storage: exit() => _exit(). when exec is failed, child process needs to use _exit()

src/lxc/storage/nbd.c

@@ -48,8 +48,8 @@ struct nbd_attach_data {
 	const char *path;
 };
 
-static bool clone_attach_nbd(const char *nbd, const char *path);
 static int do_attach_nbd(void *d);
+static bool clone_attach_nbd(const char *nbd, const char *path);
 static bool nbd_busy(int idx);
 static void nbd_detach(const char *path);
 static int nbd_get_partition(const char *src);
@@ -69,16 +69,21 @@ bool attach_nbd(char *src, struct lxc_conf *conf)
 	p = strchr(orig, ':');
 	if (p)
 		*p = '\0';
+
 	while (1) {
 		sprintf(path, "/dev/nbd%d", i);
+
 		if (!file_exists(path))
 			return false;
+
 		if (nbd_busy(i)) {
 			i++;
 			continue;
 		}
+
 		if (!clone_attach_nbd(path, orig))
 			return false;
+
 		conf->nbd_idx = i;
 		return true;
 	}
@@ -152,10 +157,10 @@ int nbd_mount(struct lxc_storage *bdev)
 	}
 
 	/* It might take awhile for the partition files to show up */
-	if (partition) {
+	if (partition)
 		if (!wait_for_partition(path))
 			return -2;
-	}
+
 	ret = mount_unknown_fs(path, bdev->dest, bdev->mntopts);
 	if (ret < 0)
 		ERROR("Error mounting %s", bdev->src);
@@ -178,6 +183,7 @@ bool requires_nbd(const char *path)
 {
 	if (strncmp(path, "nbd:", 4) == 0)
 		return true;
+
 	return false;
 }
 
@@ -226,6 +232,7 @@ static int do_attach_nbd(void *d)
 				exit(0);
 			} else if (fdsi.ssi_signo == SIGCHLD) {
 				int status;
+
 				/* If qemu-nbd fails, or is killed by a signal,
 				 * then exit */
 				while (waitpid(-1, &status, WNOHANG) > 0) {
@@ -240,12 +247,13 @@ static int do_attach_nbd(void *d)
 	}
 
 	close(sfd);
+
 	if (sigprocmask(SIG_UNBLOCK, &mask, NULL) == -1)
 		WARN("Warning: unblocking signals for nbd watcher");
 
 	execlp("qemu-nbd", "qemu-nbd", "-c", nbd, path, (char *)NULL);
 	SYSERROR("Error executing qemu-nbd");
-	exit(1);
+	_exit(1);
 }
 
 static bool clone_attach_nbd(const char *nbd, const char *path)
@@ -259,6 +267,7 @@ static bool clone_attach_nbd(const char *nbd, const char *path)
 	pid = lxc_clone(do_attach_nbd, &data, CLONE_NEWPID);
 	if (pid < 0)
 		return false;
+
 	return true;
 }
 
@@ -270,6 +279,7 @@ static bool nbd_busy(int idx)
 	ret = snprintf(path, 100, "/sys/block/nbd%d/pid", idx);
 	if (ret < 0 || ret >= 100)
 		return true;
+
 	return file_exists(path);
 }
 
@@ -282,15 +292,17 @@ static void nbd_detach(const char *path)
 		SYSERROR("Error forking to detach nbd");
 		return;
 	}
+
 	if (pid) {
 		ret = wait_for_pid(pid);
 		if (ret < 0)
 			ERROR("nbd disconnect returned an error");
 		return;
 	}
+
 	execlp("qemu-nbd", "qemu-nbd", "-d", path, (char *)NULL);
 	SYSERROR("Error executing qemu-nbd");
-	exit(1);
+	_exit(1);
 }
 
 /*
@@ -303,24 +315,31 @@ static int nbd_get_partition(const char *src)
 	char *p = strchr(src, ':');
 	if (!p)
 		return 0;
+
 	p = strchr(p+1, ':');
 	if (!p)
 		return 0;
+
 	p++;
+
 	if (*p < '1' || *p > '9')
 		return 0;
+
 	return *p - '0';
 }
 
 static bool wait_for_partition(const char *path)
 {
 	int count = 0;
+
 	while (count < 5) {
 		if (file_exists(path))
 			return true;
+
 		sleep(1);
 		count++;
 	}
+
 	ERROR("Device %s did not show up after 5 seconds", path);
 	return false;
 }