| /* |
| * 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/fault-inject.h> |
| #include <linux/list_sort.h> |
| #include <linux/delay.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/block.h> |
| |
| #include "blk.h" |
| |
| EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); |
| EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); |
| EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); |
| |
| /* |
| * 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_do_io_stat(rq)) |
| return; |
| |
| cpu = part_stat_lock(); |
| |
| if (!new_io) { |
| part = rq->part; |
| part_stat_inc(cpu, part, merges[rw]); |
| } else { |
| part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); |
| if (!hd_struct_try_get(part)) { |
| /* |
| * The partition is already being removed, |
| * the request will be accounted on the disk only |
| * |
| * We take a reference on disk->part0 although that |
| * partition will never be deleted, so we can treat |
| * it as any other partition. |
| */ |
| part = &rq->rq_disk->part0; |
| hd_struct_get(part); |
| } |
| part_round_stats(cpu, part); |
| part_inc_in_flight(part, rw); |
| rq->part = part; |
| } |
| |
| part_stat_unlock(); |
| } |
| |
| 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 = (sector_t) -1; |
| INIT_HLIST_NODE(&rq->hash); |
| RB_CLEAR_NODE(&rq->rb_node); |
| rq->cmd = rq->__cmd; |
| rq->cmd_len = BLK_MAX_CDB; |
| rq->tag = -1; |
| rq->ref_count = 1; |
| rq->start_time = jiffies; |
| set_start_time_ns(rq); |
| rq->part = NULL; |
| } |
| EXPORT_SYMBOL(blk_rq_init); |
| |
| static void req_bio_endio(struct request *rq, struct bio *bio, |
| unsigned int nbytes, int error) |
| { |
| if (error) |
| clear_bit(BIO_UPTODATE, &bio->bi_flags); |
| else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) |
| error = -EIO; |
| |
| if (unlikely(nbytes > bio->bi_size)) { |
| printk(KERN_ERR "%s: want %u bytes done, %u left\n", |
| __func__, nbytes, bio->bi_size); |
| nbytes = bio->bi_size; |
| } |
| |
| if (unlikely(rq->cmd_flags & REQ_QUIET)) |
| set_bit(BIO_QUIET, &bio->bi_flags); |
| |
| bio->bi_size -= nbytes; |
| bio->bi_sector += (nbytes >> 9); |
| |
| if (bio_integrity(bio)) |
| bio_integrity_advance(bio, nbytes); |
| |
| /* don't actually finish bio if it's part of flush sequence */ |
| if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ)) |
| bio_endio(bio, error); |
| } |
| |
| void blk_dump_rq_flags(struct request *rq, char *msg) |
| { |
| 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 %u/%u\n", |
| (unsigned long long)blk_rq_pos(rq), |
| blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); |
| printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n", |
| rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq)); |
| |
| if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { |
| printk(KERN_INFO " cdb: "); |
| for (bit = 0; bit < BLK_MAX_CDB; bit++) |
| printk("%02x ", rq->cmd[bit]); |
| printk("\n"); |
| } |
| } |
| EXPORT_SYMBOL(blk_dump_rq_flags); |
| |
| static void blk_delay_work(struct work_struct *work) |
| { |
| struct request_queue *q; |
| |
| q = container_of(work, struct request_queue, delay_work.work); |
| spin_lock_irq(q->queue_lock); |
| __blk_run_queue(q); |
| spin_unlock_irq(q->queue_lock); |
| } |
| |
| /** |
| * blk_delay_queue - restart queueing after defined interval |
| * @q: The &struct request_queue in question |
| * @msecs: Delay in msecs |
| * |
| * Description: |
| * Sometimes queueing needs to be postponed for a little while, to allow |
| * resources to come back. This function will make sure that queueing is |
| * restarted around the specified time. |
| */ |
| void blk_delay_queue(struct request_queue *q, unsigned long msecs) |
| { |
| queue_delayed_work(kblockd_workqueue, &q->delay_work, |
| msecs_to_jiffies(msecs)); |
| } |
| EXPORT_SYMBOL(blk_delay_queue); |
| |
| /** |
| * blk_start_queue - restart a previously stopped queue |
| * @q: The &struct request_queue in question |
| * |
| * Description: |
| * blk_start_queue() will clear the stop flag on the queue, and call |
| * the request_fn for the queue if it was in a stopped state when |
| * entered. Also see blk_stop_queue(). Queue lock must be held. |
| **/ |
| void blk_start_queue(struct request_queue *q) |
| { |
| WARN_ON(!irqs_disabled()); |
| |
| queue_flag_clear(QUEUE_FLAG_STOPPED, q); |
| __blk_run_queue(q); |
| } |
| EXPORT_SYMBOL(blk_start_queue); |
| |
| /** |
| * blk_stop_queue - stop a queue |
| * @q: The &struct request_queue in question |
| * |
| * Description: |
| * The Linux block layer assumes that a block driver will consume all |
| * entries on the request queue when the request_fn strategy is called. |
| * Often this will not happen, because of hardware limitations (queue |
| * depth settings). If a device driver gets a 'queue full' response, |
| * or if it simply chooses not to queue more I/O at one point, it can |
| * call this function to prevent the request_fn from being called until |
| * the driver has signalled it's ready to go again. This happens by calling |
| * blk_start_queue() to restart queue operations. Queue lock must be held. |
| **/ |
| void blk_stop_queue(struct request_queue *q) |
| { |
| __cancel_delayed_work(&q->delay_work); |
| queue_flag_set(QUEUE_FLAG_STOPPED, q); |
| } |
| EXPORT_SYMBOL(blk_stop_queue); |
| |
| /** |
| * blk_sync_queue - cancel any pending callbacks on a queue |
| * @q: the queue |
| * |
| * Description: |
| * The block layer may perform asynchronous callback activity |
| * on a queue, such as calling the unplug function after a timeout. |
| * A block device may call blk_sync_queue to ensure that any |
| * such activity is cancelled, thus allowing it to release resources |
| * that the callbacks might use. The caller must already have made sure |
| * that its ->make_request_fn will not re-add plugging prior to calling |
| * this function. |
| * |
| * This function does not cancel any asynchronous activity arising |
| * out of elevator or throttling code. That would require elevaotor_exit() |
| * and blk_throtl_exit() to be called with queue lock initialized. |
| * |
| */ |
| void blk_sync_queue(struct request_queue *q) |
| { |
| del_timer_sync(&q->timeout); |
| cancel_delayed_work_sync(&q->delay_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) |
| { |
| if (unlikely(blk_queue_stopped(q))) |
| return; |
| |
| q->request_fn(q); |
| } |
| EXPORT_SYMBOL(__blk_run_queue); |
| |
| /** |
| * blk_run_queue_async - run a single device queue in workqueue context |
| * @q: The queue to run |
| * |
| * Description: |
| * Tells kblockd to perform the equivalent of @blk_run_queue on behalf |
| * of us. |
| */ |
| void blk_run_queue_async(struct request_queue *q) |
| { |
| if (likely(!blk_queue_stopped(q))) { |
| __cancel_delayed_work(&q->delay_work); |
| queue_delayed_work(kblockd_workqueue, &q->delay_work, 0); |
| } |
| } |
| EXPORT_SYMBOL(blk_run_queue_async); |
| |
| /** |
| * blk_run_queue - run a single device queue |
| * @q: The queue to run |
| * |
| * Description: |
| * Invoke request handling on this queue, if it has pending work to do. |
| * May be used to restart queueing when a request has completed. |
| */ |
| void blk_run_queue(struct request_queue *q) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| __blk_run_queue(q); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| EXPORT_SYMBOL(blk_run_queue); |
| |
| void blk_put_queue(struct request_queue *q) |
| { |
| kobject_put(&q->kobj); |
| } |
| EXPORT_SYMBOL(blk_put_queue); |
| |
| /** |
| * blk_drain_queue - drain requests from request_queue |
| * @q: queue to drain |
| * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV |
| * |
| * Drain requests from @q. If @drain_all is set, all requests are drained. |
| * If not, only ELVPRIV requests are drained. The caller is responsible |
| * for ensuring that no new requests which need to be drained are queued. |
| */ |
| void blk_drain_queue(struct request_queue *q, bool drain_all) |
| { |
| while (true) { |
| int nr_rqs; |
| |
| spin_lock_irq(q->queue_lock); |
| |
| elv_drain_elevator(q); |
| if (drain_all) |
| blk_throtl_drain(q); |
| |
| __blk_run_queue(q); |
| |
| if (drain_all) |
| nr_rqs = q->rq.count[0] + q->rq.count[1]; |
| else |
| nr_rqs = q->rq.elvpriv; |
| |
| spin_unlock_irq(q->queue_lock); |
| |
| if (!nr_rqs) |
| break; |
| msleep(10); |
| } |
| } |
| |
| /** |
| * blk_cleanup_queue - shutdown a request queue |
| * @q: request queue to shutdown |
| * |
| * Mark @q DEAD, drain all pending requests, destroy and put it. All |
| * future requests will be failed immediately with -ENODEV. |
| */ |
| void blk_cleanup_queue(struct request_queue *q) |
| { |
