block: change the request allocation/congestion logic to be sync/async based
This makes sure that we never wait on async IO for sync requests, instead of doing the split on writes vs reads. Signed-off-by: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jens Axboe
Linus Torvalds
Родитель
0221c81b1b
Коммит
1faa16d228
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@ -484,11 +484,11 @@ static int blk_init_free_list(struct request_queue *q)
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{
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struct request_list *rl = &q->rq;
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rl->count[READ] = rl->count[WRITE] = 0;
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rl->starved[READ] = rl->starved[WRITE] = 0;
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rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
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rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
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rl->elvpriv = 0;
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init_waitqueue_head(&rl->wait[READ]);
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init_waitqueue_head(&rl->wait[WRITE]);
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init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
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init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
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rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
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mempool_free_slab, request_cachep, q->node);
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@ -699,18 +699,18 @@ static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
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ioc->last_waited = jiffies;
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}
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static void __freed_request(struct request_queue *q, int rw)
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static void __freed_request(struct request_queue *q, int sync)
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{
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struct request_list *rl = &q->rq;
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if (rl->count[rw] < queue_congestion_off_threshold(q))
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blk_clear_queue_congested(q, rw);
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if (rl->count[sync] < queue_congestion_off_threshold(q))
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blk_clear_queue_congested(q, sync);
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if (rl->count[rw] + 1 <= q->nr_requests) {
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if (waitqueue_active(&rl->wait[rw]))
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wake_up(&rl->wait[rw]);
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if (rl->count[sync] + 1 <= q->nr_requests) {
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if (waitqueue_active(&rl->wait[sync]))
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wake_up(&rl->wait[sync]);
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blk_clear_queue_full(q, rw);
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blk_clear_queue_full(q, sync);
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}
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}
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@ -718,18 +718,18 @@ static void __freed_request(struct request_queue *q, int rw)
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* A request has just been released. Account for it, update the full and
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* congestion status, wake up any waiters. Called under q->queue_lock.
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*/
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static void freed_request(struct request_queue *q, int rw, int priv)
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static void freed_request(struct request_queue *q, int sync, int priv)
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{
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struct request_list *rl = &q->rq;
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rl->count[rw]--;
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rl->count[sync]--;
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if (priv)
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rl->elvpriv--;
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__freed_request(q, rw);
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__freed_request(q, sync);
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if (unlikely(rl->starved[rw ^ 1]))
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__freed_request(q, rw ^ 1);
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if (unlikely(rl->starved[sync ^ 1]))
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__freed_request(q, sync ^ 1);
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}
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/*
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@ -743,15 +743,15 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
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struct request *rq = NULL;
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struct request_list *rl = &q->rq;
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struct io_context *ioc = NULL;
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const int rw = rw_flags & 0x01;
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const bool is_sync = rw_is_sync(rw_flags) != 0;
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int may_queue, priv;
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may_queue = elv_may_queue(q, rw_flags);
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if (may_queue == ELV_MQUEUE_NO)
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goto rq_starved;
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if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
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if (rl->count[rw]+1 >= q->nr_requests) {
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if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
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if (rl->count[is_sync]+1 >= q->nr_requests) {
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ioc = current_io_context(GFP_ATOMIC, q->node);
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/*
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* The queue will fill after this allocation, so set
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@ -759,9 +759,9 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
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* This process will be allowed to complete a batch of
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* requests, others will be blocked.
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*/
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if (!blk_queue_full(q, rw)) {
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if (!blk_queue_full(q, is_sync)) {
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ioc_set_batching(q, ioc);
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blk_set_queue_full(q, rw);
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blk_set_queue_full(q, is_sync);
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} else {
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if (may_queue != ELV_MQUEUE_MUST
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&& !ioc_batching(q, ioc)) {
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@ -774,7 +774,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
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}
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}
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}
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blk_set_queue_congested(q, rw);
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blk_set_queue_congested(q, is_sync);
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}
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/*
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@ -782,11 +782,11 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
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* limit of requests, otherwise we could have thousands of requests
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* allocated with any setting of ->nr_requests
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*/
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if (rl->count[rw] >= (3 * q->nr_requests / 2))
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if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
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goto out;
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rl->count[rw]++;
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rl->starved[rw] = 0;
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rl->count[is_sync]++;
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rl->starved[is_sync] = 0;
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priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
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if (priv)
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@ -804,7 +804,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
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* wait queue, but this is pretty rare.
