block: Clean up special command handling logic

Remove special-casing of non-rw fs style requests (discard). The nomerge
flags are consolidated in blk_types.h, and rq_mergeable() and
bio_mergeable() have been modified to use them.

bio_is_rw() is used in place of bio_has_data() a few places. This is
done to to distinguish true reads and writes from other fs type requests
that carry a payload (e.g. write same).

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 35 insertions, 14 deletions

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 52b9cbc3e4da..e54305cacc98 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -386,9 +386,28 @@ static inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
 /*
  * Check whether this bio carries any data or not. A NULL bio is allowed.
  */
-static inline int bio_has_data(struct bio *bio)
+static inline bool bio_has_data(struct bio *bio)
 {
-        return bio && bio->bi_io_vec != NULL;
+        if (bio && bio->bi_vcnt)
+                return true;
+
+        return false;
+}
+
+static inline bool bio_is_rw(struct bio *bio)
+{
+        if (!bio_has_data(bio))
+                return false;
+
+        return true;
+}
+
+static inline bool bio_mergeable(struct bio *bio)
+{
+        if (bio->bi_rw & REQ_NOMERGE_FLAGS)
+                return false;
+
+        return true;
 }
 
 /*
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 3eefbb291192..1b229664f573 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -194,6 +194,10 @@ enum rq_flag_bits {
          REQ_DISCARD | REQ_NOIDLE | REQ_FLUSH | REQ_FUA | REQ_SECURE)
 #define REQ_CLONE_MASK          REQ_COMMON_MASK
 
+/* This mask is used for both bio and request merge checking */
+#define REQ_NOMERGE_FLAGS \
+        (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA)
+
 #define REQ_RAHEAD              (1 << __REQ_RAHEAD)
 #define REQ_THROTTLED           (1 << __REQ_THROTTLED)
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4a2ab7c85393..3a6fea7460f1 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -540,8 +540,7 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 
 #define blk_account_rq(rq) \
         (((rq)->cmd_flags & REQ_STARTED) && \
-         ((rq)->cmd_type == REQ_TYPE_FS || \
-          ((rq)->cmd_flags & REQ_DISCARD)))
+         ((rq)->cmd_type == REQ_TYPE_FS))
 
 #define blk_pm_request(rq)      \
         ((rq)->cmd_type == REQ_TYPE_PM_SUSPEND || \
@@ -595,17 +594,16 @@ static inline void blk_clear_rl_full(struct request_list *rl, bool sync)
         rl->flags &= ~flag;
 }
 
+static inline bool rq_mergeable(struct request *rq)
+{
+        if (rq->cmd_type != REQ_TYPE_FS)
+                return false;
 
-/*
- * mergeable request must not have _NOMERGE or _BARRIER bit set, nor may
- * it already be started by driver.
- */
-#define RQ_NOMERGE_FLAGS        \
-        (REQ_NOMERGE | REQ_STARTED | REQ_SOFTBARRIER | REQ_FLUSH | REQ_FUA | REQ_DISCARD)
-#define rq_mergeable(rq)        \
-        (!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
-         (((rq)->cmd_flags & REQ_DISCARD) || \
-          (rq)->cmd_type == REQ_TYPE_FS))
+        if (rq->cmd_flags & REQ_NOMERGE_FLAGS)
+                return false;
+
+        return true;
+}
 
 /*
  * q->prep_rq_fn return values