Re: Reiser4 SCSI Bug?

[Isaac Chanin <chanin@WPI.EDU>]

Hans Reiser wrote:
> Isaac Chanin wrote:
> 
> 
>>Hans Reiser wrote:
>>
>>
>>>It should be not 256, but BIO_MAX_PAGES, yes?   Defining limits in two
>>>places is bad, yes?
>>>
>>>
>>
>>Yeah, I think the code is running into two different limits here.
>>Reiser4 wants it to be nr, but limits it to BIO_MAX_PAGES.  However,
>>apparently, the BIO_MAX_PAGES limit does not take into consideration
>>the underlying 256 limit imposed by bio_alloc.
>>
>>I'm not quite sure if having the two different limits is a bad thing
>>in this case, unless BIO_MAX_PAGES can be made to (or is supposed to,
>>and there's a bug) take into account the 256 limit.
>>
>>I suppose the other solution is to not use bio_alloc et al due to the
>>256 limit, and find another method that allows values as large as
>>BIO_MAX_PAGES, under the current implementation, will grow to.
>>
>>
> 
> but you said:
> 
> "In any case, BIO_MAX_PAGES is defined to be 256"
> 
> Now I am confused.
> 
> We should use the same macro defining our limit as the underlying layer uses.  What macro is that called?
> 
> 

Right, it would be far better to do min(BIO_MAX_PAGES, ...); rather than 
using 256 directly.  It's defined in include/linux/bio.h which is 
already included in wander.c.