block: introduce struct rq_map_data to use reserved pages

This patch introduces struct rq_map_data to enable bio_copy_use_iov()
use reserved pages.

Currently, bio_copy_user_iov allocates bounce pages but
drivers/scsi/sg.c wants to allocate pages by itself and use
them. struct rq_map_data can be used to pass allocated pages to
bio_copy_user_iov.

The current users of bio_copy_user_iov simply passes NULL (they don't
want to use pre-allocated pages).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Douglas Gilbert <dougg@torque.net>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/block/bsg.c b/block/bsg.c
index e7a142e9916c..56cb343c76d8 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -283,8 +283,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, int has_write_perm)
                 next_rq->cmd_type = rq->cmd_type;
 
                 dxferp = (void*)(unsigned long)hdr->din_xferp;
-                ret =  blk_rq_map_user(q, next_rq, dxferp, hdr->din_xfer_len,
-                                       GFP_KERNEL);
+                ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
+                                       hdr->din_xfer_len, GFP_KERNEL);
                 if (ret)
                         goto out;
         }
@@ -299,7 +299,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, int has_write_perm)
                 dxfer_len = 0;
 
         if (dxfer_len) {
-                ret = blk_rq_map_user(q, rq, dxferp, dxfer_len, GFP_KERNEL);
+                ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
+                                      GFP_KERNEL);
                 if (ret)
                         goto out;
         }