--- /dev/null
+/*
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright (C) 1994, Karl Keyte: Added support for disk statistics
+ * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
+ * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
+ * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
+ * - July2000
+ * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
+ */
+
+/*
+ * This handles all read/write requests to block devices
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/backing-dev.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/kernel_stat.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/fault-inject.h>
+#include <linux/list_sort.h>
+#include <linux/delay.h>
+#include <linux/ratelimit.h>
+#include <linux/pm_runtime.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/block.h>
+
+#include "blk.h"
+#include "blk-cgroup.h"
+#include "blk-mq.h"
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
+EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
+
+DEFINE_IDA(blk_queue_ida);
+
+/*
+ * For the allocated request tables
+ */
+struct kmem_cache *request_cachep = NULL;
+
+/*
+ * For queue allocation
+ */
+struct kmem_cache *blk_requestq_cachep;
+
+/*
+ * Controlling structure to kblockd
+ */
+static struct workqueue_struct *kblockd_workqueue;
+
+void blk_queue_congestion_threshold(struct request_queue *q)
+{
+ int nr;
+
+ nr = q->nr_requests - (q->nr_requests / 8) + 1;
+ if (nr > q->nr_requests)
+ nr = q->nr_requests;
+ q->nr_congestion_on = nr;
+
+ nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
+ if (nr < 1)
+ nr = 1;
+ q->nr_congestion_off = nr;
+}
+
+/**
+ * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
+ * @bdev: device
+ *
+ * Locates the passed device's request queue and returns the address of its
+ * backing_dev_info. This function can only be called if @bdev is opened
+ * and the return value is never NULL.
+ */
+struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
+{
+ struct request_queue *q = bdev_get_queue(bdev);
+
+ return &q->backing_dev_info;
+}
+EXPORT_SYMBOL(blk_get_backing_dev_info);
+
+void blk_rq_init(struct request_queue *q, struct request *rq)
+{
+ memset(rq, 0, sizeof(*rq));
+
+ INIT_LIST_HEAD(&rq->queuelist);
+ INIT_LIST_HEAD(&rq->timeout_list);
+#ifdef CONFIG_PREEMPT_RT_FULL
+ INIT_WORK(&rq->work, __blk_mq_complete_request_remote_work);
+#endif
+ rq->cpu = -1;
+ rq->q = q;
+ rq->__sector = (sector_t) -1;
+ INIT_HLIST_NODE(&rq->hash);
+ RB_CLEAR_NODE(&rq->rb_node);
+ rq->cmd = rq->__cmd;
+ rq->cmd_len = BLK_MAX_CDB;
+ rq->tag = -1;
+ rq->start_time = jiffies;
+ set_start_time_ns(rq);
+ rq->part = NULL;
+}
+EXPORT_SYMBOL(blk_rq_init);
+
+static void req_bio_endio(struct request *rq, struct bio *bio,
+ unsigned int nbytes, int error)
+{
+ if (error)
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+ error = -EIO;
+
+ if (unlikely(rq->cmd_flags & REQ_QUIET))
+ set_bit(BIO_QUIET, &bio->bi_flags);
+
+ bio_advance(bio, nbytes);
+
+ /* don't actually finish bio if it's part of flush sequence */
+ if (bio->bi_iter.bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
+ bio_endio(bio, error);
+}
+
+void blk_dump_rq_flags(struct request *rq, char *msg)
+{
+ int bit;
+
+ printk(KERN_INFO "%s: dev %s: type=%x, flags=%llx\n", msg,
+ rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
+ (unsigned long long) rq->cmd_flags);
+
+ printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
+ (unsigned long long)blk_rq_pos(rq),
+ blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
+ printk(KERN_INFO " bio %p, biotail %p, len %u\n",
+ rq->bio, rq->biotail, blk_rq_bytes(rq));
+
+ if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
+ printk(KERN_INFO " cdb: ");
+ for (bit = 0; bit < BLK_MAX_CDB; bit++)
+ printk("%02x ", rq->cmd[bit]);
+ printk("\n");
+ }
+}
+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. Queue lock must be held.
+ */
+void blk_delay_queue(struct request_queue *q, unsigned long msecs)
+{
+ if (likely(!blk_queue_dead(q)))
+ queue_delayed_work(kblockd_workqueue, &q->delay_work,
+ msecs_to_jiffies(msecs));
+}
+EXPORT_SYMBOL(blk_delay_queue);
+
+/**
+ * blk_start_queue - restart a previously stopped queue
+ * @q: The &struct request_queue in question
+ *
+ * Description:
+ * blk_start_queue() will clear the stop flag on the queue, and call
+ * the request_fn for the queue if it was in a stopped state when
+ * entered. Also see blk_stop_queue(). Queue lock must be held.
+ **/
+void blk_start_queue(struct request_queue *q)
+{
+ WARN_ON_NONRT(!irqs_disabled());
+
+ queue_flag_clear(QUEUE_FLAG_STOPPED, q);
+ __blk_run_queue(q);
+}
+EXPORT_SYMBOL(blk_start_queue);
+
+/**
+ * blk_stop_queue - stop a queue
+ * @q: The &struct request_queue in question
+ *
+ * Description:
+ * The Linux block layer assumes that a block driver will consume all
+ * entries on the request queue when the request_fn strategy is called.
+ * Often this will not happen, because of hardware limitations (queue
+ * depth settings). If a device driver gets a 'queue full' response,
+ * or if it simply chooses not to queue more I/O at one point, it can
+ * call this function to prevent the request_fn from being called until
+ * the driver has signalled it's ready to go again. This happens by calling
+ * blk_start_queue() to restart queue operations. Queue lock must be held.
+ **/
+void blk_stop_queue(struct request_queue *q)
+{
+ cancel_delayed_work(&q->delay_work);
+ queue_flag_set(QUEUE_FLAG_STOPPED, q);
+}
+EXPORT_SYMBOL(blk_stop_queue);
+
+/**
+ * blk_sync_queue - cancel any pending callbacks on a queue
+ * @q: the queue
+ *
+ * Description:
+ * The block layer may perform asynchronous callback activity
+ * on a queue, such as calling the unplug function after a timeout.
+ * A block device may call blk_sync_queue to ensure that any
+ * such activity is cancelled, thus allowing it to release resources
+ * that the callbacks might use. The caller must already have made sure
+ * that its ->make_request_fn will not re-add plugging prior to calling
+ * this function.
+ *
+ * This function does not cancel any asynchronous activity arising
+ * out of elevator or throttling code. That would require elevator_exit()
+ * and blkcg_exit_queue() to be called with queue lock initialized.
+ *
+ */
+void blk_sync_queue(struct request_queue *q)
+{
+ del_timer_sync(&q->timeout);
+
+ if (q->mq_ops) {
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ cancel_delayed_work_sync(&hctx->run_work);
+ cancel_delayed_work_sync(&hctx->delay_work);
+ }
+ } else {
+ cancel_delayed_work_sync(&q->delay_work);
+ }
+}
+EXPORT_SYMBOL(blk_sync_queue);
+
+/**
+ * __blk_run_queue_uncond - run a queue whether or not it has been stopped
+ * @q: The queue to run
+ *
+ * Description:
+ * Invoke request handling on a queue if there are any pending requests.
+ * May be used to restart request handling after a request has completed.
+ * This variant runs the queue whether or not the queue has been
+ * stopped. Must be called with the queue lock held and interrupts
+ * disabled. See also @blk_run_queue.
+ */
+inline void __blk_run_queue_uncond(struct request_queue *q)
+{
+ if (unlikely(blk_queue_dead(q)))
+ return;
+
+ /*
+ * Some request_fn implementations, e.g. scsi_request_fn(), unlock
+ * the queue lock internally. As a result multiple threads may be
+ * running such a request function concurrently. Keep track of the
+ * number of active request_fn invocations such that blk_drain_queue()
+ * can wait until all these request_fn calls have finished.
+ */
+ q->request_fn_active++;
+ q->request_fn(q);
+ q->request_fn_active--;
+}
+
+/**
+ * __blk_run_queue - run a single device queue
+ * @q: The queue to run
+ *
+ * Description:
+ * See @blk_run_queue. This variant must be called with the queue lock
+ * held and interrupts disabled.
+ */
+void __blk_run_queue(struct request_queue *q)
+{
+ if (unlikely(blk_queue_stopped(q)))
+ return;
+
+ __blk_run_queue_uncond(q);
+}
+EXPORT_SYMBOL(__blk_run_queue);
+
+/**
+ * blk_run_queue_async - run a single device queue in workqueue context
+ * @q: The queue to run
+ *
+ * Description:
+ * Tells kblockd to perform the equivalent of @blk_run_queue on behalf
+ * of us. The caller must hold the queue lock.
+ */
+void blk_run_queue_async(struct request_queue *q)
+{
+ if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q)))
+ mod_delayed_work(kblockd_workqueue, &q->delay_work, 0);
+}
+EXPORT_SYMBOL(blk_run_queue_async);
+
+/**
+ * blk_run_queue - run a single device queue
+ * @q: The queue to run
+ *
+ * Description:
+ * Invoke request handling on this queue, if it has pending work to do.
+ * May be used to restart queueing when a request has completed.
+ */
+void blk_run_queue(struct request_queue *q)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ __blk_run_queue(q);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+EXPORT_SYMBOL(blk_run_queue);
+
+void blk_put_queue(struct request_queue *q)
+{
+ kobject_put(&q->kobj);
+}
+EXPORT_SYMBOL(blk_put_queue);
+
+/**
+ * __blk_drain_queue - drain requests from request_queue
+ * @q: queue to drain
+ * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV
+ *
+ * Drain requests from @q. If @drain_all is set, all requests are drained.
+ * If not, only ELVPRIV requests are drained. The caller is responsible
+ * for ensuring that no new requests which need to be drained are queued.
+ */
+static void __blk_drain_queue(struct request_queue *q, bool drain_all)
+ __releases(q->queue_lock)
+ __acquires(q->queue_lock)
+{
+ int i;
+
+ lockdep_assert_held(q->queue_lock);
+
+ while (true) {
+ bool drain = false;
+
+ /*
+ * The caller might be trying to drain @q before its
+ * elevator is initialized.
+ */
+ if (q->elevator)
+ elv_drain_elevator(q);
+
+ blkcg_drain_queue(q);
+
+ /*
+ * This function might be called on a queue which failed
+ * driver init after queue creation or is not yet fully
+ * active yet. Some drivers (e.g. fd and loop) get unhappy
+ * in such cases. Kick queue iff dispatch queue has
+ * something on it and @q has request_fn set.
+ */
+ if (!list_empty(&q->queue_head) && q->request_fn)
+ __blk_run_queue(q);
+
+ drain |= q->nr_rqs_elvpriv;
+ drain |= q->request_fn_active;
+
+ /*
+ * Unfortunately, requests are queued at and tracked from
+ * multiple places and there's no single counter which can
+ * be drained. Check all the queues and counters.
+ */
+ if (drain_all) {
+ struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
+ drain |= !list_empty(&q->queue_head);
+ for (i = 0; i < 2; i++) {
+ drain |= q->nr_rqs[i];
+ drain |= q->in_flight[i];
+ if (fq)
+ drain |= !list_empty(&fq->flush_queue[i]);
+ }
+ }
+
+ if (!drain)
+ break;
+
+ spin_unlock_irq(q->queue_lock);
+
+ msleep(10);
+
+ spin_lock_irq(q->queue_lock);
+ }
+
+ /*
+ * With queue marked dead, any woken up waiter will fail the
+ * allocation path, so the wakeup chaining is lost and we're
+ * left with hung waiters. We need to wake up those waiters.
+ */
+ if (q->request_fn) {
+ struct request_list *rl;
+
+ blk_queue_for_each_rl(rl, q)
+ for (i = 0; i < ARRAY_SIZE(rl->wait); i++)
+ wake_up_all(&rl->wait[i]);
+ }
+}
+
+/**
+ * blk_queue_bypass_start - enter queue bypass mode
+ * @q: queue of interest
+ *
+ * In bypass mode, only the dispatch FIFO queue of @q is used. This
+ * function makes @q enter bypass mode and drains all requests which were
+ * throttled or issued before. On return, it's guaranteed that no request
+ * is being throttled or has ELVPRIV set and blk_queue_bypass() %true
+ * inside queue or RCU read lock.
