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Subject[PATCH 14/17] scsi: replace custom rq mapping with blk_rq_map_kern_sgl()
Date
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>
---
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);

--
1.6.0.2


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