[SCSI] block: make blk_rq_map_user take a NULL user-space buffer for WRITE

The commit 818827669d85b84241696ffef2de485db46b0b5e (block: make
blk_rq_map_user take a NULL user-space buffer) extended
blk_rq_map_user to accept a NULL user-space buffer with a READ
command. It was necessary to convert sg to use the block layer mapping
API.

This patch extends blk_rq_map_user again for a WRITE command. It is
necessary to convert st and osst drivers to use the block layer
apping API.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

4 files changed, 10 insertions, 10 deletions

diff --git a/block/blk-map.c b/block/blk-map.c
index c7e55b23a2bc..f103729b462f 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -42,7 +42,7 @@ static int __blk_rq_unmap_user(struct bio *bio)
 
 static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
                              struct rq_map_data *map_data, void __user *ubuf,
-                             unsigned int len, int null_mapped, gfp_t gfp_mask)
+                             unsigned int len, gfp_t gfp_mask)
 {
         unsigned long uaddr;
         struct bio *bio, *orig_bio;
@@ -63,7 +63,7 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
         if (IS_ERR(bio))
                 return PTR_ERR(bio);
 
-        if (null_mapped)
+        if (map_data && map_data->null_mapped)
                 bio->bi_flags |= (1 << BIO_NULL_MAPPED);
 
         orig_bio = bio;
@@ -114,17 +114,15 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
 {
         unsigned long bytes_read = 0;
         struct bio *bio = NULL;
-        int ret, null_mapped = 0;
+        int ret;
 
         if (len > (q->max_hw_sectors << 9))
                 return -EINVAL;
         if (!len)
                 return -EINVAL;
-        if (!ubuf) {
-                if (!map_data || rq_data_dir(rq) != READ)
-                        return -EINVAL;
-                null_mapped = 1;
-        }
+
+        if (!ubuf && (!map_data || !map_data->null_mapped))
+                return -EINVAL;
 
         while (bytes_read != len) {
                 unsigned long map_len, end, start;
@@ -143,7 +141,7 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
                         map_len -= PAGE_SIZE;
 
                 ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,
-                                        null_mapped, gfp_mask);
+                                        gfp_mask);
                 if (ret < 0)
                         goto unmap_rq;
                 if (!bio)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 7d0b3d9ee43b..8f0bd3f7a59f 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1670,6 +1670,7 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd)
                 md->page_order = req_schp->page_order;
                 md->nr_entries = req_schp->k_use_sg;
                 md->offset = 0;
+                md->null_mapped = hp->dxferp ? 0 : 1;
         }
 
         if (iov_count)
diff --git a/fs/bio.c b/fs/bio.c
index 13be075806b6..062299acbccd 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -859,7 +859,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
         /*
          * success
          */
-        if (!write_to_vm) {
+        if (!write_to_vm && (!map_data || !map_data->null_mapped)) {
                 ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 0);
                 if (ret)
                         goto cleanup;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 811e5342c452..044467ef7b11 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -691,6 +691,7 @@ struct rq_map_data {
         int page_order;
         int nr_entries;
         unsigned long offset;
+        int null_mapped;
 };
 
 struct req_iterator {