Re: [Qemu-devel] [PATCH 2/2] Add serial number support for virtio_blk, V3

[Christoph Hellwig]

You should probably include rusty as he's collecting the patches
for the virtio guest drivers.

Also can you send the patch inline next time? That makes quoting it for
review a lot easier.


 drivers/block/virtio_blk.c |   32 +++++++++++++++++++++++++++++---
 include/linux/virtio_blk.h |    6 ++++++
 2 files changed, 35 insertions(+), 3 deletions(-)
=================================================================
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -146,12 +146,37 @@ static void do_virtblk_request(struct re
                vblk->vq->vq_ops->kick(vblk->vq);
 }
 
+/* return serial# in IDE identify data (all other fields are currently zero)
+ */
+static int virtblk_identity(struct block_device *bdev, void *buf)
+{
+       struct virtio_blk *vblk = bdev->bd_disk->private_data;
+       u16 *id;
+       int rv;
+
+       if (!(id = kzalloc(ATA_ID_WORDS, GFP_KERNEL)))
+               rv = -ENOMEM;
+       else if ((rv = virtio_config_buf(vblk->vdev, VIRTIO_BLK_F_SN,
+               offsetof(struct virtio_blk_config, serial), &id[ATA_ID_SERNO],
+               ATA_ID_SERNO_LEN)))
+                       ;
+       else if (copy_to_user(buf, id, ATA_ID_WORDS))
+               rv = -EFAULT;
+       else
+               rv = 0;
+       if (id)
+               kfree(id);
+        return (rv);
+}
+
 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
                         unsigned cmd, unsigned long data)
 {
-       return scsi_cmd_ioctl(bdev->bd_disk->queue,
-                             bdev->bd_disk, mode, cmd,
-                             (void __user *)data);
+       if (cmd == HDIO_GET_IDENTITY)
+               return (virtblk_identity(bdev, (void __user *)data));
+       else
+               return scsi_cmd_ioctl(bdev->bd_disk->queue, bdev->bd_disk,
+                       mode, cmd, (void __user *)data);
 }
 

This looks functionally correct, but pretty far from normal kernel coding
style.  I'd envision something like this instead:

/*
 * IDE-compatible identify ioctl.
 *
 * Currenlyt only returns the serial number and leaves all other fields
 * zero.
 */
static int virtblk_identity(struct gendisk *disk, void *argp)
{
        struct virtio_blk *vblk = disk->private_data;
        u16 *id;
        int error = -ENOMEM;

        id = kzalloc(ATA_ID_WORDS, GFP_KERNEL)
        if (!id)
                goto out;

        error = virtio_config_buf(vblk->vdev, VIRTIO_BLK_F_SN,
                                  offsetof(struct virtio_blk_config, serial),
                                  &id[ATA_ID_SERNO], ATA_ID_SERNO_LEN);
        if (error)
                goto out_kfree;

        if (copy_to_user(argp, id, ATA_ID_WORDS))
                error = -EFAULT;

out_kfree:
        kfree(id);
out:
        return error;
}


static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
                         unsigned cmd, unsigned long arg)
{
        struct gendisk *disk = bdev->bd_disk;
        void __user *argp = (void __user *arg);

        switch (cmd) {
        case HDIO_GET_IDENTITY:
                return virtblk_identity(disk, argp);
        default:
                return scsi_cmd_ioctl(disk->queue, disk, mode, cmd, argp);
        }
}