Re: [PATCH] IB/rxe: Don't clamp residual length to mtu

[Johannes Thumshirn <jthumshirn-l3A5Bk7waGM@public.gmane.org>]

On Thu, Apr 06, 2017 at 02:49:44PM +0200, Johannes Thumshirn wrote:
> When reading a RDMA WRITE FIRST packet we copy the DMA length from the RDMA
> header into the qp->resp.resid variable for later use. Later in check_rkey()
> we clamp it to the MTU if the packet is an  RDMA WRITE packet and has a
> residual length bigger than the MTU. Later in write_data_in() we subtract the
> payload of the packet from the residual length. If the packet happens to have a
> payload of exactly the MTU size we end up with a residual length of 0 despite
> the packet not being the last in the conversation. When the next packet in the
> conversation arrives, we don't have any residual length left and thus set the QP
> into an error state.
> 
> This broke NVMe over Fabrics functionality over rdma_rxe.ko
> 
> The patch was verified using the following test.
> 
>  # echo eth0 > /sys/module/rdma_rxe/parameters/add
>  # nvme connect -t rdma -a 192.168.155.101 -s 1023 -n nvmf-test
>  # mkfs.xfs -fK /dev/nvme0n1
>  meta-data=/dev/nvme0n1           isize=256    agcount=4, agsize=65536 blks
>           =                       sectsz=4096  attr=2, projid32bit=1
>           =                       crc=0        finobt=0, sparse=0
>  data     =                       bsize=4096   blocks=262144, imaxpct=25
>           =                       sunit=0      swidth=0 blks
>  naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
>  log      =internal log           bsize=4096   blocks=2560, version=2
>           =                       sectsz=4096  sunit=1 blks, lazy-count=1
>  realtime =none                   extsz=4096   blocks=0, rtextents=0
>  # mount /dev/nvme0n1 /tmp/
>  [  148.923263] XFS (nvme0n1): Mounting V4 Filesystem
>  [  148.961196] XFS (nvme0n1): Ending clean mount
>  # dd if=/dev/urandom of=test.bin bs=1M count=128
>  128+0 records in
>  128+0 records out
>  134217728 bytes (134 MB, 128 MiB) copied, 0.437991 s, 306 MB/s
>  # sha256sum test.bin
>  cde42941f045efa8c4f0f157ab6f29741753cdd8d1cff93a6b03649d83c4129a  test.bin
>  # cp test.bin /tmp/
>  sha256sum /tmp/test.bin
>  cde42941f045efa8c4f0f157ab6f29741753cdd8d1cff93a6b03649d83c4129a  /tmp/test.bin
> 
> Signed-off-by: Johannes Thumshirn <jthumshirn-l3A5Bk7waGM@public.gmane.org>
> Cc: Hannes Reinecke <hare-l3A5Bk7waGM@public.gmane.org>
> Cc: Sagi Grimberg <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>
> Cc: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> ---

Doug anything left here? I already have an Ack from Moni. This patch is needed
to get NVMe over Fabrics working on rxe so I'd like to see it in v4.12.

Thanks,
	Johannes

-- 
Johannes Thumshirn                                          Storage
jthumshirn-l3A5Bk7waGM@public.gmane.org                                +49 911 74053 689
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