[PULL 060/108] virtiofsd: Add ID to the log with FUSE_LOG_DEBUG level

[Dr. David Alan Gilbert (git)]

From: Masayoshi Mizuma <address@hidden>

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 <address@hidden>

Signed-off-by: Dr. David Alan Gilbert <address@hidden>
  added rework as suggested by Daniel P. Berrangé during review
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
 tools/virtiofsd/passthrough_ll.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index ff6910fd73..f08324f000 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -43,6 +43,7 @@
 #include <cap-ng.h>
 #include <dirent.h>
 #include <errno.h>
+#include <glib.h>
 #include <inttypes.h>
 #include <limits.h>
 #include <pthread.h>
@@ -2268,10 +2269,17 @@ static void setup_nofile_rlimit(void)
 
 static void log_func(enum fuse_log_level level, const char *fmt, va_list ap)
 {
+    g_autofree char *localfmt = NULL;
+
     if (current_log_level < level) {
         return;
     }
 
+    if (current_log_level == FUSE_LOG_DEBUG) {
+        localfmt = g_strdup_printf("[ID: %08ld] %s", syscall(__NR_gettid), 
fmt);
+        fmt = localfmt;
+    }
+
     if (use_syslog) {
         int priority = LOG_ERR;
         switch (level) {
-- 
2.24.1