On Wed, Aug 27 2008, FUJITA Tomonori wrote: > On Tue, 26 Aug 2008 09:56:28 +0200 > Jens Axboe <jens.axboe@xxxxxxxxxx> wrote: > > > On Tue, Aug 26 2008, FUJITA Tomonori wrote: > > > This patchset converts sg to use the block layer functions. That is, > > > sg doesn't use scsi_execute_async() any more. This is a part of the > > > overdue task to remove scsi_req_map_sg. > > > > > > I tested this patchset with sg v3 and the old interface (struct > > > sg_header) via SG_IO (v3) and the vfs API. > > > > > > > > > Doug, > > > > > > 1. I don't demote the sg driver's GFP_ATOMIC to GFP_KERNEL. sg always > > > uses GFP_ATOMIC as before. > > > > > > 2. I don't remove GFP_DMA allocation. As before, sg allocates reserved > > > pages with GFP_DMA (sfp->low_dma case). > > > > > > 3. I keep the reserved buffer per struct sg_fd as before. > > > > > > 4. I use high-order page allocation for reserved buffer as before. sg > > > works well with HBAs that have the limitation of the number of sg > > > entries. > > > > > > 5. I think that you were concern about the overhead of the block layer > > > functions. But if you look at scsi_execute_async() that sg uses now, > > > you can find that scsi_execute_async() uses the block layer functions > > > internally. So the current sg incurs the overhead (if such overhead > > > exists). > > > > > > > > > Jens, > > > > > > I keep the block API changes to a minimum (I might need more changes > > > for st/osst but I'd like to progress step by step). I did only two > > > things. > > > > > > 1. I add gfp_mask argument to blk_rq_map_user and blk_rq_map_user_iov. > > > > > > 2. I introduces struct rq_map_data holding pages. sg puts > > > pre-allocated pages to it and passes it to bio_copy_user_iov(). The > > > current users of bio_copy_user_iov simply passes NULL. blk_rq_map_user > > > and blk_rq_map_user_iov take a pointer to struct rq_map_data and in > > > the end bio_copy_user_iov gets it. > > > > > > > > > This patchset against the for-linus branch in Jens' tree + the two > > > patches for 2.6.27: > > > > > > http://marc.info/?l=linux-kernel&m=121964251911717&w=2 > > > http://marc.info/?l=linux-kernel&m=121964241911611&w=2 > > > > > > After Jens rebases the for-2.6.28 brach, I'll update this patchset > > > too. > > > > Thanks a lot for doing this work, it's been pending for a long time. > > I've rebased for-2.6.28 on top of for-linus to ease this integration, so > > if you could resend the patchset then I can add it. > > Thanks, I put an updated version against the for-2.6.28 branch in your > tree: > > git://git.kernel.org/pub/scm/linux/kernel/git/tomo/linux-2.6-misc.git sg-block > > > Can you wait for a little while before applying this to your > for-2.6.28 branch? We need Doug's ACK on this. Sure, just let me know... > But I think that it's nice if you can send this to linux-next since > testing this patchset on linux-next is good. for-2.6.28 is already in linux-next, so once this gets applied it'll get tested there as well. And in -mm. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
