Re: [BIO] request->flags ambiguity

[Jens Axboe <axboe@suse.de>]

On Fri, Jun 27 2003, Samium Gromoff wrote:
> 	I might just be completely off base, but something struck me
> 	lately as odd, and i`d like to hear what you folks think about
> 	the issue.
> 
> 	I`m wondering about the ambiguity of the struct request->flags
> 	field.
> 
> 	Is it ok to have a possibility of a request with conflicting
> 	meanings attached to it?  For example REQ_CMD | REQ_PM_SHUTDOWN
> 	| REQ_SPECIAL.

No of course not.

> 	It may be, depending on the implementation, that they are not
> 	completely conflicting, but its hard to believe that there is
> 	zero ambiguity at all.
> 
> 	If i`m not mistaken this looks as creating opportunities for
> 	various subtle bugs.
> 
> 	Shouldn`t it make more sense to separate request-type-indicator
> 	flags into a separate unambiguous type field, which would take
> 	one of the following values: - read/write request - sense query
> 	- power control - special request
> 
> 	And not a currently possible combination of all of them, which
> 	seem to be the current situation.

There has been talk of that before, search the archives.

-- 
Jens Axboe