block: remove struct request buffer member

This was used in the olden days, back when onions were proper
yellow. Basically it mapped to the current buffer to be
transferred. With highmem being added more than a decade ago,
most drivers map pages out of a bio, and rq->buffer isn't
pointing at anything valid.

Convert old style drivers to just use bio_data().

For the discard payload use case, just reference the page
in the bio.

Signed-off-by: Jens Axboe <axboe@fb.com>

2 files changed, 4 insertions, 9 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 0f3bddcb6b1a..3cc82d3dec78 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1018,8 +1018,6 @@ static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
                 return BLKPREP_DEFER;
         }
 
-        req->buffer = NULL;
-
         /* 
          * Next, walk the list, and fill in the addresses and sizes of
          * each segment.
@@ -1156,7 +1154,6 @@ int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
                 BUG_ON(blk_rq_bytes(req));
 
                 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
-                req->buffer = NULL;
         }
 
         cmd->cmd_len = req->cmd_len;
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index efcbcd182863..06d154d20faa 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -739,14 +739,11 @@ static int sd_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
 
         blk_add_request_payload(rq, page, len);
         ret = scsi_setup_blk_pc_cmnd(sdp, rq);
-        rq->buffer = page_address(page);
         rq->__data_len = nr_bytes;
 
 out:
-        if (ret != BLKPREP_OK) {
+        if (ret != BLKPREP_OK)
                 __free_page(page);
-                rq->buffer = NULL;
-        }
         return ret;
 }
 
@@ -843,8 +840,9 @@ static void sd_unprep_fn(struct request_queue *q, struct request *rq)
         struct scsi_cmnd *SCpnt = rq->special;
 
         if (rq->cmd_flags & REQ_DISCARD) {
-                free_page((unsigned long)rq->buffer);
-                rq->buffer = NULL;
+                struct bio *bio = rq->bio;
+
+                __free_page(bio->bi_io_vec->bv_page);
         }
         if (SCpnt->cmnd != rq->cmd) {
                 mempool_free(SCpnt->cmnd, sd_cdb_pool);