block: consolidate __invalidate_device and fsync_bdev

We currently have two interfaces that take a block_devices and the find
a mounted file systems to flush or invaldidate data on it.  Both are a
bit problematic because they only work for the "main" block devices
that is used as s_dev for the super_block, and because they don't call
into the file system at all.

Merge the two into a new bdev_mark_dead helper that does both the
syncing and invalidation and which is properly documented.  This is
in preparation of merging the functionality into the ->mark_dead
holder operation so that it will work on additional block devices
used by a file systems and give us a single entry point for invalidation
of dead devices or media.

Note that a single standalone fsync_bdev call for an obscure ioctl
remains for now, but that one will also be deal with in a bit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Message-Id: <20230811100828.1897174-14-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

include/linux/blkdev.h

@@ -751,6 +751,7 @@ static inline int bdev_read_only(struct block_device *bdev)
 
 bool set_capacity_and_notify(struct gendisk *disk, sector_t size);
 void disk_force_media_change(struct gendisk *disk);
+void bdev_mark_dead(struct block_device *bdev, bool surprise);
 
 void add_disk_randomness(struct gendisk *disk) __latent_entropy;
 void rand_initialize_disk(struct gendisk *disk);
@@ -809,7 +810,6 @@ int __register_blkdev(unsigned int major, const char *name,
 void unregister_blkdev(unsigned int major, const char *name);
 
 bool disk_check_media_change(struct gendisk *disk);
-int __invalidate_device(struct block_device *bdev, bool kill_dirty);
 void set_capacity(struct gendisk *disk, sector_t size);
 
 #ifdef CONFIG_BLOCK_HOLDER_DEPRECATED