goggin, edward wrote:
On Thu, 07 Jul 2005 23:19:57 -0500
Mike Christie <michaelc@xxxxxxxxxxx> wrote
...
The bio handling for these REQ_BLOCK_PC requests shouldn't be
treated any
differently than the more typical REQ_CMD type block io request.
what is meant by this last comment specifically?
Just trying to make a case that a device pass through read command
issued to a block device should transfer to user space only the
user requested number of bytes minus the residual from the transfer
(as is done for block device read and write requests) and not always
transfer the number of bytes requested by the user.
ah ok, I thought it was referring to something else, nevermind.
Was the reason it does SG_IO reads becuase opens on the device were not
allowed? Was not being able to open a dm device a bug or by design? For
devices that do not support SG_IO like NBD, dasd and if you do
dm-multipath with AOE, another solution may have to be found.