| spinlock_t *lock = q->queue_lock; |
| |
| /* mark @q DEAD, no new request or merges will be allowed afterwards */ |
| mutex_lock(&q->sysfs_lock); |
| queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); |
| |
| spin_lock_irq(lock); |
| queue_flag_set(QUEUE_FLAG_NOMERGES, q); |
| queue_flag_set(QUEUE_FLAG_NOXMERGES, q); |
| queue_flag_set(QUEUE_FLAG_DEAD, q); |
| |
| if (q->queue_lock != &q->__queue_lock) |
| q->queue_lock = &q->__queue_lock; |
| |
| spin_unlock_irq(lock); |
| mutex_unlock(&q->sysfs_lock); |
| |
| /* drain all requests queued before DEAD marking */ |
| blk_drain_queue(q, true); |
| |
| /* @q won't process any more request, flush async actions */ |
| del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); |
| blk_sync_queue(q); |
| |
| /* @q is and will stay empty, shutdown and put */ |
| 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; |
| |
| if (unlikely(rl->rq_pool)) |
| return 0; |
| |
| rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; |
| rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; |
| rl->elvpriv = 0; |
| init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); |
| init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); |
| |
| rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, 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.ra_pages = |
| (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; |
| q->backing_dev_info.state = 0; |
| q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; |
| q->backing_dev_info.name = "block"; |
| |
| err = bdi_init(&q->backing_dev_info); |
| if (err) { |
| kmem_cache_free(blk_requestq_cachep, q); |
| return NULL; |
| } |
| |
| if (blk_throtl_init(q)) { |
| kmem_cache_free(blk_requestq_cachep, q); |
| return NULL; |
| } |
| |
| setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, |
| laptop_mode_timer_fn, (unsigned long) q); |
| setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q); |
| INIT_LIST_HEAD(&q->timeout_list); |
| INIT_LIST_HEAD(&q->flush_queue[0]); |
| INIT_LIST_HEAD(&q->flush_queue[1]); |
| INIT_LIST_HEAD(&q->flush_data_in_flight); |
| INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); |
| |
| kobject_init(&q->kobj, &blk_queue_ktype); |
| |
| mutex_init(&q->sysfs_lock); |
| spin_lock_init(&q->__queue_lock); |
| |
| /* |
| * By default initialize queue_lock to internal lock and driver can |
| * override it later if need be. |
| */ |
| q->queue_lock = &q->__queue_lock; |
| |
| 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 *uninit_q, *q; |
| |
| uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id); |
| if (!uninit_q) |
| return NULL; |
| |
| q = blk_init_allocated_queue_node(uninit_q, rfn, lock, node_id); |
| if (!q) |
| blk_cleanup_queue(uninit_q); |
| |
| return q; |
| } |
| EXPORT_SYMBOL(blk_init_queue_node); |
| |
| struct request_queue * |
| blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn, |
| spinlock_t *lock) |
| { |
| return blk_init_allocated_queue_node(q, rfn, lock, -1); |
| } |
| EXPORT_SYMBOL(blk_init_allocated_queue); |
| |
| struct request_queue * |
| blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn, |
| spinlock_t *lock, int node_id) |
| { |
| if (!q) |
| return NULL; |
| |
| q->node = node_id; |
| if (blk_init_free_list(q)) |
| return NULL; |
| |
| q->request_fn = rfn; |
| q->prep_rq_fn = NULL; |
| q->unprep_rq_fn = NULL; |
| q->queue_flags = QUEUE_FLAG_DEFAULT; |
| |
| /* Override internal queue lock with supplied lock pointer */ |
| if (lock) |
| q->queue_lock = lock; |
| |
| /* |
| * This also sets hw/phys segments, boundary and size |
| */ |
| blk_queue_make_request(q, blk_queue_bio); |
| |
| q->sg_reserved_size = INT_MAX; |
| |
| /* |
| * all done |
| */ |
| if (!elevator_init(q, NULL)) { |
| blk_queue_congestion_threshold(q); |
| return q; |
| } |
| |
| return NULL; |
| } |
| EXPORT_SYMBOL(blk_init_allocated_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; |
| } |
| EXPORT_SYMBOL(blk_get_queue); |
| |
| 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, unsigned int flags, 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 = flags | REQ_ALLOCED; |
| |
| if ((flags & REQ_ELVPRIV) && |
| unlikely(elv_set_request(q, rq, gfp_mask))) { |
| mempool_free(rq, q->rq.rq_pool); |
| return NULL; |
| } |
| |
| 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 sync) |
| { |
| struct request_list *rl = &q->rq; |
| |
| if (rl->count[sync] < queue_congestion_off_threshold(q)) |
| blk_clear_queue_congested(q, sync); |
| |
| if (rl->count[sync] + 1 <= q->nr_requests) { |
| if (waitqueue_active(&rl->wait[sync])) |
| wake_up(&rl->wait[sync]); |
| |
| blk_clear_queue_full(q, sync); |
| } |
| } |
| |
| /* |
| * A request has just been released. Account for it, update the full and |
| * congestion status, wake up any waiters. Called under q->queue_lock. |
| */ |
| static void freed_request(struct request_queue *q, unsigned int flags) |
| { |
| struct request_list *rl = &q->rq; |
| int sync = rw_is_sync(flags); |
| |
| rl->count[sync]--; |
| if (flags & REQ_ELVPRIV) |
| rl->elvpriv--; |
| |
| __freed_request(q, sync); |
| |
| if (unlikely(rl->starved[sync ^ 1])) |
| __freed_request(q, sync ^ 1); |
| } |
| |
| /* |
| * Determine if elevator data should be initialized when allocating the |
| * request associated with @bio. |
| */ |
| static bool blk_rq_should_init_elevator(struct bio *bio) |
| { |
| if (!bio) |
| return true; |
| |
| /* |
| * Flush requests do not use the elevator so skip initialization. |
| * This allows a request to share the flush and elevator data. |
| */ |
| if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) |
| return false; |
| |
| return true; |
| } |
| |
| /** |
| * get_request - get a free request |
| * @q: request_queue to allocate request from |
| * @rw_flags: RW and SYNC flags |
| * @bio: bio to allocate request for (can be %NULL) |
| * @gfp_mask: allocation mask |
| * |
| * Get a free request from @q. This function may fail under memory |
| * pressure or if @q is dead. |
| * |
| * Must be callled with @q->queue_lock held and, |
| * Returns %NULL on failure, with @q->queue_lock held. |
| * Returns !%NULL on success, with @q->queue_lock *not held*. |
| */ |
| static struct request *get_request(struct request_queue *q, int rw_flags, |
| struct bio *bio, gfp_t gfp_mask) |
| { |
| struct request *rq = NULL; |
| struct request_list *rl = &q->rq; |
| struct io_context *ioc = NULL; |
| const bool is_sync = rw_is_sync(rw_flags) != 0; |
| int may_queue; |
| |
| if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
| return NULL; |
| |
| may_queue = elv_may_queue(q, rw_flags); |
| if (may_queue == ELV_MQUEUE_NO) |
| goto rq_starved; |
| |
| if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { |
| if (rl->count[is_sync]+1 >= q->nr_requests) { |
| 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, is_sync)) { |
| ioc_set_batching(q, ioc); |
| blk_set_queue_full(q, is_sync); |
| } else { |
| if (may_queue != ELV_MQUEUE_MUST |
| && !ioc_batching(q, ioc)) { |
| /* |
| * The queue is full and the allocating |
| * process is not a "batcher", and not |
| * exempted by the IO scheduler |
| */ |
| goto out; |
| } |
| } |
| } |
| blk_set_queue_congested(q, is_sync); |
| } |
| |
| /* |
| * Only allow batching queuers to allocate up to 50% over the defined |
| * limit of requests, otherwise we could have thousands of requests |
| * allocated with any setting of ->nr_requests |
| */ |
| if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) |
| goto out; |
| |
| rl->count[is_sync]++; |
| rl->starved[is_sync] = 0; |
| |
| if (blk_rq_should_init_elevator(bio) && |
| !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags)) { |
| rw_flags |= REQ_ELVPRIV; |
| rl->elvpriv++; |
| } |
| |
| if (blk_queue_io_stat(q)) |
| rw_flags |= REQ_IO_STAT; |
| spin_unlock_irq(q->queue_lock); |
| |
| rq = blk_alloc_request(q, rw_flags, 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_flags); |
| |
| /* |
| * in the very unlikely event that allocation failed and no |
| * requests for this direction was pending, mark us starved |
| * so that freeing of a request in the other direction will |
| * notice us. another possible fix would be to split the |
| * rq mempool into READ and WRITE |
| */ |
| rq_starved: |
| if (unlikely(rl->count[is_sync] == 0)) |
| rl->starved[is_sync] = 1; |
| |
| 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_flags & 1); |
| out: |
| return rq; |
| } |
| |
| /** |
| * get_request_wait - get a free request with retry |
| * @q: request_queue to allocate request from |
| * @rw_flags: RW and SYNC flags |
| * @bio: bio to allocate request for (can be %NULL) |
| * |
| * Get a free request from @q. This function keeps retrying under memory |
