Re: [PATCH for-next 4/4] nvme-multipath: add multipathing for uring-passthrough commands

From: Kanchan Joshi <joshi.k@samsung.com>
To: Stefan Metzmacher <metze@samba.org>
Cc: Sagi Grimberg <sagi@grimberg.me>,
	hch@lst.de, kbusch@kernel.org, axboe@kernel.dk,
	io-uring@vger.kernel.org, linux-nvme@lists.infradead.org,
	linux-block@vger.kernel.org, asml.silence@gmail.com,
	joshiiitr@gmail.com, anuj20.g@samsung.com, gost.dev@samsung.com
Subject: Re: [PATCH for-next 4/4] nvme-multipath: add multipathing for uring-passthrough commands
Date: Tue, 12 Jul 2022 00:24:06 +0530	[thread overview]
Message-ID: <20220711185406.GB20562@test-zns> (raw)
In-Reply-To: <5c71b8f6-afec-8ef6-0a70-d13e71ded79c@samba.org>

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On Mon, Jul 11, 2022 at 05:12:23PM +0200, Stefan Metzmacher wrote:
>Hi Sagi,
>
>>>@@ -189,6 +190,12 @@ enum {
>>>      NVME_REQ_USERCMD        = (1 << 1),
>>>  };
>>>+static inline struct nvme_uring_cmd_pdu *nvme_uring_cmd_pdu(
>>>+        struct io_uring_cmd *ioucmd)
>>>+{
>
>Shouldn't we have a BUILD_BUG_ON(sizeof(struct nvme_uring_cmd_pdu) > sizeof(ioucmd->pdu));
>here?
Not sure if I got the concern. We have this already inside
nvme_ns_uring_cmd function.

>>>+    return (struct nvme_uring_cmd_pdu *)&ioucmd->pdu;
>>>+}
>>>+
>
>>>diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
>>>index d734599cbcd7..57f4dfc83316 100644
>>>--- a/include/linux/io_uring.h
>>>+++ b/include/linux/io_uring.h
>>>@@ -15,6 +15,8 @@ enum io_uring_cmd_flags {
>>>      IO_URING_F_SQE128        = 4,
>>>      IO_URING_F_CQE32        = 8,
>>>      IO_URING_F_IOPOLL        = 16,
>>>+    /* to indicate that it is a MPATH req*/
>>>+    IO_URING_F_MPATH        = 32,
>
>Isn't that nvme specific? If so I don't think it belongs in io_uring.h at all...

Right. Removing this was bit ugly in nvme, but yes, need to kill this in
v2.

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