| /* |
| * 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/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/blktrace_api.h> |
| #include <linux/fault-inject.h> |
| |
| #include "blk.h" |
| |
| static int __make_request(struct request_queue *q, struct bio *bio); |
| |
| /* |
| * For the allocated request tables |
| */ |
| static struct kmem_cache *request_cachep; |
| |
| /* |
| * For queue allocation |
| */ |
| struct kmem_cache *blk_requestq_cachep; |
| |
| /* |
| * Controlling structure to kblockd |
| */ |
| static struct workqueue_struct *kblockd_workqueue; |
| |
| static void drive_stat_acct(struct request *rq, int new_io) |
| { |
| struct hd_struct *part; |
| int rw = rq_data_dir(rq); |
| int cpu; |
| |
| if (!blk_fs_request(rq) || !rq->rq_disk) |
| return; |
| |
| cpu = part_stat_lock(); |
| part = disk_map_sector_rcu(rq->rq_disk, rq->sector); |
| |
| if (!new_io) |
| part_stat_inc(cpu, part, merges[rw]); |
| else { |
| part_round_stats(cpu, part); |
| part_inc_in_flight(part); |
| } |
| |
| part_stat_unlock(); |
| } |
| |
| 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 |
| * |
| * Will return NULL if the request queue cannot be located. |
| */ |
| struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) |
| { |
| struct backing_dev_info *ret = NULL; |
| struct request_queue *q = bdev_get_queue(bdev); |
| |
| if (q) |
| ret = &q->backing_dev_info; |
| return ret; |
| } |
| 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); |
| rq->cpu = -1; |
| rq->q = q; |
| rq->sector = rq->hard_sector = (sector_t) -1; |
| INIT_HLIST_NODE(&rq->hash); |
| RB_CLEAR_NODE(&rq->rb_node); |
| rq->cmd = rq->__cmd; |
| rq->tag = -1; |
| rq->ref_count = 1; |
| } |
| EXPORT_SYMBOL(blk_rq_init); |
| |
| static void req_bio_endio(struct request *rq, struct bio *bio, |
| unsigned int nbytes, int error) |
| { |
| struct request_queue *q = rq->q; |
| |
| if (&q->bar_rq != rq) { |
| if (error) |
| clear_bit(BIO_UPTODATE, &bio->bi_flags); |
| else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) |
| error = -EIO; |
| |
| if (unlikely(nbytes > bio->bi_size)) { |
| printk(KERN_ERR "%s: want %u bytes done, %u left\n", |
| __func__, nbytes, bio->bi_size); |
| nbytes = bio->bi_size; |
| } |
| |
| bio->bi_size -= nbytes; |
| bio->bi_sector += (nbytes >> 9); |
| |
| if (bio_integrity(bio)) |
| bio_integrity_advance(bio, nbytes); |
| |
| if (bio->bi_size == 0) |
| bio_endio(bio, error); |
| } else { |
| |
| /* |
| * Okay, this is the barrier request in progress, just |
| * record the error; |
| */ |
| if (error && !q->orderr) |
| q->orderr = error; |
| } |
| } |
| |
| void blk_dump_rq_flags(struct request *rq, char *msg) |
| { |
| int bit; |
| |
| printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg, |
| rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, |
| rq->cmd_flags); |
| |
| printk(KERN_INFO " sector %llu, nr/cnr %lu/%u\n", |
| (unsigned long long)rq->sector, |
| rq->nr_sectors, |
| rq->current_nr_sectors); |
| printk(KERN_INFO " bio %p, biotail %p, buffer %p, data %p, len %u\n", |
| rq->bio, rq->biotail, |
| rq->buffer, rq->data, |
| rq->data_len); |
| |
| if (blk_pc_request(rq)) { |
| 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); |
| |
| /* |
| * "plug" the device if there are no outstanding requests: this will |
| * force the transfer to start only after we have put all the requests |
| * on the list. |
| * |
| * This is called with interrupts off and no requests on the queue and |
| * with the queue lock held. |
| */ |
| void blk_plug_device(struct request_queue *q) |
| { |
| WARN_ON(!irqs_disabled()); |
| |
| /* |
| * don't plug a stopped queue, it must be paired with blk_start_queue() |
| * which will restart the queueing |
| */ |
| if (blk_queue_stopped(q)) |
| return; |
| |
| if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) { |
| mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); |
| blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG); |
| } |
| } |
| EXPORT_SYMBOL(blk_plug_device); |
| |
| /** |
| * blk_plug_device_unlocked - plug a device without queue lock held |
| * @q: The &struct request_queue to plug |
| * |
| * Description: |
| * Like @blk_plug_device(), but grabs the queue lock and disables |
| * interrupts. |
| **/ |
| void blk_plug_device_unlocked(struct request_queue *q) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| blk_plug_device(q); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| EXPORT_SYMBOL(blk_plug_device_unlocked); |
| |
| /* |
| * remove the queue from the plugged list, if present. called with |
| * queue lock held and interrupts disabled. |
| */ |
| int blk_remove_plug(struct request_queue *q) |
| { |
| WARN_ON(!irqs_disabled()); |
| |
| if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q)) |
| return 0; |
| |
| del_timer(&q->unplug_timer); |
| return 1; |
| } |
| EXPORT_SYMBOL(blk_remove_plug); |
| |
| /* |
| * remove the plug and let it rip.. |
| */ |
| void __generic_unplug_device(struct request_queue *q) |
| { |
| if (unlikely(blk_queue_stopped(q))) |
| return; |
| |
| if (!blk_remove_plug(q)) |
| return; |
| |
| q->request_fn(q); |
| } |
| EXPORT_SYMBOL(__generic_unplug_device); |
| |
| /** |
| * generic_unplug_device - fire a request queue |
| * @q: The &struct request_queue in question |
| * |
| * Description: |
| * Linux uses plugging to build bigger requests queues before letting |
| * the device have at them. If a queue is plugged, the I/O scheduler |
| * is still adding and merging requests on the queue. Once the queue |
| * gets unplugged, the request_fn defined for the queue is invoked and |
| * transfers started. |
| **/ |
| void generic_unplug_device(struct request_queue *q) |
| { |
| if (blk_queue_plugged(q)) { |
| spin_lock_irq(q->queue_lock); |
| __generic_unplug_device(q); |
| spin_unlock_irq(q->queue_lock); |
| } |
| } |
| EXPORT_SYMBOL(generic_unplug_device); |
| |
| static void blk_backing_dev_unplug(struct backing_dev_info *bdi, |
| struct page *page) |
| { |
| struct request_queue *q = bdi->unplug_io_data; |
| |
| blk_unplug(q); |
| } |
| |
| void blk_unplug_work(struct work_struct *work) |
| { |
| struct request_queue *q = |
| container_of(work, struct request_queue, unplug_work); |
| |
| blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, |
| q->rq.count[READ] + q->rq.count[WRITE]); |
| |
| q->unplug_fn(q); |
| } |
| |
| void blk_unplug_timeout(unsigned long data) |
| { |
| struct request_queue *q = (struct request_queue *)data; |
| |
| blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL, |
| q->rq.count[READ] + q->rq.count[WRITE]); |
| |
| kblockd_schedule_work(q, &q->unplug_work); |
| } |
| |
| void blk_unplug(struct request_queue *q) |
| { |
| /* |
| * devices don't necessarily have an ->unplug_fn defined |
| */ |
| if (q->unplug_fn) { |
| blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, |
| q->rq.count[READ] + q->rq.count[WRITE]); |
| |
| q->unplug_fn(q); |
| } |
| } |
| EXPORT_SYMBOL(blk_unplug); |
| |
| static void blk_invoke_request_fn(struct request_queue *q) |
| { |
| /* |
| * one level of recursion is ok and is much faster than kicking |
| * the unplug handling |
| */ |
| if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { |
| q->request_fn(q); |
| queue_flag_clear(QUEUE_FLAG_REENTER, q); |
| } else { |
| queue_flag_set(QUEUE_FLAG_PLUGGED, q); |
| kblockd_schedule_work(q, &q->unplug_work); |
| } |
| } |
| |
| /** |
| * 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(!irqs_disabled()); |
| |
| queue_flag_clear(QUEUE_FLAG_STOPPED, q); |
| blk_invoke_request_fn(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) |
| { |
| blk_remove_plug(q); |
| 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. |
| * |
| */ |
| void blk_sync_queue(struct request_queue *q) |
| { |
| del_timer_sync(&q->unplug_timer); |
| kblockd_flush_work(&q->unplug_work); |
| } |
| EXPORT_SYMBOL(blk_sync_queue); |
| |
| /** |
| * blk_run_queue - run a single device queue |
| * @q: The queue to run |
| */ |
| void __blk_run_queue(struct request_queue *q) |
| { |
| blk_remove_plug(q); |
| |
| /* |
| * Only recurse once to avoid overrunning the stack, let the unplug |
| * handling reinvoke the handler shortly if we already got there. |
| */ |
| if (!elv_queue_empty(q)) |
| blk_invoke_request_fn(q); |
| } |
| EXPORT_SYMBOL(__blk_run_queue); |
| |
| /** |
| * blk_run_queue - run a single device queue |
| * @q: The queue to run |
| */ |
| 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); |
| } |
| |
| void blk_cleanup_queue(struct request_queue *q) |
| { |
| /* |
| * We know we have process context here, so we can be a little |
| * cautious and ensure that pending block actions on this device |
| * are done before moving on. Going into this function, we should |
| * not have processes doing IO to this device. |
| */ |
| blk_sync_queue(q); |
| |
| mutex_lock(&q->sysfs_lock); |
| queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); |
| mutex_unlock(&q->sysfs_lock); |
| |
| if (q->elevator) |
| elevator_exit(q->elevator); |
| |
| blk_put_queue(q); |
| } |
| EXPORT_SYMBOL(blk_cleanup_queue); |
| |
| static int blk_init_free_list(struct request_queue *q) |
| { |
| struct request_list *rl = &q->rq; |
| |
| rl->count[READ] = rl->count[WRITE] = 0; |
| rl->starved[READ] = rl->starved[WRITE] = 0; |
| rl->elvpriv = 0; |
| init_waitqueue_head(&rl->wait[READ]); |
| init_waitqueue_head(&rl->wait[WRITE]); |
| |
| rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
| mempool_free_slab, request_cachep, q->node); |
| |
| if (!rl->rq_pool) |
| return -ENOMEM; |
| |
| return 0; |
| } |
| |
| struct request_queue *blk_alloc_queue(gfp_t gfp_mask) |
| { |
| return blk_alloc_queue_node(gfp_mask, -1); |
| } |
| 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->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; |
| q->backing_dev_info.unplug_io_data = q; |
| err = bdi_init(&q->backing_dev_info); |
| if (err) { |
| kmem_cache_free(blk_requestq_cachep, q); |
| return NULL; |
| } |
| |
| init_timer(&q->unplug_timer); |
| setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); |
| INIT_LIST_HEAD(&q->timeout_list); |
| |
| kobject_init(&q->kobj, &blk_queue_ktype); |
| |
| mutex_init(&q->sysfs_lock); |
| spin_lock_init(&q->__queue_lock); |
| |
| return q; |
| } |
| 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, -1); |
| } |
| 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 *q = blk_alloc_queue_node(GFP_KERNEL, node_id); |
| |
| if (!q) |
| return NULL; |
| |
| q->node = node_id; |
| if (blk_init_free_list(q)) { |
| kmem_cache_free(blk_requestq_cachep, q); |
| return NULL; |
| } |
| |
| /* |
| * if caller didn't supply a lock, they get per-queue locking with |
| * our embedded lock |
| */ |
| if (!lock) |
| lock = &q->__queue_lock; |
| |
| q->request_fn = rfn; |
| q->prep_rq_fn = NULL; |
| q->unplug_fn = generic_unplug_device; |
| q->queue_flags = (1 << QUEUE_FLAG_CLUSTER); |
| q->queue_lock = lock; |
| |
| blk_queue_segment_boundary(q, 0xffffffff); |
| |
| blk_queue_make_request(q, __make_request); |
| blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE); |
| |
| blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); |
| blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); |
| |
| q->sg_reserved_size = INT_MAX; |
| |
| blk_set_cmd_filter_defaults(&q->cmd_filter); |
| |
| /* |
| * all done |
| */ |
| if (!elevator_init(q, NULL)) { |
| blk_queue_congestion_threshold(q); |
| return q; |
| } |
| |
| blk_put_queue(q); |
| return NULL; |
| } |
| EXPORT_SYMBOL(blk_init_queue_node); |
| |
| int blk_get_queue(struct request_queue *q) |
| { |
| if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { |
| kobject_get(&q->kobj); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static inline void blk_free_request(struct request_queue *q, struct request *rq) |
| { |
| if (rq->cmd_flags & REQ_ELVPRIV) |
| elv_put_request(q, rq); |
| mempool_free(rq, q->rq.rq_pool); |
| } |
| |
| static struct request * |
| blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask) |
| { |
| struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); |
| |
| if (!rq) |
| return NULL; |
| |
| blk_rq_init(q, rq); |
| |
| rq->cmd_flags = rw | REQ_ALLOCED; |
| |
| if (priv) { |
| if (unlikely(elv_set_request(q, rq, gfp_mask))) { |
| mempool_free(rq, q->rq.rq_pool); |
| return NULL; |
| } |
| rq->cmd_flags |= REQ_ELVPRIV; |
| } |
| |
| return rq; |
| } |
| |
| /* |
| * 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_queue *q, int rw) |
| { |
| struct request_list *rl = &q->rq; |
| |
| if (rl->count[rw] < queue_congestion_off_threshold(q)) |
| blk_clear_queue_congested(q, rw); |
| |
| if (rl->count[rw] + 1 <= q->nr_requests) { |
| if (waitqueue_active(&rl->wait[rw])) |
| wake_up(&rl->wait[rw]); |
| |
| blk_clear_queue_full(q, rw); |
| } |
| } |
| |
| /* |
| * 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_queue *q, int rw, int priv) |
| { |
| struct request_list *rl = &q->rq; |
| |
| rl->count[rw]--; |
| if (priv) |
| rl->elvpriv--; |
| |
| __freed_request(q, rw); |
| |
| if (unlikely(rl->starved[rw ^ 1])) |
| __freed_request(q, rw ^ 1); |
| } |
| |
| #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) |
| /* |
| * Get a free request, queue_lock must be held. |
| * Returns NULL on failure, with queue_lock held. |
| * Returns !NULL on success, with queue_lock *not held*. |
| */ |
| static struct request *get_request(struct request_queue *q, int rw_flags, |
| struct bio *bio, gfp_t gfp_mask) |
| { |
| struct request *rq = NULL; |
| struct request_list *rl = &q->rq; |
| struct io_context *ioc = NULL; |
| const int rw = rw_flags & 0x01; |
| int may_queue, priv; |
| |
| may_queue = elv_may_queue(q, rw_flags); |
| if (may_queue == ELV_MQUEUE_NO) |
| goto rq_starved; |
| |
| if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) { |
| if (rl->count[rw]+1 >= q->nr_requests) { |
| ioc = current_io_context(GFP_ATOMIC, q->node); |
| /* |
| * 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_queue_full(q, rw)) { |
| ioc_set_batching(q, ioc); |
| blk_set_queue_full(q, rw); |
| } 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 |
| */ |
| goto out; |
| } |
| } |
| } |
| blk_set_queue_congested(q, rw); |
| } |
| |
| /* |
| * 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[rw] >= (3 * q->nr_requests / 2)) |
| goto out; |
| |
| rl->count[rw]++; |
| rl->starved[rw] = 0; |
| |
| priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
| if (priv) |
| rl->elvpriv++; |
| |
| spin_unlock_irq(q->queue_lock); |
| |
| rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); |
| if (unlikely(!rq)) { |
| /* |
| * 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(q, rw, priv); |
| |
| /* |
| * 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[rw] == 0)) |
| rl->starved[rw] = 1; |
| |
| goto 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--; |
| |
| blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ); |
| out: |
| return rq; |
| } |
| |
| /* |
| * No available requests for this queue, unplug the device and wait for some |
| * requests to become available. |
| * |
| * Called with q->queue_lock held, and returns with it unlocked. |
| */ |
| static struct request *get_request_wait(struct request_queue *q, int rw_flags, |
| struct bio *bio) |
| { |
| const int rw = rw_flags & 0x01; |
| struct request *rq; |
| |
| rq = get_request(q, rw_flags, bio, GFP_NOIO); |
| while (!rq) { |
| DEFINE_WAIT(wait); |
| struct io_context *ioc; |
| struct request_list *rl = &q->rq; |
| |
| prepare_to_wait_exclusive(&rl->wait[rw], &wait, |
| TASK_UNINTERRUPTIBLE); |
| |
| blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ); |
| |
| __generic_unplug_device(q); |
| 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 = current_io_context(GFP_NOIO, q->node); |
| ioc_set_batching(q, ioc); |
| |
| spin_lock_irq(q->queue_lock); |
| finish_wait(&rl->wait[rw], &wait); |
| |
| rq = get_request(q, rw_flags, bio, GFP_NOIO); |
| }; |
| |
| return rq; |
| } |
| |
| struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) |
| { |
| struct request *rq; |
| |
| BUG_ON(rw != READ && rw != WRITE); |
| |
| spin_lock_irq(q->queue_lock); |
| if (gfp_mask & __GFP_WAIT) { |
| rq = get_request_wait(q, rw, NULL); |
| } else { |
| rq = get_request(q, rw, NULL, gfp_mask); |
| if (!rq) |
| spin_unlock_irq(q->queue_lock); |
| } |
| /* q->queue_lock is unlocked at this point */ |
| |
| return rq; |
| } |
| EXPORT_SYMBOL(blk_get_request); |
| |
| /** |
| * blk_start_queueing - initiate dispatch of requests to device |
| * @q: request queue to kick into gear |
| * |
| * This is basically a helper to remove the need to know whether a queue |
| * is plugged or not if someone just wants to initiate dispatch of requests |
| * for this queue. |
| * |
| * The queue lock must be held with interrupts disabled. |
| */ |
| void blk_start_queueing(struct request_queue *q) |
| { |
| if (!blk_queue_plugged(q)) |
| q->request_fn(q); |
| else |
| __generic_unplug_device(q); |
| } |
| EXPORT_SYMBOL(blk_start_queueing); |
| |
| /** |
| * 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); |
| blk_add_trace_rq(q, rq, BLK_TA_REQUEUE); |
| |
| if (blk_rq_tagged(rq)) |
| blk_queue_end_tag(q, rq); |
| |
| elv_requeue_request(q, rq); |
| } |
| EXPORT_SYMBOL(blk_requeue_request); |
| |
| /** |
| * blk_insert_request - insert a special request into a request queue |
| * @q: request queue where request should be inserted |
| * @rq: request to be inserted |
| * @at_head: insert request at head or tail of queue |
| * @data: private data |
| * |
| * Description: |
| * Many block devices need to execute commands asynchronously, so they don't |
| * block the whole kernel from preemption during request execution. This is |
| * accomplished normally by inserting aritficial requests tagged as |
| * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them |
| * be scheduled for actual execution by the request queue. |
| * |
| * We have the option of inserting the head or the tail of the queue. |
| * Typically we use the tail for new ioctls and so forth. We use the head |
| * of the queue for things like a QUEUE_FULL message from a device, or a |
| * host that is unable to accept a particular command. |
| */ |
| void blk_insert_request(struct request_queue *q, struct request *rq, |
| int at_head, void *data) |
| { |
| int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
| unsigned long flags; |
| |
| /* |
| * tell I/O scheduler that this isn't a regular read/write (ie it |
| * must not attempt merges on this) and that it acts as a soft |
| * barrier |
| */ |
| rq->cmd_type = REQ_TYPE_SPECIAL; |
| rq->cmd_flags |= REQ_SOFTBARRIER; |
| |
| rq->special = data; |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| |
| /* |
| * If command is tagged, release the tag |
| */ |
| if (blk_rq_tagged(rq)) |
| blk_queue_end_tag(q, rq); |
| |
| drive_stat_acct(rq, 1); |
| __elv_add_request(q, rq, where, 0); |
| blk_start_queueing(q); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| EXPORT_SYMBOL(blk_insert_request); |
| |
| /* |
| * add-request adds a request to the linked list. |
| * queue lock is held and interrupts disabled, as we muck with the |
| * request queue list. |
| */ |
| static inline void add_request(struct request_queue *q, struct request *req) |
| { |
| drive_stat_acct(req, 1); |
| |
| /* |
| * elevator indicated where it wants this request to be |
| * inserted at elevator_merge time |
| */ |
| __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); |
| } |
| |
| static void part_round_stats_single(int cpu, struct hd_struct *part, |
| unsigned long now) |
| { |
| if (now == part->stamp) |
| return; |
| |
| if (part->in_flight) { |
| __part_stat_add(cpu, part, time_in_queue, |
| part->in_flight * (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. |
| * |
| * 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); |
| |
| /* |
| * queue lock must be held |
| */ |
| void __blk_put_request(struct request_queue *q, struct request *req) |
| { |
| if (unlikely(!q)) |
| return; |
| if (unlikely(--req->ref_count)) |
| return; |
| |
| elv_completed_request(q, req); |
| |
| /* |
| * 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) { |
| int rw = rq_data_dir(req); |
| int priv = req->cmd_flags & REQ_ELVPRIV; |
| |
| BUG_ON(!list_empty(&req->queuelist)); |
| BUG_ON(!hlist_unhashed(&req->hash)); |
| |
| blk_free_request(q, req); |
| freed_request(q, rw, priv); |
| } |
| } |
| EXPORT_SYMBOL_GPL(__blk_put_request); |
| |
| void blk_put_request(struct request *req) |
| { |
| unsigned long flags; |
| struct request_queue *q = req->q; |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| __blk_put_request(q, req); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| EXPORT_SYMBOL(blk_put_request); |
| |
| void init_request_from_bio(struct request *req, struct bio *bio) |
| { |
| req->cpu = bio->bi_comp_cpu; |
| req->cmd_type = REQ_TYPE_FS; |
| |
| /* |
| * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST) |
| */ |
| if (bio_rw_ahead(bio) || bio_failfast(bio)) |
| req->cmd_flags |= REQ_FAILFAST; |
| |
| /* |
| * REQ_BARRIER implies no merging, but lets make it explicit |
| */ |
| if (unlikely(bio_discard(bio))) { |
| req->cmd_flags |= REQ_DISCARD; |
| if (bio_barrier(bio)) |
| req->cmd_flags |= REQ_SOFTBARRIER; |
| req->q->prepare_discard_fn(req->q, req); |
| } else if (unlikely(bio_barrier(bio))) |
| req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE); |
| |
| if (bio_sync(bio)) |
| req->cmd_flags |= REQ_RW_SYNC; |
| if (bio_rw_meta(bio)) |
| req->cmd_flags |= REQ_RW_META; |
| |
| req->errors = 0; |
| req->hard_sector = req->sector = bio->bi_sector; |
| req->ioprio = bio_prio(bio); |
| req->start_time = jiffies; |
| blk_rq_bio_prep(req->q, req, bio); |
| } |
| |
| static int __make_request(struct request_queue *q, struct bio *bio) |
| { |
| struct request *req; |
| int el_ret, nr_sectors, barrier, discard, err; |
| const unsigned short prio = bio_prio(bio); |
| const int sync = bio_sync(bio); |
| int rw_flags; |
| |
| nr_sectors = bio_sectors(bio); |
| |
| /* |
| * 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); |
| |
| barrier = bio_barrier(bio); |
| if (unlikely(barrier) && bio_has_data(bio) && |
| (q->next_ordered == QUEUE_ORDERED_NONE)) { |
| err = -EOPNOTSUPP; |
| goto end_io; |
| } |
| |
| discard = bio_discard(bio); |
| if (unlikely(discard) && !q->prepare_discard_fn) { |
| err = -EOPNOTSUPP; |
| goto end_io; |
| } |
| |
| spin_lock_irq(q->queue_lock); |
| |
| if (unlikely(barrier) || elv_queue_empty(q)) |
| goto get_rq; |
| |
| el_ret = elv_merge(q, &req, bio); |
| switch (el_ret) { |
| case ELEVATOR_BACK_MERGE: |
| BUG_ON(!rq_mergeable(req)); |
| |
| if (!ll_back_merge_fn(q, req, bio)) |
| break; |
| |
| blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE); |
| |
| req->biotail->bi_next = bio; |
| req->biotail = bio; |
| req->nr_sectors = req->hard_nr_sectors += nr_sectors; |
| req->ioprio = ioprio_best(req->ioprio, prio); |
| if (!blk_rq_cpu_valid(req)) |
| req->cpu = bio->bi_comp_cpu; |
| drive_stat_acct(req, 0); |
| if (!attempt_back_merge(q, req)) |
| elv_merged_request(q, req, el_ret); |
| goto out; |
| |
| case ELEVATOR_FRONT_MERGE: |
| BUG_ON(!rq_mergeable(req)); |
| |
| if (!ll_front_merge_fn(q, req, bio)) |
| break; |
| |
| blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE); |
| |
| bio->bi_next = req->bio; |
| req->bio = bio; |
| |
| /* |
| * may not be valid. if the low level driver said |
| * it didn't need a bounce buffer then it better |
| * not touch req->buffer either... |
| */ |
| req->buffer = bio_data(bio); |
| req->current_nr_sectors = bio_cur_sectors(bio); |
| req->hard_cur_sectors = req->current_nr_sectors; |
| req->sector = req->hard_sector = bio->bi_sector; |
| req->nr_sectors = req->hard_nr_sectors += nr_sectors; |
| req->ioprio = ioprio_best(req->ioprio, prio); |
| if (!blk_rq_cpu_valid(req)) |
| req->cpu = bio->bi_comp_cpu; |
| drive_stat_acct(req, 0); |
| if (!attempt_front_merge(q, req)) |
| elv_merged_request(q, req, el_ret); |
| goto out; |
| |
| /* ELV_NO_MERGE: elevator says don't/can't merge. */ |
| default: |
| ; |
| } |
| |
| get_rq: |
| /* |
| * 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_RW_SYNC; |
| |
| /* |
| * Grab a free request. This is might sleep but can not fail. |
| * Returns with the queue unlocked. |
| */ |
| req = get_request_wait(q, rw_flags, bio); |
| |
| /* |
| * 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); |
| |
| spin_lock_irq(q->queue_lock); |
| if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || |
| bio_flagged(bio, BIO_CPU_AFFINE)) |
| req->cpu = blk_cpu_to_group(smp_processor_id()); |
| if (elv_queue_empty(q)) |
| blk_plug_device(q); |
| add_request(q, req); |
| out: |
| if (sync) |
| __generic_unplug_device(q); |
| spin_unlock_irq(q->queue_lock); |
| return 0; |
| |
| end_io: |
| bio_endio(bio, err); |
| return 0; |
| } |
| |
| /* |
| * 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_sector += p->start_sect; |
| bio->bi_bdev = bdev->bd_contains; |
| |
| blk_add_trace_remap(bdev_get_queue(bio->bi_bdev), bio, |
| bdev->bd_dev, bio->bi_sector, |
| bio->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->bi_sector + bio_sectors(bio), |
| (long long)(bio->bi_bdev->bd_inode->i_size >> 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 int should_fail_request(struct bio *bio) |
| { |
| struct hd_struct *part = bio->bi_bdev->bd_part; |
| |
| if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail) |
| return should_fail(&fail_make_request, bio->bi_size); |
| |
| return 0; |
| } |
| |
| static int __init fail_make_request_debugfs(void) |
| { |
| return init_fault_attr_dentries(&fail_make_request, |
| "fail_make_request"); |
| } |
| |
| late_initcall(fail_make_request_debugfs); |
| |
| #else /* CONFIG_FAIL_MAKE_REQUEST */ |
| |
| static inline int should_fail_request(struct bio *bio) |
| { |
| return 0; |
| } |
| |
| #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 = bio->bi_bdev->bd_inode->i_size >> 9; |
| if (maxsector) { |
| sector_t sector = bio->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; |
| } |
| |
| /** |
| * 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 change bi_dev and |
| * bi_sector for remaps as it sees fit. So the values of these fields |
| * should NOT be depended on after the call to generic_make_request. |
| */ |
| static inline void __generic_make_request(struct bio *bio) |
| { |
| struct request_queue *q; |
| sector_t old_sector; |
| int ret, nr_sectors = bio_sectors(bio); |
| dev_t old_dev; |
| int err = -EIO; |
| |
| might_sleep(); |
| |
| if (bio_check_eod(bio, nr_sectors)) |
| goto end_io; |
| |
| /* |
| * Resolve the mapping until finished. (drivers are |
| * still free to implement/resolve their own stacking |
| * by explicitly returning 0) |
| * |
| * NOTE: we don't repeat the blk_size check for each new device. |
| * Stacking drivers are expected to know what they are doing. |
| */ |
| old_sector = -1; |
| old_dev = 0; |
| do { |
| char b[BDEVNAME_SIZE]; |
| |
| q = bdev_get_queue(bio->bi_bdev); |
| if (!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_sector); |
| end_io: |
| bio_endio(bio, err); |
| break; |
| } |
| |
| if (unlikely(nr_sectors > q->max_hw_sectors)) { |
| printk(KERN_ERR "bio too big device %s (%u > %u)\n", |
| bdevname(bio->bi_bdev, b), |
| bio_sectors(bio), |
| q->max_hw_sectors); |
| goto end_io; |
| } |
| |
| if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
| goto end_io; |
| |
| if (should_fail_request(bio)) |
| 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_integrity_enabled(bio) && bio_integrity_prep(bio)) |
| goto end_io; |
| |
| if (old_sector != -1) |
| blk_add_trace_remap(q, bio, old_dev, bio->bi_sector, |
| old_sector); |
| |
| blk_add_trace_bio(q, bio, BLK_TA_QUEUE); |
| |
| old_sector = bio->bi_sector; |
| old_dev = bio->bi_bdev->bd_dev; |
| |
| if (bio_check_eod(bio, nr_sectors)) |
| goto end_io; |
| if ((bio_empty_barrier(bio) && !q->prepare_flush_fn) || |
| (bio_discard(bio) && !q->prepare_discard_fn)) { |
| err = -EOPNOTSUPP; |
| goto end_io; |
| } |
| |
| ret = q->make_request_fn(q, bio); |
| } while (ret); |
| } |
| |
| /* |
| * 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,tail} to keep a list of requests |
| * submited by a make_request_fn function. |
| * current->bio_tail 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 |
| */ |
| void generic_make_request(struct bio *bio) |
| { |
| if (current->bio_tail) { |
| /* make_request is active */ |
| *(current->bio_tail) = bio; |
| bio->bi_next = NULL; |
| current->bio_tail = &bio->bi_next; |
| 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 the next (which is NULL) and bio_tail |
| * to &bio_list, thus initialising the bio_list of new bios to be |
| * added. __generic_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 fixup bio_list and |
| * bio_tail or bi_next, and call into __generic_make_request again. |
| * |
| * The loop was structured like this to make only one call to |
| * __generic_make_request (which is important as it is large and |
| * inlined) and to keep the structure simple. |
| */ |
| BUG_ON(bio->bi_next); |
| do { |
| current->bio_list = bio->bi_next; |
| if (bio->bi_next == NULL) |
| current->bio_tail = ¤t->bio_list; |
| else |
| bio->bi_next = NULL; |
| __generic_make_request(bio); |
| bio = current->bio_list; |
| } while (bio); |
| current->bio_tail = 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) |
| { |
| int count = bio_sectors(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)) { |
| if (rw & WRITE) { |
| count_vm_events(PGPGOUT, count); |
| } else { |
| task_io_account_read(bio->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\n", |
| current->comm, task_pid_nr(current), |
| (rw & WRITE) ? "WRITE" : "READ", |
| (unsigned long long)bio->bi_sector, |
| bdevname(bio->bi_bdev, b)); |
| } |
| } |
| |
| 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 fuction. |
| * 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 agaist |
| * 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->nr_sectors > q->max_sectors || |
| rq->data_len > q->max_hw_sectors << 9) { |
| 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 > q->max_phys_segments || |
| rq->nr_phys_segments > q->max_hw_segments) { |
| 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; |
| |
| if (blk_rq_check_limits(q, rq)) |
| return -EIO; |
| |
| #ifdef CONFIG_FAIL_MAKE_REQUEST |
| if (rq->rq_disk && rq->rq_disk->part0.make_it_fail && |
| should_fail(&fail_make_request, blk_rq_bytes(rq))) |
| return -EIO; |
| #endif |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| |
| /* |
| * Submitting request must be dequeued before calling this function |
| * because it will be linked to another request_queue |
| */ |
| BUG_ON(blk_queued_rq(rq)); |
| |
| drive_stat_acct(rq, 1); |
| __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); |
| |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(blk_insert_cloned_request); |
| |
| /** |
| * __end_that_request_first - end I/O on a request |
| * @req: 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 @req, and sets it up |
| * for the next range of segments (if any) in the cluster. |
| * |
| * Return: |
| * %0 - we are done with this request, call end_that_request_last() |
| * %1 - still buffers pending for this request |
| **/ |
| static int __end_that_request_first(struct request *req, int error, |
| int nr_bytes) |
| { |
| int total_bytes, bio_nbytes, next_idx = 0; |
| struct bio *bio; |
| |
| blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE); |
| |
| /* |
| * for a REQ_TYPE_BLOCK_PC request, we want to carry any eventual |
| * sense key with us all the way through |
| */ |
| if (!blk_pc_request(req)) |
| req->errors = 0; |
| |
| if (error && (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))) { |
| printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n", |
| req->rq_disk ? req->rq_disk->disk_name : "?", |
| (unsigned long long)req->sector); |
| } |
| |
| if (blk_fs_request(req) && req->rq_disk) { |
| const int rw = rq_data_dir(req); |
| struct hd_struct *part; |
| int cpu; |
| |
| cpu = part_stat_lock(); |
| part = disk_map_sector_rcu(req->rq_disk, req->sector); |
| part_stat_add(cpu, part, sectors[rw], nr_bytes >> 9); |
| part_stat_unlock(); |
| } |
| |
| total_bytes = bio_nbytes = 0; |
| while ((bio = req->bio) != NULL) { |
| int nbytes; |
| |
| /* |
| * For an empty barrier request, the low level driver must |
| * store a potential error location in ->sector. We pass |
| * that back up in ->bi_sector. |
| */ |
| if (blk_empty_barrier(req)) |
| bio->bi_sector = req->sector; |
| |
| if (nr_bytes >= bio->bi_size) { |
| req->bio = bio->bi_next; |
| nbytes = bio->bi_size; |
| req_bio_endio(req, bio, nbytes, error); |
| next_idx = 0; |
| bio_nbytes = 0; |
| } else { |
| int idx = bio->bi_idx + next_idx; |
| |
| if (unlikely(bio->bi_idx >= bio->bi_vcnt)) { |
| blk_dump_rq_flags(req, "__end_that"); |
| printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", |
| __func__, bio->bi_idx, bio->bi_vcnt); |
| break; |
| } |
| |
| nbytes = bio_iovec_idx(bio, idx)->bv_len; |
| BIO_BUG_ON(nbytes > bio->bi_size); |
| |
| /* |
| * not a complete bvec done |
| */ |
| if (unlikely(nbytes > nr_bytes)) { |
| bio_nbytes += nr_bytes; |
| total_bytes += nr_bytes; |
| break; |
| } |
| |
| /* |
| * advance to the next vector |
| */ |
