block: rename bio bi_rw to bi_opf

Since commit 63a4cc24867d, bio->bi_rw contains flags in the lower
portion and the op code in the higher portions. This means that
old code that relies on manually setting bi_rw is most likely
going to be broken. Instead of letting that brokeness linger,
rename the member, to force old and out-of-tree code to break
at compile time instead of at runtime.

No intended functional changes in this commit.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/bio.h b/include/linux/bio.h
index e09a889..59ffaa6 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -95,7 +95,7 @@
 
 static inline bool bio_mergeable(struct bio *bio)
 {
-	if (bio->bi_rw & REQ_NOMERGE_FLAGS)
+	if (bio->bi_opf & REQ_NOMERGE_FLAGS)
 		return false;
 
 	return true;
@@ -318,7 +318,7 @@
 
 static inline struct bio_integrity_payload *bio_integrity(struct bio *bio)
 {
-	if (bio->bi_rw & REQ_INTEGRITY)
+	if (bio->bi_opf & REQ_INTEGRITY)
 		return bio->bi_integrity;
 
 	return NULL;
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index f77150a..10648e3 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -714,9 +714,9 @@
 
 	if (!throtl) {
 		blkg = blkg ?: q->root_blkg;
-		blkg_rwstat_add(&blkg->stat_bytes, bio_op(bio), bio->bi_rw,
+		blkg_rwstat_add(&blkg->stat_bytes, bio_op(bio), bio->bi_opf,
 				bio->bi_iter.bi_size);
-		blkg_rwstat_add(&blkg->stat_ios, bio_op(bio), bio->bi_rw, 1);
+		blkg_rwstat_add(&blkg->stat_ios, bio_op(bio), bio->bi_opf, 1);
 	}
 
 	rcu_read_unlock();
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index f254eb2..436f43f 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -27,8 +27,9 @@
 	struct bio		*bi_next;	/* request queue link */
 	struct block_device	*bi_bdev;
 	int			bi_error;
-	unsigned int		bi_rw;		/* bottom bits req flags,
-						 * top bits REQ_OP
+	unsigned int		bi_opf;		/* bottom bits req flags,
+						 * top bits REQ_OP. Use
+						 * accessors.
 						 */
 	unsigned short		bi_flags;	/* status, command, etc */
 	unsigned short		bi_ioprio;
@@ -89,13 +90,13 @@
 };
 
 #define BIO_OP_SHIFT	(8 * sizeof(unsigned int) - REQ_OP_BITS)
-#define bio_op(bio)	((bio)->bi_rw >> BIO_OP_SHIFT)
+#define bio_op(bio)	((bio)->bi_opf >> BIO_OP_SHIFT)
 
 #define bio_set_op_attrs(bio, op, op_flags) do {		\
 	WARN_ON(op >= (1 << REQ_OP_BITS));			\
-	(bio)->bi_rw &= ((1 << BIO_OP_SHIFT) - 1);		\
-	(bio)->bi_rw |= ((unsigned int) (op) << BIO_OP_SHIFT);	\
-	(bio)->bi_rw |= op_flags;				\
+	(bio)->bi_opf &= ((1 << BIO_OP_SHIFT) - 1);		\
+	(bio)->bi_opf |= ((unsigned int) (op) << BIO_OP_SHIFT);	\
+	(bio)->bi_opf |= op_flags;				\
 } while (0)
 
 #define BIO_RESET_BYTES		offsetof(struct bio, bi_max_vecs)
@@ -138,7 +139,7 @@
 
 /*
  * Request flags.  For use in the cmd_flags field of struct request, and in
- * bi_rw of struct bio.  Note that some flags are only valid in either one.
+ * bi_opf of struct bio.  Note that some flags are only valid in either one.
  */
 enum rq_flag_bits {
 	/* common flags */