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Add specialized block driver scsi generic API (Avi Kivity) 

When a scsi device is backed by a scsi generic device instead of an
ordinary host block device, the block API is abused in a couple of annoying
ways:

 - nb_sectors is negative, and specifies a byte count instead of a sector count
 - offset is ignored, since scsi-generic is essentially a packet protocol

This overloading makes hacking the block layer difficult.  Remove it by
introducing a new explicit API for scsi-generic devices.  The new API
is still backed by the old implementation, but at least the users are
insulated.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6822 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-03-12 19:57:08 +00:00
parent 943984c7a5
commit 7d78066926
3 changed files with 52 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
block.c
View File

@ -1675,3 +1675,25 @@ int bdrv_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
return drv->bdrv_ioctl(bs, req, buf);
return -ENOTSUP;
}
int bdrv_sg_send_command(BlockDriverState *bs, void *buf, int count)
{
return bdrv_pwrite(bs, -1, buf, count);
}
int bdrv_sg_recv_response(BlockDriverState *bs, void *buf, int count)
{
return bdrv_pread(bs, -1, buf, count);
}
BlockDriverAIOCB *bdrv_sg_aio_read(BlockDriverState *bs, void *buf, int count,
BlockDriverCompletionFunc *cb, void *opaque)
{
return bdrv_aio_read(bs, 0, buf, -(int64_t)count, cb, opaque);
}
BlockDriverAIOCB *bdrv_sg_aio_write(BlockDriverState *bs, void *buf, int count,
BlockDriverCompletionFunc *cb, void *opaque)
{
return bdrv_aio_write(bs, 0, buf, -(int64_t)count, cb, opaque);
}

8
block.h
View File

@ -101,6 +101,14 @@ BlockDriverAIOCB *bdrv_aio_write(BlockDriverState *bs, int64_t sector_num,
BlockDriverCompletionFunc *cb, void *opaque);
void bdrv_aio_cancel(BlockDriverAIOCB *acb);
/* sg packet commands */
int bdrv_sg_send_command(BlockDriverState *bs, void *buf, int count);
int bdrv_sg_recv_response(BlockDriverState *bs, void *buf, int count);
BlockDriverAIOCB *bdrv_sg_aio_read(BlockDriverState *bs, void *buf, int count,
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *bdrv_sg_aio_write(BlockDriverState *bs, void *buf, int count,
BlockDriverCompletionFunc *cb, void *opaque);
/* Ensure contents are flushed to disk. */
void bdrv_flush(BlockDriverState *bs);
void bdrv_flush_all(void);

39
hw/scsi-generic.c
View File

@ -201,6 +201,7 @@ static int execute_command(BlockDriverState *bdrv,
SCSIRequest *r, int direction,
BlockDriverCompletionFunc *complete)
{
int ret;
r->io_header.interface_id = 'S';
r->io_header.dxfer_direction = direction;
@ -214,25 +215,27 @@ static int execute_command(BlockDriverState *bdrv,
r->io_header.usr_ptr = r;
r->io_header.flags |= SG_FLAG_DIRECT_IO;
if (bdrv_pwrite(bdrv, -1, &r->io_header, sizeof(r->io_header)) == -1) {
ret = bdrv_sg_send_command(bdrv, &r->io_header, sizeof(r->io_header));
if (ret < 0) {
BADF("execute_command: write failed ! (%d)\n", errno);
return -1;
}
if (complete == NULL) {
int ret;
r->aiocb = NULL;
while ((ret = bdrv_pread(bdrv, -1, &r->io_header,
sizeof(r->io_header))) == -1 &&
errno == EINTR);
if (ret == -1) {
while ((ret = bdrv_sg_recv_response(bdrv, &r->io_header,
sizeof(r->io_header))) < 0 &&
ret == -EINTR)
;
if (ret < 0) {
BADF("execute_command: read failed !\n");
return -1;
}
return 0;
}
r->aiocb = bdrv_aio_read(bdrv, 0, (uint8_t*)&r->io_header,
-(int64_t)sizeof(r->io_header), complete, r);
r->aiocb = bdrv_sg_aio_read(bdrv, (uint8_t*)&r->io_header,
sizeof(r->io_header), complete, r);
if (r->aiocb == NULL) {
BADF("execute_command: read failed !\n");
return -1;
@ -634,14 +637,15 @@ static int get_blocksize(BlockDriverState *bdrv)
io_header.sbp = sensebuf;
io_header.timeout = 6000; /* XXX */
ret = bdrv_pwrite(bdrv, -1, &io_header, sizeof(io_header));
if (ret == -1)
ret = bdrv_sg_send_command(bdrv, &io_header, sizeof(io_header));
if (ret < 0)
return -1;
while ((ret = bdrv_pread(bdrv, -1, &io_header, sizeof(io_header))) == -1 &&
errno == EINTR);
while ((ret = bdrv_sg_recv_response(bdrv, &io_header, sizeof(io_header))) < 0 &&
ret == -EINTR)
;
if (ret == -1)
if (ret < 0)
return -1;
return (buf[4] << 24) | (buf[5] << 16) | (buf[6] << 8) | buf[7];
@ -671,14 +675,15 @@ static int get_stream_blocksize(BlockDriverState *bdrv)
io_header.sbp = sensebuf;
io_header.timeout = 6000; /* XXX */
ret = bdrv_pwrite(bdrv, -1, &io_header, sizeof(io_header));
if (ret == -1)
ret = bdrv_sg_send_command(bdrv, &io_header, sizeof(io_header));
if (ret < 0)
return -1;
while ((ret = bdrv_pread(bdrv, -1, &io_header, sizeof(io_header))) == -1 &&
errno == EINTR);
while ((ret = bdrv_sg_recv_response(bdrv, &io_header, sizeof(io_header))) < 0 &&
ret == -EINTR)
;
if (ret == -1)
if (ret < 0)
return -1;
return (buf[9] << 16) | (buf[10] << 8) | buf[11];