+ */
+void blk_queue_bypass_start(struct request_queue *q)
+{
+ spin_lock_irq(q->queue_lock);
+ q->bypass_depth++;
+ queue_flag_set(QUEUE_FLAG_BYPASS, q);
+ spin_unlock_irq(q->queue_lock);
+
+ /*
+ * Queues start drained. Skip actual draining till init is
+ * complete. This avoids lenghty delays during queue init which
+ * can happen many times during boot.
+ */
+ if (blk_queue_init_done(q)) {
+ spin_lock_irq(q->queue_lock);
+ __blk_drain_queue(q, false);
+ spin_unlock_irq(q->queue_lock);
+
+ /* ensure blk_queue_bypass() is %true inside RCU read lock */
+ synchronize_rcu();
+ }
+}
+EXPORT_SYMBOL_GPL(blk_queue_bypass_start);
+
+/**
+ * blk_queue_bypass_end - leave queue bypass mode
+ * @q: queue of interest
+ *
+ * Leave bypass mode and restore the normal queueing behavior.
+ */
+void blk_queue_bypass_end(struct request_queue *q)
+{
+ spin_lock_irq(q->queue_lock);
+ if (!--q->bypass_depth)
+ queue_flag_clear(QUEUE_FLAG_BYPASS, q);
+ WARN_ON_ONCE(q->bypass_depth < 0);
+ spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL_GPL(blk_queue_bypass_end);
+
+void blk_set_queue_dying(struct request_queue *q)
+{
+ queue_flag_set_unlocked(QUEUE_FLAG_DYING, q);
+
+ if (q->mq_ops)
+ blk_mq_wake_waiters(q);
+ else {
+ struct request_list *rl;
+
+ blk_queue_for_each_rl(rl, q) {
+ if (rl->rq_pool) {
+ wake_up(&rl->wait[BLK_RW_SYNC]);
+ wake_up(&rl->wait[BLK_RW_ASYNC]);
+ }
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(blk_set_queue_dying);
+
+/**
+ * blk_cleanup_queue - shutdown a request queue
+ * @q: request queue to shutdown
+ *
+ * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
+ * put it. All future requests will be failed immediately with -ENODEV.
+ */
+void blk_cleanup_queue(struct request_queue *q)
+{
+ spinlock_t *lock = q->queue_lock;
+
+ /* mark @q DYING, no new request or merges will be allowed afterwards */
+ mutex_lock(&q->sysfs_lock);
+ blk_set_queue_dying(q);
+ spin_lock_irq(lock);
+
+ /*
+ * A dying queue is permanently in bypass mode till released. Note
+ * that, unlike blk_queue_bypass_start(), we aren't performing
+ * synchronize_rcu() after entering bypass mode to avoid the delay
+ * as some drivers create and destroy a lot of queues while
+ * probing. This is still safe because blk_release_queue() will be
+ * called only after the queue refcnt drops to zero and nothing,
+ * RCU or not, would be traversing the queue by then.
+ */
+ q->bypass_depth++;
+ queue_flag_set(QUEUE_FLAG_BYPASS, q);
+
+ queue_flag_set(QUEUE_FLAG_NOMERGES, q);
+ queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
+ queue_flag_set(QUEUE_FLAG_DYING, q);
+ spin_unlock_irq(lock);
+ mutex_unlock(&q->sysfs_lock);
+
+ /*
+ * Drain all requests queued before DYING marking. Set DEAD flag to
+ * prevent that q->request_fn() gets invoked after draining finished.
+ */
+ if (q->mq_ops) {
+ blk_mq_freeze_queue(q);
+ spin_lock_irq(lock);
+ } else {
+ spin_lock_irq(lock);
+ __blk_drain_queue(q, true);
+ }
+ queue_flag_set(QUEUE_FLAG_DEAD, q);
+ spin_unlock_irq(lock);
+
+ /* @q won't process any more request, flush async actions */
+ del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
+ blk_sync_queue(q);
+
+ if (q->mq_ops)
+ blk_mq_free_queue(q);
+
+ spin_lock_irq(lock);
+ if (q->queue_lock != &q->__queue_lock)
+ q->queue_lock = &q->__queue_lock;
+ spin_unlock_irq(lock);
+
+ bdi_destroy(&q->backing_dev_info);
+
+ /* @q is and will stay empty, shutdown and put */
+ blk_put_queue(q);
+}
+EXPORT_SYMBOL(blk_cleanup_queue);
+
+/* Allocate memory local to the request queue */
+static void *alloc_request_struct(gfp_t gfp_mask, void *data)
+{
+ int nid = (int)(long)data;
+ return kmem_cache_alloc_node(request_cachep, gfp_mask, nid);
+}
+
+static void free_request_struct(void *element, void *unused)
+{
+ kmem_cache_free(request_cachep, element);
+}
+
+int blk_init_rl(struct request_list *rl, struct request_queue *q,
+ gfp_t gfp_mask)
+{
+ if (unlikely(rl->rq_pool))
+ return 0;
+
+ rl->q = q;
+ rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
+ rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
+ init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
+ init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
+
+ rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, alloc_request_struct,
+ free_request_struct,
+ (void *)(long)q->node, gfp_mask,
+ q->node);
+ if (!rl->rq_pool)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void blk_exit_rl(struct request_list *rl)
+{
+ if (rl->rq_pool)
+ mempool_destroy(rl->rq_pool);
+}
+
+struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
+{
+ return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
+}
+EXPORT_SYMBOL(blk_alloc_queue);
+
+struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
+{
+ struct request_queue *q;
+ int err;
+
+ q = kmem_cache_alloc_node(blk_requestq_cachep,
+ gfp_mask | __GFP_ZERO, node_id);
+ if (!q)
+ return NULL;
+
+ q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
+ if (q->id < 0)
+ goto fail_q;
+
+ q->backing_dev_info.ra_pages =
+ (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
+ q->backing_dev_info.state = 0;
+ q->backing_dev_info.capabilities = 0;
+ q->backing_dev_info.name = "block";
+ q->node = node_id;
+
+ err = bdi_init(&q->backing_dev_info);
+ if (err)
+ goto fail_id;
+
+ setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
+ laptop_mode_timer_fn, (unsigned long) q);
+ setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
+ INIT_LIST_HEAD(&q->queue_head);
+ INIT_LIST_HEAD(&q->timeout_list);
+ INIT_LIST_HEAD(&q->icq_list);
+#ifdef CONFIG_BLK_CGROUP
+ INIT_LIST_HEAD(&q->blkg_list);
+#endif
+ INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
+
+ kobject_init(&q->kobj, &blk_queue_ktype);
+
+ mutex_init(&q->sysfs_lock);
+ spin_lock_init(&q->__queue_lock);
+
+ /*
+ * By default initialize queue_lock to internal lock and driver can
+ * override it later if need be.
+ */
+ q->queue_lock = &q->__queue_lock;
+
+ /*
+ * A queue starts its life with bypass turned on to avoid
+ * unnecessary bypass on/off overhead and nasty surprises during
+ * init. The initial bypass will be finished when the queue is
+ * registered by blk_register_queue().
+ */
+ q->bypass_depth = 1;
+ __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
+
+ init_swait_head(&q->mq_freeze_wq);
+
+ if (blkcg_init_queue(q))
+ goto fail_bdi;
+
+ return q;
+
+fail_bdi:
+ bdi_destroy(&q->backing_dev_info);
+fail_id:
+ ida_simple_remove(&blk_queue_ida, q->id);
+fail_q:
+ kmem_cache_free(blk_requestq_cachep, q);
+ return NULL;
+}
+EXPORT_SYMBOL(blk_alloc_queue_node);
+
+/**
+ * blk_init_queue - prepare a request queue for use with a block device
+ * @rfn: The function to be called to process requests that have been
+ * placed on the queue.
+ * @lock: Request queue spin lock
+ *
+ * Description:
+ * If a block device wishes to use the standard request handling procedures,
+ * which sorts requests and coalesces adjacent requests, then it must
+ * call blk_init_queue(). The function @rfn will be called when there
+ * are requests on the queue that need to be processed. If the device
+ * supports plugging, then @rfn may not be called immediately when requests
+ * are available on the queue, but may be called at some time later instead.
+ * Plugged queues are generally unplugged when a buffer belonging to one
+ * of the requests on the queue is needed, or due to memory pressure.
+ *
+ * @rfn is not required, or even expected, to remove all requests off the
+ * queue, but only as many as it can handle at a time. If it does leave
+ * requests on the queue, it is responsible for arranging that the requests
+ * get dealt with eventually.
+ *
+ * The queue spin lock must be held while manipulating the requests on the
+ * request queue; this lock will be taken also from interrupt context, so irq
+ * disabling is needed for it.
+ *
+ * Function returns a pointer to the initialized request queue, or %NULL if
+ * it didn't succeed.
+ *
+ * Note:
+ * blk_init_queue() must be paired with a blk_cleanup_queue() call
+ * when the block device is deactivated (such as at module unload).
+ **/
+
+struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
+{
+ return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
+}
+EXPORT_SYMBOL(blk_init_queue);
+
+struct request_queue *
+blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
+{
+ struct request_queue *uninit_q, *q;
+
+ uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
+ if (!uninit_q)
+ return NULL;
+
+ q = blk_init_allocated_queue(uninit_q, rfn, lock);
+ if (!q)
+ blk_cleanup_queue(uninit_q);
+
+ return q;
+}
+EXPORT_SYMBOL(blk_init_queue_node);
+
+static void blk_queue_bio(struct request_queue *q, struct bio *bio);
+
+struct request_queue *
+blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
+ spinlock_t *lock)
+{
+ if (!q)
+ return NULL;
+
+ q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, 0);
+ if (!q->fq)
+ return NULL;
+
+ if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
+ goto fail;
+
+ q->request_fn = rfn;
+ q->prep_rq_fn = NULL;
+ q->unprep_rq_fn = NULL;
+ q->queue_flags |= QUEUE_FLAG_DEFAULT;
+
+ /* Override internal queue lock with supplied lock pointer */
+ if (lock)
+ q->queue_lock = lock;
+
+ /*
+ * This also sets hw/phys segments, boundary and size
+ */
+ blk_queue_make_request(q, blk_queue_bio);
+
+ q->sg_reserved_size = INT_MAX;
+
+ /* Protect q->elevator from elevator_change */
+ mutex_lock(&q->sysfs_lock);
+
+ /* init elevator */
+ if (elevator_init(q, NULL)) {
+ mutex_unlock(&q->sysfs_lock);
+ goto fail;
+ }
+
+ mutex_unlock(&q->sysfs_lock);
+
+ return q;
+
+fail:
+ blk_free_flush_queue(q->fq);
+ return NULL;
+}
+EXPORT_SYMBOL(blk_init_allocated_queue);
+
+bool blk_get_queue(struct request_queue *q)
+{
+ if (likely(!blk_queue_dying(q))) {
+ __blk_get_queue(q);
+ return true;
+ }
+
+ return false;
+}
+EXPORT_SYMBOL(blk_get_queue);
+
+static inline void blk_free_request(struct request_list *rl, struct request *rq)
+{
+ if (rq->cmd_flags & REQ_ELVPRIV) {
+ elv_put_request(rl->q, rq);
+ if (rq->elv.icq)
+ put_io_context(rq->elv.icq->ioc);
+ }
+
+ mempool_free(rq, rl->rq_pool);
+}
+
+/*
+ * ioc_batching returns true if the ioc is a valid batching request and
+ * should be given priority access to a request.
+ */
+static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
+{
+ if (!ioc)
+ return 0;
+
+ /*
+ * Make sure the process is able to allocate at least 1 request
+ * even if the batch times out, otherwise we could theoretically
+ * lose wakeups.
+ */
+ return ioc->nr_batch_requests == q->nr_batching ||
+ (ioc->nr_batch_requests > 0
+ && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
+}
+
+/*
+ * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
+ * will cause the process to be a "batcher" on all queues in the system. This
+ * is the behaviour we want though - once it gets a wakeup it should be given
+ * a nice run.
+ */
+static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
+{
+ if (!ioc || ioc_batching(q, ioc))
+ return;
+
+ ioc->nr_batch_requests = q->nr_batching;
+ ioc->last_waited = jiffies;
+}
+
+static void __freed_request(struct request_list *rl, int sync)
+{
+ struct request_queue *q = rl->q;
+
+ /*
+ * bdi isn't aware of blkcg yet. As all async IOs end up root
+ * blkcg anyway, just use root blkcg state.
+ */
+ if (rl == &q->root_rl &&
+ rl->count[sync] < queue_congestion_off_threshold(q))
+ blk_clear_queue_congested(q, sync);
+
+ if (rl->count[sync] + 1 <= q->nr_requests) {
+ if (waitqueue_active(&rl->wait[sync]))
+ wake_up(&rl->wait[sync]);
+
+ blk_clear_rl_full(rl, sync);
+ }
+}
+
+/*
+ * A request has just been released. Account for it, update the full and
+ * congestion status, wake up any waiters. Called under q->queue_lock.
+ */
+static void freed_request(struct request_list *rl, unsigned int flags)
+{
+ struct request_queue *q = rl->q;
+ int sync = rw_is_sync(flags);
+
+ q->nr_rqs[sync]--;
+ rl->count[sync]--;
+ if (flags & REQ_ELVPRIV)
+ q->nr_rqs_elvpriv--;
+
+ __freed_request(rl, sync);
+
+ if (unlikely(rl->starved[sync ^ 1]))
+ __freed_request(rl, sync ^ 1);
+}
+
+int blk_update_nr_requests(struct request_queue *q, unsigned int nr)
+{
+ struct request_list *rl;
+
+ spin_lock_irq(q->queue_lock);
+ q->nr_requests = nr;
+ blk_queue_congestion_threshold(q);
+
+ /* congestion isn't cgroup aware and follows root blkcg for now */
+ rl = &q->root_rl;
+
+ if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
+ blk_set_queue_congested(q, BLK_RW_SYNC);
+ else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
+ blk_clear_queue_congested(q, BLK_RW_SYNC);
+
+ if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
+ blk_set_queue_congested(q, BLK_RW_ASYNC);
+ else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
+ blk_clear_queue_congested(q, BLK_RW_ASYNC);
+
+ blk_queue_for_each_rl(rl, q) {
+ if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
+ blk_set_rl_full(rl, BLK_RW_SYNC);
+ } else {
+ blk_clear_rl_full(rl, BLK_RW_SYNC);
+ wake_up(&rl->wait[BLK_RW_SYNC]);
+ }
+
+ if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
+ blk_set_rl_full(rl, BLK_RW_ASYNC);
+ } else {
+ blk_clear_rl_full(rl, BLK_RW_ASYNC);
+ wake_up(&rl->wait[BLK_RW_ASYNC]);
+ }
+ }
+
+ spin_unlock_irq(q->queue_lock);
+ return 0;
+}
+
+/*
+ * 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;
+}
+
+/**
+ * rq_ioc - determine io_context for request allocation
+ * @bio: request being allocated is for this bio (can be %NULL)
+ *
+ * Determine io_context to use for request allocation for @bio. May return
+ * %NULL if %current->io_context doesn't exist.
+ */
+static struct io_context *rq_ioc(struct bio *bio)
+{
+#ifdef CONFIG_BLK_CGROUP
+ if (bio && bio->bi_ioc)
+ return bio->bi_ioc;
+#endif
+ return current->io_context;
+}
+
+/**
+ * __get_request - get a free request
+ * @rl: request list to allocate from
+ * @rw_flags: RW and SYNC flags
+ * @bio: bio to allocate request for (can be %NULL)
+ * @gfp_mask: allocation mask
+ *
+ * Get a free request from @q. This function may fail under memory
+ * pressure or if @q is dead.
+ *
+ * Must be called with @q->queue_lock held and,
+ * Returns ERR_PTR on failure, with @q->queue_lock held.
+ * Returns request pointer on success, with @q->queue_lock *not held*.
+ */
+static struct request *__get_request(struct request_list *rl, int rw_flags,
+ struct bio *bio, gfp_t gfp_mask)
+{
+ struct request_queue *q = rl->q;
+ struct request *rq;
+ struct elevator_type *et = q->elevator->type;
+ struct io_context *ioc = rq_ioc(bio);
+ struct io_cq *icq = NULL;
+ const bool is_sync = rw_is_sync(rw_flags) != 0;
+ int may_queue;
+
+ if (unlikely(blk_queue_dying(q)))
+ return ERR_PTR(-ENODEV);
+
+ may_queue = elv_may_queue(q, rw_flags);
+ if (may_queue == ELV_MQUEUE_NO)
+ goto rq_starved;
+
+ if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
+ if (rl->count[is_sync]+1 >= q->nr_requests) {
+ /*
+ * The queue will fill after this allocation, so set
+ * it as full, and mark this process as "batching".
+ * This process will be allowed to complete a batch of
+ * requests, others will be blocked.
+ */
+ if (!blk_rl_full(rl, is_sync)) {
+ ioc_set_batching(q, ioc);
+ blk_set_rl_full(rl, is_sync);
+ } else {
+ if (may_queue != ELV_MQUEUE_MUST
+ && !ioc_batching(q, ioc)) {
+ /*
+ * The queue is full and the allocating
+ * process is not a "batcher", and not
+ * exempted by the IO scheduler
+ */
+ return ERR_PTR(-ENOMEM);
+ }
+ }
+ }
+ /*
+ * bdi isn't aware of blkcg yet. As all async IOs end up
+ * root blkcg anyway, just use root blkcg state.
+ */
+ if (rl == &q->root_rl)
+ blk_set_queue_congested(q, is_sync);
+ }
+
+ /*
+ * Only allow batching queuers to allocate up to 50% over the defined
+ * limit of requests, otherwise we could have thousands of requests
+ * allocated with any setting of ->nr_requests
+ */
+ if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
+ return ERR_PTR(-ENOMEM);
+
+ q->nr_rqs[is_sync]++;
+ rl->count[is_sync]++;
+ rl->starved[is_sync] = 0;
+
+ /*
+ * Decide whether the new request will be managed by elevator. If
+ * so, mark @rw_flags and increment elvpriv. Non-zero elvpriv will
+ * prevent the current elevator from being destroyed until the new
+ * request is freed. This guarantees icq's won't be destroyed and
+ * makes creating new ones safe.
+ *
+ * Also, lookup icq while holding queue_lock. If it doesn't exist,
+ * it will be created after releasing queue_lock.
+ */
+ if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
+ rw_flags |= REQ_ELVPRIV;
+ q->nr_rqs_elvpriv++;
+ if (et->icq_cache && ioc)
+ icq = ioc_lookup_icq(ioc, q);
+ }
+
+ if (blk_queue_io_stat(q))
+ rw_flags |= REQ_IO_STAT;
+ spin_unlock_irq(q->queue_lock);
+
+ /* allocate and init request */
+ rq = mempool_alloc(rl->rq_pool, gfp_mask);
+ if (!rq)
+ goto fail_alloc;
+
+ blk_rq_init(q, rq);
+ blk_rq_set_rl(rq, rl);
+ rq->cmd_flags = rw_flags | REQ_ALLOCED;
+
+ /* init elvpriv */
+ if (rw_flags & REQ_ELVPRIV) {
+ if (unlikely(et->icq_cache && !icq)) {
+ if (ioc)
+ icq = ioc_create_icq(ioc, q, gfp_mask);
+ if (!icq)
+ goto fail_elvpriv;
+ }
+
+ rq->elv.icq = icq;
+ if (unlikely(elv_set_request(q, rq, bio, gfp_mask)))
+ goto fail_elvpriv;
+
+ /* @rq->elv.icq holds io_context until @rq is freed */
+ if (icq)
+ get_io_context(icq->ioc);
+ }
+out:
+ /*
+ * ioc may be NULL here, and ioc_batching will be false. That's
+ * OK, if the queue is under the request limit then requests need
+ * not count toward the nr_batch_requests limit. There will always
+ * be some limit enforced by BLK_BATCH_TIME.
+ */
+ if (ioc_batching(q, ioc))
+ ioc->nr_batch_requests--;
+
+ trace_block_getrq(q, bio, rw_flags & 1);
+ return rq;
+
+fail_elvpriv:
+ /*
+ * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed
+ * and may fail indefinitely under memory pressure and thus
+ * shouldn't stall IO. Treat this request as !elvpriv. This will
+ * disturb iosched and blkcg but weird is bettern than dead.
+ */
+ printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n",
+ __func__, dev_name(q->backing_dev_info.dev));
+
+ rq->cmd_flags &= ~REQ_ELVPRIV;
+ rq->elv.icq = NULL;
+
+ spin_lock_irq(q->queue_lock);
+ q->nr_rqs_elvpriv--;
+ spin_unlock_irq(q->queue_lock);
+ goto out;
+
+fail_alloc:
+ /*
+ * Allocation failed presumably due to memory. Undo anything we
+ * might have messed up.
+ *
+ * Allocating task should really be put onto the front of the wait
+ * queue, but this is pretty rare.
+ */
+ spin_lock_irq(q->queue_lock);
+ freed_request(rl, rw_flags);
+
+ /*
+ * in the very unlikely event that allocation failed and no
+ * requests for this direction was pending, mark us starved so that
+ * freeing of a request in the other direction will notice
+ * us. another possible fix would be to split the rq mempool into
+ * READ and WRITE
+ */
+rq_starved:
+ if (unlikely(rl->count[is_sync] == 0))
+ rl->starved[is_sync] = 1;
+ return ERR_PTR(-ENOMEM);
+}
+
+/**
+ * get_request - get a free request
+ * @q: request_queue to allocate request from
+ * @rw_flags: RW and SYNC flags
+ * @bio: bio to allocate request for (can be %NULL)
+ * @gfp_mask: allocation mask
+ *
+ * Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this
+ * function keeps retrying under memory pressure and fails iff @q is dead.
+ *
+ * Must be called with @q->queue_lock held and,
+ * Returns ERR_PTR on failure, with @q->queue_lock held.
+ * Returns request pointer on success, with @q->queue_lock *not held*.
+ */
+static struct request *get_request(struct request_queue *q, int rw_flags,
+ struct bio *bio, gfp_t gfp_mask)
+{
+ const bool is_sync = rw_is_sync(rw_flags) != 0;
+ DEFINE_WAIT(wait);
+ struct request_list *rl;
+ struct request *rq;
+
+ rl = blk_get_rl(q, bio); /* transferred to @rq on success */
+retry:
+ rq = __get_request(rl, rw_flags, bio, gfp_mask);
+ if (!IS_ERR(rq))
+ return rq;
+
+ if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {
+ blk_put_rl(rl);
+ return rq;
+ }
+
+ /* wait on @rl and retry */
+ prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
+ TASK_UNINTERRUPTIBLE);
+
+ trace_block_sleeprq(q, bio, rw_flags & 1);
+
+ spin_unlock_irq(q->queue_lock);
+ io_schedule();
+
+ /*
+ * After sleeping, we become a "batching" process and will be able
+ * to allocate at least one request, and up to a big batch of them
+ * for a small period time. See ioc_batching, ioc_set_batching
+ */
+ ioc_set_batching(q, current->io_context);
+
+ spin_lock_irq(q->queue_lock);
+ finish_wait(&rl->wait[is_sync], &wait);
+
+ goto retry;
+}
+
+static struct request *blk_old_get_request(struct request_queue *q, int rw,
+ gfp_t gfp_mask)
+{
+ struct request *rq;
+
+ BUG_ON(rw != READ && rw != WRITE);
+
+ /* create ioc upfront */
+ create_io_context(gfp_mask, q->node);
+
+ spin_lock_irq(q->queue_lock);
+ rq = get_request(q, rw, NULL, gfp_mask);
+ if (IS_ERR(rq))
+ spin_unlock_irq(q->queue_lock);
+ /* q->queue_lock is unlocked at this point */
+
+ return rq;
+}
+
+struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
+{
+ if (q->mq_ops)
+ return blk_mq_alloc_request(q, rw, gfp_mask, false);
+ else
+ return blk_old_get_request(q, rw, gfp_mask);
+}
+EXPORT_SYMBOL(blk_get_request);
+
+/**
+ * blk_make_request - given a bio, allocate a corresponding struct request.
+ * @q: target request queue
+ * @bio: The bio describing the memory mappings that will be submitted for IO.
+ * It may be a chained-bio properly constructed by block/bio layer.
+ * @gfp_mask: gfp flags to be used for memory allocation
+ *
+ * blk_make_request is the parallel of generic_make_request for BLOCK_PC
+ * type commands. Where the struct request needs to be farther initialized by
+ * the caller. It is passed a &struct bio, which describes the memory info of
+ * the I/O transfer.
