udev: exclude MD from block device ownership event locking

[elogind.git] / src / udev / udevd.c

diff --git a/src/udev/udevd.c b/src/udev/udevd.c
index d79891a7ca207322072be254690905a3e54c9a7b..db935d609502c1b6f78d63b18374b27958967ac5 100644 (file)
--- a/src/udev/udevd.c
+++ b/src/udev/udevd.c
@@ -285,26 +285,17 @@ static void worker_new(struct event *event)
                                 udev_event->exec_delay = exec_delay;
 
                         /*
-                         * Take a "read lock" on the device node; this establishes
+                         * Take a shared lock on the device node; this establishes
                          * a concept of device "ownership" to serialize device
-                         * access. External processes holding a "write lock" will
+                         * access. External processes holding an exclusive lock will
                          * cause udev to skip the event handling; in the case udev
-                         * acquired the lock, the external process will block until
+                         * acquired the lock, the external process can block until
                          * udev has finished its event handling.
                          */
-
-                        /*
-                         * <kabi_> since we make check - device seems unused - we try
-                         *         ioctl to deactivate - and device is found to be opened
-                         * <kay> sure, you try to take a write lock
-                         * <kay> if you get it udev is out
-                         * <kay> if you can't get it, udev is busy
-                         * <kabi_> we cannot deactivate openned device  (as it is in-use)
-                         * <kay> maybe we should just exclude dm from that thing entirely
-                         * <kabi_> IMHO this sounds like a good plan for this moment
-                         */
-                        if (streq_ptr("block", udev_device_get_subsystem(dev)) &&
-                            !startswith("dm-", udev_device_get_sysname(dev))) {
+                        if (!streq_ptr(udev_device_get_action(dev), "remove") &&
+                            streq_ptr("block", udev_device_get_subsystem(dev)) &&
+                            !startswith(udev_device_get_sysname(dev), "dm-") &&
+                            !startswith(udev_device_get_sysname(dev), "md")) {
                                 struct udev_device *d = dev;
 
                                 if (streq_ptr("partition", udev_device_get_devtype(d)))
@@ -741,35 +732,32 @@ static int synthesize_change(struct udev_device *dev) {
 
         if (streq_ptr("block", udev_device_get_subsystem(dev)) &&
             streq_ptr("disk", udev_device_get_devtype(dev)) &&
-            !startswith("dm-", udev_device_get_sysname(dev))) {
+            !startswith(udev_device_get_sysname(dev), "dm-")) {
+                bool part_table_read = false;
+                bool has_partitions = false;
                 int fd;
                 struct udev *udev = udev_device_get_udev(dev);
                 _cleanup_udev_enumerate_unref_ struct udev_enumerate *e = NULL;
                 struct udev_list_entry *item;
 
                 /*
-                 * Try to re-read the partition table, this only succeeds if
-                 * none of the devices is busy.
-                 *
-                 * The kernel will send out a change event for the disk, and
-                 * "remove/add" for all partitions.
+                 * Try to re-read the partition table. This only succeeds if
+                 * none of the devices is busy. The kernel returns 0 if no
+                 * partition table is found, and we will not get an event for
+                 * the disk.
                  */
-                fd = open(udev_device_get_devnode(dev), O_RDONLY|O_EXCL|O_CLOEXEC|O_NOFOLLOW|O_NONBLOCK);
+                fd = open(udev_device_get_devnode(dev), O_RDONLY|O_CLOEXEC|O_NOFOLLOW|O_NONBLOCK);
                 if (fd >= 0) {
-                        r = ioctl(fd, BLKRRPART, 0);
+                        r = flock(fd, LOCK_EX|LOCK_NB);
+                        if (r >= 0)
+                                r = ioctl(fd, BLKRRPART, 0);
+
                         close(fd);
                         if (r >= 0)
-                                return 0;
+                                part_table_read = true;
                 }
 
-                /*
-                 * Re-reading the partition table did not work, synthesize "change"
-                 * events for the disk and all partitions.
-                 */
-                log_debug("device %s closed, synthesising 'change'", udev_device_get_devnode(dev));
-                strscpyl(filename, sizeof(filename), udev_device_get_syspath(dev), "/uevent", NULL);
-                write_string_file(filename, "change");
-
+                /* search for partitions */
                 e = udev_enumerate_new(udev);
                 if (!e)
                         return -ENOMEM;
@@ -783,6 +771,39 @@ static int synthesize_change(struct udev_device *dev) {
                         return r;
 
                 r = udev_enumerate_scan_devices(e);
+                if (r < 0)
+                        return r;
+
+                udev_list_entry_foreach(item, udev_enumerate_get_list_entry(e)) {
+                        _cleanup_udev_device_unref_ struct udev_device *d = NULL;
+
+                        d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
+                        if (!d)
+                                continue;
+
+                        if (!streq_ptr("partition", udev_device_get_devtype(d)))
+                                continue;
+
+                        has_partitions = true;
+                        break;
+                }
+
+                /*
+                 * We have partitions and re-read the table, the kernel already sent
+                 * out a "change" event for the disk, and "remove/add" for all
+                 * partitions.
+                 */
+                if (part_table_read && has_partitions)
+                        return 0;
+
+                /*
+                 * We have partitions but re-reading the partition table did not
+                 * work, synthesize "change" for the disk and all partitions.
+                 */
+                log_debug("device %s closed, synthesising 'change'", udev_device_get_devnode(dev));
+                strscpyl(filename, sizeof(filename), udev_device_get_syspath(dev), "/uevent", NULL);
+                write_string_file(filename, "change");
+
                 udev_list_entry_foreach(item, udev_enumerate_get_list_entry(e)) {
                         _cleanup_udev_device_unref_ struct udev_device *d = NULL;