super: remove bd_fsfreeze_sb

Remove bd_fsfreeze_sb as it's now unused and can be removed. Also move
bd_fsfreeze_count down to not have it weirdly placed in the middle of
the holder fields.

Link: https://lore.kernel.org/r/20231024-vfs-super-freeze-v2-7-599c19f4faac@kernel.orgReviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Suggested-by: Jan Kara <jack@suse.cz>
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

include/linux/blk_types.h

@@ -56,14 +56,11 @@ struct block_device {
 	void *			bd_holder;
 	const struct blk_holder_ops *bd_holder_ops;
 	struct mutex		bd_holder_lock;
-	/* The counter of freeze processes */
-	atomic_t		bd_fsfreeze_count;
 	int			bd_holders;
 	struct kobject		*bd_holder_dir;
 
-	/* Mutex for freeze */
-	struct mutex		bd_fsfreeze_mutex;
-	struct super_block	*bd_fsfreeze_sb;
+	atomic_t		bd_fsfreeze_count; /* number of freeze requests */
+	struct mutex		bd_fsfreeze_mutex; /* serialize freeze/thaw */
 
 	struct partition_meta_info *bd_meta_info;
 #ifdef CONFIG_FAIL_MAKE_REQUEST