RFC block large commands support continue

The support for large commands was dropped from the for-2.6.26 branch and will probably not get accepted into next kernel.

I have tried to take all comments from Jens and Bart. and incorporate it into a new patchset. This is basically Tomo's patchset but with proposed changes.

They are based on current linux-block/master. They will probably conflict with latest patch sent by Tomo for the blk_get_request(). Once those patches get accepted at some git tree, (Where will that be?), I will rebase these on top of them. Please CC me of any progress.

[PATCH 1/5] block: no need to initialize rq->cmd
This is 2 of Tomo's patches squashed together as they are small and do the same. Tomo is this OK?

[PATCH 2/5] block: replace sizeof(rq->cmd) with BLK_MAX_CDB
Tomos patch rebased to here

[PATCH 3/5] block: Export rq_init, rename to blk_init_rq
[PATCH 4/5] block: Use new blk_init_rq
These patches are basically what Jens and Bart has suggested, that with a small code change to blk-core.c we can memset at rq_init() and only set none zero members. We can also export that initializer and use it all over the ide tree where ever requests don't come from a request queue. (OK also at scsi_error.c)

[PATCH 5/5] block: add large command support
Now that all initialization goes through one place Tomos large command support is trivial.

Bart. This is mostly ide changes, so please if you can test it. I do not have any legacy IDE devices here at the office, it is all new sata stuff.

I hope we can put this, and later the scsi stuff, on some tree that can be tested at -mm and hopefully be ready for 2.6.27

Thanks
Boaz