BLOCK: Hide the contents of linux/bio.h if CONFIG_BLOCK=n

Hide the contents of linux/bio.h if CONFIG_BLOCK=n as there shouldn't be
compiled code that uses it.
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

include/linux/bio.h

@@ -24,6 +24,8 @@
 #include <linux/mempool.h>
 #include <linux/ioprio.h>
 
+#ifdef CONFIG_BLOCK
+
 /* Platforms may set this to teach the BIO layer about IOMMU hardware. */
 #include <asm/io.h>
 
@@ -361,4 +363,5 @@ static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 	__bio_kmap_irq((bio), (bio)->bi_idx, (flags))
 #define bio_kunmap_irq(buf,flags)	__bio_kunmap_irq(buf, flags)
 
+#endif /* CONFIG_BLOCK */
 #endif /* __LINUX_BIO_H */