Hi Sasha,
On Sun, Oct 30, 2011 at 7:35 PM, Sasha Levin <levinsasha928@xxxxxxxxx> wrote:
>> > This makes passing different ops structures easier since you don't have
>> > to keep them somewhere else after initializing disk_image.
>> >
>> > Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
On Tue, 2011-11-01 at 08:44 +0200, Pekka Enberg wrote:
>> Why do we want to do this? Why would you ever want to allocate ops via
>> malloc() or on the stack?
On Tue, Nov 1, 2011 at 1:16 PM, Sasha Levin <levinsasha928@xxxxxxxxx> wrote:
> It's mostly there to avoid having to either keep ops in a global struct
> or to malloc() them, instead - it just holds them as part of disk_image;
>
> It's useful with how we handle read-only ops now, you can see how we use
> RO image now (private mmap() with fallback to AIO with no write op).
It's not useful, it's obfuscation. The whole point of "operations"
struct is to provide an immutable and stateless virtual function
dispatch table. It's absolutely pointless to use malloc() to hold them
and seems to miss the whole point of keeping data and function pointer
separate.
Pekka
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