Commit 04678e72 authored by Johannes Thumshirn's avatar Johannes Thumshirn Committed by Jens Axboe
Browse files

blktrace: split out relaying a blktrace event 



Split out the code relaying a blktrace event to user-space using relayfs.

This enables adding a second version supporting a new version of the
protocol.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 472eca53

kernel/trace/blktrace.c

+32 −28
Original line number Diff line number Diff line
@@ -91,6 +91,26 @@ static void record_blktrace_event(struct blk_io_trace *t, pid_t pid, int cpu, 
		memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);

}



static void relay_blktrace_event(struct blk_trace *bt, unsigned long sequence,

				 pid_t pid, int cpu, sector_t sector, int bytes,

				 u32 what, int error, u64 cgid,

				 ssize_t cgid_len, void *pdu_data, int pdu_len)

{

	struct blk_io_trace *t;

	size_t trace_len = sizeof(*t) + pdu_len + cgid_len;



	t = relay_reserve(bt->rchan, trace_len);

	if (!t)

		return;



	t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

	t->sequence = sequence;

	t->time = ktime_to_ns(ktime_get());



	record_blktrace_event(t, pid, cpu, sector, bytes, what, bt->dev, error,

			      cgid, cgid_len, pdu_data, pdu_len);

}



/*

 * Send out a notify message.

 */
@@ -126,16 +146,9 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action, 
	if (!bt->rchan)

		return;



	t = relay_reserve(bt->rchan, trace_len);

	if (t) {

		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

		t->time = ktime_to_ns(ktime_get());



		record_blktrace_event(t, pid, cpu, 0, 0,

				      action | (cgid ? __BLK_TN_CGROUP : 0),

				      bt->dev, 0, cgid, cgid_len, (void *)data,

				      len);

	}

	relay_blktrace_event(bt, 0, pid, cpu, 0, 0,

			     action | (cgid ? __BLK_TN_CGROUP : 0), 0, cgid,

			     cgid_len, (void *)data, len);

}



/*
@@ -246,7 +259,6 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, 
	struct task_struct *tsk = current;

	struct ring_buffer_event *event = NULL;

	struct trace_buffer *buffer = NULL;

	struct blk_io_trace *t;

	unsigned long flags = 0;

	unsigned long *sequence;

	unsigned int trace_ctx = 0;
@@ -278,20 +290,21 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, 
		return;

	cpu = raw_smp_processor_id();



	trace_len = sizeof(*t) + pdu_len + cgid_len;

	if (blk_tracer) {

		tracing_record_cmdline(current);



		buffer = blk_tr->array_buffer.buffer;

		trace_ctx = tracing_gen_ctx_flags(0);

		trace_len = sizeof(struct blk_io_trace) + pdu_len + cgid_len;

		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,

						  trace_len, trace_ctx);

		if (!event)

			return;

		t = ring_buffer_event_data(event);



		record_blktrace_event(t, pid, cpu, sector, bytes, what, bt->dev,

				      error, cgid, cgid_len, pdu_data, pdu_len);

		record_blktrace_event(ring_buffer_event_data(event),

				      pid, cpu, sector, bytes, what, bt->dev,

				      error, cgid, cgid_len, pdu_data,

				      pdu_len);



		trace_buffer_unlock_commit(blk_tr, buffer, event, trace_ctx);

		return;
@@ -306,19 +319,10 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, 
	 * from coming in and stepping on our toes.

	 */

	local_irq_save(flags);

	t = relay_reserve(bt->rchan, trace_len);

	if (t) {

	sequence = per_cpu_ptr(bt->sequence, cpu);



		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

		t->sequence = ++(*sequence);

		t->time = ktime_to_ns(ktime_get());



		record_blktrace_event(t, pid, cpu, sector, bytes, what,

				      bt->dev, error, cgid, cgid_len,

				      pdu_data, pdu_len);

	}



	(*sequence)++;

	relay_blktrace_event(bt, *sequence, pid, cpu, sector, bytes, what,

			     error, cgid, cgid_len, pdu_data, pdu_len);

	local_irq_restore(flags);

}