| * pressure and fails iff @q is dead. |
| * |
| * Must be callled with @q->queue_lock held and, |
| * Returns %NULL on failure, with @q->queue_lock held. |
| * Returns !%NULL on success, with @q->queue_lock *not held*. |
| */ |
| static struct request *get_request_wait(struct request_queue *q, int rw_flags, |
| struct bio *bio) |
| { |
| const bool is_sync = rw_is_sync(rw_flags) != 0; |
| 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; |
| |
| if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
| return NULL; |
| |
| prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, |
| TASK_UNINTERRUPTIBLE); |
| |
| trace_block_sleeprq(q, bio, rw_flags & 1); |
| |
| spin_unlock_irq(q->queue_lock); |
| io_schedule(); |
| |
| /* |
| * After sleeping, we become a "batching" process and |
| * will be able to allocate at least one request, and |
| * up to a big batch of them for a small period time. |
| * See ioc_batching, ioc_set_batching |
| */ |
| ioc = current_io_context(GFP_NOIO, q->node); |
| ioc_set_batching(q, ioc); |
| |
| spin_lock_irq(q->queue_lock); |
| finish_wait(&rl->wait[is_sync], &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_make_request - given a bio, allocate a corresponding struct request. |
| * @q: target request queue |
| * @bio: The bio describing the memory mappings that will be submitted for IO. |
| * It may be a chained-bio properly constructed by block/bio layer. |
| * @gfp_mask: gfp flags to be used for memory allocation |
| * |
| * blk_make_request is the parallel of generic_make_request for BLOCK_PC |
| * type commands. Where the struct request needs to be farther initialized by |
| * the caller. It is passed a &struct bio, which describes the memory info of |
| * the I/O transfer. |
| * |
| * The caller of blk_make_request must make sure that bi_io_vec |
| * are set to describe the memory buffers. That bio_data_dir() will return |
| * the needed direction of the request. (And all bio's in the passed bio-chain |
| * are properly set accordingly) |
| * |
| * If called under none-sleepable conditions, mapped bio buffers must not |
| * need bouncing, by calling the appropriate masked or flagged allocator, |
| * suitable for the target device. Otherwise the call to blk_queue_bounce will |
| * BUG. |
| * |
| * WARNING: When allocating/cloning a bio-chain, careful consideration should be |
| * given to how you allocate bios. In particular, you cannot use __GFP_WAIT for |
| * anything but the first bio in the chain. Otherwise you risk waiting for IO |
| * completion of a bio that hasn't been submitted yet, thus resulting in a |
| * deadlock. Alternatively bios should be allocated using bio_kmalloc() instead |
| * of bio_alloc(), as that avoids the mempool deadlock. |
| * If possible a big IO should be split into smaller parts when allocation |
| * fails. Partial allocation should not be an error, or you risk a live-lock. |
| */ |
| struct request *blk_make_request(struct request_queue *q, struct bio *bio, |
| gfp_t gfp_mask) |
| { |
| struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask); |
| |
| if (unlikely(!rq)) |
| return ERR_PTR(-ENOMEM); |
| |
| for_each_bio(bio) { |
| struct bio *bounce_bio = bio; |
| int ret; |
| |
| blk_queue_bounce(q, &bounce_bio); |
| ret = blk_rq_append_bio(q, rq, bounce_bio); |
| if (unlikely(ret)) { |
| blk_put_request(rq); |
| return ERR_PTR(ret); |
| } |
| } |
| |
| return rq; |
| } |
| EXPORT_SYMBOL(blk_make_request); |
| |
| /** |
| * blk_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); |
| |
| BUG_ON(blk_queued_rq(rq)); |
| |
| elv_requeue_request(q, rq); |
| } |
| EXPORT_SYMBOL(blk_requeue_request); |
| |
| static void add_acct_request(struct request_queue *q, struct request *rq, |
| int where) |
| { |
| drive_stat_acct(rq, 1); |
| __elv_add_request(q, rq, where); |
| } |
| |
| /** |
| * 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->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); |
| |
| add_acct_request(q, rq, where); |
| __blk_run_queue(q); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| EXPORT_SYMBOL(blk_insert_request); |
| |
| 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)) { |
| __part_stat_add(cpu, part, time_in_queue, |
| part_in_flight(part) * (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); |
| |
| /* this is a bio leak */ |
| WARN_ON(req->bio != NULL); |
| |
| /* |
| * Request may not have originated from ll_rw_blk. if not, |
| * it didn't come out of our reserved rq pools |
| */ |
| if (req->cmd_flags & REQ_ALLOCED) { |
| unsigned int flags = req->cmd_flags; |
| |
| BUG_ON(!list_empty(&req->queuelist)); |
| BUG_ON(!hlist_unhashed(&req->hash)); |
| |
| blk_free_request(q, req); |
| freed_request(q, flags); |
| } |
| } |
| 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); |
| |
| /** |
| * blk_add_request_payload - add a payload to a request |
| * @rq: request to update |
| * @page: page backing the payload |
| * @len: length of the payload. |
| * |
| * This allows to later add a payload to an already submitted request by |
| * a block driver. The driver needs to take care of freeing the payload |
| * itself. |
| * |
| * Note that this is a quite horrible hack and nothing but handling of |
| * discard requests should ever use it. |
| */ |
| void blk_add_request_payload(struct request *rq, struct page *page, |
| unsigned int len) |
| { |
| struct bio *bio = rq->bio; |
| |
| bio->bi_io_vec->bv_page = page; |
| bio->bi_io_vec->bv_offset = 0; |
| bio->bi_io_vec->bv_len = len; |
| |
| bio->bi_size = len; |
| bio->bi_vcnt = 1; |
| bio->bi_phys_segments = 1; |
| |
| rq->__data_len = rq->resid_len = len; |
| rq->nr_phys_segments = 1; |
| rq->buffer = bio_data(bio); |
| } |
| EXPORT_SYMBOL_GPL(blk_add_request_payload); |
| |
| static bool bio_attempt_back_merge(struct request_queue *q, struct request *req, |
| struct bio *bio) |
| { |
| const int ff = bio->bi_rw & REQ_FAILFAST_MASK; |
| |
| if (!ll_back_merge_fn(q, req, bio)) |
| return false; |
| |
| trace_block_bio_backmerge(q, bio); |
| |
| if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) |
| blk_rq_set_mixed_merge(req); |
| |
| req->biotail->bi_next = bio; |
| req->biotail = bio; |
| req->__data_len += bio->bi_size; |
| req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); |
| |
| drive_stat_acct(req, 0); |
| elv_bio_merged(q, req, bio); |
| return true; |
| } |
| |
| static bool bio_attempt_front_merge(struct request_queue *q, |
| struct request *req, struct bio *bio) |
| { |
| const int ff = bio->bi_rw & REQ_FAILFAST_MASK; |
| |
| if (!ll_front_merge_fn(q, req, bio)) |
| return false; |
| |
| trace_block_bio_frontmerge(q, bio); |
| |
| if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) |
| blk_rq_set_mixed_merge(req); |
| |
| bio->bi_next = req->bio; |
| req->bio = bio; |
| |
| /* |
| * may not be valid. if the low level driver said |
| * it didn't need a bounce buffer then it better |
| * not touch req->buffer either... |
| */ |
| req->buffer = bio_data(bio); |
| req->__sector = bio->bi_sector; |
| req->__data_len += bio->bi_size; |
| req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); |
| |
| drive_stat_acct(req, 0); |
| elv_bio_merged(q, req, bio); |
| return true; |
| } |
| |
| /** |
| * attempt_plug_merge - try to merge with %current's plugged list |
| * @q: request_queue new bio is being queued at |
| * @bio: new bio being queued |
| * @request_count: out parameter for number of traversed plugged requests |
| * |
| * Determine whether @bio being queued on @q can be merged with a request |
| * on %current's plugged list. Returns %true if merge was successful, |
| * otherwise %false. |
| * |
| * This function is called without @q->queue_lock; however, elevator is |
| * accessed iff there already are requests on the plugged list which in |
| * turn guarantees validity of the elevator. |
| * |
| * Note that, on successful merge, elevator operation |
| * elevator_bio_merged_fn() will be called without queue lock. Elevator |
| * must be ready for this. |
| */ |
| static bool attempt_plug_merge(struct request_queue *q, struct bio *bio, |
| unsigned int *request_count) |
| { |
| struct blk_plug *plug; |
| struct request *rq; |
| bool ret = false; |
| |
| plug = current->plug; |
| if (!plug) |
| goto out; |
| *request_count = 0; |
| |
| list_for_each_entry_reverse(rq, &plug->list, queuelist) { |
| int el_ret; |
| |
| (*request_count)++; |
| |
| if (rq->q != q) |
| continue; |
| |
| el_ret = elv_try_merge(rq, bio); |
| if (el_ret == ELEVATOR_BACK_MERGE) { |
| ret = bio_attempt_back_merge(q, rq, bio); |
| if (ret) |
| break; |
| } else if (el_ret == ELEVATOR_FRONT_MERGE) { |
| ret = bio_attempt_front_merge(q, rq, bio); |
