block: add a bdev_check_media_change helper

Like check_disk_changed, except that it does not call ->revalidate_disk
but leaves that to the caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/genhd.c

@@ -2052,7 +2052,7 @@ void disk_flush_events(struct gendisk *disk, unsigned int mask)
  * CONTEXT:
  * Might sleep.
  */
-unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
+static unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
 {
 	struct disk_events *ev = disk->ev;
 	unsigned int pending;
@@ -2090,6 +2090,33 @@ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
 	return pending;
 }
 
+/**
+ * bdev_check_media_change - check if a removable media has been changed
+ * @bdev: block device to check
+ *
+ * Check whether a removable media has been changed, and attempt to free all
+ * dentries and inodes and invalidates all block device page cache entries in
+ * that case.
+ *
+ * Returns %true if the block device changed, or %false if not.
+ */
+bool bdev_check_media_change(struct block_device *bdev)
+{
+	unsigned int events;
+
+	events = disk_clear_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE |
+				   DISK_EVENT_EJECT_REQUEST);
+	if (!(events & DISK_EVENT_MEDIA_CHANGE))
+		return false;
+
+	if (__invalidate_device(bdev, true))
+		pr_warn("VFS: busy inodes on changed media %s\n",
+			bdev->bd_disk->disk_name);
+	set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
+	return true;
+}
+EXPORT_SYMBOL(bdev_check_media_change);
+
 /*
  * Separate this part out so that a different pointer for clearing_ptr can be
  * passed in for disk_clear_events.

fs/block_dev.c

@@ -1379,21 +1379,10 @@ EXPORT_SYMBOL(revalidate_disk_size);
  */
 int check_disk_change(struct block_device *bdev)
 {
-	struct gendisk *disk = bdev->bd_disk;
-	const struct block_device_operations *bdops = disk->fops;
-	unsigned int events;
-
-	events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
-				   DISK_EVENT_EJECT_REQUEST);
-	if (!(events & DISK_EVENT_MEDIA_CHANGE))
+	if (!bdev_check_media_change(bdev))
 		return 0;
-
-	if (__invalidate_device(bdev, true))
-		pr_warn("VFS: busy inodes on changed media %s\n",
-			disk->disk_name);
-	set_bit(BDEV_NEED_PART_SCAN, &bdev->bd_flags);
-	if (bdops->revalidate_disk)
-		bdops->revalidate_disk(bdev->bd_disk);
+	if (bdev->bd_disk->fops->revalidate_disk)
+		bdev->bd_disk->fops->revalidate_disk(bdev->bd_disk);
 	return 1;
 }
 

include/linux/genhd.h

@@ -315,7 +315,6 @@ extern void disk_unblock_events(struct gendisk *disk);
 extern void disk_flush_events(struct gendisk *disk, unsigned int mask);
 void set_capacity_revalidate_and_notify(struct gendisk *disk, sector_t size,
 		bool update_bdev);
-extern unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask);
 
 /* drivers/char/random.c */
 extern void add_disk_randomness(struct gendisk *disk) __latent_entropy;
@@ -372,6 +371,7 @@ void unregister_blkdev(unsigned int major, const char *name);
 
 void revalidate_disk_size(struct gendisk *disk, bool verbose);
 int check_disk_change(struct block_device *bdev);
+bool bdev_check_media_change(struct block_device *bdev);
 int __invalidate_device(struct block_device *bdev, bool kill_dirty);
 void bd_set_nr_sectors(struct block_device *bdev, sector_t sectors);