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SubjectRe: [PATCH 14/17] scsi: replace custom rq mapping with blk_rq_map_kern_sgl()
On 04/01/2009 04:44 PM, Tejun Heo wrote:
> Impact: hack removal
>
> SCSI needs to map sgl into rq for kernel PC requests; however, block
> API didn't have such feature so it used its own rq mapping function
> which hooked into block/bio internals and is generally considered an
> ugly hack. The private function may also produce requests which are
> bigger than queue per-rq limits.
>
> Block blk_rq_map_kern_sgl(). Kill the private implementation and use
> it.
>
> Signed-off-by: Tejun Heo <tj@kernel.org>

James, TOMO

what happened to Tomo's patches that removes all this after fixing up
all users (sg.c)?

I thought that was agreed and done? What is left to do for that to go
in.

Thanks Boaz

> ---
> drivers/scsi/scsi_lib.c | 108 +----------------------------------------------
> 1 files changed, 1 insertions(+), 107 deletions(-)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 3196c83..3fa5589 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -296,112 +296,6 @@ static void scsi_end_async(struct request *req, int uptodate)
> __blk_put_request(req->q, req);
> }
>
> -static int scsi_merge_bio(struct request *rq, struct bio *bio)
> -{
> - struct request_queue *q = rq->q;
> -
> - bio->bi_flags &= ~(1 << BIO_SEG_VALID);
> - if (rq_data_dir(rq) == WRITE)
> - bio->bi_rw |= (1 << BIO_RW);
> - blk_queue_bounce(q, &bio);
> -
> - return blk_rq_append_bio(q, rq, bio);
> -}
> -
> -static void scsi_bi_endio(struct bio *bio, int error)
> -{
> - bio_put(bio);
> -}
> -
> -/**
> - * scsi_req_map_sg - map a scatterlist into a request
> - * @rq: request to fill
> - * @sgl: scatterlist
> - * @nsegs: number of elements
> - * @bufflen: len of buffer
> - * @gfp: memory allocation flags
> - *
> - * scsi_req_map_sg maps a scatterlist into a request so that the
> - * request can be sent to the block layer. We do not trust the scatterlist
> - * sent to use, as some ULDs use that struct to only organize the pages.
> - */
> -static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
> - int nsegs, unsigned bufflen, gfp_t gfp)
> -{
> - struct request_queue *q = rq->q;
> - int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
> - unsigned int data_len = bufflen, len, bytes, off;
> - struct scatterlist *sg;
> - struct page *page;
> - struct bio *bio = NULL;
> - int i, err, nr_vecs = 0;
> -
> - for_each_sg(sgl, sg, nsegs, i) {
> - page = sg_page(sg);
> - off = sg->offset;
> - len = sg->length;
> -
> - while (len > 0 && data_len > 0) {
> - /*
> - * sg sends a scatterlist that is larger than
> - * the data_len it wants transferred for certain
> - * IO sizes
> - */
> - bytes = min_t(unsigned int, len, PAGE_SIZE - off);
> - bytes = min(bytes, data_len);
> -
> - if (!bio) {
> - nr_vecs = min_t(int, BIO_GUARANTEED_PAGES,
> - nr_pages);
> - nr_pages -= nr_vecs;
> -
> - bio = bio_alloc(gfp, nr_vecs);
> - if (!bio) {
> - err = -ENOMEM;
> - goto free_bios;
> - }
> - bio->bi_end_io = scsi_bi_endio;
> - }
> -
> - if (bio_add_pc_page(q, bio, page, bytes, off) !=
> - bytes) {
> - bio_put(bio);
> - err = -EINVAL;
> - goto free_bios;
> - }
> -
> - if (bio->bi_vcnt >= nr_vecs) {
> - err = scsi_merge_bio(rq, bio);
> - if (err) {
> - bio_endio(bio, 0);
> - goto free_bios;
> - }
> - bio = NULL;
> - }
> -
> - page++;
> - len -= bytes;
> - data_len -=bytes;
> - off = 0;
> - }
> - }
> -
> - rq->buffer = rq->data = NULL;
> - rq->data_len = bufflen;
> - return 0;
> -
> -free_bios:
> - while ((bio = rq->bio) != NULL) {
> - rq->bio = bio->bi_next;
> - /*
> - * call endio instead of bio_put incase it was bounced
> - */
> - bio_endio(bio, 0);
> - }
> -
> - return err;
> -}
> -
> /**
> * scsi_execute_async - insert request
> * @sdev: scsi device
> @@ -438,7 +332,7 @@ int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
> req->cmd_flags |= REQ_QUIET;
>
> if (use_sg)
> - err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
> + err = blk_rq_map_kern_sg(req->q, req, buffer, use_sg, gfp);
> else if (bufflen)
> err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
>



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