| if (ret) |
| break; |
| } |
| } |
| out: |
| return ret; |
| } |
| |
| void init_request_from_bio(struct request *req, struct bio *bio) |
| { |
| req->cmd_type = REQ_TYPE_FS; |
| |
| req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK; |
| if (bio->bi_rw & REQ_RAHEAD) |
| req->cmd_flags |= REQ_FAILFAST_MASK; |
| |
| req->errors = 0; |
| req->__sector = bio->bi_sector; |
| req->ioprio = bio_prio(bio); |
| blk_rq_bio_prep(req->q, req, bio); |
| } |
| |
| void blk_queue_bio(struct request_queue *q, struct bio *bio) |
| { |
| const bool sync = !!(bio->bi_rw & REQ_SYNC); |
| struct blk_plug *plug; |
| int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT; |
| struct request *req; |
| unsigned int request_count = 0; |
| |
| /* |
| * low level driver can indicate that it wants pages above a |
| * certain limit bounced to low memory (ie for highmem, or even |
| * ISA dma in theory) |
| */ |
| blk_queue_bounce(q, &bio); |
| |
| if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { |
| spin_lock_irq(q->queue_lock); |
| where = ELEVATOR_INSERT_FLUSH; |
| goto get_rq; |
| } |
| |
| /* |
| * Check if we can merge with the plugged list before grabbing |
| * any locks. |
| */ |
| if (attempt_plug_merge(q, bio, &request_count)) |
| return; |
| |
| spin_lock_irq(q->queue_lock); |
| |
| el_ret = elv_merge(q, &req, bio); |
| if (el_ret == ELEVATOR_BACK_MERGE) { |
| if (bio_attempt_back_merge(q, req, bio)) { |
| if (!attempt_back_merge(q, req)) |
| elv_merged_request(q, req, el_ret); |
| goto out_unlock; |
| } |
| } else if (el_ret == ELEVATOR_FRONT_MERGE) { |
| if (bio_attempt_front_merge(q, req, bio)) { |
| if (!attempt_front_merge(q, req)) |
| elv_merged_request(q, req, el_ret); |
| goto out_unlock; |
| } |
| } |
| |
| get_rq: |
| /* |
| * This sync check and mask will be re-done in init_request_from_bio(), |
| * but we need to set it earlier to expose the sync flag to the |
| * rq allocator and io schedulers. |
| */ |
| rw_flags = bio_data_dir(bio); |
| if (sync) |
| rw_flags |= REQ_SYNC; |
| |
| /* |
| * Grab a free request. This is might sleep but can not fail. |
| * Returns with the queue unlocked. |
| */ |
| req = get_request_wait(q, rw_flags, bio); |
| if (unlikely(!req)) { |
| bio_endio(bio, -ENODEV); /* @q is dead */ |
| goto out_unlock; |
| } |
| |
| /* |
| * After dropping the lock and possibly sleeping here, our request |
| * may now be mergeable after it had proven unmergeable (above). |
| * We don't worry about that case for efficiency. It won't happen |
| * often, and the elevators are able to handle it. |
| */ |
| init_request_from_bio(req, bio); |
| |
| if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) |
| req->cpu = raw_smp_processor_id(); |
| |
| plug = current->plug; |
| if (plug) { |
| /* |
| * If this is the first request added after a plug, fire |
| * of a plug trace. If others have been added before, check |
| * if we have multiple devices in this plug. If so, make a |
| * note to sort the list before dispatch. |
| */ |
| if (list_empty(&plug->list)) |
| trace_block_plug(q); |
| else if (!plug->should_sort) { |
| struct request *__rq; |
| |
| __rq = list_entry_rq(plug->list.prev); |
| if (__rq->q != q) |
| plug->should_sort = 1; |
| } |
| if (request_count >= BLK_MAX_REQUEST_COUNT) |
| blk_flush_plug_list(plug, false); |
| list_add_tail(&req->queuelist, &plug->list); |
| drive_stat_acct(req, 1); |
| } else { |
| spin_lock_irq(q->queue_lock); |
| add_acct_request(q, req, where); |
| __blk_run_queue(q); |
| out_unlock: |
| spin_unlock_irq(q->queue_lock); |
| } |
| } |
| EXPORT_SYMBOL_GPL(blk_queue_bio); /* for device mapper only */ |
| |
| /* |
| * 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_bio_remap(bdev_get_queue(bio->bi_bdev), bio, |
| bdev->bd_dev, |
| 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)(i_size_read(bio->bi_bdev->bd_inode) >> 9)); |
| |
| set_bit(BIO_EOF, &bio->bi_flags); |
| } |
| |
| #ifdef CONFIG_FAIL_MAKE_REQUEST |
| |
| static DECLARE_FAULT_ATTR(fail_make_request); |
| |
| static int __init setup_fail_make_request(char *str) |
| { |
| return setup_fault_attr(&fail_make_request, str); |
| } |
| __setup("fail_make_request=", setup_fail_make_request); |
| |
| static bool should_fail_request(struct hd_struct *part, unsigned int bytes) |
| { |
| return part->make_it_fail && should_fail(&fail_make_request, bytes); |
| } |
| |
| static int __init fail_make_request_debugfs(void) |
| { |
| struct dentry *dir = fault_create_debugfs_attr("fail_make_request", |
| NULL, &fail_make_request); |
| |
| return IS_ERR(dir) ? PTR_ERR(dir) : 0; |
| } |
| |
| late_initcall(fail_make_request_debugfs); |
| |
| #else /* CONFIG_FAIL_MAKE_REQUEST */ |
| |
| static inline bool should_fail_request(struct hd_struct *part, |
| unsigned int bytes) |
| { |
| return false; |
| } |
| |
| #endif /* CONFIG_FAIL_MAKE_REQUEST */ |
| |
| /* |
| * Check whether this bio extends beyond the end of the device. |
| */ |
| static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) |
| { |
| sector_t maxsector; |
| |
| if (!nr_sectors) |
| return 0; |
| |
| /* Test device or partition size, when known. */ |
| maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9; |
| if (maxsector) { |
| sector_t sector = bio->bi_sector; |
| |
| if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { |
| /* |
| * This may well happen - the kernel calls bread() |
| * without checking the size of the device, e.g., when |
| * mounting a device. |
| */ |
| handle_bad_sector(bio); |
| return 1; |
| } |
| } |
| |
| return 0; |
| } |
| |
| static noinline_for_stack bool |
| generic_make_request_checks(struct bio *bio) |
| { |
| struct request_queue *q; |
| int nr_sectors = bio_sectors(bio); |
| int err = -EIO; |
| char b[BDEVNAME_SIZE]; |
| struct hd_struct *part; |
| |
| might_sleep(); |
| |
| if (bio_check_eod(bio, nr_sectors)) |
| goto end_io; |
| |
| q = bdev_get_queue(bio->bi_bdev); |
| if (unlikely(!q)) { |
| printk(KERN_ERR |
| "generic_make_request: Trying to access " |
| "nonexistent block-device %s (%Lu)\n", |
| bdevname(bio->bi_bdev, b), |
| (long long) bio->bi_sector); |
| goto end_io; |
| } |
| |
| if (unlikely(!(bio->bi_rw & REQ_DISCARD) && |
| nr_sectors > queue_max_hw_sectors(q))) { |
| printk(KERN_ERR "bio too big device %s (%u > %u)\n", |
| bdevname(bio->bi_bdev, b), |
| bio_sectors(bio), |
| queue_max_hw_sectors(q)); |
| goto end_io; |
| } |
| |
| part = bio->bi_bdev->bd_part; |
| if (should_fail_request(part, bio->bi_size) || |
| should_fail_request(&part_to_disk(part)->part0, |
| bio->bi_size)) |
| goto end_io; |
| |
| /* |
| * If this device has partitions, remap block n |
| * of partition p to block n+start(p) of the disk. |
| */ |
| blk_partition_remap(bio); |
| |
| if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) |
| goto end_io; |
| |
| if (bio_check_eod(bio, nr_sectors)) |
| goto end_io; |
| |
| /* |
| * Filter flush bio's early so that make_request based |
| * drivers without flush support don't have to worry |
| * about them. |
| */ |
| if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) { |
| bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA); |
| if (!nr_sectors) { |
| err = 0; |
| goto end_io; |
| } |
| } |
| |
| if ((bio->bi_rw & REQ_DISCARD) && |
| (!blk_queue_discard(q) || |
| ((bio->bi_rw & REQ_SECURE) && |
| !blk_queue_secdiscard(q)))) { |
| err = -EOPNOTSUPP; |
| goto end_io; |
| } |
| |
| if (blk_throtl_bio(q, bio)) |
| return false; /* throttled, will be resubmitted later */ |
| |
| trace_block_bio_queue(q, bio); |
| return true; |
| |
| end_io: |
| bio_endio(bio, err); |
| return false; |
| } |
| |
| /** |
| * generic_make_request - hand a buffer to its device driver for I/O |
| * @bio: The bio describing the location in memory and on the device. |
| * |
| * generic_make_request() is used to make I/O requests of block |
| * devices. It is passed a &struct bio, which describes the I/O that needs |
| * to be done. |
| * |
| * generic_make_request() does not return any status. The |
| * success/failure status of the request, along with notification of |
| * completion, is delivered asynchronously through the bio->bi_end_io |
| * function described (one day) else where. |
| * |
| * The caller of generic_make_request must make sure that bi_io_vec |
| * are set to describe the memory buffer, and that bi_dev and bi_sector are |
| * set to describe the device address, and the |
| * bi_end_io and optionally bi_private are set to describe how |
| * completion notification should be signaled. |
| * |
| * generic_make_request and the drivers it calls may use bi_next if this |
| * bio happens to be merged with someone else, and may resubmit the bio to |
