From e467cde238184d1b0923db2cd61ae1c5a6dc15aa Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 22 Oct 2007 11:03:38 +1000 Subject: Block driver using virtio. The block driver uses scatter-gather lists with sg[0] being the request information (struct virtio_blk_outhdr) with the type, sector and inbuf id. The next N sg entries are the bio itself, then the last sg is the status byte. Whether the N entries are in or out depends on whether it's a read or a write. We accept the normal (SCSI) ioctls: they get handed through to the other side which can then handle it or reply that it's unsupported. It's not clear that this actually works in general, since I don't know if blk_pc_request() requests have an accurate rq_data_dir(). Although we try to reply -ENOTTY on unsupported commands, ioctl(fd, CDROMEJECT) returns success to userspace. This needs a separate patch. Signed-off-by: Rusty Russell Cc: Jens Axboe --- include/linux/virtio_blk.h | 51 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 include/linux/virtio_blk.h (limited to 'include/linux/virtio_blk.h') diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h new file mode 100644 index 000000000000..7bd2bce0cfd9 --- /dev/null +++ b/include/linux/virtio_blk.h @@ -0,0 +1,51 @@ +#ifndef _LINUX_VIRTIO_BLK_H +#define _LINUX_VIRTIO_BLK_H +#include + +/* The ID for virtio_block */ +#define VIRTIO_ID_BLOCK 2 + +/* Feature bits */ +#define VIRTIO_CONFIG_BLK_F 0x40 +#define VIRTIO_BLK_F_BARRIER 1 /* Does host support barriers? */ + +/* The capacity (in 512-byte sectors). */ +#define VIRTIO_CONFIG_BLK_F_CAPACITY 0x41 +/* The maximum segment size. */ +#define VIRTIO_CONFIG_BLK_F_SIZE_MAX 0x42 +/* The maximum number of segments. */ +#define VIRTIO_CONFIG_BLK_F_SEG_MAX 0x43 + +/* These two define direction. */ +#define VIRTIO_BLK_T_IN 0 +#define VIRTIO_BLK_T_OUT 1 + +/* This bit says it's a scsi command, not an actual read or write. */ +#define VIRTIO_BLK_T_SCSI_CMD 2 + +/* Barrier before this op. */ +#define VIRTIO_BLK_T_BARRIER 0x80000000 + +/* This is the first element of the read scatter-gather list. */ +struct virtio_blk_outhdr +{ + /* VIRTIO_BLK_T* */ + __u32 type; + /* io priority. */ + __u32 ioprio; + /* Sector (ie. 512 byte offset) */ + __u64 sector; + /* Where to put reply. */ + __u64 id; +}; + +#define VIRTIO_BLK_S_OK 0 +#define VIRTIO_BLK_S_IOERR 1 +#define VIRTIO_BLK_S_UNSUPP 2 + +/* This is the first element of the write scatter-gather list */ +struct virtio_blk_inhdr +{ + unsigned char status; +}; +#endif /* _LINUX_VIRTIO_BLK_H */ -- cgit v1.2.1