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*/
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spin_lock_irq(q->queue_lock);
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freed_request(q, rw, priv);
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freed_request(q, is_sync, priv);
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/*
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* in the very unlikely event that allocation failed and no
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@ -814,8 +814,8 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
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* rq mempool into READ and WRITE
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*/
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rq_starved:
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if (unlikely(rl->count[rw] == 0))
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rl->starved[rw] = 1;
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if (unlikely(rl->count[is_sync] == 0))
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rl->starved[is_sync] = 1;
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goto out;
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}
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@ -829,7 +829,7 @@ rq_starved:
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if (ioc_batching(q, ioc))
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ioc->nr_batch_requests--;
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trace_block_getrq(q, bio, rw);
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trace_block_getrq(q, bio, rw_flags & 1);
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out:
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return rq;
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}
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@ -843,7 +843,7 @@ out:
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static struct request *get_request_wait(struct request_queue *q, int rw_flags,
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struct bio *bio)
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{
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const int rw = rw_flags & 0x01;
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const bool is_sync = rw_is_sync(rw_flags) != 0;
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struct request *rq;
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rq = get_request(q, rw_flags, bio, GFP_NOIO);
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@ -852,10 +852,10 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
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struct io_context *ioc;
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struct request_list *rl = &q->rq;
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prepare_to_wait_exclusive(&rl->wait[rw], &wait,
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prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
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TASK_UNINTERRUPTIBLE);
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trace_block_sleeprq(q, bio, rw);
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trace_block_sleeprq(q, bio, rw_flags & 1);
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__generic_unplug_device(q);
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spin_unlock_irq(q->queue_lock);
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@ -871,7 +871,7 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
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ioc_set_batching(q, ioc);
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spin_lock_irq(q->queue_lock);
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finish_wait(&rl->wait[rw], &wait);
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finish_wait(&rl->wait[is_sync], &wait);
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rq = get_request(q, rw_flags, bio, GFP_NOIO);
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};
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@ -1070,14 +1070,14 @@ void __blk_put_request(struct request_queue *q, struct request *req)
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* it didn't come out of our reserved rq pools
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*/
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if (req->cmd_flags & REQ_ALLOCED) {
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int rw = rq_data_dir(req);
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int is_sync = rq_is_sync(req) != 0;
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int priv = req->cmd_flags & REQ_ELVPRIV;
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BUG_ON(!list_empty(&req->queuelist));
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BUG_ON(!hlist_unhashed(&req->hash));
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blk_free_request(q, req);
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freed_request(q, rw, priv);
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freed_request(q, is_sync, priv);
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}
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}
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EXPORT_SYMBOL_GPL(__blk_put_request);
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@ -48,28 +48,28 @@ queue_requests_store(struct request_queue *q, const char *page, size_t count)
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q->nr_requests = nr;
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blk_queue_congestion_threshold(q);
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if (rl->count[READ] >= queue_congestion_on_threshold(q))
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blk_set_queue_congested(q, READ);
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else if (rl->count[READ] < queue_congestion_off_threshold(q))
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blk_clear_queue_congested(q, READ);
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if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
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blk_set_queue_congested(q, BLK_RW_SYNC);
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else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
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blk_clear_queue_congested(q, BLK_RW_SYNC);
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if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
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blk_set_queue_congested(q, WRITE);
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else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
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blk_clear_queue_congested(q, WRITE);
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if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
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blk_set_queue_congested(q, BLK_RW_ASYNC);
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else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
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blk_clear_queue_congested(q, BLK_RW_ASYNC);
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if (rl->count[READ] >= q->nr_requests) {
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blk_set_queue_full(q, READ);
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} else if (rl->count[READ]+1 <= q->nr_requests) {
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blk_clear_queue_full(q, READ);
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wake_up(&rl->wait[READ]);
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if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
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blk_set_queue_full(q, BLK_RW_SYNC);
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} else if (rl->count[BLK_RW_SYNC]+1 <= q->nr_requests) {
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blk_clear_queue_full(q, BLK_RW_SYNC);
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wake_up(&rl->wait[BLK_RW_SYNC]);