| * a lower device by calling into generic_make_request recursively, which |
| * means the bio should NOT be touched after the call to ->make_request_fn. |
| */ |
| void generic_make_request(struct bio *bio) |
| { |
| struct bio_list bio_list_on_stack; |
| |
| if (!generic_make_request_checks(bio)) |
| return; |
| |
| /* |
| * We only want one ->make_request_fn to be active at a time, else |
| * stack usage with stacked devices could be a problem. So use |
| * current->bio_list to keep a list of requests submited by a |
| * make_request_fn function. current->bio_list is also used as a |
| * flag to say if generic_make_request is currently active in this |
| * task or not. If it is NULL, then no make_request is active. If |
| * it is non-NULL, then a make_request is active, and new requests |
| * should be added at the tail |
| */ |
| if (current->bio_list) { |
| bio_list_add(current->bio_list, bio); |
| return; |
| } |
| |
| /* following loop may be a bit non-obvious, and so deserves some |
| * explanation. |
| * Before entering the loop, bio->bi_next is NULL (as all callers |
| * ensure that) so we have a list with a single bio. |
| * We pretend that we have just taken it off a longer list, so |
| * we assign bio_list to a pointer to the bio_list_on_stack, |
| * thus initialising the bio_list of new bios to be |
| * added. ->make_request() may indeed add some more bios |
| * through a recursive call to generic_make_request. If it |
| * did, we find a non-NULL value in bio_list and re-enter the loop |
| * from the top. In this case we really did just take the bio |
| * of the top of the list (no pretending) and so remove it from |
| * bio_list, and call into ->make_request() again. |
| */ |
| BUG_ON(bio->bi_next); |
| bio_list_init(&bio_list_on_stack); |
| current->bio_list = &bio_list_on_stack; |
| do { |
| struct request_queue *q = bdev_get_queue(bio->bi_bdev); |
| |
| q->make_request_fn(q, bio); |
| |
| bio = bio_list_pop(current->bio_list); |
| } while (bio); |
| current->bio_list = NULL; /* deactivate */ |
| } |
| EXPORT_SYMBOL(generic_make_request); |
| |
| /** |
| * submit_bio - submit a bio to the block device layer for I/O |
| * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) |
| * @bio: The &struct bio which describes the I/O |
| * |
| * submit_bio() is very similar in purpose to generic_make_request(), and |
| * uses that function to do most of the work. Both are fairly rough |
| * interfaces; @bio must be presetup and ready for I/O. |
| * |
| */ |
| void submit_bio(int rw, struct bio *bio) |
| { |
| 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) && !(rw & REQ_DISCARD)) { |
| 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 (%u sectors)\n", |
| current->comm, task_pid_nr(current), |
| (rw & WRITE) ? "WRITE" : "READ", |
| (unsigned long long)bio->bi_sector, |
| bdevname(bio->bi_bdev, b), |
| count); |
| } |
| } |
| |
| generic_make_request(bio); |
| } |
| EXPORT_SYMBOL(submit_bio); |
| |
| /** |
| * blk_rq_check_limits - Helper function to check a request for the queue limit |
| * @q: the queue |
| * @rq: the request being checked |
| * |
| * Description: |
| * @rq may have been made based on weaker limitations of upper-level queues |
| * in request stacking drivers, and it may violate the limitation of @q. |
| * Since the block layer and the underlying device driver trust @rq |
| * after it is inserted to @q, it should be checked against @q before |
| * the insertion using this generic function. |
| * |
| * This function should also be useful for request stacking drivers |
| * in some cases below, so export this function. |
| * Request stacking drivers like request-based dm may change the queue |
| * limits while requests are in the queue (e.g. dm's table swapping). |
| * Such request stacking drivers should check those requests 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->cmd_flags & REQ_DISCARD) |
| return 0; |
| |
| if (blk_rq_sectors(rq) > queue_max_sectors(q) || |
| blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 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 > queue_max_segments(q)) { |
| printk(KERN_ERR "%s: over max segments limit.\n", __func__); |
| return -EIO; |
| } |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(blk_rq_check_limits); |
| |
| /** |
| * blk_insert_cloned_request - Helper for stacking drivers to submit a request |
| * @q: the queue to submit the request |
| * @rq: the request being queued |
| */ |
| int blk_insert_cloned_request(struct request_queue *q, struct request *rq) |
| { |
| unsigned long flags; |
| int where = ELEVATOR_INSERT_BACK; |
| |
| if (blk_rq_check_limits(q, rq)) |
| return -EIO; |
| |
| if (rq->rq_disk && |
| should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) |
| return -EIO; |
| |
| 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)); |
| |
| if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA)) |
| where = ELEVATOR_INSERT_FLUSH; |
| |
| add_acct_request(q, rq, where); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(blk_insert_cloned_request); |
| |
| /** |
| * blk_rq_err_bytes - determine number of bytes till the next failure boundary |
| * @rq: request to examine |
| * |
| * Description: |
| * A request could be merge of IOs which require different failure |
| * handling. This function determines the number of bytes which |
| * can be failed from the beginning of the request without |
| * crossing into area which need to be retried further. |
| * |
| * Return: |
| * The number of bytes to fail. |
| * |
| * Context: |
| * queue_lock must be held. |
| */ |
| unsigned int blk_rq_err_bytes(const struct request *rq) |
| { |
| unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; |
| unsigned int bytes = 0; |
| struct bio *bio; |
| |
| if (!(rq->cmd_flags & REQ_MIXED_MERGE)) |
| return blk_rq_bytes(rq); |
| |
| /* |
| * Currently the only 'mixing' which can happen is between |
| * different fastfail types. We can safely fail portions |
| * which have all the failfast bits that the first one has - |
| * the ones which are at least as eager to fail as the first |
| * one. |
| */ |
| for (bio = rq->bio; bio; bio = bio->bi_next) { |
| if ((bio->bi_rw & ff) != ff) |
| break; |
| bytes += bio->bi_size; |
| } |
| |
| /* this could lead to infinite loop */ |
| BUG_ON(blk_rq_bytes(rq) && !bytes); |
| return bytes; |
| } |
| EXPORT_SYMBOL_GPL(blk_rq_err_bytes); |
| |
| static void blk_account_io_completion(struct request *req, unsigned int bytes) |
| { |
| if (blk_do_io_stat(req)) { |
| const int rw = rq_data_dir(req); |
| struct hd_struct *part; |
| int cpu; |
| |
| cpu = part_stat_lock(); |
| part = req->part; |
| part_stat_add(cpu, part, sectors[rw], bytes >> 9); |
| part_stat_unlock(); |
| } |
| } |
| |
| static void blk_account_io_done(struct request *req) |
| { |
| /* |
| * Account IO completion. flush_rq isn't accounted as a |
| * normal IO on queueing nor completion. Accounting the |
| * containing request is enough. |
| */ |
| if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) { |
| unsigned long duration = jiffies - req->start_time; |
| const int rw = rq_data_dir(req); |
| struct hd_struct *part; |
| int cpu; |
| |
| cpu = part_stat_lock(); |
| part = req->part; |
| |
| part_stat_inc(cpu, part, ios[rw]); |
| part_stat_add(cpu, part, ticks[rw], duration); |
| part_round_stats(cpu, part); |
| part_dec_in_flight(part, rw); |
| |
| hd_struct_put(part); |
| part_stat_unlock(); |
| } |
| } |
| |
| /** |
| * blk_peek_request - peek at the top of a request queue |
| * @q: request queue to peek at |
| * |
| * Description: |
| * Return the request at the top of @q. The returned request |
| * should be started using blk_start_request() before LLD starts |
| * processing it. |
| * |
| * Return: |
| * Pointer to the request at the top of @q if available. Null |
| * otherwise. |
| * |
| * Context: |
| * queue_lock must be held. |
| */ |
| struct request *blk_peek_request(struct request_queue *q) |
| { |
| struct request *rq; |
| int ret; |
| |
| while ((rq = __elv_next_request(q)) != NULL) { |
| if (!(rq->cmd_flags & REQ_STARTED)) { |
| /* |
| * This is the first time the device driver |
| * sees this request (possibly after |
| * requeueing). Notify IO scheduler. |
| */ |
| if (rq->cmd_flags & REQ_SORTED) |
| elv_activate_rq(q, rq); |
| |
| /* |
| * just mark as started even if we don't start |
| * it, a request that has been delayed should |
| * not be passed by new incoming requests |
| */ |
| rq->cmd_flags |= REQ_STARTED; |
| trace_block_rq_issue(q, rq); |
| } |
| |
| if (!q->boundary_rq || q->boundary_rq == rq) { |
| q->end_sector = rq_end_sector(rq); |
| q->boundary_rq = NULL; |
| } |
| |
