bdev: move ->bd_ro_warned to ->__bd_flags

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

block/blk-core.c

@@ -514,10 +514,11 @@ static inline void bio_check_ro(struct bio *bio)
 		if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
 			return;
 
-		if (bio->bi_bdev->bd_ro_warned)
+		if (bdev_test_flag(bio->bi_bdev, BD_RO_WARNED))
 			return;
 
-		bio->bi_bdev->bd_ro_warned = true;
+		bdev_set_flag(bio->bi_bdev, BD_RO_WARNED);
+
 		/*
 		 * Use ioctl to set underlying disk of raid/dm to read-only
 		 * will trigger this.

include/linux/blk_types.h

@@ -50,6 +50,7 @@ struct block_device {
 #define BD_READ_ONLY		(1u<<8) // read-only policy
 #define BD_WRITE_HOLDER		(1u<<9)
 #define BD_HAS_SUBMIT_BIO	(1u<<10)
+#define BD_RO_WARNED		(1u<<11)
 	dev_t			bd_dev;
 	struct inode		*bd_inode;	/* will die */
 
@@ -69,7 +70,6 @@ struct block_device {
 #ifdef CONFIG_FAIL_MAKE_REQUEST
 	bool			bd_make_it_fail;
 #endif
-	bool			bd_ro_warned;
 	int			bd_writers;
 	/*
 	 * keep this out-of-line as it's both big and not needed in the fast