bsg: add bidi support

bsg uses the rq->next_rq pointer for a bidi request.

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

1 files changed, 49 insertions, 25 deletions

diff --git a/block/bsg.c b/block/bsg.c
index 5f4abc902a00..13ecc951a4c0 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -95,6 +95,7 @@ struct bsg_command {
         struct list_head list;
         struct request *rq;
         struct bio *bio;
+        struct bio *bidi_bio;
         int err;
         struct sg_io_v4 hdr;
         struct sg_io_v4 __user *uhdr;
@@ -243,16 +244,6 @@ bsg_validate_sgv4_hdr(request_queue_t *q, struct sg_io_v4 *hdr, int *rw)
         if (hdr->protocol || hdr->subprotocol)
                 return -EINVAL;
 
-        /*
-         * looks sane, if no data then it should be fine from our POV
-         */
-        if (!hdr->dout_xfer_len && !hdr->din_xfer_len)
-                return 0;
-
-        /* not supported currently */
-        if (hdr->dout_xfer_len && hdr->din_xfer_len)
-                return -EINVAL;
-
         *rw = hdr->dout_xfer_len ? WRITE : READ;
 
         return 0;
@@ -265,7 +256,7 @@ static struct request *
 bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
 {
         request_queue_t *q = bd->queue;
-        struct request *rq;
+        struct request *rq, *next_rq = NULL;
         int ret, rw = 0; /* shut up gcc */
         unsigned int dxfer_len;
         void *dxferp = NULL;
@@ -282,11 +273,30 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
          * map scatter-gather elements seperately and string them to request
          */
         rq = blk_get_request(q, rw, GFP_KERNEL);
+        if (!rq)
+                return ERR_PTR(-ENOMEM);
         ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, test_bit(BSG_F_WRITE_PERM,
                                                        &bd->flags));
-        if (ret) {
-                blk_put_request(rq);
-                return ERR_PTR(ret);
+        if (ret)
+                goto out;
+
+        if (rw == WRITE && hdr->din_xfer_len) {
+                if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
+                        ret = -EOPNOTSUPP;
+                        goto out;
+                }
+
+                next_rq = blk_get_request(q, READ, GFP_KERNEL);
+                if (!next_rq) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+                rq->next_rq = next_rq;
+
+                dxferp = (void*)(unsigned long)hdr->din_xferp;
+                ret =  blk_rq_map_user(q, next_rq, dxferp, hdr->din_xfer_len);
+                if (ret)
+                        goto out;
         }
 
         if (hdr->dout_xfer_len) {
@@ -300,14 +310,17 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
 
         if (dxfer_len) {
                 ret = blk_rq_map_user(q, rq, dxferp, dxfer_len);
-                if (ret) {
-                        dprintk("failed map at %d\n", ret);
-                        blk_put_request(rq);
-                        rq = ERR_PTR(ret);
-                }
+                if (ret)
+                        goto out;
         }
-
         return rq;
+out:
+        blk_put_request(rq);
+        if (next_rq) {
+                blk_rq_unmap_user(next_rq->bio);
+                blk_put_request(next_rq);
+        }
+        return ERR_PTR(ret);
 }
 
 /*
@@ -346,6 +359,8 @@ static void bsg_add_command(struct bsg_device *bd, request_queue_t *q,
          */
         bc->rq = rq;
         bc->bio = rq->bio;
+        if (rq->next_rq)
+                bc->bidi_bio = rq->next_rq->bio;
         bc->hdr.duration = jiffies;
         spin_lock_irq(&bd->lock);
         list_add_tail(&bc->list, &bd->busy_list);
@@ -402,7 +417,7 @@ static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
 }
 
 static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
-                                    struct bio *bio)
+                                    struct bio *bio, struct bio *bidi_bio)
 {
         int ret = 0;
 
@@ -431,6 +446,11 @@ static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
                         ret = -EFAULT;
         }
 
+        if (rq->next_rq) {
+                blk_rq_unmap_user(bidi_bio);
+                blk_put_request(rq->next_rq);
+        }
+
         blk_rq_unmap_user(bio);
         blk_put_request(rq);
 
@@ -477,7 +497,8 @@ static int bsg_complete_all_commands(struct bsg_device *bd)
                 if (IS_ERR(bc))
                         break;
 
-                tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio);
+                tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
+                                                bc->bidi_bio);
                 if (!ret)
                         ret = tret;
 
@@ -511,7 +532,8 @@ __bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
                  * after completing the request. so do that here,
                  * bsg_complete_work() cannot do that for us
                  */
-                ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio);
+                ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
+                                               bc->bidi_bio);
 
                 if (copy_to_user(buf, (char *) &bc->hdr, sizeof(bc->hdr)))
                         ret = -EFAULT;
@@ -868,7 +890,7 @@ bsg_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
         }
         case SG_IO: {
                 struct request *rq;
-                struct bio *bio;
+                struct bio *bio, *bidi_bio = NULL;
                 struct sg_io_v4 hdr;
 
                 if (copy_from_user(&hdr, uarg, sizeof(hdr)))
@@ -879,8 +901,10 @@ bsg_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
                         return PTR_ERR(rq);
 
                 bio = rq->bio;
+                if (rq->next_rq)
+                        bidi_bio = rq->next_rq->bio;
                 blk_execute_rq(bd->queue, NULL, rq, 0);
-                blk_complete_sgv4_hdr_rq(rq, &hdr, bio);
+                blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 
                 if (copy_to_user(uarg, &hdr, sizeof(hdr)))
                         return -EFAULT;