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block, bfq: remove batches of confusing ifdefs
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Commit a33801e ("block, bfq: move debug blkio stats behind
CONFIG_DEBUG_BLK_CGROUP") introduced two batches of confusing ifdefs:
one reported in [1], plus a similar one in another function. This
commit removes both batches, in the way suggested in [1].

[1] https://www.spinics.net/lists/linux-block/msg20043.html

Fixes: a33801e ("block, bfq: move debug blkio stats behind CONFIG_DEBUG_BLK_CGROUP")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Luca Miccio <lucmiccio@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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@Algodev-github @axboe
Algodev-github authored and axboe committed Jan 5, 2018
1 parent a34b024 commit 9b25bd0
Showing 1 changed file with 72 additions and 55 deletions.
127 changes: 72 additions & 55 deletions block/bfq-iosched.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3743,35 +3743,16 @@ static struct request *__bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
return rq;
}

static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
{
struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
struct request *rq;
#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
struct bfq_queue *in_serv_queue, *bfqq;
bool waiting_rq, idle_timer_disabled;
#endif

spin_lock_irq(&bfqd->lock);

#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
in_serv_queue = bfqd->in_service_queue;
waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue);

rq = __bfq_dispatch_request(hctx);

idle_timer_disabled =
waiting_rq && !bfq_bfqq_wait_request(in_serv_queue);

#else
rq = __bfq_dispatch_request(hctx);
#endif
spin_unlock_irq(&bfqd->lock);
static void bfq_update_dispatch_stats(struct request_queue *q,
struct request *rq,
struct bfq_queue *in_serv_queue,
bool idle_timer_disabled)
{
struct bfq_queue *bfqq = rq ? RQ_BFQQ(rq) : NULL;

#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
bfqq = rq ? RQ_BFQQ(rq) : NULL;
if (!idle_timer_disabled && !bfqq)
return rq;
return;

/*
* rq and bfqq are guaranteed to exist until this function
Expand All @@ -3786,7 +3767,7 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
* In addition, the following queue lock guarantees that
* bfqq_group(bfqq) exists as well.
*/
spin_lock_irq(hctx->queue->queue_lock);
spin_lock_irq(q->queue_lock);
if (idle_timer_disabled)
/*
* Since the idle timer has been disabled,
Expand All @@ -3805,9 +3786,37 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
bfqg_stats_set_start_empty_time(bfqg);
bfqg_stats_update_io_remove(bfqg, rq->cmd_flags);
}
spin_unlock_irq(hctx->queue->queue_lock);
spin_unlock_irq(q->queue_lock);
}
#else
static inline void bfq_update_dispatch_stats(struct request_queue *q,
struct request *rq,
struct bfq_queue *in_serv_queue,
bool idle_timer_disabled) {}
#endif

static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx)
{
struct bfq_data *bfqd = hctx->queue->elevator->elevator_data;
struct request *rq;
struct bfq_queue *in_serv_queue;
bool waiting_rq, idle_timer_disabled;

spin_lock_irq(&bfqd->lock);

in_serv_queue = bfqd->in_service_queue;
waiting_rq = in_serv_queue && bfq_bfqq_wait_request(in_serv_queue);

rq = __bfq_dispatch_request(hctx);

idle_timer_disabled =
waiting_rq && !bfq_bfqq_wait_request(in_serv_queue);

spin_unlock_irq(&bfqd->lock);

bfq_update_dispatch_stats(hctx->queue, rq, in_serv_queue,
idle_timer_disabled);

return rq;
}

Expand Down Expand Up @@ -4335,16 +4344,46 @@ static bool __bfq_insert_request(struct bfq_data *bfqd, struct request *rq)
return idle_timer_disabled;
}

#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
static void bfq_update_insert_stats(struct request_queue *q,
struct bfq_queue *bfqq,
bool idle_timer_disabled,
unsigned int cmd_flags)
{
if (!bfqq)
return;

/*
* bfqq still exists, because it can disappear only after
* either it is merged with another queue, or the process it
* is associated with exits. But both actions must be taken by
* the same process currently executing this flow of
* instructions.
*
* In addition, the following queue lock guarantees that
* bfqq_group(bfqq) exists as well.
*/
spin_lock_irq(q->queue_lock);
bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, cmd_flags);
if (idle_timer_disabled)
bfqg_stats_update_idle_time(bfqq_group(bfqq));
spin_unlock_irq(q->queue_lock);
}
#else
static inline void bfq_update_insert_stats(struct request_queue *q,
struct bfq_queue *bfqq,
bool idle_timer_disabled,
unsigned int cmd_flags) {}
#endif

static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
bool at_head)
{
struct request_queue *q = hctx->queue;
struct bfq_data *bfqd = q->elevator->elevator_data;
#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
struct bfq_queue *bfqq = RQ_BFQQ(rq);
bool idle_timer_disabled = false;
unsigned int cmd_flags;
#endif

spin_lock_irq(&bfqd->lock);
if (blk_mq_sched_try_insert_merge(q, rq)) {
Expand All @@ -4363,17 +4402,13 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
else
list_add_tail(&rq->queuelist, &bfqd->dispatch);
} else {
#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
idle_timer_disabled = __bfq_insert_request(bfqd, rq);
/*
* Update bfqq, because, if a queue merge has occurred
* in __bfq_insert_request, then rq has been
* redirected into a new queue.
*/
bfqq = RQ_BFQQ(rq);
#else
__bfq_insert_request(bfqd, rq);
#endif

if (rq_mergeable(rq)) {
elv_rqhash_add(q, rq);
Expand All @@ -4382,35 +4417,17 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
}
}

#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
/*
* Cache cmd_flags before releasing scheduler lock, because rq
* may disappear afterwards (for example, because of a request
* merge).
*/
cmd_flags = rq->cmd_flags;
#endif

spin_unlock_irq(&bfqd->lock);

#if defined(CONFIG_BFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
if (!bfqq)
return;
/*
* bfqq still exists, because it can disappear only after
* either it is merged with another queue, or the process it
* is associated with exits. But both actions must be taken by
* the same process currently executing this flow of
* instruction.
*
* In addition, the following queue lock guarantees that
* bfqq_group(bfqq) exists as well.
*/
spin_lock_irq(q->queue_lock);
bfqg_stats_update_io_add(bfqq_group(bfqq), bfqq, cmd_flags);
if (idle_timer_disabled)
bfqg_stats_update_idle_time(bfqq_group(bfqq));
spin_unlock_irq(q->queue_lock);
#endif
bfq_update_insert_stats(q, bfqq, idle_timer_disabled,
cmd_flags);
}

static void bfq_insert_requests(struct blk_mq_hw_ctx *hctx,
Expand Down

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