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SubjectRe: [PATCH rc6] block: Fix CDROMEJECT to work in more cases


On Tue, 20 Dec 2005, Jens Axboe wrote:
>
> WRITEs cannot have length 0, and READs cannot as well. Since it's just
> one bit for direction, those are the rules.

Jens, your logic doesn't make sense.

There clearly _are_ commands with a 0 data-length.

And commands _have_ to be either READ or WRITE. We don't have a choice.
ll_rw_block: blk_get_request() even has a BIG_ON() that enforces that.

So claiming that reads and writes cannot have zere data-length is INSANE.

So reads and writes HAVE to accept a zero data length. End of story. If
there is some path in the SCSI layer that refuses it, that part must be
fixed, or you have to add a new "NONE" (and perhaps "BOTH") direction.

Linus
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