Merging upstream version 4.2+20231121.

Signed-off-by: Daniel Baumann <daniel@debian.org>

udev.c

@@ -0,0 +1,194 @@
+/*
+ * mdadm - manage Linux "md" devices aka RAID arrays.
+ *
+ * Copyright (C) 2022 Mateusz Grzonka <mateusz.grzonka@intel.com>
+ *
+ *    This program is free software; you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation; either version 2 of the License, or
+ *    (at your option) any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include	"mdadm.h"
+#include	"udev.h"
+#include	"md_p.h"
+#include	"md_u.h"
+#include	<sys/wait.h>
+#include	<signal.h>
+#include	<limits.h>
+#include	<syslog.h>
+#include	<libudev.h>
+
+static char *unblock_path;
+
+/*
+ * udev_is_available() - Checks for udev in the system.
+ *
+ * Function looks whether udev directories are available and MDADM_NO_UDEV env defined.
+ *
+ * Return:
+ * true if udev is available,
+ * false if not
+ */
+bool udev_is_available(void)
+{
+	struct stat stb;
+
+	if (stat("/dev/.udev", &stb) != 0 &&
+	    stat("/run/udev", &stb) != 0)
+		return false;
+	if (check_env("MDADM_NO_UDEV") == 1)
+		return false;
+	return true;
+}
+
+#ifndef NO_LIBUDEV
+
+static struct udev *udev;
+static struct udev_monitor *udev_monitor;
+
+/*
+ * udev_release() - Drops references of udev and udev_monitor.
+ */
+static void udev_release(void)
+{
+	udev_monitor_unref(udev_monitor);
+	udev_unref(udev);
+}
+
+/*
+ * udev_initialize() - Initializes udev and udev_monitor structures.
+ *
+ * Function initializes udev, udev_monitor, and sets udev_monitor filter for block devices.
+ *
+ * Return:
+ * UDEV_STATUS_SUCCESS on success
+ * UDEV_STATUS_ERROR on error
+ * UDEV_STATUS_ERROR_NO_UDEV when udev not available
+ */
+static enum udev_status udev_initialize(void)
+{
+	if (!udev_is_available()) {
+		pr_err("No udev.\n");
+		return UDEV_STATUS_ERROR_NO_UDEV;
+	}
+
+	udev = udev_new();
+	if (!udev) {
+		pr_err("Cannot initialize udev.\n");
+		return UDEV_STATUS_ERROR;
+	}
+
+	udev_monitor = udev_monitor_new_from_netlink(udev, "udev");
+	if (!udev_monitor) {
+		pr_err("Cannot initialize udev monitor.\n");
+		udev = udev_unref(udev);
+		return UDEV_STATUS_ERROR;
+	}
+
+	if (udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, "block", 0) < 0) {
+		pr_err("Cannot add udev monitor event filter for md devices.\n");
+		udev_release();
+		return UDEV_STATUS_ERROR;
+	}
+	if (udev_monitor_enable_receiving(udev_monitor) < 0) {
+		pr_err("Cannot enable receiving udev events through udev monitor.\n");
+		udev_release();
+		return UDEV_STATUS_ERROR;
+	}
+	atexit(udev_release);
+	return UDEV_STATUS_SUCCESS;
+}
+
+/*
+ * udev_wait_for_events() - Waits for events from udev.
+ * @seconds: Timeout in seconds.
+ *
+ * Function waits udev events, wakes up on event or timeout.
+ *
+ * Return:
+ * UDEV_STATUS_SUCCESS on detected event
+ * UDEV_STATUS_TIMEOUT on timeout
+ * UDEV_STATUS_ERROR on error
+ */
+enum udev_status udev_wait_for_events(int seconds)
+{
+	int fd;
+	fd_set readfds;
+	struct timeval tv;
+	int ret;
+
+	if (!udev || !udev_monitor) {
+		ret = udev_initialize();
+		if (ret != UDEV_STATUS_SUCCESS)
+			return ret;
+	}
+
+	fd = udev_monitor_get_fd(udev_monitor);
+	if (fd < 0) {
+		pr_err("Cannot access file descriptor associated with udev monitor.\n");
+		return UDEV_STATUS_ERROR;
+	}
+
+	FD_ZERO(&readfds);
+	FD_SET(fd, &readfds);
+	tv.tv_sec = seconds;
+	tv.tv_usec = 0;
+
+	if (select(fd + 1, &readfds, NULL, NULL, &tv) > 0 && FD_ISSET(fd, &readfds))
+		if (udev_monitor_receive_device(udev_monitor))
+			return UDEV_STATUS_SUCCESS; /* event detected */
+	return UDEV_STATUS_TIMEOUT;
+}
+#endif
+
+/*
+ * udev_block() - Block udev from examining newly created arrays.
+ *
+ * When array is created, we don't want udev to examine it immediately.
+ * Function creates /run/mdadm/creating-mdXXX and expects that udev rule
+ * will notice it and act accordingly.
+ *
+ * Return:
+ * UDEV_STATUS_SUCCESS when successfully blocked udev
+ * UDEV_STATUS_ERROR on error
+ */
+enum udev_status udev_block(char *devnm)
+{
+	int fd;
+	char *path = xcalloc(1, BUFSIZ);
+
+	snprintf(path, BUFSIZ, "/run/mdadm/creating-%s", devnm);
+
+	fd = open(path, O_CREAT | O_RDWR, 0600);
+	if (!is_fd_valid(fd)) {
+		pr_err("Cannot block udev, error creating blocking file.\n");
+		pr_err("%s: %s\n", strerror(errno), path);
+		free(path);
+		return UDEV_STATUS_ERROR;
+	}
+
+	close(fd);
+	unblock_path = path;
+	return UDEV_STATUS_SUCCESS;
+}
+
+/*
+ * udev_unblock() - Unblock udev.
+ */
+void udev_unblock(void)
+{
+	if (unblock_path)
+		unlink(unblock_path);
+	free(unblock_path);
+	unblock_path = NULL;
+}