[PATCH v2 3/4] blktrace: use rbuf->stats.full as a drop indicator in relayfs
From: Jason Xing <hidden>
Date: 2025-05-15 06:17:52
Also in:
linux-block, lkml
Subsystem:
block layer, the rest, tracing · Maintainers:
Jens Axboe, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Jason Xing <kernelxing@tencent.com> 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. Through incrementing full_count to keep track of how many times we encountered a full buffer issue, it aids the user space app in telling how many lost events appear. Reviewed-by: Yushan Zhou <redacted> Signed-off-by: Jason Xing <kernelxing@tencent.com> --- v2 1. adjust accordingly together with patch 2. --- kernel/trace/blktrace.c | 22 ++-------------------- 1 file changed, 2 insertions(+), 20 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index d1a89714e805..f4c103aceacd 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c@@ -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_dump(bt->rchan, RELAY_DUMP_BUF_FULL); char buf[16]; - snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped)); + snprintf(buf, sizeof(buf), "%lu\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;
--
2.43.5