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}
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if (rl->count[WRITE] >= q->nr_requests) {
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blk_set_queue_full(q, WRITE);
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} else if (rl->count[WRITE]+1 <= q->nr_requests) {
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blk_clear_queue_full(q, WRITE);
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wake_up(&rl->wait[WRITE]);
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if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
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blk_set_queue_full(q, BLK_RW_ASYNC);
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} else if (rl->count[BLK_RW_ASYNC]+1 <= q->nr_requests) {
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blk_clear_queue_full(q, BLK_RW_ASYNC);
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wake_up(&rl->wait[BLK_RW_ASYNC]);
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}
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spin_unlock_irq(q->queue_lock);
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return ret;
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@ -677,7 +677,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
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}
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if (unplug_it && blk_queue_plugged(q)) {
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int nrq = q->rq.count[READ] + q->rq.count[WRITE]
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int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC]
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- q->in_flight;
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if (nrq >= q->unplug_thresh)
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@ -24,8 +24,8 @@ struct dentry;
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*/
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enum bdi_state {
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BDI_pdflush, /* A pdflush thread is working this device */
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BDI_write_congested, /* The write queue is getting full */
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BDI_read_congested, /* The read queue is getting full */
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BDI_async_congested, /* The async (write) queue is getting full */
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BDI_sync_congested, /* The sync queue is getting full */
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BDI_unused, /* Available bits start here */
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};
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@ -215,18 +215,18 @@ static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
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static inline int bdi_read_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, 1 << BDI_read_congested);
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return bdi_congested(bdi, 1 << BDI_sync_congested);
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}
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static inline int bdi_write_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, 1 << BDI_write_congested);
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return bdi_congested(bdi, 1 << BDI_async_congested);
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}
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static inline int bdi_rw_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, (1 << BDI_read_congested)|
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(1 << BDI_write_congested));
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return bdi_congested(bdi, (1 << BDI_sync_congested) |
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(1 << BDI_async_congested));
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}
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void clear_bdi_congested(struct backing_dev_info *bdi, int rw);
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@ -38,6 +38,10 @@ struct request;
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typedef void (rq_end_io_fn)(struct request *, int);
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struct request_list {
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/*
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* count[], starved[], and wait[] are indexed by
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* BLK_RW_SYNC/BLK_RW_ASYNC
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*/
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int count[2];
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int starved[2];
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int elvpriv;
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@ -66,6 +70,11 @@ enum rq_cmd_type_bits {
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REQ_TYPE_ATA_PC,
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};
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enum {
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BLK_RW_ASYNC = 0,
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BLK_RW_SYNC = 1,
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};
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/*
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* For request of type REQ_TYPE_LINUX_BLOCK, rq->cmd[0] is the opcode being
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* sent down (similar to how REQ_TYPE_BLOCK_PC means that ->cmd[] holds a
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@ -103,7 +112,7 @@ enum rq_flag_bits {
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__REQ_QUIET, /* don't worry about errors */
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__REQ_PREEMPT, /* set for "ide_preempt" requests */
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__REQ_ORDERED_COLOR, /* is before or after barrier */
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__REQ_RW_SYNC, /* request is sync (O_DIRECT) */
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__REQ_RW_SYNC, /* request is sync (sync write or read) */
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__REQ_ALLOCED, /* request came from our alloc pool */
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__REQ_RW_META, /* metadata io request */
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__REQ_COPY_USER, /* contains copies of user pages */
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@ -438,8 +447,8 @@ struct request_queue
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#define QUEUE_FLAG_CLUSTER 0 /* cluster several segments into 1 */
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#define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */
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#define QUEUE_FLAG_STOPPED 2 /* queue is stopped */
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#define QUEUE_FLAG_READFULL 3 /* read queue has been filled */
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#define QUEUE_FLAG_WRITEFULL 4 /* write queue has been filled */
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#define QUEUE_FLAG_SYNCFULL 3 /* read queue has been filled */
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#define QUEUE_FLAG_ASYNCFULL 4 /* write queue has been filled */
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#define QUEUE_FLAG_DEAD 5 /* queue being torn down */
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#define QUEUE_FLAG_REENTER 6 /* Re-entrancy avoidance */
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#define QUEUE_FLAG_PLUGGED 7 /* queue is plugged */
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@ -611,32 +620,41 @@ enum {
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#define rq_data_dir(rq) ((rq)->cmd_flags & 1)
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|
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/*
|
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* We regard a request as sync, if it's a READ or a SYNC write.