+ *
+ * The caller of blk_make_request must make sure that bi_io_vec
+ * are set to describe the memory buffers. That bio_data_dir() will return
+ * the needed direction of the request. (And all bio's in the passed bio-chain
+ * are properly set accordingly)
+ *
+ * If called under none-sleepable conditions, mapped bio buffers must not
+ * need bouncing, by calling the appropriate masked or flagged allocator,
+ * suitable for the target device. Otherwise the call to blk_queue_bounce will
+ * BUG.
+ *
+ * WARNING: When allocating/cloning a bio-chain, careful consideration should be
+ * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
+ * anything but the first bio in the chain. Otherwise you risk waiting for IO
+ * completion of a bio that hasn't been submitted yet, thus resulting in a
+ * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
+ * of bio_alloc(), as that avoids the mempool deadlock.
+ * If possible a big IO should be split into smaller parts when allocation
+ * fails. Partial allocation should not be an error, or you risk a live-lock.
+ */
+struct request *blk_make_request(struct request_queue *q, struct bio *bio,
+ gfp_t gfp_mask)
+{
+ struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
+
+ if (IS_ERR(rq))
+ return rq;
+
+ blk_rq_set_block_pc(rq);
+
+ for_each_bio(bio) {
+ struct bio *bounce_bio = bio;
+ int ret;
+
+ blk_queue_bounce(q, &bounce_bio);
+ ret = blk_rq_append_bio(q, rq, bounce_bio);
+ if (unlikely(ret)) {
+ blk_put_request(rq);
+ return ERR_PTR(ret);
+ }
+ }
+
+ return rq;
+}
+EXPORT_SYMBOL(blk_make_request);
+
+/**
+ * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
+ * @rq: request to be initialized
+ *
+ */
+void blk_rq_set_block_pc(struct request *rq)
+{
+ rq->cmd_type = REQ_TYPE_BLOCK_PC;
+ rq->__data_len = 0;
+ rq->__sector = (sector_t) -1;
+ rq->bio = rq->biotail = NULL;
+ memset(rq->__cmd, 0, sizeof(rq->__cmd));
+}
+EXPORT_SYMBOL(blk_rq_set_block_pc);
+
+/**
+ * blk_requeue_request - put a request back on queue
+ * @q: request queue where request should be inserted
+ * @rq: request to be inserted
+ *
+ * Description:
+ * Drivers often keep queueing requests until the hardware cannot accept
+ * more, when that condition happens we need to put the request back
+ * on the queue. Must be called with queue lock held.
+ */
+void blk_requeue_request(struct request_queue *q, struct request *rq)
+{
+ blk_delete_timer(rq);
+ blk_clear_rq_complete(rq);
+ trace_block_rq_requeue(q, rq);
+
+ if (rq->cmd_flags & REQ_QUEUED)
+ blk_queue_end_tag(q, rq);
+
+ BUG_ON(blk_queued_rq(rq));
+
+ elv_requeue_request(q, rq);
+}
+EXPORT_SYMBOL(blk_requeue_request);
+
+static void add_acct_request(struct request_queue *q, struct request *rq,
+ int where)
+{
+ blk_account_io_start(rq, true);
+ __elv_add_request(q, rq, where);
+}
+
+static void part_round_stats_single(int cpu, struct hd_struct *part,
+ unsigned long now)
+{
+ int inflight;
+
+ if (now == part->stamp)
+ return;
+
+ inflight = part_in_flight(part);
+ if (inflight) {
+ __part_stat_add(cpu, part, time_in_queue,
+ inflight * (now - part->stamp));
+ __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
+ }
+ part->stamp = now;
+}
+
+/**
+ * part_round_stats() - Round off the performance stats on a struct disk_stats.
+ * @cpu: cpu number for stats access
+ * @part: target partition
+ *
+ * The average IO queue length and utilisation statistics are maintained
+ * by observing the current state of the queue length and the amount of
+ * time it has been in this state for.
+ *
+ * Normally, that accounting is done on IO completion, but that can result
+ * in more than a second's worth of IO being accounted for within any one
+ * second, leading to >100% utilisation. To deal with that, we call this
+ * function to do a round-off before returning the results when reading
+ * /proc/diskstats. This accounts immediately for all queue usage up to
+ * the current jiffies and restarts the counters again.
+ */
+void part_round_stats(int cpu, struct hd_struct *part)
+{
+ unsigned long now = jiffies;
+
+ if (part->partno)
+ part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
+ part_round_stats_single(cpu, part, now);
+}
+EXPORT_SYMBOL_GPL(part_round_stats);
+
+#ifdef CONFIG_PM
+static void blk_pm_put_request(struct request *rq)
+{
+ if (rq->q->dev && !(rq->cmd_flags & REQ_PM) && !--rq->q->nr_pending)
+ pm_runtime_mark_last_busy(rq->q->dev);
+}
+#else
+static inline void blk_pm_put_request(struct request *rq) {}
+#endif
+
+/*
+ * queue lock must be held
+ */
+void __blk_put_request(struct request_queue *q, struct request *req)
+{
+ if (unlikely(!q))
+ return;
+
+ if (q->mq_ops) {
+ blk_mq_free_request(req);
+ return;
+ }
+
+ blk_pm_put_request(req);
+
+ elv_completed_request(q, req);
+
+ /* this is a bio leak */
+ WARN_ON(req->bio != NULL);
+
+ /*
+ * Request may not have originated from ll_rw_blk. if not,
+ * it didn't come out of our reserved rq pools
+ */
+ if (req->cmd_flags & REQ_ALLOCED) {
+ unsigned int flags = req->cmd_flags;
+ struct request_list *rl = blk_rq_rl(req);
+
+ BUG_ON(!list_empty(&req->queuelist));
+ BUG_ON(ELV_ON_HASH(req));
+
+ blk_free_request(rl, req);
+ freed_request(rl, flags);
+ blk_put_rl(rl);
+ }
+}
+EXPORT_SYMBOL_GPL(__blk_put_request);
+
+void blk_put_request(struct request *req)
+{
+ struct request_queue *q = req->q;
+
+ if (q->mq_ops)
+ blk_mq_free_request(req);
+ else {
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ __blk_put_request(q, req);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ }
+}
+EXPORT_SYMBOL(blk_put_request);
+
+/**
+ * blk_add_request_payload - add a payload to a request
+ * @rq: request to update
+ * @page: page backing the payload
+ * @len: length of the payload.
+ *
+ * This allows to later add a payload to an already submitted request by
+ * a block driver. The driver needs to take care of freeing the payload
+ * itself.
+ *
+ * Note that this is a quite horrible hack and nothing but handling of
+ * discard requests should ever use it.
+ */
+void blk_add_request_payload(struct request *rq, struct page *page,
+ unsigned int len)
+{
+ struct bio *bio = rq->bio;
+
+ bio->bi_io_vec->bv_page = page;
+ bio->bi_io_vec->bv_offset = 0;
+ bio->bi_io_vec->bv_len = len;
+
+ bio->bi_iter.bi_size = len;
+ bio->bi_vcnt = 1;
+ bio->bi_phys_segments = 1;
+
+ rq->__data_len = rq->resid_len = len;
+ rq->nr_phys_segments = 1;
+}
+EXPORT_SYMBOL_GPL(blk_add_request_payload);
+
+bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
+ struct bio *bio)
+{
+ const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
+
+ if (!ll_back_merge_fn(q, req, bio))
+ return false;
+
+ trace_block_bio_backmerge(q, req, 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_iter.bi_size;
+ req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
+
+ blk_account_io_start(req, false);
+ return true;
+}
+
+bool bio_attempt_front_merge(struct request_queue *q, struct request *req,
+ struct bio *bio)
+{
+ const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
+
+ if (!ll_front_merge_fn(q, req, bio))
+ return false;
+
+ trace_block_bio_frontmerge(q, req, bio);
+
+ if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
+ blk_rq_set_mixed_merge(req);
+
+ bio->bi_next = req->bio;
+ req->bio = bio;
+
+ req->__sector = bio->bi_iter.bi_sector;
+ req->__data_len += bio->bi_iter.bi_size;
+ req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
+
+ blk_account_io_start(req, false);
+ return true;
+}
+
+/**
+ * blk_attempt_plug_merge - try to merge with %current's plugged list
+ * @q: request_queue new bio is being queued at
+ * @bio: new bio being queued
+ * @request_count: out parameter for number of traversed plugged requests
+ *
+ * Determine whether @bio being queued on @q can be merged with a request
+ * on %current's plugged list. Returns %true if merge was successful,
+ * otherwise %false.
+ *
+ * Plugging coalesces IOs from the same issuer for the same purpose without
+ * going through @q->queue_lock. As such it's more of an issuing mechanism
+ * than scheduling, and the request, while may have elvpriv data, is not
+ * added on the elevator at this point. In addition, we don't have
+ * reliable access to the elevator outside queue lock. Only check basic
+ * merging parameters without querying the elevator.
+ *
+ * Caller must ensure !blk_queue_nomerges(q) beforehand.
+ */
+bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
+ unsigned int *request_count)
+{
+ struct blk_plug *plug;
+ struct request *rq;
+ bool ret = false;
+ struct list_head *plug_list;
+
+ plug = current->plug;
+ if (!plug)
+ goto out;
+ *request_count = 0;
+
+ if (q->mq_ops)
+ plug_list = &plug->mq_list;
+ else
+ plug_list = &plug->list;
+
+ list_for_each_entry_reverse(rq, plug_list, queuelist) {
+ int el_ret;
+
+ if (rq->q == q)
+ (*request_count)++;
+
+ if (rq->q != q || !blk_rq_merge_ok(rq, bio))
+ continue;
+
+ el_ret = blk_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->cmd_type = REQ_TYPE_FS;
+
+ req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
+ if (bio->bi_rw & REQ_RAHEAD)
+ req->cmd_flags |= REQ_FAILFAST_MASK;
+
+ req->errors = 0;
+ req->__sector = bio->bi_iter.bi_sector;
+ req->ioprio = bio_prio(bio);
+ blk_rq_bio_prep(req->q, req, bio);
+}
+
+static void blk_queue_bio(struct request_queue *q, struct bio *bio)
+{
+ const bool sync = !!(bio->bi_rw & REQ_SYNC);
+ struct blk_plug *plug;
+ int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
+ struct request *req;
+ unsigned int request_count = 0;
+
+ /*
+ * low level driver can indicate that it wants pages above a
+ * certain limit bounced to low memory (ie for highmem, or even
+ * ISA dma in theory)
+ */
+ blk_queue_bounce(q, &bio);
+
+ if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
+ bio_endio(bio, -EIO);
+ return;
+ }
+
+ if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
+ spin_lock_irq(q->queue_lock);
+ where = ELEVATOR_INSERT_FLUSH;
+ goto get_rq;
+ }
+
+ /*
+ * Check if we can merge with the plugged list before grabbing
+ * any locks.
+ */
+ if (!blk_queue_nomerges(q) &&
+ blk_attempt_plug_merge(q, bio, &request_count))
+ return;
+
+ spin_lock_irq(q->queue_lock);
+
+ el_ret = elv_merge(q, &req, bio);
+ if (el_ret == ELEVATOR_BACK_MERGE) {
+ if (bio_attempt_back_merge(q, req, bio)) {
+ elv_bio_merged(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) {
+ if (bio_attempt_front_merge(q, req, bio)) {
+ elv_bio_merged(q, req, bio);
+ if (!attempt_front_merge(q, req))
+ elv_merged_request(q, req, el_ret);
+ goto out_unlock;
+ }
+ }
+
+get_rq:
+ /*
+ * This sync check and mask will be re-done in init_request_from_bio(),
+ * but we need to set it earlier to expose the sync flag to the
+ * rq allocator and io schedulers.
+ */
+ rw_flags = bio_data_dir(bio);
+ if (sync)
+ rw_flags |= REQ_SYNC;
+
+ /*
+ * Grab a free request. This is might sleep but can not fail.
+ * Returns with the queue unlocked.
+ */
+ req = get_request(q, rw_flags, bio, GFP_NOIO);
+ if (IS_ERR(req)) {
+ bio_endio(bio, PTR_ERR(req)); /* @q is dead */
+ goto out_unlock;
+ }
+
+ /*
+ * After dropping the lock and possibly sleeping here, our request
+ * may now be mergeable after it had proven unmergeable (above).
+ * We don't worry about that case for efficiency. It won't happen
+ * often, and the elevators are able to handle it.
