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ISCSI: force use of sg for SMC and SSC devices

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If the device we open is a SMC or SSC device, then force the use of sg. We
dont have any medium changer or tape emulation so only passthrough via
real sg or scsi-generic via iscsi would work anyway.

Forcing sg also makes qemu skip trying to read from the device to guess
the image format by reading from the device (find_image_format()).
SMC devices do not implement READ6/10/12/16 so it is not possible to
read from them (SSC have different CDBs).

With this patch I can successfully manage a SMC device wiht iscsi in
passthrough mode.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
[Added TYPE_TAPE handling - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ronnie Sahlberg 2012-05-26 14:56:41 +10:00 committed by Paolo Bonzini
parent 983924532f
commit 622695a458
1 changed files with 10 additions and 0 deletions
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10
block/iscsi.c
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@ -1022,6 +1022,16 @@ static int iscsi_open(BlockDriverState *bs, const char *filename, int flags)
if (iscsi_url != NULL) {
iscsi_destroy_url(iscsi_url);
}
/* Medium changer or tape. We dont have any emulation for this so this must
* be sg ioctl compatible. We force it to be sg, otherwise qemu will try
* to read from the device to guess the image format.
*/
if (iscsilun->type == TYPE_MEDIUM_CHANGER ||
iscsilun->type == TYPE_TAPE) {
bs->sg = 1;
}
return 0;
failed: