#include <linux/writeback.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/fault-inject.h>
+#include <linux/list_sort.h>
#define CREATE_TRACE_POINTS
#include <trace/events/block.h>
static void req_bio_endio(struct request *rq, struct bio *bio,
unsigned int nbytes, int error)
{
- struct request_queue *q = rq->q;
-
- if (&q->flush_rq != rq) {
- if (error)
- clear_bit(BIO_UPTODATE, &bio->bi_flags);
- else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
- error = -EIO;
+ if (error)
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+ error = -EIO;
- if (unlikely(nbytes > bio->bi_size)) {
- printk(KERN_ERR "%s: want %u bytes done, %u left\n",
- __func__, nbytes, bio->bi_size);
- nbytes = bio->bi_size;
- }
+ if (unlikely(nbytes > bio->bi_size)) {
+ printk(KERN_ERR "%s: want %u bytes done, %u left\n",
+ __func__, nbytes, bio->bi_size);
+ nbytes = bio->bi_size;
+ }
- if (unlikely(rq->cmd_flags & REQ_QUIET))
- set_bit(BIO_QUIET, &bio->bi_flags);
+ if (unlikely(rq->cmd_flags & REQ_QUIET))
+ set_bit(BIO_QUIET, &bio->bi_flags);
- bio->bi_size -= nbytes;
- bio->bi_sector += (nbytes >> 9);
+ bio->bi_size -= nbytes;
+ bio->bi_sector += (nbytes >> 9);
- if (bio_integrity(bio))
- bio_integrity_advance(bio, nbytes);
+ if (bio_integrity(bio))
+ bio_integrity_advance(bio, nbytes);
- if (bio->bi_size == 0)
- bio_endio(bio, error);
- } else {
- /*
- * Okay, this is the sequenced flush request in
- * progress, just record the error;
- */
- if (error && !q->flush_err)
- q->flush_err = error;
- }
+ /* don't actually finish bio if it's part of flush sequence */
+ if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
+ bio_endio(bio, error);
}
void blk_dump_rq_flags(struct request *rq, char *msg)
}
EXPORT_SYMBOL(blk_dump_rq_flags);
+static void blk_delay_work(struct work_struct *work)
+{
+ struct request_queue *q;
+
+ q = container_of(work, struct request_queue, delay_work.work);
+ spin_lock_irq(q->queue_lock);
+ __blk_run_queue(q);
+ spin_unlock_irq(q->queue_lock);
+}
+
+/**
+ * blk_delay_queue - restart queueing after defined interval
+ * @q: The &struct request_queue in question
+ * @msecs: Delay in msecs
+ *
+ * Description:
+ * Sometimes queueing needs to be postponed for a little while, to allow
+ * resources to come back. This function will make sure that queueing is
+ * restarted around the specified time.
+ */
+void blk_delay_queue(struct request_queue *q, unsigned long msecs)
+{
+ schedule_delayed_work(&q->delay_work, msecs_to_jiffies(msecs));
+}
+EXPORT_SYMBOL(blk_delay_queue);
+
/*
* "plug" the device if there are no outstanding requests: this will
* force the transfer to start only after we have put all the requests
void blk_stop_queue(struct request_queue *q)
{
blk_remove_plug(q);
+ cancel_delayed_work(&q->delay_work);
queue_flag_set(QUEUE_FLAG_STOPPED, q);
}
EXPORT_SYMBOL(blk_stop_queue);
del_timer_sync(&q->timeout);
cancel_work_sync(&q->unplug_work);
throtl_shutdown_timer_wq(q);
+ cancel_delayed_work_sync(&q->delay_work);
}
EXPORT_SYMBOL(blk_sync_queue);
init_timer(&q->unplug_timer);
setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
INIT_LIST_HEAD(&q->timeout_list);
- INIT_LIST_HEAD(&q->pending_flushes);
+ INIT_LIST_HEAD(&q->flush_queue[0]);
+ INIT_LIST_HEAD(&q->flush_queue[1]);
+ INIT_LIST_HEAD(&q->flush_data_in_flight);
INIT_WORK(&q->unplug_work, blk_unplug_work);
+ INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
kobject_init(&q->kobj, &blk_queue_ktype);
static inline void blk_free_request(struct request_queue *q, struct request *rq)
{
+ BUG_ON(rq->cmd_flags & REQ_ON_PLUG);
+
if (rq->cmd_flags & REQ_ELVPRIV)
elv_put_request(q, rq);
mempool_free(rq, q->rq.rq_pool);
__freed_request(q, sync ^ 1);
}
+/*
+ * Determine if elevator data should be initialized when allocating the
+ * request associated with @bio.
+ */
+static bool blk_rq_should_init_elevator(struct bio *bio)
+{
+ if (!bio)
+ return true;
+
+ /*
+ * Flush requests do not use the elevator so skip initialization.
+ * This allows a request to share the flush and elevator data.
+ */
+ if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
+ return false;
+
+ return true;
+}
+
/*
* Get a free request, queue_lock must be held.
* Returns NULL on failure, with queue_lock held.
struct request_list *rl = &q->rq;
struct io_context *ioc = NULL;
const bool is_sync = rw_is_sync(rw_flags) != 0;
- int may_queue, priv;
+ int may_queue, priv = 0;
may_queue = elv_may_queue(q, rw_flags);
if (may_queue == ELV_MQUEUE_NO)
rl->count[is_sync]++;
rl->starved[is_sync] = 0;
- priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
- if (priv)
- rl->elvpriv++;
+ if (blk_rq_should_init_elevator(bio)) {
+ priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+ if (priv)
+ rl->elvpriv++;
+ }
if (blk_queue_io_stat(q))
rw_flags |= REQ_IO_STAT;
}
EXPORT_SYMBOL(blk_requeue_request);
+static void add_acct_request(struct request_queue *q, struct request *rq,
+ int where)
+{
+ drive_stat_acct(rq, 1);
+ __elv_add_request(q, rq, where, 0);
+}
+
/**
* blk_insert_request - insert a special request into a request queue
* @q: request queue where request should be inserted
if (blk_rq_tagged(rq))
blk_queue_end_tag(q, rq);
- drive_stat_acct(rq, 1);
- __elv_add_request(q, rq, where, 0);
+ add_acct_request(q, rq, where);
__blk_run_queue(q);
spin_unlock_irqrestore(q->queue_lock, flags);
}
}
EXPORT_SYMBOL_GPL(blk_add_request_payload);
+static bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
+ struct bio *bio)
+{
+ const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
+
+ /*
+ * Debug stuff, kill later
+ */
+ if (!rq_mergeable(req)) {
+ blk_dump_rq_flags(req, "back");
+ return false;
+ }
+
+ if (!ll_back_merge_fn(q, req, bio))
+ return false;
+
+ trace_block_bio_backmerge(q, bio);
+
+ if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
+ blk_rq_set_mixed_merge(req);
+
+ req->biotail->bi_next = bio;
+ req->biotail = bio;
+ req->__data_len += bio->bi_size;
+ req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
+
+ drive_stat_acct(req, 0);
+ return true;
+}
+
+static bool bio_attempt_front_merge(struct request_queue *q,
+ struct request *req, struct bio *bio)
+{
+ const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
+ sector_t sector;
+
+ /*
+ * Debug stuff, kill later
+ */
+ if (!rq_mergeable(req)) {
+ blk_dump_rq_flags(req, "front");
+ return false;
+ }
+
+ if (!ll_front_merge_fn(q, req, bio))
+ return false;
+
+ trace_block_bio_frontmerge(q, bio);
+
+ if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
+ blk_rq_set_mixed_merge(req);
+
+ sector = bio->bi_sector;
+
+ bio->bi_next = req->bio;
+ req->bio = bio;
+
+ /*
+ * may not be valid. if the low level driver said
+ * it didn't need a bounce buffer then it better
+ * not touch req->buffer either...
+ */
+ req->buffer = bio_data(bio);
+ req->__sector = bio->bi_sector;
+ req->__data_len += bio->bi_size;
+ req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
+
+ drive_stat_acct(req, 0);
+ return true;
+}
+
+/*
+ * Attempts to merge with the plugged list in the current process. Returns
+ * true if merge was succesful, otherwise false.
+ */
+static bool attempt_plug_merge(struct task_struct *tsk, struct request_queue *q,
+ struct bio *bio)
+{
+ struct blk_plug *plug;
+ struct request *rq;
+ bool ret = false;
+
+ plug = tsk->plug;
+ if (!plug)
+ goto out;
+
+ list_for_each_entry_reverse(rq, &plug->list, queuelist) {
+ int el_ret;
+
+ if (rq->q != q)
+ continue;
+
+ el_ret = elv_try_merge(rq, bio);
+ if (el_ret == ELEVATOR_BACK_MERGE) {
+ ret = bio_attempt_back_merge(q, rq, bio);
+ if (ret)
+ break;
+ } else if (el_ret == ELEVATOR_FRONT_MERGE) {
+ ret = bio_attempt_front_merge(q, rq, bio);
+ if (ret)
+ break;
+ }
+ }
+out:
+ return ret;
+}
+
void init_request_from_bio(struct request *req, struct bio *bio)
{
req->cpu = bio->bi_comp_cpu;
blk_rq_bio_prep(req->q, req, bio);
}
-/*
- * Only disabling plugging for non-rotational devices if it does tagging
- * as well, otherwise we do need the proper merging
- */
-static inline bool queue_should_plug(struct request_queue *q)
-{
- return !(blk_queue_nonrot(q) && blk_queue_tagged(q));
-}
-
static int __make_request(struct request_queue *q, struct bio *bio)
{
- struct request *req;
- int el_ret;
- unsigned int bytes = bio->bi_size;
- const unsigned short prio = bio_prio(bio);
const bool sync = !!(bio->bi_rw & REQ_SYNC);
- const bool unplug = !!(bio->bi_rw & REQ_UNPLUG);
- const unsigned long ff = bio->bi_rw & REQ_FAILFAST_MASK;
- int where = ELEVATOR_INSERT_SORT;
- int rw_flags;
+ struct blk_plug *plug;
+ int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
+ struct request *req;
/*
* low level driver can indicate that it wants pages above a
*/
blk_queue_bounce(q, &bio);
- spin_lock_irq(q->queue_lock);
-
if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
- where = ELEVATOR_INSERT_FRONT;
+ spin_lock_irq(q->queue_lock);
+ where = ELEVATOR_INSERT_FLUSH;
goto get_rq;
}
- if (elv_queue_empty(q))
- goto get_rq;
-
- el_ret = elv_merge(q, &req, bio);
- switch (el_ret) {
- case ELEVATOR_BACK_MERGE:
- BUG_ON(!rq_mergeable(req));
-
- if (!ll_back_merge_fn(q, req, bio))
- break;
-
- trace_block_bio_backmerge(q, bio);
-
- if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
- blk_rq_set_mixed_merge(req);
-
- req->biotail->bi_next = bio;
- req->biotail = bio;
- req->__data_len += bytes;
- req->ioprio = ioprio_best(req->ioprio, prio);
- if (!blk_rq_cpu_valid(req))
- req->cpu = bio->bi_comp_cpu;
- drive_stat_acct(req, 0);
- elv_bio_merged(q, req, bio);
- if (!attempt_back_merge(q, req))
- elv_merged_request(q, req, el_ret);
+ /*
+ * Check if we can merge with the plugged list before grabbing
+ * any locks.
+ */
+ if (attempt_plug_merge(current, q, bio))
goto out;
- case ELEVATOR_FRONT_MERGE:
- BUG_ON(!rq_mergeable(req));
-
- if (!ll_front_merge_fn(q, req, bio))
- break;
-
- trace_block_bio_frontmerge(q, bio);
+ spin_lock_irq(q->queue_lock);
- if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) {
- blk_rq_set_mixed_merge(req);
- req->cmd_flags &= ~REQ_FAILFAST_MASK;
- req->cmd_flags |= ff;
+ el_ret = elv_merge(q, &req, bio);
+ if (el_ret == ELEVATOR_BACK_MERGE) {
+ BUG_ON(req->cmd_flags & REQ_ON_PLUG);
+ if (bio_attempt_back_merge(q, req, bio)) {
+ if (!attempt_back_merge(q, req))
+ elv_merged_request(q, req, el_ret);
+ goto out_unlock;
+ }
+ } else if (el_ret == ELEVATOR_FRONT_MERGE) {
+ BUG_ON(req->cmd_flags & REQ_ON_PLUG);
+ if (bio_attempt_front_merge(q, req, bio)) {
+ if (!attempt_front_merge(q, req))
+ elv_merged_request(q, req, el_ret);
+ goto out_unlock;
}
-
- bio->bi_next = req->bio;
- req->bio = bio;
-
- /*
- * may not be valid. if the low level driver said
- * it didn't need a bounce buffer then it better
- * not touch req->buffer either...
- */
- req->buffer = bio_data(bio);
- req->__sector = bio->bi_sector;
- req->__data_len += bytes;
- req->ioprio = ioprio_best(req->ioprio, prio);
- if (!blk_rq_cpu_valid(req))
- req->cpu = bio->bi_comp_cpu;
- drive_stat_acct(req, 0);
- elv_bio_merged(q, req, bio);
- if (!attempt_front_merge(q, req))
- elv_merged_request(q, req, el_ret);
- goto out;
-
- /* ELV_NO_MERGE: elevator says don't/can't merge. */
- default:
- ;
}
get_rq:
*/
init_request_from_bio(req, bio);
- spin_lock_irq(q->queue_lock);
if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
- bio_flagged(bio, BIO_CPU_AFFINE))
- req->cpu = blk_cpu_to_group(smp_processor_id());
- if (queue_should_plug(q) && elv_queue_empty(q))
- blk_plug_device(q);
-
- /* insert the request into the elevator */
- drive_stat_acct(req, 1);
- __elv_add_request(q, req, where, 0);
+ bio_flagged(bio, BIO_CPU_AFFINE)) {
+ req->cpu = blk_cpu_to_group(get_cpu());
+ put_cpu();
+ }
+
+ plug = current->plug;
+ if (plug && !sync) {
+ if (!plug->should_sort && !list_empty(&plug->list)) {
+ struct request *__rq;
+
+ __rq = list_entry_rq(plug->list.prev);
+ if (__rq->q != q)
+ plug->should_sort = 1;
+ }
+ /*
+ * Debug flag, kill later
+ */
+ req->cmd_flags |= REQ_ON_PLUG;
+ list_add_tail(&req->queuelist, &plug->list);
+ drive_stat_acct(req, 1);
+ } else {
+ spin_lock_irq(q->queue_lock);
+ add_acct_request(q, req, where);
+ __blk_run_queue(q);
+out_unlock:
+ spin_unlock_irq(q->queue_lock);
+ }
out:
- if (unplug || !queue_should_plug(q))
- __generic_unplug_device(q);
- spin_unlock_irq(q->queue_lock);
return 0;
}
*/
BUG_ON(blk_queued_rq(rq));
- drive_stat_acct(rq, 1);
- __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
-
+ add_acct_request(q, rq, ELEVATOR_INSERT_BACK);
spin_unlock_irqrestore(q->queue_lock, flags);
return 0;
* normal IO on queueing nor completion. Accounting the
* containing request is enough.
*/
- if (blk_do_io_stat(req) && req != &req->q->flush_rq) {
+ if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
unsigned long duration = jiffies - req->start_time;
const int rw = rq_data_dir(req);
struct hd_struct *part;
}
EXPORT_SYMBOL(kblockd_schedule_delayed_work);
+#define PLUG_MAGIC 0x91827364
+
+void blk_start_plug(struct blk_plug *plug)
+{
+ struct task_struct *tsk = current;
+
+ plug->magic = PLUG_MAGIC;
+ INIT_LIST_HEAD(&plug->list);
+ plug->should_sort = 0;
+
+ /*
+ * If this is a nested plug, don't actually assign it. It will be
+ * flushed on its own.
+ */
+ if (!tsk->plug) {
+ /*
+ * Store ordering should not be needed here, since a potential
+ * preempt will imply a full memory barrier
+ */
+ tsk->plug = plug;
+ }
+}
+EXPORT_SYMBOL(blk_start_plug);
+
+static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
+{
+ struct request *rqa = container_of(a, struct request, queuelist);
+ struct request *rqb = container_of(b, struct request, queuelist);
+
+ return !(rqa->q == rqb->q);
+}
+
+static void flush_plug_list(struct blk_plug *plug)
+{
+ struct request_queue *q;
+ unsigned long flags;
+ struct request *rq;
+
+ BUG_ON(plug->magic != PLUG_MAGIC);
+
+ if (list_empty(&plug->list))
+ return;
+
+ if (plug->should_sort)
+ list_sort(NULL, &plug->list, plug_rq_cmp);
+
+ q = NULL;
+ local_irq_save(flags);
+ while (!list_empty(&plug->list)) {
+ rq = list_entry_rq(plug->list.next);
+ list_del_init(&rq->queuelist);
+ BUG_ON(!(rq->cmd_flags & REQ_ON_PLUG));
+ BUG_ON(!rq->q);
+ if (rq->q != q) {
+ if (q) {
+ __blk_run_queue(q);
+ spin_unlock(q->queue_lock);
+ }
+ q = rq->q;
+ spin_lock(q->queue_lock);
+ }
+ rq->cmd_flags &= ~REQ_ON_PLUG;
+
+ /*
+ * rq is already accounted, so use raw insert
+ */
+ __elv_add_request(q, rq, ELEVATOR_INSERT_SORT, 0);
+ }
+
+ if (q) {
+ __blk_run_queue(q);
+ spin_unlock(q->queue_lock);
+ }
+
+ BUG_ON(!list_empty(&plug->list));
+ local_irq_restore(flags);
+}
+
+static void __blk_finish_plug(struct task_struct *tsk, struct blk_plug *plug)
+{
+ flush_plug_list(plug);
+
+ if (plug == tsk->plug)
+ tsk->plug = NULL;
+}
+
+void blk_finish_plug(struct blk_plug *plug)
+{
+ if (plug)
+ __blk_finish_plug(current, plug);
+}
+EXPORT_SYMBOL(blk_finish_plug);
+
+void __blk_flush_plug(struct task_struct *tsk, struct blk_plug *plug)
+{
+ __blk_finish_plug(tsk, plug);
+ tsk->plug = plug;
+}
+EXPORT_SYMBOL(__blk_flush_plug);
+
int __init blk_dev_init(void)
{
BUILD_BUG_ON(__REQ_NR_BITS > 8 *
projects / deliverable / linux.git / blobdiff