From: Jason Gunthorpe <jgg@nvidia.com>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: <linux-rdma@vger.kernel.org>
Subject: Re: [PATCH v3] IB/isert: fix unaligned immediate-data handling
Date: Wed, 9 Sep 2020 13:49:15 -0300 [thread overview]
Message-ID: <20200909164915.GA887151@nvidia.com> (raw)
In-Reply-To: <20200904195039.31687-1-sagi@grimberg.me>
On Fri, Sep 04, 2020 at 12:50:39PM -0700, Sagi Grimberg wrote:
> Currently we allocate rx buffers in a single contiguous buffers for
> headers (iser and iscsi) and data trailer. This means that most likely
> the data starting offset is aligned to 76 bytes (size of both headers).
>
> This worked fine for years, but at some point this broke, resulting in
> data corruptions in isert when a command comes with immediate data
> and the underlying backend device assumes 512 bytes buffer alignment.
>
> We assume a hard-requirement for all direct I/O buffers to be 512 bytes
> aligned. To fix this, we should avoid passing unaligned buffers for I/O.
>
> Instead, we allocate our recv buffers with some extra space such that we
> can have the data portion align to 512 byte boundary. This also means
> that we cannot reference headers or data using structure but rather
> accessors (as they may move based on alignment). Also, get rid of the
> wrong __packed annotation from iser_rx_desc as this has only harmful
> effects (not aligned to anything).
>
> This affects the rx descriptors for iscsi login and data plane.
>
> Fixes: 3d75ca0adef4 ("block: introduce multi-page bvec helpers")
> Reported-by: Stephen Rust <srust@blockbridge.com>
> Tested-by: Doug Dumitru <doug@dumitru.com>
> Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
> ---
> Changes from v2:
> - fixed 2 redundant newlines
> - added fixes tag
> Changes from v1:
> - revised change log
Applied to for-rc, thanks
Jason
prev parent reply other threads:[~2020-09-09 16:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-04 19:50 [PATCH v3] IB/isert: fix unaligned immediate-data handling Sagi Grimberg
2020-09-09 16:49 ` Jason Gunthorpe [this message]
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