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e467cde238
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>
51 lines
1.2 KiB
C
51 lines
1.2 KiB
C
#ifndef _LINUX_VIRTIO_BLK_H
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#define _LINUX_VIRTIO_BLK_H
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#include <linux/virtio_config.h>
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/* The ID for virtio_block */
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#define VIRTIO_ID_BLOCK 2
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/* Feature bits */
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#define VIRTIO_CONFIG_BLK_F 0x40
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#define VIRTIO_BLK_F_BARRIER 1 /* Does host support barriers? */
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/* The capacity (in 512-byte sectors). */
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#define VIRTIO_CONFIG_BLK_F_CAPACITY 0x41
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/* The maximum segment size. */
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#define VIRTIO_CONFIG_BLK_F_SIZE_MAX 0x42
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/* The maximum number of segments. */
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#define VIRTIO_CONFIG_BLK_F_SEG_MAX 0x43
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/* These two define direction. */
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#define VIRTIO_BLK_T_IN 0
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#define VIRTIO_BLK_T_OUT 1
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/* This bit says it's a scsi command, not an actual read or write. */
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#define VIRTIO_BLK_T_SCSI_CMD 2
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/* Barrier before this op. */
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#define VIRTIO_BLK_T_BARRIER 0x80000000
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/* This is the first element of the read scatter-gather list. */
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struct virtio_blk_outhdr
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{
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/* VIRTIO_BLK_T* */
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__u32 type;
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/* io priority. */
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__u32 ioprio;
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/* Sector (ie. 512 byte offset) */
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__u64 sector;
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/* Where to put reply. */
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__u64 id;
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};
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#define VIRTIO_BLK_S_OK 0
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#define VIRTIO_BLK_S_IOERR 1
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#define VIRTIO_BLK_S_UNSUPP 2
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/* This is the first element of the write scatter-gather list */
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struct virtio_blk_inhdr
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{
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unsigned char status;
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};
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#endif /* _LINUX_VIRTIO_BLK_H */
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