|
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* We regard a request as sync, if either a read or a sync write
|
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*/
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#define rq_is_sync(rq) (rq_data_dir((rq)) == READ || (rq)->cmd_flags & REQ_RW_SYNC)
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static inline bool rw_is_sync(unsigned int rw_flags)
|
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{
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return !(rw_flags & REQ_RW) || (rw_flags & REQ_RW_SYNC);
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}
|
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|
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static inline bool rq_is_sync(struct request *rq)
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{
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return rw_is_sync(rq->cmd_flags);
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}
|
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|
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#define rq_is_meta(rq) ((rq)->cmd_flags & REQ_RW_META)
|
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static inline int blk_queue_full(struct request_queue *q, int rw)
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static inline int blk_queue_full(struct request_queue *q, int sync)
|
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{
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if (rw == READ)
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return test_bit(QUEUE_FLAG_READFULL, &q->queue_flags);
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return test_bit(QUEUE_FLAG_WRITEFULL, &q->queue_flags);
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if (sync)
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return test_bit(QUEUE_FLAG_SYNCFULL, &q->queue_flags);
|
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return test_bit(QUEUE_FLAG_ASYNCFULL, &q->queue_flags);
|
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}
|
||||
|
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static inline void blk_set_queue_full(struct request_queue *q, int rw)
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static inline void blk_set_queue_full(struct request_queue *q, int sync)
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{
|
||||
if (rw == READ)
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queue_flag_set(QUEUE_FLAG_READFULL, q);
|
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if (sync)
|
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queue_flag_set(QUEUE_FLAG_SYNCFULL, q);
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else
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queue_flag_set(QUEUE_FLAG_WRITEFULL, q);
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queue_flag_set(QUEUE_FLAG_ASYNCFULL, q);
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}
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|
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static inline void blk_clear_queue_full(struct request_queue *q, int rw)
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static inline void blk_clear_queue_full(struct request_queue *q, int sync)
|
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{
|
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if (rw == READ)
|
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queue_flag_clear(QUEUE_FLAG_READFULL, q);
|
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if (sync)
|
||||
queue_flag_clear(QUEUE_FLAG_SYNCFULL, q);
|
||||
else
|
||||
queue_flag_clear(QUEUE_FLAG_WRITEFULL, q);
|
||||
queue_flag_clear(QUEUE_FLAG_ASYNCFULL, q);
|
||||
}
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -284,12 +284,12 @@ static wait_queue_head_t congestion_wqh[2] = {
|
|||
};
|
||||
|
||||
|
||||
void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
|
||||
void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
|
||||
{
|
||||
enum bdi_state bit;
|
||||
wait_queue_head_t *wqh = &congestion_wqh[rw];
|
||||
wait_queue_head_t *wqh = &congestion_wqh[sync];
|
||||
|
||||
bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
|
||||
bit = sync ? BDI_sync_congested : BDI_async_congested;
|
||||
clear_bit(bit, &bdi->state);
|
||||
smp_mb__after_clear_bit();
|
||||
if (waitqueue_active(wqh))
|
||||
|
|
@ -297,11 +297,11 @@ void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
|
|||
}
|
||||
EXPORT_SYMBOL(clear_bdi_congested);
|
||||
|
||||
void set_bdi_congested(struct backing_dev_info *bdi, int rw)
|
||||
void set_bdi_congested(struct backing_dev_info *bdi, int sync)
|
||||
{
|
||||
enum bdi_state bit;
|
||||
|
||||
bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
|
||||
bit = sync ? BDI_sync_congested : BDI_async_congested;
|
||||
set_bit(bit, &bdi->state);
|
||||
}
|
||||
EXPORT_SYMBOL(set_bdi_congested);
|
||||
|
|
|
|||
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Ссылка в новой задаче