diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 774c31dce7c0..c0bbeb470754 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -395,6 +395,83 @@ static int virtblk_name_format(char *prefix, int index, char *buf, int buflen) return 0; } +static int virtblk_get_cache_mode(struct virtio_device *vdev) +{ + u8 writeback; + int err; + + err = virtio_config_val(vdev, VIRTIO_BLK_F_CONFIG_WCE, + offsetof(struct virtio_blk_config, wce), + &writeback); + if (err) + writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE); + + return writeback; +} + +static void virtblk_update_cache_mode(struct virtio_device *vdev) +{ + u8 writeback = virtblk_get_cache_mode(vdev); + struct virtio_blk *vblk = vdev->priv; + + if (writeback) + blk_queue_flush(vblk->disk->queue, REQ_FLUSH); + else + blk_queue_flush(vblk->disk->queue, 0); + + revalidate_disk(vblk->disk); +} + +static const char *const virtblk_cache_types[] = { + "write through", "write back" +}; + +static ssize_t +virtblk_cache_type_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct gendisk *disk = dev_to_disk(dev); + struct virtio_blk *vblk = disk->private_data; + struct virtio_device *vdev = vblk->vdev; + int i; + u8 writeback; + + BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE)); + for (i = ARRAY_SIZE(virtblk_cache_types); --i >= 0; ) + if (sysfs_streq(buf, virtblk_cache_types[i])) + break; + + if (i < 0) + return -EINVAL; + + writeback = i; + vdev->config->set(vdev, + offsetof(struct virtio_blk_config, wce), + &writeback, sizeof(writeback)); + + virtblk_update_cache_mode(vdev); + return count; +} + +static ssize_t +virtblk_cache_type_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct gendisk *disk = dev_to_disk(dev); + struct virtio_blk *vblk = disk->private_data; + u8 writeback = virtblk_get_cache_mode(vblk->vdev); + + BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types)); + return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]); +} + +static const struct device_attribute dev_attr_cache_type_ro = + __ATTR(cache_type, S_IRUGO, + virtblk_cache_type_show, NULL); +static const struct device_attribute dev_attr_cache_type_rw = + __ATTR(cache_type, S_IRUGO|S_IWUSR, + virtblk_cache_type_show, virtblk_cache_type_store); + static int __devinit virtblk_probe(struct virtio_device *vdev) { struct virtio_blk *vblk; @@ -471,8 +548,7 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) vblk->index = index; /* configure queue flush support */ - if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) - blk_queue_flush(q, REQ_FLUSH); + virtblk_update_cache_mode(vdev); /* If disk is read-only in the host, the guest should obey */ if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) @@ -550,6 +626,14 @@ static int __devinit virtblk_probe(struct virtio_device *vdev) if (err) goto out_del_disk; + if (virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE)) + err = device_create_file(disk_to_dev(vblk->disk), + &dev_attr_cache_type_rw); + else + err = device_create_file(disk_to_dev(vblk->disk), + &dev_attr_cache_type_ro); + if (err) + goto out_del_disk; return 0; out_del_disk: @@ -642,7 +726,7 @@ static const struct virtio_device_id id_table[] = { static unsigned int features[] = { VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI, - VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY + VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE }; /* diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h index e0edb40ca7aa..e2aba15f545d 100644 --- a/include/linux/virtio_blk.h +++ b/include/linux/virtio_blk.h @@ -37,8 +37,9 @@ #define VIRTIO_BLK_F_RO 5 /* Disk is read-only */ #define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/ #define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */ -#define VIRTIO_BLK_F_FLUSH 9 /* Cache flush command support */ +#define VIRTIO_BLK_F_WCE 9 /* Writeback mode enabled after reset */ #define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */ +#define VIRTIO_BLK_F_CONFIG_WCE 11 /* Writeback mode available in config */ #define VIRTIO_BLK_ID_BYTES 20 /* ID string length */ @@ -69,6 +70,8 @@ struct virtio_blk_config { /* optimal sustained I/O size in logical blocks. */ __u32 opt_io_size; + /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */ + __u8 wce; } __attribute__((packed)); /*