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new scsi-generic abstraction, use SG_IO (Christoph Hellwig)

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Okay, I started looking into how to handle scsi-generic I/O in the
new world order.

I think the best is to use the SG_IO ioctl instead of the read/write
interface as that allows us to support scsi passthrough on disk/cdrom
devices, too.  See Hannes patch on the kvm list from August for an
example.

Now that we always do ioctls we don't need another abstraction than
bdrv_ioctl for the synchronous requests for now, and for asynchronous
requests I've added a aio_ioctl abstraction keeping it simple.

Long-term we might want to move the ops to a higher-level abstraction
and let the low-level code fill out the request header, but I'm lazy
enough to leave that to the people trying to support scsi-passthrough
on a non-Linux OS.

Tested lightly by issuing various sg_ commands from sg3-utils in a guest
to a host CDROM device.


Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6895 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-03-28 17:28:41 +00:00
parent 64a7fde8e8
commit 221f715d90
7 changed files with 117 additions and 139 deletions
Download patch file Download diff file Expand all files Collapse all files

7
posix-aio-compat.h
View file

@ -29,12 +29,16 @@ struct qemu_paiocb
int aio_fildes;
void *aio_buf;
size_t aio_nbytes;
#define aio_ioctl_cmd aio_nbytes /* for QEMU_PAIO_IOCTL */
int ev_signo;
off_t aio_offset;
/* private */
TAILQ_ENTRY(qemu_paiocb) node;
int is_write;
int aio_type;
#define QEMU_PAIO_READ 0x01
#define QEMU_PAIO_WRITE 0x02
#define QEMU_PAIO_IOCTL 0x03
ssize_t ret;
int active;
};
@ -49,6 +53,7 @@ struct qemu_paioinit
int qemu_paio_init(struct qemu_paioinit *aioinit);
int qemu_paio_read(struct qemu_paiocb *aiocb);
int qemu_paio_write(struct qemu_paiocb *aiocb);
int qemu_paio_ioctl(struct qemu_paiocb *aiocb);
int qemu_paio_error(struct qemu_paiocb *aiocb);
ssize_t qemu_paio_return(struct qemu_paiocb *aiocb);
int qemu_paio_cancel(int fd, struct qemu_paiocb *aiocb);