+ */
+ init_request_from_bio(req, bio);
+
+ if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags))
+ req->cpu = raw_smp_processor_id();
+
+ plug = current->plug;
+ if (plug) {
+ /*
+ * If this is the first request added after a plug, fire
+ * of a plug trace.
+ */
+ if (!request_count)
+ trace_block_plug(q);
+ else {
+ if (request_count >= BLK_MAX_REQUEST_COUNT) {
+ blk_flush_plug_list(plug, false);
+ trace_block_plug(q);
+ }
+ }
+ list_add_tail(&req->queuelist, &plug->list);
+ blk_account_io_start(req, true);
+ } 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);
+ }
+}
+
+/*
+ * If bio->bi_dev is a partition, remap the location
+ */
+static inline void blk_partition_remap(struct bio *bio)
+{
+ struct block_device *bdev = bio->bi_bdev;
+
+ if (bio_sectors(bio) && bdev != bdev->bd_contains) {
+ struct hd_struct *p = bdev->bd_part;
+
+ bio->bi_iter.bi_sector += p->start_sect;
+ bio->bi_bdev = bdev->bd_contains;
+
+ trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
+ bdev->bd_dev,
+ bio->bi_iter.bi_sector - p->start_sect);
+ }
+}
+
+static void handle_bad_sector(struct bio *bio)
+{
+ char b[BDEVNAME_SIZE];
+
+ printk(KERN_INFO "attempt to access beyond end of device\n");
+ printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
+ bdevname(bio->bi_bdev, b),
+ bio->bi_rw,
+ (unsigned long long)bio_end_sector(bio),
+ (long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
+
+ set_bit(BIO_EOF, &bio->bi_flags);
+}
+
+#ifdef CONFIG_FAIL_MAKE_REQUEST
+
+static DECLARE_FAULT_ATTR(fail_make_request);
+
+static int __init setup_fail_make_request(char *str)
+{
+ return setup_fault_attr(&fail_make_request, str);
+}
+__setup("fail_make_request=", setup_fail_make_request);
+
+static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
+{
+ return part->make_it_fail && should_fail(&fail_make_request, bytes);
+}
+
+static int __init fail_make_request_debugfs(void)
+{
+ struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
+ NULL, &fail_make_request);
+
+ return PTR_ERR_OR_ZERO(dir);
+}
+
+late_initcall(fail_make_request_debugfs);
+
+#else /* CONFIG_FAIL_MAKE_REQUEST */
+
+static inline bool should_fail_request(struct hd_struct *part,
+ unsigned int bytes)
+{
+ return false;
+}
+
+#endif /* CONFIG_FAIL_MAKE_REQUEST */
+
+/*
+ * Check whether this bio extends beyond the end of the device.
+ */
+static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
+{
+ sector_t maxsector;
+
+ if (!nr_sectors)
+ return 0;
+
+ /* Test device or partition size, when known. */
+ maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
+ if (maxsector) {
+ sector_t sector = bio->bi_iter.bi_sector;
+
+ if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
+ /*
+ * This may well happen - the kernel calls bread()
+ * without checking the size of the device, e.g., when
+ * mounting a device.
+ */
+ handle_bad_sector(bio);
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+static noinline_for_stack bool
+generic_make_request_checks(struct bio *bio)
+{
+ struct request_queue *q;
+ int nr_sectors = bio_sectors(bio);
+ int err = -EIO;
+ char b[BDEVNAME_SIZE];
+ struct hd_struct *part;
+
+ might_sleep();
+
+ if (bio_check_eod(bio, nr_sectors))
+ goto end_io;
+
+ q = bdev_get_queue(bio->bi_bdev);
+ if (unlikely(!q)) {
+ printk(KERN_ERR
+ "generic_make_request: Trying to access "
+ "nonexistent block-device %s (%Lu)\n",
+ bdevname(bio->bi_bdev, b),
+ (long long) bio->bi_iter.bi_sector);
+ goto end_io;
+ }
+
+ if (likely(bio_is_rw(bio) &&
+ nr_sectors > queue_max_hw_sectors(q))) {
+ printk(KERN_ERR "bio too big device %s (%u > %u)\n",
+ bdevname(bio->bi_bdev, b),
+ bio_sectors(bio),
+ queue_max_hw_sectors(q));
+ goto end_io;
+ }
+
+ part = bio->bi_bdev->bd_part;
+ if (should_fail_request(part, bio->bi_iter.bi_size) ||
+ should_fail_request(&part_to_disk(part)->part0,
+ bio->bi_iter.bi_size))
+ goto end_io;
+
+ /*
+ * If this device has partitions, remap block n
+ * of partition p to block n+start(p) of the disk.
+ */
+ blk_partition_remap(bio);
+
+ if (bio_check_eod(bio, nr_sectors))
+ goto end_io;
+
+ /*
+ * Filter flush bio's early so that make_request based
+ * drivers without flush support don't have to worry
+ * about them.
+ */
+ if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
+ bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
+ if (!nr_sectors) {
+ err = 0;
+ goto end_io;
+ }
+ }
+
+ if ((bio->bi_rw & REQ_DISCARD) &&
+ (!blk_queue_discard(q) ||
+ ((bio->bi_rw & REQ_SECURE) && !blk_queue_secdiscard(q)))) {
+ err = -EOPNOTSUPP;
+ goto end_io;
+ }
+
+ if (bio->bi_rw & REQ_WRITE_SAME && !bdev_write_same(bio->bi_bdev)) {
+ err = -EOPNOTSUPP;
+ goto end_io;
+ }
+
+ /*
+ * Various block parts want %current->io_context and lazy ioc
+ * allocation ends up trading a lot of pain for a small amount of
+ * memory. Just allocate it upfront. This may fail and block
+ * layer knows how to live with it.
+ */
+ create_io_context(GFP_ATOMIC, q->node);
+
+ if (blk_throtl_bio(q, bio))
+ return false; /* throttled, will be resubmitted later */
+
+ trace_block_bio_queue(q, bio);
+ return true;
+
+end_io:
+ bio_endio(bio, err);
+ return false;
+}
+
+/**
+ * generic_make_request - hand a buffer to its device driver for I/O
+ * @bio: The bio describing the location in memory and on the device.
+ *
+ * generic_make_request() is used to make I/O requests of block
+ * devices. It is passed a &struct bio, which describes the I/O that needs
+ * to be done.
+ *
+ * generic_make_request() does not return any status. The
+ * success/failure status of the request, along with notification of
+ * completion, is delivered asynchronously through the bio->bi_end_io
+ * function described (one day) else where.
+ *
+ * The caller of generic_make_request must make sure that bi_io_vec
+ * are set to describe the memory buffer, and that bi_dev and bi_sector are
+ * set to describe the device address, and the
+ * bi_end_io and optionally bi_private are set to describe how
+ * completion notification should be signaled.
+ *
+ * generic_make_request and the drivers it calls may use bi_next if this
+ * bio happens to be merged with someone else, and may resubmit the bio to
+ * a lower device by calling into generic_make_request recursively, which
+ * means the bio should NOT be touched after the call to ->make_request_fn.
+ */
+void generic_make_request(struct bio *bio)
+{
+ struct bio_list bio_list_on_stack;
+
+ if (!generic_make_request_checks(bio))
+ return;
+
+ /*
+ * We only want one ->make_request_fn to be active at a time, else
+ * stack usage with stacked devices could be a problem. So use
+ * current->bio_list to keep a list of requests submited by a
+ * make_request_fn function. current->bio_list is also used as a
+ * flag to say if generic_make_request is currently active in this
+ * task or not. If it is NULL, then no make_request is active. If
+ * it is non-NULL, then a make_request is active, and new requests
+ * should be added at the tail
+ */
+ if (current->bio_list) {
+ bio_list_add(current->bio_list, bio);
+ return;
+ }
+
+ /* following loop may be a bit non-obvious, and so deserves some
+ * explanation.
+ * Before entering the loop, bio->bi_next is NULL (as all callers
+ * ensure that) so we have a list with a single bio.
+ * We pretend that we have just taken it off a longer list, so
+ * we assign bio_list to a pointer to the bio_list_on_stack,
+ * thus initialising the bio_list of new bios to be
+ * added. ->make_request() may indeed add some more bios
+ * through a recursive call to generic_make_request. If it
+ * did, we find a non-NULL value in bio_list and re-enter the loop
+ * from the top. In this case we really did just take the bio
+ * of the top of the list (no pretending) and so remove it from
+ * bio_list, and call into ->make_request() again.
+ */
+ BUG_ON(bio->bi_next);
+ bio_list_init(&bio_list_on_stack);
+ current->bio_list = &bio_list_on_stack;
+ do {
+ struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+
+ q->make_request_fn(q, bio);
+
+ bio = bio_list_pop(current->bio_list);
+ } while (bio);
+ current->bio_list = NULL; /* deactivate */
+}
+EXPORT_SYMBOL(generic_make_request);
+
+/**
+ * submit_bio - submit a bio to the block device layer for I/O
+ * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
+ * @bio: The &struct bio which describes the I/O
+ *
+ * submit_bio() is very similar in purpose to generic_make_request(), and
+ * uses that function to do most of the work. Both are fairly rough
+ * interfaces; @bio must be presetup and ready for I/O.
+ *
+ */
+void submit_bio(int rw, struct bio *bio)
+{
+ bio->bi_rw |= rw;
+
+ /*
+ * If it's a regular read/write or a barrier with data attached,
+ * go through the normal accounting stuff before submission.
+ */
+ if (bio_has_data(bio)) {
+ unsigned int count;
+
+ if (unlikely(rw & REQ_WRITE_SAME))
+ count = bdev_logical_block_size(bio->bi_bdev) >> 9;
+ else
+ count = bio_sectors(bio);
+
+ if (rw & WRITE) {
+ count_vm_events(PGPGOUT, count);
+ } else {
+ task_io_account_read(bio->bi_iter.bi_size);
+ count_vm_events(PGPGIN, count);
+ }
+
+ if (unlikely(block_dump)) {
+ char b[BDEVNAME_SIZE];
+ printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
+ current->comm, task_pid_nr(current),
+ (rw & WRITE) ? "WRITE" : "READ",
+ (unsigned long long)bio->bi_iter.bi_sector,
+ bdevname(bio->bi_bdev, b),
+ count);
+ }
+ }
+
+ generic_make_request(bio);
+}
+EXPORT_SYMBOL(submit_bio);
+
+/**
+ * blk_rq_check_limits - Helper function to check a request for the queue limit
+ * @q: the queue
+ * @rq: the request being checked
+ *
+ * Description:
+ * @rq may have been made based on weaker limitations of upper-level queues
+ * in request stacking drivers, and it may violate the limitation of @q.
+ * Since the block layer and the underlying device driver trust @rq
+ * after it is inserted to @q, it should be checked against @q before
+ * the insertion using this generic function.
+ *
+ * This function should also be useful for request stacking drivers
+ * in some cases below, so export this function.
+ * Request stacking drivers like request-based dm may change the queue
+ * limits while requests are in the queue (e.g. dm's table swapping).
+ * Such request stacking drivers should check those requests against
+ * the new queue limits again when they dispatch those requests,
+ * although such checkings are also done against the old queue limits
+ * when submitting requests.
+ */
+int blk_rq_check_limits(struct request_queue *q, struct request *rq)
+{
+ if (!rq_mergeable(rq))
+ return 0;
+
+ if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
+ printk(KERN_ERR "%s: over max size limit.\n", __func__);
+ return -EIO;
+ }
+
+ /*
+ * queue's settings related to segment counting like q->bounce_pfn
+ * may differ from that of other stacking queues.
+ * Recalculate it to check the request correctly on this queue's
+ * limitation.
+ */
+ blk_recalc_rq_segments(rq);
+ if (rq->nr_phys_segments > queue_max_segments(q)) {
+ printk(KERN_ERR "%s: over max segments limit.\n", __func__);
+ return -EIO;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(blk_rq_check_limits);
+
+/**
+ * blk_insert_cloned_request - Helper for stacking drivers to submit a request
+ * @q: the queue to submit the request
+ * @rq: the request being queued
+ */
+int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
+{
+ unsigned long flags;
+ int where = ELEVATOR_INSERT_BACK;
+
+ if (blk_rq_check_limits(q, rq))
+ return -EIO;
+
+ if (rq->rq_disk &&
+ should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
+ return -EIO;
+
+ if (q->mq_ops) {
+ if (blk_queue_io_stat(q))
+ blk_account_io_start(rq, true);
+ blk_mq_insert_request(rq, false, true, true);
+ return 0;
+ }
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ if (unlikely(blk_queue_dying(q))) {
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ return -ENODEV;
+ }
+
+ /*
+ * Submitting request must be dequeued before calling this function
+ * because it will be linked to another request_queue
+ */
+ BUG_ON(blk_queued_rq(rq));
+
+ if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA))
+ where = ELEVATOR_INSERT_FLUSH;
+
+ add_acct_request(q, rq, where);
+ if (where == ELEVATOR_INSERT_FLUSH)
+ __blk_run_queue(q);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
+
+/**
+ * blk_rq_err_bytes - determine number of bytes till the next failure boundary
+ * @rq: request to examine
+ *
+ * Description:
+ * A request could be merge of IOs which require different failure
+ * handling. This function determines the number of bytes which
+ * can be failed from the beginning of the request without
+ * crossing into area which need to be retried further.
