block: add REQ_OP definitions and helpers

The following patches separate the operation (WRITE, READ, DISCARD,
etc) from the rq_flag_bits flags. This patch adds definitions for
request/bio operations (REQ_OPs) and adds request/bio accessors to
get/set the op.

In this patch the REQ_OPs match the REQ rq_flag_bits ones
for compat reasons while all the code is converted to use the
op accessors in the set. In the last patches the op will become a
number and the accessors and helpers in this patch will be dropped
or updated.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

include/linux/bio.h

@@ -44,6 +44,9 @@
 #define BIO_MAX_SIZE		(BIO_MAX_PAGES << PAGE_SHIFT)
 #define BIO_MAX_SECTORS		(BIO_MAX_SIZE >> 9)
 
+#define bio_op(bio)				(op_from_rq_bits((bio)->bi_rw))
+#define bio_set_op_attrs(bio, op, flags)	((bio)->bi_rw |= (op | flags))
+
 /*
  * upper 16 bits of bi_rw define the io priority of this bio
  */

include/linux/blk_types.h

@@ -242,6 +242,30 @@ enum rq_flag_bits {
 #define REQ_HASHED		(1ULL << __REQ_HASHED)
 #define REQ_MQ_INFLIGHT		(1ULL << __REQ_MQ_INFLIGHT)
 
+enum req_op {
+	REQ_OP_READ,
+	REQ_OP_WRITE		= REQ_WRITE,
+	REQ_OP_DISCARD		= REQ_DISCARD,
+	REQ_OP_WRITE_SAME	= REQ_WRITE_SAME,
+};
+
+/*
+ * tmp cpmpat. Users used to set the write bit for all non reads, but
+ * we will be dropping the bitmap use for ops. Support both until
+ * the end of the patchset.
+ */
+static inline int op_from_rq_bits(u64 flags)
+{
+	if (flags & REQ_OP_DISCARD)
+		return REQ_OP_DISCARD;
+	else if (flags & REQ_OP_WRITE_SAME)
+		return REQ_OP_WRITE_SAME;
+	else if (flags & REQ_OP_WRITE)
+		return REQ_OP_WRITE;
+	else
+		return REQ_OP_READ;
+}
+
 typedef unsigned int blk_qc_t;
 #define BLK_QC_T_NONE	-1U
 #define BLK_QC_T_SHIFT	16

include/linux/blkdev.h

@@ -200,6 +200,13 @@ struct request {
 	struct request *next_rq;
 };
 
+#define req_op(req)		(op_from_rq_bits((req)->cmd_flags))
+#define req_set_op(req, op)	((req)->cmd_flags |= op)
+#define req_set_op_attrs(req, op, flags) do {	\
+	req_set_op(req, op);			\
+	(req)->cmd_flags |= flags;		\
+} while (0)
+
 static inline unsigned short req_get_ioprio(struct request *req)
 {
 	return req->ioprio;
@@ -597,7 +604,8 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 
 #define list_entry_rq(ptr)	list_entry((ptr), struct request, queuelist)
 
-#define rq_data_dir(rq)		((int)((rq)->cmd_flags & 1))
+#define rq_data_dir(rq) \
+	(op_is_write(op_from_rq_bits(rq->cmd_flags)) ? WRITE : READ)
 
 /*
  * Driver can handle struct request, if it either has an old style

include/linux/fs.h

@@ -2464,15 +2464,37 @@ extern void make_bad_inode(struct inode *);
 extern bool is_bad_inode(struct inode *);
 
 #ifdef CONFIG_BLOCK
+/*
+ * tmp cpmpat. Users used to set the write bit for all non reads, but
+ * we will be dropping the bitmap use for ops. Support both until
+ * the end of the patchset.
+ */
+static inline bool op_is_write(unsigned long flags)
+{
+	if (flags & (REQ_OP_WRITE | REQ_OP_WRITE_SAME | REQ_OP_DISCARD))
+		return true;
+	else
+		return false;
+}
+
 /*
  * return READ, READA, or WRITE
  */
-#define bio_rw(bio)		((bio)->bi_rw & (RW_MASK | RWA_MASK))
+static inline int bio_rw(struct bio *bio)
+{
+	if (op_is_write(op_from_rq_bits(bio->bi_rw)))
+		return WRITE;
+
+	return bio->bi_rw & RWA_MASK;
+}
 
 /*
  * return data direction, READ or WRITE
  */
-#define bio_data_dir(bio)	((bio)->bi_rw & 1)
+static inline int bio_data_dir(struct bio *bio)
+{
+	return op_is_write(op_from_rq_bits(bio->bi_rw)) ? WRITE : READ;
+}
 
 extern void check_disk_size_change(struct gendisk *disk,
 				   struct block_device *bdev);