block: better op and flags encoding

Now that we don't need the common flags to overflow outside the range
of a 32-bit type we can encode them the same way for both the bio and
request fields.  This in addition allows us to place the operation
first (and make some room for more ops while we're at it) and to
stop having to shift around the operation values.

In addition this allows passing around only one value in the block layer
instead of two (and eventuall also in the file systems, but we can do
that later) and thus clean up a lot of code.

Last but not least this allows decreasing the size of the cmd_flags
field in struct request to 32-bits.  Various functions passing this
value could also be updated, but I'd like to avoid the churn for now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 2 insertions, 24 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b4415feac679..8396da2bb698 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -142,7 +142,7 @@ struct request {
 
 	int cpu;
 	unsigned cmd_type;
-	u64 cmd_flags;
+	unsigned int cmd_flags;		/* op and common flags */
 	req_flags_t rq_flags;
 	unsigned long atomic_flags;
 
@@ -244,20 +244,6 @@ struct request {
 	struct request *next_rq;
 };
 
-#define REQ_OP_SHIFT (8 * sizeof(u64) - REQ_OP_BITS)
-#define req_op(req)  ((req)->cmd_flags >> REQ_OP_SHIFT)
-
-#define req_set_op(req, op) do {				\
-	WARN_ON(op >= (1 << REQ_OP_BITS));			\
-	(req)->cmd_flags &= ((1ULL << REQ_OP_SHIFT) - 1);	\
-	(req)->cmd_flags |= ((u64) (op) << REQ_OP_SHIFT);	\
-} while (0)
-
-#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;
@@ -741,17 +727,9 @@ static inline unsigned int blk_queue_zone_size(struct request_queue *q)
 	return blk_queue_is_zoned(q) ? q->limits.chunk_sectors : 0;
 }
 
-/*
- * We regard a request as sync, if either a read or a sync write
- */
-static inline bool rw_is_sync(int op, unsigned int rw_flags)
-{
-	return op == REQ_OP_READ || (rw_flags & REQ_SYNC);
-}
-
 static inline bool rq_is_sync(struct request *rq)
 {
-	return rw_is_sync(req_op(rq), rq->cmd_flags);
+	return op_is_sync(rq->cmd_flags);
 }
 
 static inline bool blk_rl_full(struct request_list *rl, bool sync)