[PATCH] block: implement elv_insert and use it (fix ordcolor flipping bug)
q->ordcolor must only be flipped on initial queueing of a hardbarrier
request.
Constructing ordered sequence and requeueing used to pass through
__elv_add_request() which flips q->ordcolor when it sees a barrier
request.
This patch separates out elv_insert() from __elv_add_request() and uses
elv_insert() when constructing ordered sequence and requeueing.
elv_insert() inserts the given request at the specified position and
does nothing else.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/block/elevator.c b/block/elevator.c
index 2fc269f..24b702d 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -293,7 +293,7 @@
rq->flags &= ~REQ_STARTED;
- __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE, 0);
+ elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
}
static void elv_drain_elevator(request_queue_t *q)
@@ -310,41 +310,11 @@
}
}
-void __elv_add_request(request_queue_t *q, struct request *rq, int where,
- int plug)
+void elv_insert(request_queue_t *q, struct request *rq, int where)
{
struct list_head *pos;
unsigned ordseq;
- if (q->ordcolor)
- rq->flags |= REQ_ORDERED_COLOR;
-
- if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
- /*
- * toggle ordered color
- */
- if (blk_barrier_rq(rq))
- q->ordcolor ^= 1;
-
- /*
- * barriers implicitly indicate back insertion
- */
- if (where == ELEVATOR_INSERT_SORT)
- where = ELEVATOR_INSERT_BACK;
-
- /*
- * this request is scheduling boundary, update end_sector
- */
- if (blk_fs_request(rq)) {
- q->end_sector = rq_end_sector(rq);
- q->boundary_rq = rq;
- }
- } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)
- where = ELEVATOR_INSERT_BACK;
-
- if (plug)
- blk_plug_device(q);
-
rq->q = q;
switch (where) {
@@ -425,6 +395,42 @@
}
}
+void __elv_add_request(request_queue_t *q, struct request *rq, int where,
+ int plug)
+{
+ if (q->ordcolor)
+ rq->flags |= REQ_ORDERED_COLOR;
+
+ if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
+ /*
+ * toggle ordered color
+ */
+ if (blk_barrier_rq(rq))
+ q->ordcolor ^= 1;
+
+ /*
+ * barriers implicitly indicate back insertion
+ */
+ if (where == ELEVATOR_INSERT_SORT)
+ where = ELEVATOR_INSERT_BACK;
+
+ /*
+ * this request is scheduling boundary, update
+ * end_sector
+ */
+ if (blk_fs_request(rq)) {
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = rq;
+ }
+ } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT)
+ where = ELEVATOR_INSERT_BACK;
+
+ if (plug)
+ blk_plug_device(q);
+
+ elv_insert(q, rq, where);
+}
+
void elv_add_request(request_queue_t *q, struct request *rq, int where,
int plug)
{
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index ee5ed98..03d9c82 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -454,7 +454,7 @@
rq->end_io = end_io;
q->prepare_flush_fn(q, rq);
- __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
+ elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
}
static inline struct request *start_ordered(request_queue_t *q,
@@ -490,7 +490,7 @@
else
q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
- __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0);
+ elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
if (q->ordered & QUEUE_ORDERED_PREFLUSH) {
queue_flush(q, QUEUE_ORDERED_PREFLUSH);
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 23fe746..18cf1f3 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -82,6 +82,7 @@
extern void elv_dispatch_sort(request_queue_t *, struct request *);
extern void elv_add_request(request_queue_t *, struct request *, int, int);
extern void __elv_add_request(request_queue_t *, struct request *, int, int);
+extern void elv_insert(request_queue_t *, struct request *, int);
extern int elv_merge(request_queue_t *, struct request **, struct bio *);
extern void elv_merge_requests(request_queue_t *, struct request *,
struct request *);
