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path: root/drivers/block/virtio_blk.c
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Diffstat (limited to 'drivers/block/virtio_blk.c')
-rw-r--r--drivers/block/virtio_blk.c64
1 files changed, 51 insertions, 13 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 258bc2ae288..23b7c48df84 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -225,16 +225,6 @@ static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
struct gendisk *disk = bdev->bd_disk;
struct virtio_blk *vblk = disk->private_data;
- if (cmd == 0x56424944) { /* 'VBID' */
- void __user *usr_data = (void __user *)data;
- char id_str[VIRTIO_BLK_ID_BYTES];
- int err;
-
- err = virtblk_get_id(disk, id_str);
- if (!err && copy_to_user(usr_data, id_str, VIRTIO_BLK_ID_BYTES))
- err = -EFAULT;
- return err;
- }
/*
* Only allow the generic SCSI ioctls if the host can support it.
*/
@@ -281,6 +271,27 @@ static int index_to_minor(int index)
return index << PART_BITS;
}
+static ssize_t virtblk_serial_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ int err;
+
+ /* sysfs gives us a PAGE_SIZE buffer */
+ BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
+
+ buf[VIRTIO_BLK_ID_BYTES] = '\0';
+ err = virtblk_get_id(disk, buf);
+ if (!err)
+ return strlen(buf);
+
+ if (err == -EIO) /* Unsupported? Make it empty. */
+ return 0;
+
+ return err;
+}
+DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
+
static int __devinit virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
@@ -366,12 +377,32 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
vblk->disk->driverfs_dev = &vdev->dev;
index++;
- /* If barriers are supported, tell block layer that queue is ordered */
- if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
+ if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) {
+ /*
+ * If the FLUSH feature is supported we do have support for
+ * flushing a volatile write cache on the host. Use that
+ * to implement write barrier support.
+ */
blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH,
virtblk_prepare_flush);
- else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
+ } else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) {
+ /*
+ * If the BARRIER feature is supported the host expects us
+ * to order request by tags. This implies there is not
+ * volatile write cache on the host, and that the host
+ * never re-orders outstanding I/O. This feature is not
+ * useful for real life scenarious and deprecated.
+ */
blk_queue_ordered(q, QUEUE_ORDERED_TAG, NULL);
+ } else {
+ /*
+ * If the FLUSH feature is not supported we must assume that
+ * the host does not perform any kind of volatile write
+ * caching. We still need to drain the queue to provider
+ * proper barrier semantics.
+ */
+ blk_queue_ordered(q, QUEUE_ORDERED_DRAIN, NULL);
+ }
/* If disk is read-only in the host, the guest should obey */
if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
@@ -445,8 +476,15 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
add_disk(vblk->disk);
+ err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
+ if (err)
+ goto out_del_disk;
+
return 0;
+out_del_disk:
+ del_gendisk(vblk->disk);
+ blk_cleanup_queue(vblk->disk->queue);
out_put_disk:
put_disk(vblk->disk);
out_mempool: