Commit 7f217389 authored by Jason Xing's avatar Jason Xing Committed by Andrew Morton
Browse files

blktrace: use rbuf->stats.full as a drop indicator in relayfs 

Replace internal subbuf_start in blktrace with the default policy in
relayfs.

Remove dropped field from struct blktrace.  Correspondingly, call the
common helper in relay.  By incrementing full_count to keep track of how
many times we encountered a full buffer issue, user space will know how
many events were lost.

Link: https://lkml.kernel.org/r/20250612061201.34272-5-kerneljasonxing@gmail.com


Signed-off-by: default avatarJason Xing <kernelxing@tencent.com>
Reviewed-by: default avatarYushan Zhou <katrinzhou@tencent.com>
Reviewed-by: default avatarJens Axboe <axboe@kernel.dk>
Reviewed-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a53202ce

kernel/trace/blktrace.c

+2 −20
Original line number Diff line number Diff line
@@ -415,9 +415,10 @@ static ssize_t blk_dropped_read(struct file *filp, char __user *buffer, 
				size_t count, loff_t *ppos)

{

	struct blk_trace *bt = filp->private_data;

	size_t dropped = relay_stats(bt->rchan, RELAY_STATS_BUF_FULL);

	char buf[16];



	snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));

	snprintf(buf, sizeof(buf), "%zu\n", dropped);



	return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));

}
@@ -456,23 +457,6 @@ static const struct file_operations blk_msg_fops = { 
	.llseek =	noop_llseek,

};



/*

 * Keep track of how many times we encountered a full subbuffer, to aid

 * the user space app in telling how many lost events there were.

 */

static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,

				     void *prev_subbuf)

{

	struct blk_trace *bt;



	if (!relay_buf_full(buf))

		return 1;



	bt = buf->chan->private_data;

	atomic_inc(&bt->dropped);

	return 0;

}



static int blk_remove_buf_file_callback(struct dentry *dentry)

{

	debugfs_remove(dentry);
@@ -491,7 +475,6 @@ static struct dentry *blk_create_buf_file_callback(const char *filename, 
}



static const struct rchan_callbacks blk_relay_callbacks = {

	.subbuf_start		= blk_subbuf_start_callback,

	.create_buf_file	= blk_create_buf_file_callback,

	.remove_buf_file	= blk_remove_buf_file_callback,

};
@@ -580,7 +563,6 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, 
	}



	bt->dev = dev;

	atomic_set(&bt->dropped, 0);

	INIT_LIST_HEAD(&bt->running_list);



	ret = -EIO;