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nbd: trace sending nbd requests

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This adds a tracepoint that can both observe the nbd request being sent
to the server, as well as modify that request , e.g., setting a flag in
the request that will cause the server to collect detailed tracing data.

The struct request * being handled is included to permit correlation
with the block tracepoints.

Signed-off-by: Matt Mullins <mmullins@fb.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Matt Mullins 2019-04-26 11:49:48 -07:00 committed by Alexei Starovoitov
parent 9df1c28bb7
commit ea106722c7
3 changed files with 62 additions and 0 deletions
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1
MAINTAINERS
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@ -10741,6 +10741,7 @@ L: linux-block@vger.kernel.org
L: nbd@other.debian.org
F: Documentation/blockdev/nbd.txt
F: drivers/block/nbd.c
F: include/trace/events/nbd.h
F: include/uapi/linux/nbd.h
NETWORK DROP MONITOR

5
drivers/block/nbd.c
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@ -44,6 +44,9 @@
#include <linux/nbd-netlink.h>
#include <net/genetlink.h>
#define CREATE_TRACE_POINTS
#include <trace/events/nbd.h>
static DEFINE_IDR(nbd_index_idr);
static DEFINE_MUTEX(nbd_index_mutex);
static int nbd_total_devices = 0;
@ -526,6 +529,8 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
handle = nbd_cmd_handle(cmd);
memcpy(request.handle, &handle, sizeof(handle));
trace_nbd_send_request(&request, nbd->index, blk_mq_rq_from_pdu(cmd));
dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
req, nbdcmd_to_ascii(type),
(unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));

56
include/trace/events/nbd.h Normal file
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@ -0,0 +1,56 @@
/* SPDX-License-Identifier: GPL-2.0 */
#undef TRACE_SYSTEM
#define TRACE_SYSTEM nbd
#if !defined(_TRACE_NBD_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_NBD_H
#include <linux/tracepoint.h>
DECLARE_EVENT_CLASS(nbd_send_request,
TP_PROTO(struct nbd_request *nbd_request, int index,
struct request *rq),
TP_ARGS(nbd_request, index, rq),
TP_STRUCT__entry(
__field(struct nbd_request *, nbd_request)
__field(u64, dev_index)
__field(struct request *, request)
),
TP_fast_assign(
__entry->nbd_request = 0;
__entry->dev_index = index;
__entry->request = rq;
),
TP_printk("nbd%lld: request %p", __entry->dev_index, __entry->request)
);
#ifdef DEFINE_EVENT_WRITABLE
#undef NBD_DEFINE_EVENT
#define NBD_DEFINE_EVENT(template, call, proto, args, size) \
DEFINE_EVENT_WRITABLE(template, call, PARAMS(proto), \
PARAMS(args), size)
#else
#undef NBD_DEFINE_EVENT
#define NBD_DEFINE_EVENT(template, call, proto, args, size) \
DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args))
#endif
NBD_DEFINE_EVENT(nbd_send_request, nbd_send_request,
TP_PROTO(struct nbd_request *nbd_request, int index,
struct request *rq),
TP_ARGS(nbd_request, index, rq),
sizeof(struct nbd_request)
);
#endif
/* This part must be outside protection */
#include <trace/define_trace.h>