Re: [Patch 1/2] cciss: fix for 2TB support

From: Andrew Morton
Date: Wed Feb 21 2007 - 22:18:14 EST

On Wed, 21 Feb 2007 15:10:39 -0600 "Mike Miller (OS Dev)" <mikem@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

> Patch 1/2
> This patch changes the way we determine if a logical volume is larger than 2TB. The
> original test looked for a total_size of 0. Originally we added 1 to the total_size.
> That would make our read_capacity return size 0 for >2TB lv's. We assumed that we
> could not have a lv size of 0 so it seemed OK until we were in a clustered system. The
> backup node would see a size of 0 due to the reservation on the drive. That caused
> the driver to switch to 16-byte CDB's which are not supported on older controllers.
> After that everything was broken.
> It may seem petty but I don't see the value in trying to determine if the LBA is
> beyond the 2TB boundary. That's why when we switch we use 16-byte CDB's for all
> read/write operations.
> Please consider this for inclusion.
> ...
> + if (total_size == 0xFFFFFFFF) {

I seem to remember having already questioned this. total_size is sector_t, which
can be either 32-bit or 64-bit. Are you sure that comparison works as
intended in both cases?

> + if(total_size == 0xFFFFFFFF) {
> cciss_read_capacity_16(cntl_num, i, 0,
> &total_size, &block_size);
> hba[cntl_num]->cciss_read = CCISS_READ_16;

Here too.
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