| next_idx++; |
| bio_nbytes += nbytes; |
| } |
| |
| total_bytes += nbytes; |
| nr_bytes -= nbytes; |
| |
| bio = req->bio; |
| if (bio) { |
| /* |
| * end more in this run, or just return 'not-done' |
| */ |
| if (unlikely(nr_bytes <= 0)) |
| break; |
| } |
| } |
| |
| /* |
| * completely done |
| */ |
| if (!req->bio) |
| return 0; |
| |
| /* |
| * if the request wasn't completed, update state |
| */ |
| if (bio_nbytes) { |
| req_bio_endio(req, bio, bio_nbytes, error); |
| bio->bi_idx += next_idx; |
| bio_iovec(bio)->bv_offset += nr_bytes; |
| bio_iovec(bio)->bv_len -= nr_bytes; |
| } |
| |
| blk_recalc_rq_sectors(req, total_bytes >> 9); |
| blk_recalc_rq_segments(req); |
| return 1; |
| } |
| |
| /* |
| * queue lock must be held |
| */ |
| static void end_that_request_last(struct request *req, int error) |
| { |
| struct gendisk *disk = req->rq_disk; |
| |
| blk_delete_timer(req); |
| |
| if (blk_rq_tagged(req)) |
| blk_queue_end_tag(req->q, req); |
| |
| if (blk_queued_rq(req)) |
| blkdev_dequeue_request(req); |
| |
| if (unlikely(laptop_mode) && blk_fs_request(req)) |
| laptop_io_completion(); |
| |
| /* |
| * Account IO completion. bar_rq isn't accounted as a normal |
| * IO on queueing nor completion. Accounting the containing |
| * request is enough. |
| */ |
| if (disk && blk_fs_request(req) && req != &req->q->bar_rq) { |
| 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 = disk_map_sector_rcu(disk, req->sector); |
| |
| 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); |
| |
| part_stat_unlock(); |
| } |
| |
| 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); |
| } |
| } |
| |
| static inline void __end_request(struct request *rq, int uptodate, |
| unsigned int nr_bytes) |
| { |
| int error = 0; |
| |
| if (uptodate <= 0) |
| error = uptodate ? uptodate : -EIO; |
| |
| __blk_end_request(rq, error, nr_bytes); |
| } |
| |
| /** |
| * blk_rq_bytes - Returns bytes left to complete in the entire request |
| * @rq: the request being processed |
| **/ |
| unsigned int blk_rq_bytes(struct request *rq) |
| { |
| if (blk_fs_request(rq)) |
| return rq->hard_nr_sectors << 9; |
| |
| return rq->data_len; |
| } |
| EXPORT_SYMBOL_GPL(blk_rq_bytes); |
| |
| /** |
| * blk_rq_cur_bytes - Returns bytes left to complete in the current segment |
| * @rq: the request being processed |
| **/ |
| unsigned int blk_rq_cur_bytes(struct request *rq) |
| { |
| if (blk_fs_request(rq)) |
| return rq->current_nr_sectors << 9; |
| |
| if (rq->bio) |
| return rq->bio->bi_size; |
| |
| return rq->data_len; |
| } |
| EXPORT_SYMBOL_GPL(blk_rq_cur_bytes); |
| |
| /** |
| * end_queued_request - end all I/O on a queued request |
| * @rq: the request being processed |
| * @uptodate: error value or %0/%1 uptodate flag |
| * |
| * Description: |
| * Ends all I/O on a request, and removes it from the block layer queues. |
| * Not suitable for normal I/O completion, unless the driver still has |
| * the request attached to the block layer. |
| * |
| **/ |
| void end_queued_request(struct request *rq, int uptodate) |
| { |
| __end_request(rq, uptodate, blk_rq_bytes(rq)); |
| } |
| EXPORT_SYMBOL(end_queued_request); |
| |
| /** |
| * end_dequeued_request - end all I/O on a dequeued request |
| * @rq: the request being processed |
| * @uptodate: error value or %0/%1 uptodate flag |
| * |
| * Description: |
| * Ends all I/O on a request. The request must already have been |
| * dequeued using blkdev_dequeue_request(), as is normally the case |
| * for most drivers. |
| * |
| **/ |
| void end_dequeued_request(struct request *rq, int uptodate) |
| { |
| __end_request(rq, uptodate, blk_rq_bytes(rq)); |
| } |
| EXPORT_SYMBOL(end_dequeued_request); |
| |
| |
| /** |
| * end_request - end I/O on the current segment of the request |
| * @req: the request being processed |
| * @uptodate: error value or %0/%1 uptodate flag |
| * |
| * Description: |
| * Ends I/O on the current segment of a request. If that is the only |
| * remaining segment, the request is also completed and freed. |
| * |
| * This is a remnant of how older block drivers handled I/O completions. |
| * Modern drivers typically end I/O on the full request in one go, unless |
| * they have a residual value to account for. For that case this function |
| * isn't really useful, unless the residual just happens to be the |
| * full current segment. In other words, don't use this function in new |
| * code. Use blk_end_request() or __blk_end_request() to end partial parts |
| * of a request, or end_dequeued_request() and end_queued_request() to |
| * completely end IO on a dequeued/queued request. |
| * |
| **/ |
| void end_request(struct request *req, int uptodate) |
| { |
| __end_request(req, uptodate, req->hard_cur_sectors << 9); |
| } |
| EXPORT_SYMBOL(end_request); |
| |
| static int end_that_request_data(struct request *rq, int error, |
| unsigned int nr_bytes, unsigned int bidi_bytes) |
| { |
| if (rq->bio) { |
| if (__end_that_request_first(rq, error, nr_bytes)) |
| return 1; |
| |
| /* Bidi request must be completed as a whole */ |
| if (blk_bidi_rq(rq) && |
| __end_that_request_first(rq->next_rq, error, bidi_bytes)) |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * blk_end_io - Generic end_io function to complete a request. |
| * @rq: the request being processed |
| * @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 |
| * @drv_callback: function called between completion of bios in the request |
| * and completion of the request. |
| * If the callback returns non %0, this helper returns without |
| * completion of the request. |
