Re: [PATCH v4 2/7] scsi-generic: pass max_segments via max_iov field in BlockLimits

[Eric Blake]

On Tue, Jun 08, 2021 at 03:16:29PM +0200, Paolo Bonzini wrote:
> I/O to a disk via read/write is not limited by the number of segments allowed
> by the host adapter; the kernel can split requests if needed, and the limit
> imposed by the host adapter can be very low (256k or so) to avoid that SG_IO
> returns EINVAL if memory is heavily fragmented.

to avoid SG_IO returning EINVAL

> 
> Since this value is only interesting for SG_IO-based I/O, do not include
> it in the max_transfer and only take it into account when patching the
> block limits VPD page in the scsi-generic device.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  block/file-posix.c     | 3 +--
>  hw/scsi/scsi-generic.c | 6 ++++--
>  2 files changed, 5 insertions(+), 4 deletions(-)
>

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
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