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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
        Minwoo Im <minwoo.im.dev@gmail.com>,
        Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 58/90] nvmet: fix data_len to 0 for bdev-backed write_zeroes
Date:   Mon, 24 Jun 2019 17:56:48 +0800
Message-Id: <20190624092317.912727803@linuxfoundation.org>
In-Reply-To: <20190624092313.788773607@linuxfoundation.org>
References: <20190624092313.788773607@linuxfoundation.org>
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[ Upstream commit 3562f5d9f21e7779ae442a45197fed6cb247fd22 ]

The WRITE ZEROES command has no data transfer so that we need to
initialize the struct (nvmet_req *req)->data_len to 0x0.  While
(nvmet_req *req)->transfer_len is initialized in nvmet_req_init(),
data_len will be initialized by nowhere which might cause the failure
with status code NVME_SC_SGL_INVALID_DATA | NVME_SC_DNR randomly.  It's
because nvmet_req_execute() checks like:

	if (unlikely(req->data_len != req->transfer_len)) {
		req->error_loc = offsetof(struct nvme_common_command, dptr);
		nvmet_req_complete(req, NVME_SC_SGL_INVALID_DATA | NVME_SC_DNR);
	} else
		req->execute(req);

This patch fixes req->data_len not to be a randomly assigned by
initializing it to 0x0 when preparing the command in
nvmet_bdev_parse_io_cmd().

nvmet_file_parse_io_cmd() which is for file-backed I/O has already
initialized the data_len field to 0x0, though.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/nvme/target/io-cmd-bdev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 7bc9f6240432..1096dd01ca22 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -239,6 +239,7 @@ u16 nvmet_bdev_parse_io_cmd(struct nvmet_req *req)
 		return 0;
 	case nvme_cmd_write_zeroes:
 		req->execute = nvmet_bdev_execute_write_zeroes;
+		req->data_len = 0;
 		return 0;
 	default:
 		pr_err("unhandled cmd %d on qid %d\n", cmd->common.opcode,
-- 
2.20.1