On 2014-10-25 at 17:16, Peter Lieven wrote:
Am 23.10.2014 um 13:18 schrieb Max Reitz:
On 2014-10-16 at 09:54, Peter Lieven wrote:
the limit of 0xffffff for 16 byte CDBs is intentional to
avoid overflows on 32-bit architectures.
How is it related to 32 bit? I somehow feel like it has to do something with
the result of sector_lun2qemu() which involves block_size...
iscsilun->bl.max_xfer_len is 32-bit unsigned while nb_sectors is usually
signed. Furthermore as you suspected nb_sectors is always 512Byte sectors
while iscsilun->block_size can be 4k or even more.
I will change the code to set max_xfer_len to 0xffffffff and limit the output of
sector_lun2qemu() to INT_MAX in the bs->bl.max_transfer_length case.
However, in real life you will never want to have a transfer of 0x3fffffff
blocks, won't you?
I'd be fine with a single block, but QEMU guests matter more than me. :-)
I was just wondering how you ended up with 2^24 - 1 as it would be (2^32
- 1) / 256. I do remember IDE doing 16-bit-transfers, so I could imagine
how this works out with 512 byte sector size, but this isn't IDE, so...
(sorry, it's been a while since I worked with the SCSI protocol myself)
Max
Peter
Signed-off-by: Peter Lieven <p...@kamp.de>
Reviewed-by: Ronnie Sahlberg <ronniesahlb...@gmail.com>
---
block/iscsi.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/block/iscsi.c b/block/iscsi.c
index 3a01de0..c873d13 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -1449,10 +1449,18 @@ static void iscsi_close(BlockDriverState *bs)
static void iscsi_refresh_limits(BlockDriverState *bs, Error **errp)
{
- IscsiLun *iscsilun = bs->opaque;
-
/* We don't actually refresh here, but just return data queried in
* iscsi_open(): iscsi targets don't change their limits. */
+
+ IscsiLun *iscsilun = bs->opaque;
+ uint32_t max_xfer_len = iscsilun->use_16_for_rw ? 0xffffff : 0xffff;
+
+ if (iscsilun->bl.max_xfer_len) {
+ max_xfer_len = MIN(max_xfer_len, iscsilun->bl.max_xfer_len);
+ }
+
+ bs->bl.max_transfer_length = sector_lun2qemu(max_xfer_len, iscsilun);
+
if (iscsilun->lbp.lbpu) {
if (iscsilun->bl.max_unmap < 0xffffffff) {
bs->bl.max_discard = sector_lun2qemu(iscsilun->bl.max_unmap,
