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authorRusty Russell <rusty@rustcorp.com.au>2007-10-22 11:03:38 +1000
committerRusty Russell <rusty@rustcorp.com.au>2007-10-23 15:49:54 +1000
commite467cde238184d1b0923db2cd61ae1c5a6dc15aa (patch)
tree1383321c88ca25fcad20f56f14a8ca658bb25fb3 /include/linux/virtio_blk.h
parent296f96fcfc160e29c01819c0c7b20c2dc8320edd (diff)
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 <rusty@rustcorp.com.au> Cc: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'include/linux/virtio_blk.h')
-rw-r--r--include/linux/virtio_blk.h51
1 files changed, 51 insertions, 0 deletions
diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
new file mode 100644
index 00000000000..7bd2bce0cfd
--- /dev/null
+++ b/include/linux/virtio_blk.h
@@ -0,0 +1,51 @@
+#ifndef _LINUX_VIRTIO_BLK_H
+#define _LINUX_VIRTIO_BLK_H
+#include <linux/virtio_config.h>
+
+/* 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 */