+ *
+ * Return:
+ * The number of bytes to fail.
+ *
+ * Context:
+ * queue_lock must be held.
+ */
+unsigned int blk_rq_err_bytes(const struct request *rq)
+{
+ unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
+ unsigned int bytes = 0;
+ struct bio *bio;
+
+ if (!(rq->cmd_flags & REQ_MIXED_MERGE))
+ return blk_rq_bytes(rq);
+
+ /*
+ * Currently the only 'mixing' which can happen is between
+ * different fastfail types. We can safely fail portions
+ * which have all the failfast bits that the first one has -
+ * the ones which are at least as eager to fail as the first
+ * one.
+ */
+ for (bio = rq->bio; bio; bio = bio->bi_next) {
+ if ((bio->bi_rw & ff) != ff)
+ break;
+ bytes += bio->bi_iter.bi_size;
+ }
+
+ /* this could lead to infinite loop */
+ BUG_ON(blk_rq_bytes(rq) && !bytes);
+ return bytes;
+}
+EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
+
+void blk_account_io_completion(struct request *req, unsigned int bytes)
+{
+ if (blk_do_io_stat(req)) {
+ const int rw = rq_data_dir(req);
+ struct hd_struct *part;
+ int cpu;
+
+ cpu = part_stat_lock();
+ part = req->part;
+ part_stat_add(cpu, part, sectors[rw], bytes >> 9);
+ part_stat_unlock();
+ }
+}
+
+void blk_account_io_done(struct request *req)
+{
+ /*
+ * Account IO completion. flush_rq isn't accounted as a
+ * normal IO on queueing nor completion. Accounting the
+ * containing request is enough.
+ */
+ 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;
+ int cpu;
+
+ cpu = part_stat_lock();
+ part = req->part;
+
+ part_stat_inc(cpu, part, ios[rw]);
+ part_stat_add(cpu, part, ticks[rw], duration);
+ part_round_stats(cpu, part);
+ part_dec_in_flight(part, rw);
+
+ hd_struct_put(part);
+ part_stat_unlock();
+ }
+}
+
+#ifdef CONFIG_PM
+/*
+ * Don't process normal requests when queue is suspended
+ * or in the process of suspending/resuming
+ */
+static struct request *blk_pm_peek_request(struct request_queue *q,
+ struct request *rq)
+{
+ if (q->dev && (q->rpm_status == RPM_SUSPENDED ||
+ (q->rpm_status != RPM_ACTIVE && !(rq->cmd_flags & REQ_PM))))
+ return NULL;
+ else
+ return rq;
+}
+#else
+static inline struct request *blk_pm_peek_request(struct request_queue *q,
+ struct request *rq)
+{
+ return rq;
+}
+#endif
+
+void blk_account_io_start(struct request *rq, bool new_io)
+{
+ struct hd_struct *part;
+ int rw = rq_data_dir(rq);
+ int cpu;
+
+ if (!blk_do_io_stat(rq))
+ return;
+
+ cpu = part_stat_lock();
+
+ if (!new_io) {
+ part = rq->part;
+ part_stat_inc(cpu, part, merges[rw]);
+ } else {
+ part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
+ if (!hd_struct_try_get(part)) {
+ /*
+ * The partition is already being removed,
+ * the request will be accounted on the disk only
+ *
+ * We take a reference on disk->part0 although that
+ * partition will never be deleted, so we can treat
+ * it as any other partition.
+ */
+ part = &rq->rq_disk->part0;
+ hd_struct_get(part);
+ }
+ part_round_stats(cpu, part);
+ part_inc_in_flight(part, rw);
+ rq->part = part;
+ }
+
+ part_stat_unlock();
+}
+
+/**
+ * blk_peek_request - peek at the top of a request queue
+ * @q: request queue to peek at
+ *
+ * Description:
+ * Return the request at the top of @q. The returned request
+ * should be started using blk_start_request() before LLD starts
+ * processing it.
+ *
+ * Return:
+ * Pointer to the request at the top of @q if available. Null
+ * otherwise.
+ *
+ * Context:
+ * queue_lock must be held.
+ */
+struct request *blk_peek_request(struct request_queue *q)
+{
+ struct request *rq;
+ int ret;
+
+ while ((rq = __elv_next_request(q)) != NULL) {
+
+ rq = blk_pm_peek_request(q, rq);
+ if (!rq)
+ break;
+
+ if (!(rq->cmd_flags & REQ_STARTED)) {
+ /*
+ * This is the first time the device driver
+ * sees this request (possibly after
+ * requeueing). Notify IO scheduler.
+ */
+ if (rq->cmd_flags & REQ_SORTED)
+ elv_activate_rq(q, rq);
+
+ /*
+ * just mark as started even if we don't start
+ * it, a request that has been delayed should
+ * not be passed by new incoming requests
+ */
+ rq->cmd_flags |= REQ_STARTED;
+ trace_block_rq_issue(q, rq);
+ }
+
+ if (!q->boundary_rq || q->boundary_rq == rq) {
+ q->end_sector = rq_end_sector(rq);
+ q->boundary_rq = NULL;
+ }
+
+ if (rq->cmd_flags & REQ_DONTPREP)
+ break;
+
+ if (q->dma_drain_size && blk_rq_bytes(rq)) {
+ /*
+ * make sure space for the drain appears we
+ * know we can do this because max_hw_segments
+ * has been adjusted to be one fewer than the
+ * device can handle
+ */
+ rq->nr_phys_segments++;
+ }
+
+ if (!q->prep_rq_fn)
+ break;
+
+ ret = q->prep_rq_fn(q, rq);
+ if (ret == BLKPREP_OK) {
+ break;
+ } else if (ret == BLKPREP_DEFER) {
+ /*
+ * the request may have been (partially) prepped.
+ * we need to keep this request in the front to
+ * avoid resource deadlock. REQ_STARTED will
+ * prevent other fs requests from passing this one.
+ */
+ if (q->dma_drain_size && blk_rq_bytes(rq) &&
+ !(rq->cmd_flags & REQ_DONTPREP)) {
+ /*
+ * remove the space for the drain we added
+ * so that we don't add it again
+ */
+ --rq->nr_phys_segments;
+ }
+
+ rq = NULL;
+ break;
+ } else if (ret == BLKPREP_KILL) {
+ rq->cmd_flags |= REQ_QUIET;
+ /*
+ * Mark this request as started so we don't trigger
+ * any debug logic in the end I/O path.
+ */
+ blk_start_request(rq);
+ __blk_end_request_all(rq, -EIO);
+ } else {
+ printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
+ break;
+ }
+ }
+
+ return rq;
+}
+EXPORT_SYMBOL(blk_peek_request);
+
+void blk_dequeue_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+
+ BUG_ON(list_empty(&rq->queuelist));
+ BUG_ON(ELV_ON_HASH(rq));
+
+ list_del_init(&rq->queuelist);
+
+ /*
+ * the time frame between a request being removed from the lists
+ * and to it is freed is accounted as io that is in progress at
+ * the driver side.
+ */
+ if (blk_account_rq(rq)) {
+ q->in_flight[rq_is_sync(rq)]++;
+ set_io_start_time_ns(rq);
+ }
+}
+
+/**
+ * blk_start_request - start request processing on the driver
+ * @req: request to dequeue
+ *
+ * Description:
+ * Dequeue @req and start timeout timer on it. This hands off the
+ * request to the driver.
+ *
+ * Block internal functions which don't want to start timer should
+ * call blk_dequeue_request().
+ *
+ * Context:
+ * queue_lock must be held.
+ */
+void blk_start_request(struct request *req)
+{
+ blk_dequeue_request(req);
+
+ /*
+ * We are now handing the request to the hardware, initialize
+ * resid_len to full count and add the timeout handler.
+ */
+ req->resid_len = blk_rq_bytes(req);
+ if (unlikely(blk_bidi_rq(req)))
+ req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
+
+ BUG_ON(test_bit(REQ_ATOM_COMPLETE, &req->atomic_flags));
+ blk_add_timer(req);
+}
+EXPORT_SYMBOL(blk_start_request);
+
+/**
+ * blk_fetch_request - fetch a request from a request queue
+ * @q: request queue to fetch a request from
+ *
+ * Description:
+ * Return the request at the top of @q. The request is started on
+ * return and LLD can start processing it immediately.
+ *
+ * Return:
+ * Pointer to the request at the top of @q if available. Null
+ * otherwise.
+ *
+ * Context:
+ * queue_lock must be held.
+ */
+struct request *blk_fetch_request(struct request_queue *q)
+{
+ struct request *rq;
+
+ rq = blk_peek_request(q);
+ if (rq)
+ blk_start_request(rq);
+ return rq;
+}
+EXPORT_SYMBOL(blk_fetch_request);
+
+/**
+ * blk_update_request - Special helper function for request stacking drivers
+ * @req: the request being processed
+ * @error: %0 for success, < %0 for error
+ * @nr_bytes: number of bytes to complete @req
+ *
+ * Description:
+ * Ends I/O on a number of bytes attached to @req, but doesn't complete
+ * the request structure even if @req doesn't have leftover.
+ * If @req has leftover, sets it up for the next range of segments.
+ *
+ * This special helper function is only for request stacking drivers
+ * (e.g. request-based dm) so that they can handle partial completion.
+ * Actual device drivers should use blk_end_request instead.
+ *
+ * Passing the result of blk_rq_bytes() as @nr_bytes guarantees
+ * %false return from this function.
+ *
+ * Return:
+ * %false - this request doesn't have any more data
+ * %true - this request has more data
+ **/
+bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
+{
+ int total_bytes;
+
+ trace_block_rq_complete(req->q, req, nr_bytes);
+
+ if (!req->bio)
+ return false;
+
+ /*
+ * For fs requests, rq is just carrier of independent bio's
+ * and each partial completion should be handled separately.
+ * Reset per-request error on each partial completion.
+ *
+ * TODO: tj: This is too subtle. It would be better to let
+ * low level drivers do what they see fit.
+ */
+ if (req->cmd_type == REQ_TYPE_FS)
+ req->errors = 0;
+
+ if (error && req->cmd_type == REQ_TYPE_FS &&
+ !(req->cmd_flags & REQ_QUIET)) {
+ char *error_type;
+
+ switch (error) {
+ case -ENOLINK:
+ error_type = "recoverable transport";
+ break;
+ case -EREMOTEIO:
+ error_type = "critical target";
+ break;
+ case -EBADE:
+ error_type = "critical nexus";
+ break;
+ case -ETIMEDOUT:
+ error_type = "timeout";
+ break;
+ case -ENOSPC:
+ error_type = "critical space allocation";
+ break;
+ case -ENODATA:
+ error_type = "critical medium";
+ break;
+ case -EIO:
+ default:
+ error_type = "I/O";
+ break;
+ }
+ printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n",
+ __func__, error_type, req->rq_disk ?
+ req->rq_disk->disk_name : "?",
+ (unsigned long long)blk_rq_pos(req));
+
+ }
+
+ blk_account_io_completion(req, nr_bytes);
+
+ total_bytes = 0;
+ while (req->bio) {
+ struct bio *bio = req->bio;
+ unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
+
+ if (bio_bytes == bio->bi_iter.bi_size)
+ req->bio = bio->bi_next;
+
+ req_bio_endio(req, bio, bio_bytes, error);
+
+ total_bytes += bio_bytes;
+ nr_bytes -= bio_bytes;
+
+ if (!nr_bytes)
+ break;
+ }
+
+ /*
+ * completely done
+ */
+ if (!req->bio) {
+ /*
+ * Reset counters so that the request stacking driver
+ * can find how many bytes remain in the request
+ * later.
