[Virtio-fs] [PATCH 1/2] virtiofsd: Add ID to the log with FUSE_LOG_DEBUG level

[Masayoshi Mizuma]

From: Masayoshi Mizuma <m.mizuma at jp.fujitsu.com>

virtiofsd has some threads, so we see a lot of logs with debug option.
It would be useful for debugging if we can identify the specific thread
from the log.

Add ID, which is got by gettid(), to the log with FUSE_LOG_DEBUG level
so that we can grep the specific thread.

The log is like as:

  ]# ./virtiofsd -d -o vhost_user_socket=/tmp/vhostqemu0 -o source=/tmp/share0 -o cache=auto
  ...
  [ID: 00000097]    unique: 12696, success, outsize: 120
  [ID: 00000097] virtio_send_msg: elem 18: with 2 in desc of length 120
  [ID: 00000003] fv_queue_thread: Got queue event on Queue 1
  [ID: 00000003] fv_queue_thread: Queue 1 gave evalue: 1 available: in: 65552 out: 80
  [ID: 00000003] fv_queue_thread: Waiting for Queue 1 event
  [ID: 00000071] fv_queue_worker: elem 33: with 2 out desc of length 80 bad_in_num=0 bad_out_num=0
  [ID: 00000071] unique: 12694, opcode: READ (15), nodeid: 2, insize: 80, pid: 2014
  [ID: 00000071] lo_read(ino=2, size=65536, off=131072)

Signed-off-by: Masayoshi Mizuma <m.mizuma at jp.fujitsu.com>
---
 contrib/virtiofsd/passthrough_ll.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passthrough_ll.c
index 6ad021d00d..0e85d5ea74 100644
--- a/contrib/virtiofsd/passthrough_ll.c
+++ b/contrib/virtiofsd/passthrough_ll.c
@@ -2849,11 +2849,17 @@ static void setup_nofile_rlimit(void)
 }
 
 static void log_func(enum fuse_log_level level,
-		     const char *fmt, va_list ap)
+		     const char *_fmt, va_list ap)
 {
+	char *fmt = (char *)_fmt;
+
 	if (current_log_level < level)
 		return;
 
+	if (current_log_level == FUSE_LOG_DEBUG)
+		fmt = g_strdup_printf("[ID: %08ld] %s",
+				syscall(__NR_gettid), _fmt);
+
 	if (use_syslog) {
 		int priority = LOG_ERR;
 		switch (level) {
@@ -2870,6 +2876,9 @@ static void log_func(enum fuse_log_level level,
 	} else {
 		vfprintf(stderr, fmt, ap);
 	}
+
+	if (current_log_level == FUSE_LOG_DEBUG)
+		g_free(fmt);
 }
 
 static void *ireg_do(void *data)
-- 
2.18.1