| * |
| * Description: |
| * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. |
| * If @rq has leftover, sets it up for the next range of segments. |
| * |
| * Return: |
| * %0 - we are done with this request |
| * %1 - this request is not freed yet, it still has pending buffers. |
| **/ |
| static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes, |
| unsigned int bidi_bytes, |
| int (drv_callback)(struct request *)) |
| { |
| struct request_queue *q = rq->q; |
| unsigned long flags = 0UL; |
| |
| if (end_that_request_data(rq, error, nr_bytes, bidi_bytes)) |
| return 1; |
| |
| /* Special feature for tricky drivers */ |
| if (drv_callback && drv_callback(rq)) |
| return 1; |
| |
| add_disk_randomness(rq->rq_disk); |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| end_that_request_last(rq, error); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| |
| return 0; |
| } |
| |
| /** |
| * 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: |
| * %0 - we are done with this request |
| * %1 - still buffers pending for this request |
| **/ |
| int blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
| { |
| return blk_end_io(rq, error, nr_bytes, 0, NULL); |
| } |
| EXPORT_SYMBOL_GPL(blk_end_request); |
| |
| /** |
| * __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: |
| * %0 - we are done with this request |
| * %1 - still buffers pending for this request |
| **/ |
| int __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
| { |
| if (rq->bio && __end_that_request_first(rq, error, nr_bytes)) |
| return 1; |
| |
| add_disk_randomness(rq->rq_disk); |
| |
| end_that_request_last(rq, error); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(__blk_end_request); |
| |
| /** |
| * blk_end_bidi_request - Helper function for drivers to complete bidi request. |
| * @rq: the bidi request being processed |
| * @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. |
| * |
| * Return: |
| * %0 - we are done with this request |
| * %1 - still buffers pending for this request |
| **/ |
| int blk_end_bidi_request(struct request *rq, int error, unsigned int nr_bytes, |
| unsigned int bidi_bytes) |
| { |
| return blk_end_io(rq, error, nr_bytes, bidi_bytes, NULL); |
| } |
| EXPORT_SYMBOL_GPL(blk_end_bidi_request); |
| |
| /** |
| * blk_update_request - Special helper function for request stacking drivers |
| * @rq: the request being processed |
| * @error: %0 for success, < %0 for error |
| * @nr_bytes: number of bytes to complete @rq |
| * |
| * Description: |
| * Ends I/O on a number of bytes attached to @rq, but doesn't complete |
| * the request structure even if @rq doesn't have leftover. |
| * If @rq 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. |
| */ |
| void blk_update_request(struct request *rq, int error, unsigned int nr_bytes) |
| { |
| if (!end_that_request_data(rq, error, nr_bytes, 0)) { |
| /* |
| * These members are not updated in end_that_request_data() |
| * when all bios are completed. |
| * Update them so that the request stacking driver can find |
| * how many bytes remain in the request later. |
| */ |
| rq->nr_sectors = rq->hard_nr_sectors = 0; |
| rq->current_nr_sectors = rq->hard_cur_sectors = 0; |
| } |
| } |
| EXPORT_SYMBOL_GPL(blk_update_request); |
| |
| /** |
| * blk_end_request_callback - Special helper function for tricky drivers |
| * @rq: the request being processed |
| * @error: %0 for success, < %0 for error |
| * @nr_bytes: number of bytes to complete |
| * @drv_callback: function called between completion of bios in the request |
| * and completion of the request. |
| * If the callback returns non %0, this helper returns without |
| * completion of the request. |
| * |
| * 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. |
| * |
| * This special helper function is used only for existing tricky drivers. |
| * (e.g. cdrom_newpc_intr() of ide-cd) |
| * This interface will be removed when such drivers are rewritten. |
| * Don't use this interface in other places anymore. |
| * |
| * Return: |
| * %0 - we are done with this request |
| * %1 - this request is not freed yet. |
| * this request still has pending buffers or |
| * the driver doesn't want to finish this request yet. |
| **/ |
| int blk_end_request_callback(struct request *rq, int error, |
| unsigned int nr_bytes, |
| int (drv_callback)(struct request *)) |
| { |
| return blk_end_io(rq, error, nr_bytes, 0, drv_callback); |
| } |
| EXPORT_SYMBOL_GPL(blk_end_request_callback); |
| |
| 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, and |
| we want BIO_RW_AHEAD (bit 1) to imply REQ_FAILFAST (bit 1). */ |
| rq->cmd_flags |= (bio->bi_rw & 3); |
| |
| if (bio_has_data(bio)) { |
| rq->nr_phys_segments = bio_phys_segments(q, bio); |
| rq->buffer = bio_data(bio); |
| } |
| rq->current_nr_sectors = bio_cur_sectors(bio); |
| rq->hard_cur_sectors = rq->current_nr_sectors; |
| rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio); |
| rq->data_len = bio->bi_size; |
| |
| rq->bio = rq->biotail = bio; |
| |
| if (bio->bi_bdev) |
| rq->rq_disk = bio->bi_bdev->bd_disk; |
| } |
| |
| int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) |
| { |
| return queue_work(kblockd_workqueue, work); |
| } |
| EXPORT_SYMBOL(kblockd_schedule_work); |
| |
| void kblockd_flush_work(struct work_struct *work) |
| { |
| cancel_work_sync(work); |
| } |
| EXPORT_SYMBOL(kblockd_flush_work); |
| |
| int __init blk_dev_init(void) |
| { |
| kblockd_workqueue = create_workqueue("kblockd"); |
| 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; |
| } |
| |