/* * 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 <trace/block.h> #include "blk.h" DEFINE_TRACE(block_plug); DEFINE_TRACE(block_unplug_io); DEFINE_TRACE(block_unplug_timer); DEFINE_TRACE(block_getrq); DEFINE_TRACE(block_sleeprq); DEFINE_TRACE(block_rq_requeue); DEFINE_TRACE(block_bio_backmerge); DEFINE_TRACE(block_bio_frontmerge); DEFINE_TRACE(block_bio_queue); DEFINE_TRACE(block_rq_complete); DEFINE_TRACE(block_remap); /* Also used in drivers/md/dm.c */ EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap); 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); trace_block_plug(q); } } 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); } /** * 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); trace_block_unplug_io(q); q->unplug_fn(q); } void blk_unplug_timeout(unsigned long data) { struct request_queue *q = (struct request_queue *)data; trace_block_unplug_timer(q); 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) { trace_block_unplug_io(q); q->unplug_fn(q); } } EXPORT_SYMBOL(blk_unplug); static void blk_invoke_request_fn(struct request_queue *q) { if (unlikely(blk_queue_stopped(q))) return; /* * 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 * * 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) { 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 * * 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. Also * See @blk_start_queueing. * */ 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); INIT_WORK(&q->unplug_work, blk_unplug_work); 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 | 1 << QUEUE_FLAG_STACKABLE); q->queue_lock = lock; blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK); 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--; trace_block_getrq(q, bio, rw); 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); trace_block_sleeprq(q, bio, rw); __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. Should be used to start queueing on a device outside * of ->request_fn() context. Also see @blk_run_queue. * * The queue lock must be held with interrupts disabled. */ void blk_start_queueing(struct request_queue *q) { if (!blk_queue_plugged(q)) { if (unlikely(blk_queue_stopped(q))) return; 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); trace_block_rq_requeue(q, rq); 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. * @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); /* * 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)) req->cmd_flags |= (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER); if (bio_failfast_dev(bio)) req->cmd_flags |= REQ_FAILFAST_DEV; if (bio_failfast_transport(bio)) req->cmd_flags |= REQ_FAILFAST_TRANSPORT; if (bio_failfast_driver(bio)) req->cmd_flags |= REQ_FAILFAST_DRIVER; /* * 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; trace_block_bio_backmerge(q, bio); 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; trace_block_bio_frontmerge(q, bio); 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; trace_block_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) trace_block_remap(q, bio, old_dev, bio->bi_sector, old_sector); trace_block_bio_queue(q, bio); 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); /** * blkdev_dequeue_request - dequeue request and start timeout timer * @req: request to dequeue * * 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 elv_dequeue_request(). */ void blkdev_dequeue_request(struct request *req) { elv_dequeue_request(req->q, req); /* * We are now handing the request to the hardware, add the * timeout handler. */ blk_add_timer(req); } EXPORT_SYMBOL(blkdev_dequeue_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; trace_block_rq_complete(req->q, req); /* * 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; if (blk_rq_tagged(req)) blk_queue_end_tag(req->q, req); if (blk_queued_rq(req)) elv_dequeue_request(req->q, req); if (unlikely(laptop_mode) && blk_fs_request(req)) laptop_io_completion(); blk_delete_timer(req); /* * 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); } } /** * 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_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 a request. **/ void end_request(struct request *req, int uptodate) { int error = 0; if (uptodate <= 0) error = uptodate ? uptodate : -EIO; __blk_end_request(req, error, 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; } /** * 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); 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; }