+ */
+ req->__data_len = 0;
+ return false;
+ }
+
+ req->__data_len -= total_bytes;
+
+ /* update sector only for requests with clear definition of sector */
+ if (req->cmd_type == REQ_TYPE_FS)
+ req->__sector += total_bytes >> 9;
+
+ /* mixed attributes always follow the first bio */
+ if (req->cmd_flags & REQ_MIXED_MERGE) {
+ req->cmd_flags &= ~REQ_FAILFAST_MASK;
+ req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
+ }
+
+ /*
+ * If total number of sectors is less than the first segment
+ * size, something has gone terribly wrong.
+ */
+ if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
+ blk_dump_rq_flags(req, "request botched");
+ req->__data_len = blk_rq_cur_bytes(req);
+ }
+
+ /* recalculate the number of segments */
+ blk_recalc_rq_segments(req);
+
+ return true;
+}
+EXPORT_SYMBOL_GPL(blk_update_request);
+
+static bool blk_update_bidi_request(struct request *rq, int error,
+ unsigned int nr_bytes,
+ unsigned int bidi_bytes)
+{
+ if (blk_update_request(rq, error, nr_bytes))
+ return true;
+
+ /* Bidi request must be completed as a whole */
+ if (unlikely(blk_bidi_rq(rq)) &&
+ blk_update_request(rq->next_rq, error, bidi_bytes))
+ return true;
+
+ if (blk_queue_add_random(rq->q))
+ add_disk_randomness(rq->rq_disk);
+
+ return false;
+}
+
+/**
+ * blk_unprep_request - unprepare a request
+ * @req: the request
+ *
+ * This function makes a request ready for complete resubmission (or
+ * completion). It happens only after all error handling is complete,
+ * so represents the appropriate moment to deallocate any resources
+ * that were allocated to the request in the prep_rq_fn. The queue
+ * lock is held when calling this.
+ */
+void blk_unprep_request(struct request *req)
+{
+ struct request_queue *q = req->q;
+
+ req->cmd_flags &= ~REQ_DONTPREP;
+ if (q->unprep_rq_fn)
+ q->unprep_rq_fn(q, req);
+}
+EXPORT_SYMBOL_GPL(blk_unprep_request);
+
+/*
+ * queue lock must be held
+ */
+void blk_finish_request(struct request *req, int error)
+{
+ if (req->cmd_flags & REQ_QUEUED)
+ blk_queue_end_tag(req->q, req);
+
+ BUG_ON(blk_queued_rq(req));
+
+ if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
+ laptop_io_completion(&req->q->backing_dev_info);
+
+ blk_delete_timer(req);
+
+ if (req->cmd_flags & REQ_DONTPREP)
+ blk_unprep_request(req);
+
+ blk_account_io_done(req);
+
+ if (req->end_io)
+ req->end_io(req, error);
+ else {
+ if (blk_bidi_rq(req))
+ __blk_put_request(req->next_rq->q, req->next_rq);
+
+ __blk_put_request(req->q, req);
+ }
+}
+EXPORT_SYMBOL(blk_finish_request);
+
+/**
+ * blk_end_bidi_request - Complete a bidi request
+ * @rq: the request to complete
+ * @error: %0 for success, < %0 for error
+ * @nr_bytes: number of bytes to complete @rq
+ * @bidi_bytes: number of bytes to complete @rq->next_rq
+ *
+ * Description:
+ * Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
+ * Drivers that supports bidi can safely call this member for any
+ * type of request, bidi or uni. In the later case @bidi_bytes is
+ * just ignored.
+ *
+ * Return:
+ * %false - we are done with this request
+ * %true - still buffers pending for this request
+ **/
+static bool blk_end_bidi_request(struct request *rq, int error,
+ unsigned int nr_bytes, unsigned int bidi_bytes)
+{
+ struct request_queue *q = rq->q;
+ unsigned long flags;
+
+ if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
+ return true;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ blk_finish_request(rq, error);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return false;
+}
+
+/**
+ * __blk_end_bidi_request - Complete a bidi request with queue lock held
+ * @rq: the request to complete
+ * @error: %0 for success, < %0 for error
+ * @nr_bytes: number of bytes to complete @rq
+ * @bidi_bytes: number of bytes to complete @rq->next_rq
+ *
+ * Description:
+ * Identical to blk_end_bidi_request() except that queue lock is
+ * assumed to be locked on entry and remains so on return.
+ *
+ * Return:
+ * %false - we are done with this request
+ * %true - still buffers pending for this request
+ **/
+bool __blk_end_bidi_request(struct request *rq, int error,
+ unsigned int nr_bytes, unsigned int bidi_bytes)
+{
+ if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
+ return true;
+
+ blk_finish_request(rq, error);
+
+ return false;
+}
+
+/**
+ * blk_end_request - Helper function for drivers to complete the request.
+ * @rq: the request being processed
+ * @error: %0 for success, < %0 for error
+ * @nr_bytes: number of bytes to complete
+ *
+ * Description:
+ * Ends I/O on a number of bytes attached to @rq.
+ * If @rq has leftover, sets it up for the next range of segments.
+ *
+ * Return:
+ * %false - we are done with this request
+ * %true - still buffers pending for this request
+ **/
+bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
+{
+ return blk_end_bidi_request(rq, error, nr_bytes, 0);
+}
+EXPORT_SYMBOL(blk_end_request);
+
+/**
+ * blk_end_request_all - Helper function for drives to finish the request.
+ * @rq: the request to finish
+ * @error: %0 for success, < %0 for error
+ *
+ * Description:
+ * Completely finish @rq.
+ */
+void blk_end_request_all(struct request *rq, int error)
+{
+ bool pending;
+ unsigned int bidi_bytes = 0;
+
+ if (unlikely(blk_bidi_rq(rq)))
+ bidi_bytes = blk_rq_bytes(rq->next_rq);
+
+ pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
+ BUG_ON(pending);
+}
+EXPORT_SYMBOL(blk_end_request_all);
+
+/**
+ * blk_end_request_cur - Helper function to finish the current request chunk.
+ * @rq: the request to finish the current chunk for
+ * @error: %0 for success, < %0 for error
+ *
+ * Description:
+ * Complete the current consecutively mapped chunk from @rq.
+ *
+ * Return:
+ * %false - we are done with this request
+ * %true - still buffers pending for this request
+ */
+bool blk_end_request_cur(struct request *rq, int error)
+{
+ return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
+}
+EXPORT_SYMBOL(blk_end_request_cur);
+
+/**
+ * blk_end_request_err - Finish a request till the next failure boundary.
+ * @rq: the request to finish till the next failure boundary for
+ * @error: must be negative errno
+ *
+ * Description:
+ * Complete @rq till the next failure boundary.
+ *
+ * Return:
+ * %false - we are done with this request
+ * %true - still buffers pending for this request
+ */
+bool blk_end_request_err(struct request *rq, int error)
+{
+ WARN_ON(error >= 0);
+ return blk_end_request(rq, error, blk_rq_err_bytes(rq));
+}
+EXPORT_SYMBOL_GPL(blk_end_request_err);
+
+/**
+ * __blk_end_request - Helper function for drivers to complete the request.
+ * @rq: the request being processed
+ * @error: %0 for success, < %0 for error
+ * @nr_bytes: number of bytes to complete
+ *
+ * Description:
+ * Must be called with queue lock held unlike blk_end_request().
+ *
+ * Return:
+ * %false - we are done with this request
+ * %true - still buffers pending for this request
+ **/
+bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
+{
+ return __blk_end_bidi_request(rq, error, nr_bytes, 0);
+}
+EXPORT_SYMBOL(__blk_end_request);
+
+/**
+ * __blk_end_request_all - Helper function for drives to finish the request.
+ * @rq: the request to finish
+ * @error: %0 for success, < %0 for error
+ *
+ * Description:
+ * Completely finish @rq. Must be called with queue lock held.
+ */
+void __blk_end_request_all(struct request *rq, int error)
+{
+ bool pending;
+ unsigned int bidi_bytes = 0;
+
+ if (unlikely(blk_bidi_rq(rq)))
+ bidi_bytes = blk_rq_bytes(rq->next_rq);
+
+ pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
+ BUG_ON(pending);
+}
+EXPORT_SYMBOL(__blk_end_request_all);
+
+/**
+ * __blk_end_request_cur - Helper function to finish the current request chunk.
+ * @rq: the request to finish the current chunk for
+ * @error: %0 for success, < %0 for error
+ *
+ * Description:
+ * Complete the current consecutively mapped chunk from @rq. Must
+ * be called with queue lock held.
+ *
+ * Return:
+ * %false - we are done with this request
+ * %true - still buffers pending for this request
+ */
+bool __blk_end_request_cur(struct request *rq, int error)
+{
+ return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
+}
+EXPORT_SYMBOL(__blk_end_request_cur);
+
+/**
+ * __blk_end_request_err - Finish a request till the next failure boundary.
+ * @rq: the request to finish till the next failure boundary for
+ * @error: must be negative errno
+ *
+ * Description:
+ * Complete @rq till the next failure boundary. Must be called
+ * with queue lock held.
+ *
+ * Return:
+ * %false - we are done with this request
+ * %true - still buffers pending for this request
+ */
+bool __blk_end_request_err(struct request *rq, int error)
+{
+ WARN_ON(error >= 0);
+ return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
+}
+EXPORT_SYMBOL_GPL(__blk_end_request_err);
+
+void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
+ rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
+
+ if (bio_has_data(bio))
+ rq->nr_phys_segments = bio_phys_segments(q, bio);
+
+ rq->__data_len = bio->bi_iter.bi_size;
+ rq->bio = rq->biotail = bio;
+
+ if (bio->bi_bdev)
+ rq->rq_disk = bio->bi_bdev->bd_disk;
+}
+
+#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
+/**
+ * rq_flush_dcache_pages - Helper function to flush all pages in a request
+ * @rq: the request to be flushed
+ *
+ * Description:
+ * Flush all pages in @rq.
+ */
+void rq_flush_dcache_pages(struct request *rq)
+{
+ struct req_iterator iter;
+ struct bio_vec bvec;
+
+ rq_for_each_segment(bvec, rq, iter)
+ flush_dcache_page(bvec.bv_page);
+}
+EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
+#endif
+
+/**
+ * blk_lld_busy - Check if underlying low-level drivers of a device are busy
+ * @q : the queue of the device being checked
+ *
+ * Description:
+ * Check if underlying low-level drivers of a device are busy.
+ * If the drivers want to export their busy state, they must set own
+ * exporting function using blk_queue_lld_busy() first.
+ *
+ * Basically, this function is used only by request stacking drivers
+ * to stop dispatching requests to underlying devices when underlying
+ * devices are busy. This behavior helps more I/O merging on the queue
+ * of the request stacking driver and prevents I/O throughput regression
+ * on burst I/O load.
+ *
+ * Return:
+ * 0 - Not busy (The request stacking driver should dispatch request)
+ * 1 - Busy (The request stacking driver should stop dispatching request)
+ */
+int blk_lld_busy(struct request_queue *q)
+{
+ if (q->lld_busy_fn)
+ return q->lld_busy_fn(q);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(blk_lld_busy);
+
+/**
+ * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
+ * @rq: the clone request to be cleaned up
+ *
+ * Description:
+ * Free all bios in @rq for a cloned request.
+ */
+void blk_rq_unprep_clone(struct request *rq)
+{
+ struct bio *bio;
+
+ while ((bio = rq->bio) != NULL) {
+ rq->bio = bio->bi_next;
+
+ bio_put(bio);
+ }
+}
+EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
+
+/*
+ * Copy attributes of the original request to the clone request.
+ * The actual data parts (e.g. ->cmd, ->sense) are not copied.
+ */
+static void __blk_rq_prep_clone(struct request *dst, struct request *src)
+{
+ dst->cpu = src->cpu;
+ dst->cmd_flags |= (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
+ dst->cmd_type = src->cmd_type;
+ dst->__sector = blk_rq_pos(src);
+ dst->__data_len = blk_rq_bytes(src);
+ dst->nr_phys_segments = src->nr_phys_segments;
+ dst->ioprio = src->ioprio;
+ dst->extra_len = src->extra_len;
+}
+
+/**
+ * blk_rq_prep_clone - Helper function to setup clone request
+ * @rq: the request to be setup
+ * @rq_src: original request to be cloned
+ * @bs: bio_set that bios for clone are allocated from
+ * @gfp_mask: memory allocation mask for bio
+ * @bio_ctr: setup function to be called for each clone bio.
