block: split out request-only flags into a new namespace

A lot of the REQ_* flags are only used on struct requests, and only of
use to the block layer and a few drivers that dig into struct request
internals.

This patch adds a new req_flags_t rq_flags field to struct request for
them, and thus dramatically shrinks the number of common requests.  It
also removes the unfortunate situation where we have to fit the fields
from the same enum into 32 bits for struct bio and 64 bits for
struct request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 48 insertions, 1 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 90097dd8b8ed..b4415feac679 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -78,6 +78,50 @@ enum rq_cmd_type_bits {
         REQ_TYPE_DRV_PRIV,              /* driver defined types from here */
 };
 
+/*
+ * request flags */
+typedef __u32 __bitwise req_flags_t;
+
+/* elevator knows about this request */
+#define RQF_SORTED              ((__force req_flags_t)(1 << 0))
+/* drive already may have started this one */
+#define RQF_STARTED             ((__force req_flags_t)(1 << 1))
+/* uses tagged queueing */
+#define RQF_QUEUED              ((__force req_flags_t)(1 << 2))
+/* may not be passed by ioscheduler */
+#define RQF_SOFTBARRIER         ((__force req_flags_t)(1 << 3))
+/* request for flush sequence */
+#define RQF_FLUSH_SEQ           ((__force req_flags_t)(1 << 4))
+/* merge of different types, fail separately */
+#define RQF_MIXED_MERGE         ((__force req_flags_t)(1 << 5))
+/* track inflight for MQ */
+#define RQF_MQ_INFLIGHT         ((__force req_flags_t)(1 << 6))
+/* don't call prep for this one */
+#define RQF_DONTPREP            ((__force req_flags_t)(1 << 7))
+/* set for "ide_preempt" requests and also for requests for which the SCSI
+   "quiesce" state must be ignored. */
+#define RQF_PREEMPT             ((__force req_flags_t)(1 << 8))
+/* contains copies of user pages */
+#define RQF_COPY_USER           ((__force req_flags_t)(1 << 9))
+/* vaguely specified driver internal error.  Ignored by the block layer */
+#define RQF_FAILED              ((__force req_flags_t)(1 << 10))
+/* don't warn about errors */
+#define RQF_QUIET               ((__force req_flags_t)(1 << 11))
+/* elevator private data attached */
+#define RQF_ELVPRIV             ((__force req_flags_t)(1 << 12))
+/* account I/O stat */
+#define RQF_IO_STAT             ((__force req_flags_t)(1 << 13))
+/* request came from our alloc pool */
+#define RQF_ALLOCED             ((__force req_flags_t)(1 << 14))
+/* runtime pm request */
+#define RQF_PM                  ((__force req_flags_t)(1 << 15))
+/* on IO scheduler merge hash */
+#define RQF_HASHED              ((__force req_flags_t)(1 << 16))
+
+/* flags that prevent us from merging requests: */
+#define RQF_NOMERGE_FLAGS \
+        (RQF_STARTED | RQF_SOFTBARRIER | RQF_FLUSH_SEQ)
+
 #define BLK_MAX_CDB     16
 
 /*
@@ -99,6 +143,7 @@ struct request {
         int cpu;
         unsigned cmd_type;
         u64 cmd_flags;
+        req_flags_t rq_flags;
         unsigned long atomic_flags;
 
         /* the following two fields are internal, NEVER access directly */
@@ -648,7 +693,7 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
                              REQ_FAILFAST_DRIVER))
 
 #define blk_account_rq(rq) \
-        (((rq)->cmd_flags & REQ_STARTED) && \
+        (((rq)->rq_flags & RQF_STARTED) && \
          ((rq)->cmd_type == REQ_TYPE_FS))
 
 #define blk_rq_cpu_valid(rq)    ((rq)->cpu != -1)
@@ -740,6 +785,8 @@ static inline bool rq_mergeable(struct request *rq)
 
         if (rq->cmd_flags & REQ_NOMERGE_FLAGS)
                 return false;
+        if (rq->rq_flags & RQF_NOMERGE_FLAGS)
+                return false;
 
         return true;
 }