changed() has never been
    used for anything else.  Remove it.