Boaz Harrosh, on 04/22/2009 05:24 PM wrote:
On 04/21/2009 03:15 PM, Vladislav Bolkhovitin wrote:
Boaz Harrosh, on 04/19/2009 02:56 PM wrote:
On 04/17/2009 04:09 AM, Nicholas A. Bellinger wrote:
[..]
Are you aware that scsi_execute_async() has gone in 2.6.30-rc1?
I'm not sure what would be the best alternative for you. I would say
a bio, but it is still being debated. Your current options are:
1. bio_alloc then loop () bio_add_pc_page, and finally blk_rq_append_bio
(Which block people don't like)
2. sglist => page-pointers-array translation and blk_rq_map_user with
struct rq_map_data mode. (not possible with all kind of sglists)
2. sglist => iovec translation and blk_rq_map_user_iov()
(Very very ugly mapping of pages to virtual pointers)
I have a similar situation with my OSD code.
Do you have somewhere in it a need to run an arbitrary CDB with data
pages stored in an sglist? Is that code accepted in the mainline?
No, I have a direct bio which comes from two sources.
1. A bio prepared by a filesystem to describe a write/read to a file (osd object)
2. A cloned bio that comes from a stacking block-device over osd-object.
So I do not have an sglist at all, anywhere in code.
If yes, why not to resurrect the necessary bits of scsi_execute_async()
(option (1) above)? It was deleted, because in 2.6.30 there are no users
of it left, but if there are users (OSD), then why not to return it?
Seems nothing better for the sg->bio case can be invented.
I hate scsi_execute_async() for lots of reasons,
1. The cover-up of an historical abuse of sglists by sg/sr
2. Override of use_sg/data-pointer crap
3. What is data-format got to do with sync/async execution
4. the need of all that scsi_io_context and the re-invention
of async_done API.
5. ...
Good riddence
Removal of what can be removed from the above I meant under "the
necessary bits".
But you might be looking into an API introduced by an RFC by
Tejun Heo in the form of blk_rq_map_kern_sgl() which should
be a more appropriate general API for your use.
Yes, it looks like what's needed.
(And is not directly usable for me in OSD)
Vlad
Boaz
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