block: fixup rq_init() a bit

Rearrange fields in cache order and initialize some fields that we didn't previously init. Remove init of ->completion_data, it's part of a union with ->hash. Luckily clearing the rb node is the same as setting it to null! Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block: fixup rq_init() a bit
Rearrange fields in cache order and initialize some fields that we didn't previously init. Remove init of ->completion_data, it's part of a union with ->hash. Luckily clearing the rb node is the same as setting it to null! Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Jens Axboe
1 parent a4ffc0a0b2
Showing 2 changed files with 20 additions and 7 deletions Side-by-side Diff
block/blk-core.c
include/linux/blkdev.h
@@ -102,27 +102,38 @@
 }
 EXPORT_SYMBOL(blk_get_backing_dev_info);
  
+/*
+ * We can't just memset() the structure, since the allocation path
+ * already stored some information in the request.
+ */
 void rq_init(struct request_queue *q, struct request *rq)
 {
 	INIT_LIST_HEAD(&rq->queuelist);
 	INIT_LIST_HEAD(&rq->donelist);
-
-	rq->errors = 0;
+	rq->q = q;
+	rq->sector = rq->hard_sector = (sector_t) -1;
+	rq->nr_sectors = rq->hard_nr_sectors = 0;
+	rq->current_nr_sectors = rq->hard_cur_sectors = 0;
 	rq->bio = rq->biotail = NULL;
 	INIT_HLIST_NODE(&rq->hash);
 	RB_CLEAR_NODE(&rq->rb_node);
+	rq->rq_disk = NULL;
+	rq->nr_phys_segments = 0;
+	rq->nr_hw_segments = 0;
 	rq->ioprio = 0;
+	rq->special = NULL;
 	rq->buffer = NULL;
+	rq->tag = -1;
+	rq->errors = 0;
 	rq->ref_count = 1;
-	rq->q = q;
-	rq->special = NULL;
+	rq->cmd_len = 0;
+	memset(rq->cmd, 0, sizeof(rq->cmd));
 	rq->data_len = 0;
+	rq->sense_len = 0;
 	rq->data = NULL;
-	rq->nr_phys_segments = 0;
 	rq->sense = NULL;
 	rq->end_io = NULL;
 	rq->end_io_data = NULL;
-	rq->completion_data = NULL;
 	rq->next_rq = NULL;
 }
  
@@ -137,7 +137,9 @@
 #define BLK_MAX_CDB	16
  
 /*
- * try to put the fields that are referenced together in the same cacheline
+ * try to put the fields that are referenced together in the same cacheline.
+ * if you modify this structure, be sure to check block/blk-core.c:rq_init()
+ * as well!
  */
 struct request {
 	struct list_head queuelist;
...	...	@@ -102,27 +102,38 @@
102	102	}
103	103	EXPORT_SYMBOL(blk_get_backing_dev_info);
104	104
	105	+/*
	106	+ * We can't just memset() the structure, since the allocation path
	107	+ * already stored some information in the request.
	108	+ */
105	109	void rq_init(struct request_queue q, struct request rq)
106	110	{
107	111	INIT_LIST_HEAD(&rq->queuelist);
108	112	INIT_LIST_HEAD(&rq->donelist);
109		-
110		- rq->errors = 0;
	113	+ rq->q = q;
	114	+ rq->sector = rq->hard_sector = (sector_t) -1;
	115	+ rq->nr_sectors = rq->hard_nr_sectors = 0;
	116	+ rq->current_nr_sectors = rq->hard_cur_sectors = 0;
111	117	rq->bio = rq->biotail = NULL;
112	118	INIT_HLIST_NODE(&rq->hash);
113	119	RB_CLEAR_NODE(&rq->rb_node);
	120	+ rq->rq_disk = NULL;
	121	+ rq->nr_phys_segments = 0;
	122	+ rq->nr_hw_segments = 0;
114	123	rq->ioprio = 0;
	124	+ rq->special = NULL;
115	125	rq->buffer = NULL;
	126	+ rq->tag = -1;
	127	+ rq->errors = 0;
116	128	rq->ref_count = 1;
117		- rq->q = q;
118		- rq->special = NULL;
	129	+ rq->cmd_len = 0;
	130	+ memset(rq->cmd, 0, sizeof(rq->cmd));
119	131	rq->data_len = 0;
	132	+ rq->sense_len = 0;
120	133	rq->data = NULL;
121		- rq->nr_phys_segments = 0;
122	134	rq->sense = NULL;
123	135	rq->end_io = NULL;
124	136	rq->end_io_data = NULL;
125		- rq->completion_data = NULL;
126	137	rq->next_rq = NULL;
127	138	}
128	139
...	...	@@ -137,7 +137,9 @@
137	137	#define BLK_MAX_CDB 16
138	138
139	139	/*
140		- * try to put the fields that are referenced together in the same cacheline
	140	+ * try to put the fields that are referenced together in the same cacheline.
	141	+ * if you modify this structure, be sure to check block/blk-core.c:rq_init()
	142	+ * as well!
141	143	*/
142	144	struct request {
143	145	struct list_head queuelist;