+ * Returns %0 for success, non %0 for failure.
+ * @data: private data to be passed to @bio_ctr
+ *
+ * Description:
+ * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
+ * The actual data parts of @rq_src (e.g. ->cmd, ->sense)
+ * are not copied, and copying such parts is the caller's responsibility.
+ * Also, pages which the original bios are pointing to are not copied
+ * and the cloned bios just point same pages.
+ * So cloned bios must be completed before original bios, which means
+ * the caller must complete @rq before @rq_src.
+ */
+int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
+ struct bio_set *bs, gfp_t gfp_mask,
+ int (*bio_ctr)(struct bio *, struct bio *, void *),
+ void *data)
+{
+ struct bio *bio, *bio_src;
+
+ if (!bs)
+ bs = fs_bio_set;
+
+ __rq_for_each_bio(bio_src, rq_src) {
+ bio = bio_clone_fast(bio_src, gfp_mask, bs);
+ if (!bio)
+ goto free_and_out;
+
+ if (bio_ctr && bio_ctr(bio, bio_src, data))
+ goto free_and_out;
+
+ if (rq->bio) {
+ rq->biotail->bi_next = bio;
+ rq->biotail = bio;
+ } else
+ rq->bio = rq->biotail = bio;
+ }
+
+ __blk_rq_prep_clone(rq, rq_src);
+
+ return 0;
+
+free_and_out:
+ if (bio)
+ bio_put(bio);
+ blk_rq_unprep_clone(rq);
+
+ return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
+
+int kblockd_schedule_work(struct work_struct *work)
+{
+ return queue_work(kblockd_workqueue, work);
+}
+EXPORT_SYMBOL(kblockd_schedule_work);
+
+int kblockd_schedule_delayed_work(struct delayed_work *dwork,
+ unsigned long delay)
+{
+ return queue_delayed_work(kblockd_workqueue, dwork, delay);
+}
+EXPORT_SYMBOL(kblockd_schedule_delayed_work);
+
+int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
+ unsigned long delay)
+{
+ return queue_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
+}
+EXPORT_SYMBOL(kblockd_schedule_delayed_work_on);
+
+/**
+ * blk_start_plug - initialize blk_plug and track it inside the task_struct
+ * @plug: The &struct blk_plug that needs to be initialized
+ *
+ * Description:
+ * Tracking blk_plug inside the task_struct will help with auto-flushing the
+ * pending I/O should the task end up blocking between blk_start_plug() and
+ * blk_finish_plug(). This is important from a performance perspective, but
+ * also ensures that we don't deadlock. For instance, if the task is blocking
+ * for a memory allocation, memory reclaim could end up wanting to free a
+ * page belonging to that request that is currently residing in our private
+ * plug. By flushing the pending I/O when the process goes to sleep, we avoid
+ * this kind of deadlock.
+ */
+void blk_start_plug(struct blk_plug *plug)
+{
+ struct task_struct *tsk = current;
+
+ INIT_LIST_HEAD(&plug->list);
+ INIT_LIST_HEAD(&plug->mq_list);
+ INIT_LIST_HEAD(&plug->cb_list);
+
+ /*
+ * 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 ||
+ (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb)));
+}
+
+/*
+ * If 'from_schedule' is true, then postpone the dispatch of requests
+ * until a safe kblockd context. We due this to avoid accidental big
+ * additional stack usage in driver dispatch, in places where the originally
+ * plugger did not intend it.
+ */
+static void queue_unplugged(struct request_queue *q, unsigned int depth,
+ bool from_schedule)
+ __releases(q->queue_lock)
+{
+ trace_block_unplug(q, depth, !from_schedule);
+
+ if (from_schedule)
+ blk_run_queue_async(q);
+ else
+ __blk_run_queue(q);
+ spin_unlock_irq(q->queue_lock);
+}
+
+static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
+{
+ LIST_HEAD(callbacks);
+
+ while (!list_empty(&plug->cb_list)) {
+ list_splice_init(&plug->cb_list, &callbacks);
+
+ while (!list_empty(&callbacks)) {
+ struct blk_plug_cb *cb = list_first_entry(&callbacks,
+ struct blk_plug_cb,
+ list);
+ list_del(&cb->list);
+ cb->callback(cb, from_schedule);
+ }
+ }
+}
+
+struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
+ int size)
+{
+ struct blk_plug *plug = current->plug;
+ struct blk_plug_cb *cb;
+
+ if (!plug)
+ return NULL;
+
+ list_for_each_entry(cb, &plug->cb_list, list)
+ if (cb->callback == unplug && cb->data == data)
+ return cb;
+
+ /* Not currently on the callback list */
+ BUG_ON(size < sizeof(*cb));
+ cb = kzalloc(size, GFP_ATOMIC);
+ if (cb) {
+ cb->data = data;
+ cb->callback = unplug;
+ list_add(&cb->list, &plug->cb_list);
+ }
+ return cb;
+}
+EXPORT_SYMBOL(blk_check_plugged);
+
+void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
+{
+ struct request_queue *q;
+ struct request *rq;
+ LIST_HEAD(list);
+ unsigned int depth;
+
+ flush_plug_callbacks(plug, from_schedule);
+
+ if (!list_empty(&plug->mq_list))
+ blk_mq_flush_plug_list(plug, from_schedule);
+
+ if (list_empty(&plug->list))
+ return;
+
+ list_splice_init(&plug->list, &list);
+
+ list_sort(NULL, &list, plug_rq_cmp);
+
+ q = NULL;
+ depth = 0;
+
+ while (!list_empty(&list)) {
+ rq = list_entry_rq(list.next);
+ list_del_init(&rq->queuelist);
+ BUG_ON(!rq->q);
+ if (rq->q != q) {
+ /*
+ * This drops the queue lock
+ */
+ if (q)
+ queue_unplugged(q, depth, from_schedule);
+ q = rq->q;
+ depth = 0;
+ spin_lock_irq(q->queue_lock);
+ }
+
+ /*
+ * Short-circuit if @q is dead
+ */
+ if (unlikely(blk_queue_dying(q))) {
+ __blk_end_request_all(rq, -ENODEV);
+ continue;
+ }
+
+ /*
+ * rq is already accounted, so use raw insert
+ */
+ if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
+ __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
+ else
+ __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
+
+ depth++;
+ }
+
+ /*
+ * This drops the queue lock
+ */
+ if (q)
+ queue_unplugged(q, depth, from_schedule);
+}
+
+void blk_finish_plug(struct blk_plug *plug)
+{
+ blk_flush_plug_list(plug, false);
+
+ if (plug == current->plug)
+ current->plug = NULL;
+}
+EXPORT_SYMBOL(blk_finish_plug);
+
+#ifdef CONFIG_PM
+/**
+ * blk_pm_runtime_init - Block layer runtime PM initialization routine
+ * @q: the queue of the device
+ * @dev: the device the queue belongs to
+ *
+ * Description:
+ * Initialize runtime-PM-related fields for @q and start auto suspend for
+ * @dev. Drivers that want to take advantage of request-based runtime PM
+ * should call this function after @dev has been initialized, and its
+ * request queue @q has been allocated, and runtime PM for it can not happen
+ * yet(either due to disabled/forbidden or its usage_count > 0). In most
+ * cases, driver should call this function before any I/O has taken place.
+ *
+ * This function takes care of setting up using auto suspend for the device,
+ * the autosuspend delay is set to -1 to make runtime suspend impossible
+ * until an updated value is either set by user or by driver. Drivers do
+ * not need to touch other autosuspend settings.
+ *
+ * The block layer runtime PM is request based, so only works for drivers
+ * that use request as their IO unit instead of those directly use bio's.
+ */
+void blk_pm_runtime_init(struct request_queue *q, struct device *dev)
+{
+ q->dev = dev;
+ q->rpm_status = RPM_ACTIVE;
+ pm_runtime_set_autosuspend_delay(q->dev, -1);
+ pm_runtime_use_autosuspend(q->dev);
+}
+EXPORT_SYMBOL(blk_pm_runtime_init);
+
+/**
+ * blk_pre_runtime_suspend - Pre runtime suspend check
+ * @q: the queue of the device
+ *
+ * Description:
+ * This function will check if runtime suspend is allowed for the device
+ * by examining if there are any requests pending in the queue. If there
+ * are requests pending, the device can not be runtime suspended; otherwise,
+ * the queue's status will be updated to SUSPENDING and the driver can
+ * proceed to suspend the device.
+ *
+ * For the not allowed case, we mark last busy for the device so that
+ * runtime PM core will try to autosuspend it some time later.
+ *
+ * This function should be called near the start of the device's
+ * runtime_suspend callback.
+ *
+ * Return:
+ * 0 - OK to runtime suspend the device
+ * -EBUSY - Device should not be runtime suspended
+ */
+int blk_pre_runtime_suspend(struct request_queue *q)
+{
+ int ret = 0;
+
+ spin_lock_irq(q->queue_lock);
+ if (q->nr_pending) {
+ ret = -EBUSY;
+ pm_runtime_mark_last_busy(q->dev);
+ } else {
+ q->rpm_status = RPM_SUSPENDING;
+ }
+ spin_unlock_irq(q->queue_lock);
+ return ret;
+}
+EXPORT_SYMBOL(blk_pre_runtime_suspend);
+
+/**
+ * blk_post_runtime_suspend - Post runtime suspend processing
+ * @q: the queue of the device
+ * @err: return value of the device's runtime_suspend function
+ *
+ * Description:
+ * Update the queue's runtime status according to the return value of the
+ * device's runtime suspend function and mark last busy for the device so
+ * that PM core will try to auto suspend the device at a later time.
+ *
+ * This function should be called near the end of the device's
+ * runtime_suspend callback.
+ */
+void blk_post_runtime_suspend(struct request_queue *q, int err)
+{
+ spin_lock_irq(q->queue_lock);
+ if (!err) {
+ q->rpm_status = RPM_SUSPENDED;
+ } else {
+ q->rpm_status = RPM_ACTIVE;
+ pm_runtime_mark_last_busy(q->dev);
+ }
+ spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_post_runtime_suspend);
+
+/**
+ * blk_pre_runtime_resume - Pre runtime resume processing
+ * @q: the queue of the device
+ *
+ * Description:
+ * Update the queue's runtime status to RESUMING in preparation for the
+ * runtime resume of the device.
+ *
+ * This function should be called near the start of the device's
+ * runtime_resume callback.
+ */
+void blk_pre_runtime_resume(struct request_queue *q)
+{
+ spin_lock_irq(q->queue_lock);
+ q->rpm_status = RPM_RESUMING;
+ spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_pre_runtime_resume);
+
+/**
+ * blk_post_runtime_resume - Post runtime resume processing
+ * @q: the queue of the device
+ * @err: return value of the device's runtime_resume function
+ *
+ * Description:
+ * Update the queue's runtime status according to the return value of the
+ * device's runtime_resume function. If it is successfully resumed, process
+ * the requests that are queued into the device's queue when it is resuming
+ * and then mark last busy and initiate autosuspend for it.
+ *
+ * This function should be called near the end of the device's
+ * runtime_resume callback.
+ */
+void blk_post_runtime_resume(struct request_queue *q, int err)
+{
+ spin_lock_irq(q->queue_lock);
+ if (!err) {
+ q->rpm_status = RPM_ACTIVE;
+ __blk_run_queue(q);
+ pm_runtime_mark_last_busy(q->dev);
+ pm_request_autosuspend(q->dev);
+ } else {
+ q->rpm_status = RPM_SUSPENDED;
+ }
+ spin_unlock_irq(q->queue_lock);
+}
+EXPORT_SYMBOL(blk_post_runtime_resume);
+#endif
+
+int __init blk_dev_init(void)
+{
+ BUILD_BUG_ON(__REQ_NR_BITS > 8 *
+ sizeof(((struct request *)0)->cmd_flags));
+
+ /* used for unplugging and affects IO latency/throughput - HIGHPRI */
+ kblockd_workqueue = alloc_workqueue("kblockd",
+ WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
+ if (!kblockd_workqueue)
+ panic("Failed to create kblockd\n");
+
+ request_cachep = kmem_cache_create("blkdev_requests",
+ sizeof(struct request), 0, SLAB_PANIC, NULL);
+
+ blk_requestq_cachep = kmem_cache_create("blkdev_queue",
+ sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
+
+ return 0;
+}
Code Review / kvmfornfv.git / blobdiff