Re: [PATCH] [MTD] BLOCK_RO: Readonly Block Device Layer Over MTD

[Vitaly Wool <vwool@ru.mvista.com>]

Hi Artem,

Artem Bityutskiy wrote:
> Hello Konstantin,
>
> On Fri, 2006-11-17 at 18:40 +0300, kbaidarov wrote:
>   
>> Description:
>> The following patch adds readonly block device layer over mtd
>> that allows to use any filesystem on this device in RO mode and
>> thus gain faster mount times and better throughput rates.
>>     
>
> This is very ambition claim. In comparison with what?
>   
With JFFS2, for instance. I hope you won't argue than squashfs is faster 
to mount than JFFS2. :-)
Please keep in mind that this is for read-only access.
> So basically this is bad eraseblock-aware mtdblock_ro? But why you
> created a new driver and with so weird name :-) ? Why didn't you just
> changed mtdblock_ro? IOW, why you didn't adapt Pantelis' patch instead
> and re-send it? (I have no idea why this patch isn't im MTD still,
>
>   
Erm, these are several questions in one.
First, this "shim" was arranged as a new driver per dwmw2's request. It 
was our first idea to modify mtdblock_ro, but it didn't work for David.
Next, I pretty much don't understand your phrase about the "weird name", 
though I might be missing something.
And the final thing is this approach is a derivative of Pantelis's 
patch. There were several "points of evolution" within. Please note that 
unlikely to Pantelis's patch, we now don't introduce *any* new fields or 
ifdef's in the generic code, there's no modifications in the existing 
code as well. It became a separate solution 5 screens worth :) It's a 
very low price for being able to use cramfs/squashfs/fat in read-only on 
NAND flash for embedded systems.

Vitaly