| if (rq->cmd_flags & REQ_DONTPREP) |
| break; |
| |
| if (q->dma_drain_size && blk_rq_bytes(rq)) { |
| /* |
| * make sure space for the drain appears we |
| * know we can do this because max_hw_segments |
| * has been adjusted to be one fewer than the |
| * device can handle |
| */ |
| rq->nr_phys_segments++; |
| } |
| |
| if (!q->prep_rq_fn) |
| break; |
| |
| ret = q->prep_rq_fn(q, rq); |
| if (ret == BLKPREP_OK) { |
| break; |
| } else if (ret == BLKPREP_DEFER) { |
| /* |
| * the request may have been (partially) prepped. |
| * we need to keep this request in the front to |
| * avoid resource deadlock. REQ_STARTED will |
| * prevent other fs requests from passing this one. |
| */ |
| if (q->dma_drain_size && blk_rq_bytes(rq) && |
| !(rq->cmd_flags & REQ_DONTPREP)) { |
| /* |
| * remove the space for the drain we added |
| * so that we don't add it again |
| */ |
| --rq->nr_phys_segments; |
| } |
| |
| rq = NULL; |
| break; |
| } else if (ret == BLKPREP_KILL) { |
| rq->cmd_flags |= REQ_QUIET; |
| /* |
| * Mark this request as started so we don't trigger |
| * any debug logic in the end I/O path. |
| */ |
| blk_start_request(rq); |
| __blk_end_request_all(rq, -EIO); |
| } else { |
| printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); |
| break; |
| } |
| } |
| |
| return rq; |
| } |
| EXPORT_SYMBOL(blk_peek_request); |
| |
| void blk_dequeue_request(struct request *rq) |
| { |
| struct request_queue *q = rq->q; |
| |
| BUG_ON(list_empty(&rq->queuelist)); |
| BUG_ON(ELV_ON_HASH(rq)); |
| |
| list_del_init(&rq->queuelist); |
| |
| /* |
| * the time frame between a request being removed from the lists |
| * and to it is freed is accounted as io that is in progress at |
| * the driver side. |
| */ |
| if (blk_account_rq(rq)) { |
| q->in_flight[rq_is_sync(rq)]++; |
| set_io_start_time_ns(rq); |
| } |
| } |
| |
| /** |
| * blk_start_request - start request processing on the driver |
| * @req: request to dequeue |
| * |
| * Description: |
| * Dequeue @req and start timeout timer on it. This hands off the |
| * request to the driver. |
| * |
| * Block internal functions which don't want to start timer should |
| * call blk_dequeue_request(). |
| * |
| * Context: |
| * queue_lock must be held. |
| */ |
| void blk_start_request(struct request *req) |
| { |
| blk_dequeue_request(req); |
| |
| /* |
| * We are now handing the request to the hardware, initialize |
| * resid_len to full count and add the timeout handler. |
| */ |
| req->resid_len = blk_rq_bytes(req); |
| if (unlikely(blk_bidi_rq(req))) |
| req->next_rq->resid_len = blk_rq_bytes(req->next_rq); |
| |
| blk_add_timer(req); |
| } |
| EXPORT_SYMBOL(blk_start_request); |
| |
| /** |
| * blk_fetch_request - fetch a request from a request queue |
| * @q: request queue to fetch a request from |
| * |
| * Description: |
| * Return the request at the top of @q. The request is started on |
| * return and LLD can start processing it immediately. |
| * |
| * Return: |
| * Pointer to the request at the top of @q if available. Null |
| * otherwise. |
| * |
| * Context: |
| * queue_lock must be held. |
| */ |
| struct request *blk_fetch_request(struct request_queue *q) |
| { |
| struct request *rq; |
| |
| rq = blk_peek_request(q); |
| if (rq) |
| blk_start_request(rq); |
| return rq; |
| } |
| EXPORT_SYMBOL(blk_fetch_request); |
| |
| /** |
| * blk_update_request - Special helper function for request stacking drivers |
| * @req: the request being processed |
| * @error: %0 for success, < %0 for error |
| * @nr_bytes: number of bytes to complete @req |
| * |
| * Description: |
| * Ends I/O on a number of bytes attached to @req, but doesn't complete |
| * the request structure even if @req doesn't have leftover. |
| * If @req has leftover, sets it up for the next range of segments. |
| * |
| * This special helper function is only for request stacking drivers |
| * (e.g. request-based dm) so that they can handle partial completion. |
| * Actual device drivers should use blk_end_request instead. |
| * |
| * Passing the result of blk_rq_bytes() as @nr_bytes guarantees |
| * %false return from this function. |
| * |
| * Return: |
| * %false - this request doesn't have any more data |
| * %true - this request has more data |
| **/ |
| bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) |
| { |
| int total_bytes, bio_nbytes, next_idx = 0; |
| struct bio *bio; |
| |
| if (!req->bio) |
| return false; |
| |
| trace_block_rq_complete(req->q, req); |
| |
| /* |
| * For fs requests, rq is just carrier of independent bio's |
| * and each partial completion should be handled separately. |
| * Reset per-request error on each partial completion. |
| * |
| * TODO: tj: This is too subtle. It would be better to let |
| * low level drivers do what they see fit. |
| */ |
| if (req->cmd_type == REQ_TYPE_FS) |
| req->errors = 0; |
| |
| if (error && req->cmd_type == REQ_TYPE_FS && |
| !(req->cmd_flags & REQ_QUIET)) { |
| char *error_type; |
| |
| switch (error) { |
| case -ENOLINK: |
| error_type = "recoverable transport"; |
| break; |
| case -EREMOTEIO: |
| error_type = "critical target"; |
| break; |
| case -EBADE: |
| error_type = "critical nexus"; |
| break; |
| case -EIO: |
| default: |
| error_type = "I/O"; |
| break; |
| } |
| printk(KERN_ERR "end_request: %s error, dev %s, sector %llu\n", |
| error_type, req->rq_disk ? req->rq_disk->disk_name : "?", |
| (unsigned long long)blk_rq_pos(req)); |
| } |
| |
| blk_account_io_completion(req, nr_bytes); |
| |
| total_bytes = bio_nbytes = 0; |
| while ((bio = req->bio) != NULL) { |
| int nbytes; |
| |
| 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(idx >= bio->bi_vcnt)) { |
| blk_dump_rq_flags(req, "__end_that"); |
| printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", |
| __func__, 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) { |
| /* |
| * Reset counters so that the request stacking driver |
| * can find how many bytes remain in the request |
| * later. |
| */ |
| req->__data_len = 0; |
| return false; |
| } |
| |
| /* |
| * 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; |
| } |
| |
| req->__data_len -= total_bytes; |
| req->buffer = bio_data(req->bio); |
| |
| /* update sector only for requests with clear definition of sector */ |
| if (req->cmd_type == REQ_TYPE_FS || (req->cmd_flags & REQ_DISCARD)) |
| req->__sector += total_bytes >> 9; |
| |
| /* mixed attributes always follow the first bio */ |
| if (req->cmd_flags & REQ_MIXED_MERGE) { |
| req->cmd_flags &= ~REQ_FAILFAST_MASK; |
| req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK; |
| } |
| |
| /* |
| * If total number of sectors is less than the first segment |
| * size, something has gone terribly wrong. |
| */ |
| if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) { |
| blk_dump_rq_flags(req, "request botched"); |
| req->__data_len = blk_rq_cur_bytes(req); |
| } |
| |
| /* recalculate the number of segments */ |
| blk_recalc_rq_segments(req); |
| |
| return true; |
| } |
| EXPORT_SYMBOL_GPL(blk_update_request); |
| |
| static bool blk_update_bidi_request(struct request *rq, int error, |
| unsigned int nr_bytes, |
| unsigned int bidi_bytes) |
| { |
| if (blk_update_request(rq, error, nr_bytes)) |
| return true; |
| |
| /* Bidi request must be completed as a whole */ |
| if (unlikely(blk_bidi_rq(rq)) && |
| blk_update_request(rq->next_rq, error, bidi_bytes)) |
| return true; |
| |
| if (blk_queue_add_random(rq->q)) |
| add_disk_randomness(rq->rq_disk); |
| |
| return false; |
| } |
| |
| /** |
| * blk_unprep_request - unprepare a request |
| * @req: the request |
| * |
| * This function makes a request ready for complete resubmission (or |
| * completion). It happens only after all error handling is complete, |
| * so represents the appropriate moment to deallocate any resources |
| * that were allocated to the request in the prep_rq_fn. The queue |
| * lock is held when calling this. |
| */ |
| void blk_unprep_request(struct request *req) |
| { |
| struct request_queue *q = req->q; |
| |
| req->cmd_flags &= ~REQ_DONTPREP; |
| if (q->unprep_rq_fn) |
| q->unprep_rq_fn(q, req); |
| } |
| EXPORT_SYMBOL_GPL(blk_unprep_request); |
| |
| /* |
| * queue lock must be held |
| */ |
| static void blk_finish_request(struct request *req, int error) |
| { |
| if (blk_rq_tagged(req)) |
| blk_queue_end_tag(req->q, req); |
| |
| BUG_ON(blk_queued_rq(req)); |
| |
| if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS) |
| laptop_io_completion(&req->q->backing_dev_info); |
| |
| blk_delete_timer(req); |
| |
| if (req->cmd_flags & REQ_DONTPREP) |
| blk_unprep_request(req); |
| |
| |
| blk_account_io_done(req); |
| |
| if (req->end_io) |
