[PATCH v3 04/11] block_dev: Introduce bd_corrupted_range() for block device

[Shiyang Ruan <ruansy.fnst@xxxxxxxxxxxxxx>]

As is show in the call tree:
 ...
 pgmap->ops->memory_failure()
  gendisk->fops->corrupted_range()
   sb->s_ops->currupted_range()
    ...
currupted_range() is called from disk(pmem) to superblock(filesystem).
Thus, we need to introduce a helper function to obtain the superblock
from a given disk.

Normally, a filesystem can be created by mkfs directly on a block device
or a parted disk. We can obtain the superblock by calling get_super().

But get_super() is not suitable for mapped device, such as LVM. To
obtain MD's superblock, we can iterate bd_holder_disks of a block device
to find out the MD that contains it. By this way, MD is able to call
corrupted_range() from its target block device.

Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxxxxx>
---
 fs/block_dev.c        | 47 ++++++++++++++++++++++++++++++++++++++++++-
 include/linux/genhd.h |  2 ++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 3b8963e228a1..755b0d351479 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1079,6 +1079,28 @@ struct bd_holder_disk {
 	int			refcnt;
 };
 
+static int bd_disk_holder_corrupted_range(struct block_device *bdev, loff_t off,
+					  size_t len, void *data)
+{
+	struct bd_holder_disk *holder;
+	struct gendisk *disk;
+	int rc = 0;
+
+	if (list_empty(&(bdev->bd_holder_disks)))
+		return -ENODEV;
+
+	list_for_each_entry(holder, &bdev->bd_holder_disks, list) {
+		disk = holder->disk;
+		if (disk->fops->corrupted_range) {
+			rc = disk->fops->corrupted_range(disk, bdev, off,
+							 len, data);
+			if (rc != -ENODEV)
+				break;
+		}
+	}
+	return rc;
+}
+
 static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
 						  struct gendisk *disk)
 {
@@ -1212,7 +1234,30 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
 	mutex_unlock(&bdev->bd_mutex);
 }
 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
-#endif
+#else
+static inline int bd_disk_holder_corrupted_range(struct block_device *bdev,
+					loff_t off, size_t len, void *data)
+{
+	return -EOPNOTSUPP;
+}
+#endif /* CONFIG_SYSFS */
+
+int bd_corrupted_range(struct block_device *bdev, loff_t disk_off,
+		       loff_t bdev_off, size_t len, void *data)
+{
+	struct super_block *sb = get_super(bdev);
+	int rc = -EOPNOTSUPP;
+
+	if (!sb) {
+		rc = bd_disk_holder_corrupted_range(bdev, disk_off, len, data);
+		return rc;
+	} else if (sb->s_op->corrupted_range)
+		rc = sb->s_op->corrupted_range(sb, bdev, bdev_off, len, data);
+	drop_super(sb);
+
+	return rc;
+}
+EXPORT_SYMBOL(bd_corrupted_range);
 
 static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
 
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 809aaa32d53c..751cbd559bba 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -314,6 +314,8 @@ void unregister_blkdev(unsigned int major, const char *name);
 bool bdev_check_media_change(struct block_device *bdev);
 int __invalidate_device(struct block_device *bdev, bool kill_dirty);
 void set_capacity(struct gendisk *disk, sector_t size);
+int bd_corrupted_range(struct block_device *bdev, loff_t disk_off,
+		       loff_t bdev_off, size_t len, void *data);
 
 /* for drivers/char/raw.c: */
 int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
-- 
2.30.0