Add a generic mechnism to notify the userspace about possible filesystem
corruption through sysfs entry (/sys/block/<bdev>/<part>/fs_unclean)
and uevent (KOBJ_CHANGE, uevent's environment variable FS_UNCLEAN=[0:1]).

To mark fs clean (e.g. after fs was fixed by userspace):

echo 0 > /sys/block/<bdev>/<part>/fs_unclean
(you will still receive uevent KOBJ_CHANGE with env var FS_UNCLEAN=0)

Signed-off-by: Denis Karpov <redacted>
---
 fs/partitions/check.c |   42 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/genhd.h |    2 ++
 2 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 99e33ef..191d89e 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c

@@ -196,6 +196,24 @@ check_partition(struct gendisk *hd, struct block_device *bdev)
 	return ERR_PTR(res);
 }
 
+void notify_part_fs_unclean(struct device *dev, uint8_t unclean)
+{
+	char event_string[13];
+	char *envp[] = { event_string, NULL };
+
+	if ((unclean != 0 && unclean != 1) ||
+		unclean == dev_to_part(dev)->fs_unclean)
+		return;
+
+	dev_to_part(dev)->fs_unclean = unclean;
+
+	sysfs_notify(&dev->kobj, NULL, "fs_unclean");
+
+	sprintf(event_string, "FS_UNCLEAN=%u", unclean);
+	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
+}
+EXPORT_SYMBOL(notify_part_fs_unclean);

 static ssize_t part_partition_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {

@@ -246,6 +264,26 @@ ssize_t part_stat_show(struct device *dev,
 		jiffies_to_msecs(part_stat_read(p, time_in_queue)));
 }
 
+ssize_t part_fs_unclean_show(struct device *dev,
+		       struct device_attribute *attr, char *buf)
+{
+	struct hd_struct *p = dev_to_part(dev);
+
+	return sprintf(buf, "%d\n", p->fs_unclean);
+}
+
+ssize_t part_fs_unclean_store(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf, size_t count)
+{
+	int i;
+
+	if (count > 0 && sscanf(buf, "%d", &i) > 0)