| req->end_io(req, error); |
| else { |
| if (blk_bidi_rq(req)) |
| __blk_put_request(req->next_rq->q, req->next_rq); |
| |
| __blk_put_request(req->q, req); |
| } |
| } |
| |
| /** |
| * blk_end_bidi_request - Complete a bidi request |
| * @rq: the request to complete |
| * @error: %0 for success, < %0 for error |
| * @nr_bytes: number of bytes to complete @rq |
| * @bidi_bytes: number of bytes to complete @rq->next_rq |
| * |
| * Description: |
| * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. |
| * Drivers that supports bidi can safely call this member for any |
| * type of request, bidi or uni. In the later case @bidi_bytes is |
| * just ignored. |
| * |
| * Return: |
| * %false - we are done with this request |
| * %true - still buffers pending for this request |
| **/ |
| static bool blk_end_bidi_request(struct request *rq, int error, |
| unsigned int nr_bytes, unsigned int bidi_bytes) |
| { |
| struct request_queue *q = rq->q; |
| unsigned long flags; |
| |
| if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
| return true; |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| blk_finish_request(rq, error); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| |
| return false; |
| } |
| |
| /** |
| * __blk_end_bidi_request - Complete a bidi request with queue lock held |
| * @rq: the request to complete |
| * @error: %0 for success, < %0 for error |
| * @nr_bytes: number of bytes to complete @rq |
| * @bidi_bytes: number of bytes to complete @rq->next_rq |
| * |
| * Description: |
| * Identical to blk_end_bidi_request() except that queue lock is |
| * assumed to be locked on entry and remains so on return. |
| * |
| * Return: |
| * %false - we are done with this request |
| * %true - still buffers pending for this request |
| **/ |
| bool __blk_end_bidi_request(struct request *rq, int error, |
| unsigned int nr_bytes, unsigned int bidi_bytes) |
| { |
| if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes)) |
| return true; |
| |
| blk_finish_request(rq, error); |
| |
| return false; |
| } |
| |
| /** |
| * blk_end_request - Helper function for drivers to complete the request. |
| * @rq: the request being processed |
| * @error: %0 for success, < %0 for error |
| * @nr_bytes: number of bytes to complete |
| * |
| * Description: |
| * Ends I/O on a number of bytes attached to @rq. |
| * If @rq has leftover, sets it up for the next range of segments. |
| * |
| * Return: |
| * %false - we are done with this request |
| * %true - still buffers pending for this request |
| **/ |
| bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
| { |
| return blk_end_bidi_request(rq, error, nr_bytes, 0); |
| } |
| EXPORT_SYMBOL(blk_end_request); |
| |
| /** |
| * blk_end_request_all - Helper function for drives to finish the request. |
| * @rq: the request to finish |
| * @error: %0 for success, < %0 for error |
| * |
| * Description: |
| * Completely finish @rq. |
| */ |
| void blk_end_request_all(struct request *rq, int error) |
| { |
| bool pending; |
| unsigned int bidi_bytes = 0; |
| |
| if (unlikely(blk_bidi_rq(rq))) |
| bidi_bytes = blk_rq_bytes(rq->next_rq); |
| |
| pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
| BUG_ON(pending); |
| } |
| EXPORT_SYMBOL(blk_end_request_all); |
| |
| /** |
| * blk_end_request_cur - Helper function to finish the current request chunk. |
| * @rq: the request to finish the current chunk for |
| * @error: %0 for success, < %0 for error |
| * |
| * Description: |
| * Complete the current consecutively mapped chunk from @rq. |
| * |
| * Return: |
| * %false - we are done with this request |
| * %true - still buffers pending for this request |
| */ |
| bool blk_end_request_cur(struct request *rq, int error) |
| { |
| return blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
| } |
| EXPORT_SYMBOL(blk_end_request_cur); |
| |
| /** |
| * blk_end_request_err - Finish a request till the next failure boundary. |
| * @rq: the request to finish till the next failure boundary for |
| * @error: must be negative errno |
| * |
| * Description: |
| * Complete @rq till the next failure boundary. |
| * |
| * Return: |
| * %false - we are done with this request |
| * %true - still buffers pending for this request |
| */ |
| bool blk_end_request_err(struct request *rq, int error) |
| { |
| WARN_ON(error >= 0); |
| return blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
| } |
| EXPORT_SYMBOL_GPL(blk_end_request_err); |
| |
| /** |
| * __blk_end_request - Helper function for drivers to complete the request. |
| * @rq: the request being processed |
| * @error: %0 for success, < %0 for error |
| * @nr_bytes: number of bytes to complete |
| * |
| * Description: |
| * Must be called with queue lock held unlike blk_end_request(). |
| * |
| * Return: |
| * %false - we are done with this request |
| * %true - still buffers pending for this request |
| **/ |
| bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) |
| { |
| return __blk_end_bidi_request(rq, error, nr_bytes, 0); |
| } |
| EXPORT_SYMBOL(__blk_end_request); |
| |
| /** |
| * __blk_end_request_all - Helper function for drives to finish the request. |
| * @rq: the request to finish |
| * @error: %0 for success, < %0 for error |
| * |
| * Description: |
| * Completely finish @rq. Must be called with queue lock held. |
| */ |
| void __blk_end_request_all(struct request *rq, int error) |
| { |
| bool pending; |
| unsigned int bidi_bytes = 0; |
| |
| if (unlikely(blk_bidi_rq(rq))) |
| bidi_bytes = blk_rq_bytes(rq->next_rq); |
| |
| pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes); |
| BUG_ON(pending); |
| } |
| EXPORT_SYMBOL(__blk_end_request_all); |
| |
| /** |
| * __blk_end_request_cur - Helper function to finish the current request chunk. |
| * @rq: the request to finish the current chunk for |
| * @error: %0 for success, < %0 for error |
| * |
| * Description: |
| * Complete the current consecutively mapped chunk from @rq. Must |
| * be called with queue lock held. |
| * |
| * Return: |
| * %false - we are done with this request |
| * %true - still buffers pending for this request |
| */ |
| bool __blk_end_request_cur(struct request *rq, int error) |
| { |
| return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); |
| } |
| EXPORT_SYMBOL(__blk_end_request_cur); |
| |
| /** |
| * __blk_end_request_err - Finish a request till the next failure boundary. |
| * @rq: the request to finish till the next failure boundary for |
| * @error: must be negative errno |
| * |
| * Description: |
| * Complete @rq till the next failure boundary. Must be called |
| * with queue lock held. |
| * |
| * Return: |
| * %false - we are done with this request |
| * %true - still buffers pending for this request |
| */ |
| bool __blk_end_request_err(struct request *rq, int error) |
| { |
| WARN_ON(error >= 0); |
| return __blk_end_request(rq, error, blk_rq_err_bytes(rq)); |
| } |
| EXPORT_SYMBOL_GPL(__blk_end_request_err); |
| |
| void blk_rq_bio_prep(struct request_queue *q, struct request *rq, |
| struct bio *bio) |
| { |
| /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */ |
| rq->cmd_flags |= bio->bi_rw & REQ_WRITE; |
| |
| if (bio_has_data(bio)) { |
| rq->nr_phys_segments = bio_phys_segments(q, bio); |
| rq->buffer = bio_data(bio); |
| } |
| rq->__data_len = bio->bi_size; |
| rq->bio = rq->biotail = bio; |
| |
| if (bio->bi_bdev) |
| rq->rq_disk = bio->bi_bdev->bd_disk; |
| } |
| |
| #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE |
| /** |
| * rq_flush_dcache_pages - Helper function to flush all pages in a request |
| * @rq: the request to be flushed |
| * |
| * Description: |
| * Flush all pages in @rq. |
| */ |
| void rq_flush_dcache_pages(struct request *rq) |
| { |
| struct req_iterator iter; |
| struct bio_vec *bvec; |
| |
| rq_for_each_segment(bvec, rq, iter) |
| flush_dcache_page(bvec->bv_page); |
| } |
| EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); |
| #endif |
| |
| /** |
| * blk_lld_busy - Check if underlying low-level drivers of a device are busy |
| * @q : the queue of the device being checked |
| * |
| * Description: |
| * Check if underlying low-level drivers of a device are busy. |
| * If the drivers want to export their busy state, they must set own |
| * exporting function using blk_queue_lld_busy() first. |
| * |
| * Basically, this function is used only by request stacking drivers |
| * to stop dispatching requests to underlying devices when underlying |
| * devices are busy. This behavior helps more I/O merging on the queue |
| * of the request stacking driver and prevents I/O throughput regression |
| * on burst I/O load. |
| * |
| * Return: |
| * 0 - Not busy (The request stacking driver should dispatch request) |
