linux-kernel - [PATCHv2] nbd: Zero from and len fields in NBD_CMD

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Date:	Sun, 25 May 2014 23:22:40 +0100
From:	Hani Benhabiles <kroosec@...il.com>
To:	Paul.Clements@...eleye.com
Cc:	nbd-general@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: [PATCHv2] nbd: Zero from and len fields in NBD_CMD_DISCONNECT.

Len field is already set to zero, but not the from field which is sent as
0xfffffffffffffe00. This makes no sense, and may cause confuse server
implementations doing sanity checks (qemu-nbd is an example.)

Signed-off-by: Hani Benhabiles <hani@...ux.com>
---

Compared to v1:
* Zero the request structure instead of conditionally zeroing specific fields.

 drivers/block/nbd.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 3a70ea2..8e1df52 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -243,14 +243,11 @@ static int nbd_send_req(struct nbd_device *nbd, struct request *req)
 	struct nbd_request request;
 	unsigned long size = blk_rq_bytes(req);

+	memset(&request, 0, sizeof(request));
 	request.magic = htonl(NBD_REQUEST_MAGIC);
 	request.type = htonl(nbd_cmd(req));

-	if (nbd_cmd(req) == NBD_CMD_FLUSH) {
-		/* Other values are reserved for FLUSH requests.  */
-		request.from = 0;
-		request.len = 0;
-	} else {
+	if (nbd_cmd(req) != NBD_CMD_FLUSH && nbd_cmd(req) != NBD_CMD_DISC) {
 		request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
 		request.len = htonl(size);
 	}
-- 
1.8.3.2

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