[PATCH] 01/05 Implement generic dispatch queue

Implements generic dispatch queue which can replace all
dispatch queues implemented by each iosched.  This reduces
code duplication, eases enforcing semantics over dispatch
queue, and simplifies specific ioscheds.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jens Axboe <axboe@suse.de>

1 files changed, 11 insertions, 6 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index efdc9b5bc05c..2c7b9154927a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -203,6 +203,7 @@ struct request {
 enum rq_flag_bits {
         __REQ_RW,               /* not set, read. set, write */
         __REQ_FAILFAST,         /* no low level driver retries */
+        __REQ_SORTED,           /* elevator knows about this request */
         __REQ_SOFTBARRIER,      /* may not be passed by ioscheduler */
         __REQ_HARDBARRIER,      /* may not be passed by drive either */
         __REQ_CMD,              /* is a regular fs rw request */
@@ -235,6 +236,7 @@ enum rq_flag_bits {
 
 #define REQ_RW          (1 << __REQ_RW)
 #define REQ_FAILFAST    (1 << __REQ_FAILFAST)
+#define REQ_SORTED      (1 << __REQ_SORTED)
 #define REQ_SOFTBARRIER (1 << __REQ_SOFTBARRIER)
 #define REQ_HARDBARRIER (1 << __REQ_HARDBARRIER)
 #define REQ_CMD         (1 << __REQ_CMD)
@@ -333,6 +335,13 @@ struct request_queue
         end_flush_fn            *end_flush_fn;
 
         /*
+         * Dispatch queue sorting
+         */
+        sector_t                last_sector;
+        struct request          *boundary_rq;
+        unsigned int            max_back_kb;
+
+        /*
          * Auto-unplugging state
          */
         struct timer_list       unplug_timer;
@@ -454,6 +463,7 @@ enum {
 #define blk_pm_request(rq)      \
         ((rq)->flags & (REQ_PM_SUSPEND | REQ_PM_RESUME))
 
+#define blk_sorted_rq(rq)       ((rq)->flags & REQ_SORTED)
 #define blk_barrier_rq(rq)      ((rq)->flags & REQ_HARDBARRIER)
 #define blk_barrier_preflush(rq)        ((rq)->flags & REQ_BAR_PREFLUSH)
 #define blk_barrier_postflush(rq)       ((rq)->flags & REQ_BAR_POSTFLUSH)
@@ -611,12 +621,7 @@ extern void end_request(struct request *req, int uptodate);
 
 static inline void blkdev_dequeue_request(struct request *req)
 {
-        BUG_ON(list_empty(&req->queuelist));
-
-        list_del_init(&req->queuelist);
-
-        if (req->rl)
-                elv_remove_request(req->q, req);
+        elv_dequeue_request(req->q, req);
 }
 
 /*