Hey Christoph, Adding CC' for MKP. On Wed, 2015-01-07 at 00:24 +0000, Nicholas A. Bellinger wrote: > From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> > > This patch avoids the arbitrary limiting of I/O size to fabric_max_sectors, > which currently has a hardcoded max of 8192 (4 MB for 512 byte sector > devices). > > This is problematic because Linux initiators have only recently started > to honor block limits MAXIMUM TRANSFER LENGTH, and other non-Linux based > initiators (eg: Fibre Channel) can also generate I/Os larger than 4 MB. > > Currently when this happens, the following message will appear on the > target resulting in I/Os being returned with non recoverable status: > > SCSI OP 28h with too big sectors 16384 exceeds fabric_max_sectors: 8192 > > Instead, use the existing hw_max_sectors value to determine the maximum > sized I/O the backend is capable of supporting. Also, change IBLOCK > backend driver to set hw_max_sectors based on queue_max_hw_sectors(), > instead of UINT_MAX. > > Reported-by: Lance Gropper <lance.gropper@xxxxxxxxxxxxx> > Reported-by: Stefan Priebe <s.priebe@xxxxxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Roland Dreier <roland@xxxxxxxxxxxxxxx> > Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> > --- > drivers/target/target_core_device.c | 8 ++++---- > drivers/target/target_core_iblock.c | 2 +- > drivers/target/target_core_sbc.c | 7 ------- > drivers/target/target_core_spc.c | 5 +---- > 4 files changed, 6 insertions(+), 16 deletions(-) > <SNIP> > diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c > index 3efff94..5795cd8 100644 > --- a/drivers/target/target_core_iblock.c > +++ b/drivers/target/target_core_iblock.c > @@ -124,7 +124,7 @@ static int iblock_configure_device(struct se_device *dev) > q = bdev_get_queue(bd); > > dev->dev_attrib.hw_block_size = bdev_logical_block_size(bd); > - dev->dev_attrib.hw_max_sectors = UINT_MAX; > + dev->dev_attrib.hw_max_sectors = queue_max_hw_sectors(q); > dev->dev_attrib.hw_queue_depth = q->nr_requests; > > /* After thinking about this a bit more, I'm starting to have second thoughts about using queue_max_hw_sectors() to set hw_max_sectors for IBLOCK. IIRC, most modern hardware is reporting a large enough value for queue_max_hw_sectors() to support 8 MB I/Os, but I'm thinking that this could end up being problematic for older hardware that is reporting much smaller values. Is there any reason why the underlying queue_max_hw_sectors() is going to trigger an -EIO failure in generic_make_request_checks() when a IBLOCK dispatched bio exceeds the reported size..? What are your thoughts for a sane default here..? --nab -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
