[PATCH] Add scatter-gather support for the block layer SG_IO

Signed-off-by: Jens Axboe <axboe@suse.de>

1 files changed, 23 insertions, 11 deletions

diff --git a/drivers/block/scsi_ioctl.c b/drivers/block/scsi_ioctl.c
index 93c4ca874be3..09a7e73a0812 100644
--- a/drivers/block/scsi_ioctl.c
+++ b/drivers/block/scsi_ioctl.c
@@ -231,17 +231,11 @@ static int sg_io(struct file *file, request_queue_t *q,
         if (verify_command(file, cmd))
                 return -EPERM;
 
-        /*
-         * we'll do that later
-         */
-        if (hdr->iovec_count)
-                return -EOPNOTSUPP;
-
         if (hdr->dxfer_len > (q->max_sectors << 9))
                 return -EIO;
 
         reading = writing = 0;
-        if (hdr->dxfer_len) {
+        if (hdr->dxfer_len)
                 switch (hdr->dxfer_direction) {
                 default:
                         return -EINVAL;
@@ -261,11 +255,29 @@ static int sg_io(struct file *file, request_queue_t *q,
         if (!rq)
                 return -ENOMEM;
 
-        if (reading || writing) {
-                ret = blk_rq_map_user(q, rq, hdr->dxferp, hdr->dxfer_len);
-                if (ret)
+        if (hdr->iovec_count) {
+                const int size = sizeof(struct sg_iovec) * hdr->iovec_count;
+                struct sg_iovec *iov;
+
+                iov = kmalloc(size, GFP_KERNEL);
+                if (!iov) {
+                        ret = -ENOMEM;
                         goto out;
-        }
+                }
+
+                if (copy_from_user(iov, hdr->dxferp, size)) {
+                        kfree(iov);
+                        ret = -EFAULT;
+                        goto out;
+                }
+
+                ret = blk_rq_map_user_iov(q, rq, iov, hdr->iovec_count);
+                kfree(iov);
+        } else if (hdr->dxfer_len)
+                ret = blk_rq_map_user(q, rq, hdr->dxferp, hdr->dxfer_len);
+
+        if (ret)
+                goto out;
 
         /*
          * fill in request structure