| * 1 - Busy (The request stacking driver should stop dispatching request) |
| */ |
| int blk_lld_busy(struct request_queue *q) |
| { |
| if (q->lld_busy_fn) |
| return q->lld_busy_fn(q); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(blk_lld_busy); |
| |
| /** |
| * blk_rq_unprep_clone - Helper function to free all bios in a cloned request |
| * @rq: the clone request to be cleaned up |
| * |
| * Description: |
| * Free all bios in @rq for a cloned request. |
| */ |
| void blk_rq_unprep_clone(struct request *rq) |
| { |
| struct bio *bio; |
| |
| while ((bio = rq->bio) != NULL) { |
| rq->bio = bio->bi_next; |
| |
| bio_put(bio); |
| } |
| } |
| EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); |
| |
| /* |
| * Copy attributes of the original request to the clone request. |
| * The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied. |
| */ |
| static void __blk_rq_prep_clone(struct request *dst, struct request *src) |
| { |
| dst->cpu = src->cpu; |
| dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE; |
| dst->cmd_type = src->cmd_type; |
| dst->__sector = blk_rq_pos(src); |
| dst->__data_len = blk_rq_bytes(src); |
| dst->nr_phys_segments = src->nr_phys_segments; |
| dst->ioprio = src->ioprio; |
| dst->extra_len = src->extra_len; |
| } |
| |
| /** |
| * blk_rq_prep_clone - Helper function to setup clone request |
| * @rq: the request to be setup |
| * @rq_src: original request to be cloned |
| * @bs: bio_set that bios for clone are allocated from |
| * @gfp_mask: memory allocation mask for bio |
| * @bio_ctr: setup function to be called for each clone bio. |
| * Returns %0 for success, non %0 for failure. |
| * @data: private data to be passed to @bio_ctr |
| * |
| * Description: |
| * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. |
| * The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense) |
| * are not copied, and copying such parts is the caller's responsibility. |
| * Also, pages which the original bios are pointing to are not copied |
| * and the cloned bios just point same pages. |
| * So cloned bios must be completed before original bios, which means |
| * the caller must complete @rq before @rq_src. |
| */ |
| int blk_rq_prep_clone(struct request *rq, struct request *rq_src, |
| struct bio_set *bs, gfp_t gfp_mask, |
| int (*bio_ctr)(struct bio *, struct bio *, void *), |
| void *data) |
| { |
| struct bio *bio, *bio_src; |
| |
| if (!bs) |
| bs = fs_bio_set; |
| |
| blk_rq_init(NULL, rq); |
| |
| __rq_for_each_bio(bio_src, rq_src) { |
| bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs); |
| if (!bio) |
| goto free_and_out; |
| |
| __bio_clone(bio, bio_src); |
| |
| if (bio_integrity(bio_src) && |
| bio_integrity_clone(bio, bio_src, gfp_mask, bs)) |
| goto free_and_out; |
| |
| if (bio_ctr && bio_ctr(bio, bio_src, data)) |
| goto free_and_out; |
| |
| if (rq->bio) { |
| rq->biotail->bi_next = bio; |
| rq->biotail = bio; |
| } else |
| rq->bio = rq->biotail = bio; |
| } |
| |
| __blk_rq_prep_clone(rq, rq_src); |
| |
| return 0; |
| |
| free_and_out: |
| if (bio) |
| bio_free(bio, bs); |
| blk_rq_unprep_clone(rq); |
| |
| return -ENOMEM; |
| } |
| EXPORT_SYMBOL_GPL(blk_rq_prep_clone); |
| |
| int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) |
| { |
| return queue_work(kblockd_workqueue, work); |
| } |
| EXPORT_SYMBOL(kblockd_schedule_work); |
| |
| int kblockd_schedule_delayed_work(struct request_queue *q, |
| struct delayed_work *dwork, unsigned long delay) |
| { |
| return queue_delayed_work(kblockd_workqueue, dwork, delay); |
| } |
| EXPORT_SYMBOL(kblockd_schedule_delayed_work); |
| |
| #define PLUG_MAGIC 0x91827364 |
| |
| /** |
| * blk_start_plug - initialize blk_plug and track it inside the task_struct |
| * @plug: The &struct blk_plug that needs to be initialized |
| * |
| * Description: |
| * Tracking blk_plug inside the task_struct will help with auto-flushing the |
| * pending I/O should the task end up blocking between blk_start_plug() and |
| * blk_finish_plug(). This is important from a performance perspective, but |
| * also ensures that we don't deadlock. For instance, if the task is blocking |
| * for a memory allocation, memory reclaim could end up wanting to free a |
| * page belonging to that request that is currently residing in our private |
| * plug. By flushing the pending I/O when the process goes to sleep, we avoid |
| * this kind of deadlock. |
| */ |
| void blk_start_plug(struct blk_plug *plug) |
| { |
| struct task_struct *tsk = current; |
| |
| plug->magic = PLUG_MAGIC; |
| INIT_LIST_HEAD(&plug->list); |
| INIT_LIST_HEAD(&plug->cb_list); |
| plug->should_sort = 0; |
| |
| /* |
| * If this is a nested plug, don't actually assign it. It will be |
| * flushed on its own. |
| */ |
| if (!tsk->plug) { |
| /* |
| * Store ordering should not be needed here, since a potential |
| * preempt will imply a full memory barrier |
| */ |
| tsk->plug = plug; |
| } |
| } |
| EXPORT_SYMBOL(blk_start_plug); |
| |
| static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) |
| { |
| struct request *rqa = container_of(a, struct request, queuelist); |
| struct request *rqb = container_of(b, struct request, queuelist); |
| |
| return !(rqa->q <= rqb->q); |
| } |
| |
| /* |
| * If 'from_schedule' is true, then postpone the dispatch of requests |
| * until a safe kblockd context. We due this to avoid accidental big |
| * additional stack usage in driver dispatch, in places where the originally |
| * plugger did not intend it. |
| */ |
| static void queue_unplugged(struct request_queue *q, unsigned int depth, |
| bool from_schedule) |
| __releases(q->queue_lock) |
| { |
| trace_block_unplug(q, depth, !from_schedule); |
| |
| /* |
| * If we are punting this to kblockd, then we can safely drop |
| * the queue_lock before waking kblockd (which needs to take |
| * this lock). |
| */ |
| if (from_schedule) { |
| spin_unlock(q->queue_lock); |
| blk_run_queue_async(q); |
| } else { |
| __blk_run_queue(q); |
| spin_unlock(q->queue_lock); |
| } |
| |
| } |
| |
| static void flush_plug_callbacks(struct blk_plug *plug) |
| { |
| LIST_HEAD(callbacks); |
| |
| if (list_empty(&plug->cb_list)) |
| return; |
| |
| list_splice_init(&plug->cb_list, &callbacks); |
| |
| while (!list_empty(&callbacks)) { |
| struct blk_plug_cb *cb = list_first_entry(&callbacks, |
| struct blk_plug_cb, |
| list); |
| list_del(&cb->list); |
| cb->callback(cb); |
| } |
| } |
| |
| void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) |
| { |
| struct request_queue *q; |
| unsigned long flags; |
| struct request *rq; |
| LIST_HEAD(list); |
| unsigned int depth; |
| |
| BUG_ON(plug->magic != PLUG_MAGIC); |
| |
| flush_plug_callbacks(plug); |
| if (list_empty(&plug->list)) |
| return; |
| |
| list_splice_init(&plug->list, &list); |
| |
| if (plug->should_sort) { |
| list_sort(NULL, &list, plug_rq_cmp); |
| plug->should_sort = 0; |
| } |
| |
| q = NULL; |
| depth = 0; |
| |
| /* |
| * Save and disable interrupts here, to avoid doing it for every |
| * queue lock we have to take. |
| */ |
| local_irq_save(flags); |
| while (!list_empty(&list)) { |
| rq = list_entry_rq(list.next); |
| list_del_init(&rq->queuelist); |
| BUG_ON(!rq->q); |
| if (rq->q != q) { |
| /* |
| * This drops the queue lock |
| */ |
| if (q) |
| queue_unplugged(q, depth, from_schedule); |
| q = rq->q; |
| depth = 0; |
| spin_lock(q->queue_lock); |
| } |
| /* |
| * rq is already accounted, so use raw insert |
| */ |
| if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) |
| __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH); |
| else |
| __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE); |
| |
| depth++; |
| } |
| |
| /* |
| * This drops the queue lock |
| */ |
| if (q) |
| queue_unplugged(q, depth, from_schedule); |
| |
| local_irq_restore(flags); |
| } |
| |
| void blk_finish_plug(struct blk_plug *plug) |
| { |
| blk_flush_plug_list(plug, false); |
| |
| if (plug == current->plug) |
| current->plug = NULL; |
| } |
| EXPORT_SYMBOL(blk_finish_plug); |
| |
| int __init blk_dev_init(void) |
| { |
| BUILD_BUG_ON(__REQ_NR_BITS > 8 * |
| sizeof(((struct request *)0)->cmd_flags)); |
| |
| /* used for unplugging and affects IO latency/throughput - HIGHPRI */ |
| kblockd_workqueue = alloc_workqueue("kblockd", |
| WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); |
| if (!kblockd_workqueue) |
| panic("Failed to create kblockd\n"); |
| |
| request_cachep = kmem_cache_create("blkdev_requests", |
| sizeof(struct request), 0, SLAB_PANIC, NULL); |
| |
| blk_requestq_cachep = kmem_cache_create("blkdev_queue", |
| sizeof(struct request_queue), 0, SLAB_PANIC, NULL); |
| |
| return 0; |
| } |