criu: change the way -v works

For most of the CLI tools I see, adding -v option increases their verbosity.

Currently, this is not the case for criu. Default verbosity is set it 2,
and using -v actually decreases the verbosity level to 1, so to increase
verbosity you need to use -vvv (or -v3). To me, this behavior is
quite counterintuitive.

This patch changes the way -v works (but retains -vNUM as it was). Now,
using -v increases verbosity by +1 from the default value (and e.g. -vvv
increases it by +3).

Surely, this changes user experience: for example someone who
was using -v (rather than -v1 or -v0) to silent warnings, will
now have verbosity increased. IMHO this is for the better.
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

Documentation/criu.txt

@@ -28,19 +28,25 @@ Common options
 ~~~~~~~~~~~~~~
 Common options are applicable to any 'command'.
 
-*-v*['num'|*v*...]::
-    Set logging level to 'num'. The higher the level, the more output
-    is produced. Either numeric values or multiple *v* can be used.
+*-v*[*v*...]::
+    Increase verbosity up from the default level. Multiple *v* can be used,
+    each increasing verbosity by one level.
+
+*-v*'num'::
+    Set verbosity level to 'num'. The higher the level, the more output
+    is produced.
     +
 The following levels are available:
-    * *-v1*, *-v*
-        only messages and errors;
-    * *-v2*, *-vv*
-        also warnings (default level);
-    * *-v3*, *-vvv*
-        also information messages and timestamps;
-    * *-v4*, *-vvvv*
-        lots of debug.
+    * *-v0*
+        no output;
+    * *-v1*
+        only errors;
+    * *-v2*
+        above plus warnings (this is the default level);
+    * *-v3*
+        above plus information messages and timestamps;
+    * *-v4*
+        above plus lots of debug.
 
 *--pidfile* 'file'::
     Write root task, service or page-server pid into a 'file'.

criu/crtools.c

@@ -217,7 +217,7 @@ int main(int argc, char *argv[], char *envp[])
 	bool has_exec_cmd = false;
 	bool has_sub_command;
 	int opt, idx;
-	int log_level = LOG_UNSET;
+	int log_level = DEFAULT_LOGLEVEL;
 	char *imgs_dir = ".";
 	static const char short_opts[] = "dSsRf:F:t:p:hcD:o:v::x::Vr:jJ:lW:L:M:";
 	static struct option long_opts[] = {
@@ -381,8 +381,6 @@ int main(int argc, char *argv[], char *envp[])
 				goto bad_arg;
 			break;
 		case 'v':
-			if (log_level == LOG_UNSET)
-				log_level = 0;
 			if (optarg) {
 				if (optarg[0] == 'v')
 					/* handle -vvvvv */
@@ -928,11 +926,12 @@ usage:
 "* Logging:\n"
 "  -o|--log-file FILE    log file name\n"
 "     --log-pid          enable per-process logging to separate FILE.pid files\n"
-"  -v[NUM]               set logging level (higher level means more output):\n"
-"                          -v1|-v    - only errors and messages\n"
-"                          -v2|-vv   - also warnings (default level)\n"
-"                          -v3|-vvv  - also information messages and timestamps\n"
-"                          -v4|-vvvv - lots of debug\n"
+"  -v[v...]            increase verbosity (can use multiple v)\n"
+"  -vNUM               set verbosity to NUM (higher level means more output):\n"
+"                          -v1 - only errors and messages\n"
+"                          -v2 - also warnings (default level)\n"
+"                          -v3 - also information messages and timestamps\n"
+"                          -v4 - lots of debug\n"
 "  --display-stats       print out dump/restore stats\n"
 "\n"
 "* Memory dumping options:\n"

criu/log.c

@@ -201,10 +201,7 @@ void log_fini(void)
 
 void log_set_loglevel(unsigned int level)
 {
-	if (level == LOG_UNSET)
-		current_loglevel = DEFAULT_LOGLEVEL;
-	else
-		current_loglevel = level;
+	current_loglevel = level;
 }
 
 unsigned int log_get_loglevel(void)