/* * 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>#include <linux/ratelimit.h> #define CREATE_TRACE_POINTS#include <trace/events/block.h> #include "blk.h"#include "blk-cgroup.h" EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); DEFINE_IDA(blk_queue_ida); /* * 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 blkcg_exit_queue() 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) { bool drain = false; int i; spin_lock_irq(q->queue_lock); /* * The caller might be trying to drain @q before its * elevator is initialized. */ if (q->elevator) elv_drain_elevator(q); blkcg_drain_queue(q); /* * This function might be called on a queue which failed * driver init after queue creation or is not yet fully * active yet. Some drivers (e.g. fd and loop) get unhappy * in such cases. Kick queue iff dispatch queue has * something on it and @q has request_fn set. */ if (!list_empty(&q->queue_head) && q->request_fn) __blk_run_queue(q); drain |= q->rq.elvpriv; /* * Unfortunately, requests are queued at and tracked from * multiple places and there's no single counter which can * be drained. Check all the queues and counters. */ if (drain_all) { drain |= !list_empty(&q->queue_head); for (i = 0; i < 2; i++) { drain |= q->rq.count[i]; drain |= q->in_flight[i]; drain |= !list_empty(&q->flush_queue[i]); } } spin_unlock_irq(q->queue_lock); if (!drain) break; msleep(10); }} /** * blk_queue_bypass_start - enter queue bypass mode * @q: queue of interest * * In bypass mode, only the dispatch FIFO queue of @q is used. This * function makes @q enter bypass mode and drains all requests which were * throttled or issued before. On return, it's guaranteed that no request * is being throttled or has ELVPRIV set and blk_queue_bypass() %true * inside queue or RCU read lock. */void blk_queue_bypass_start(struct request_queue *q){ bool drain; spin_lock_irq(q->queue_lock); drain = !q->bypass_depth++; queue_flag_set(QUEUE_FLAG_BYPASS, q); spin_unlock_irq(q->queue_lock); if (drain) { blk_drain_queue(q, false); /* ensure blk_queue_bypass() is %true inside RCU read lock */ synchronize_rcu(); }}EXPORT_SYMBOL_GPL(blk_queue_bypass_start); /** * blk_queue_bypass_end - leave queue bypass mode * @q: queue of interest * * Leave bypass mode and restore the normal queueing behavior. */void blk_queue_bypass_end(struct request_queue *q){ spin_lock_irq(q->queue_lock); if (!--q->bypass_depth) queue_flag_clear(QUEUE_FLAG_BYPASS, q); WARN_ON_ONCE(q->bypass_depth < 0); spin_unlock_irq(q->queue_lock);}EXPORT_SYMBOL_GPL(blk_queue_bypass_end); /** * 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); /* * Dead queue is permanently in bypass mode till released. Note * that, unlike blk_queue_bypass_start(), we aren't performing * synchronize_rcu() after entering bypass mode to avoid the delay * as some drivers create and destroy a lot of queues while * probing. This is still safe because blk_release_queue() will be * called only after the queue refcnt drops to zero and nothing, * RCU or not, would be traversing the queue by then. */ q->bypass_depth++; queue_flag_set(QUEUE_FLAG_BYPASS, q); queue_flag_set(QUEUE_FLAG_NOMERGES, q); queue_flag_set(QUEUE_FLAG_NOXMERGES, q); queue_flag_set(QUEUE_FLAG_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);Lines 1–500 of 3003. Load more
/* * 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> #include <linux/ratelimit.h> #define CREATE_TRACE_POINTS #include <trace/events/block.h> #include "blk.h" #include "blk-cgroup.h" EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); DEFINE_IDA(blk_queue_ida); /* * 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 blkcg_exit_queue() 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) { bool drain = false; int i; spin_lock_irq(q->queue_lock); /* * The caller might be trying to drain @q before its * elevator is initialized. */ if (q->elevator) elv_drain_elevator(q); blkcg_drain_queue(q); /* * This function might be called on a queue which failed * driver init after queue creation or is not yet fully * active yet. Some drivers (e.g. fd and loop) get unhappy * in such cases. Kick queue iff dispatch queue has * something on it and @q has request_fn set. */ if (!list_empty(&q->queue_head) && q->request_fn) __blk_run_queue(q); drain |= q->rq.elvpriv; /* * Unfortunately, requests are queued at and tracked from * multiple places and there's no single counter which can * be drained. Check all the queues and counters. */ if (drain_all) { drain |= !list_empty(&q->queue_head); for (i = 0; i < 2; i++) { drain |= q->rq.count[i]; drain |= q->in_flight[i]; drain |= !list_empty(&q->flush_queue[i]); } } spin_unlock_irq(q->queue_lock); if (!drain) break; msleep(10); } } /** * blk_queue_bypass_start - enter queue bypass mode * @q: queue of interest * * In bypass mode, only the dispatch FIFO queue of @q is used. This * function makes @q enter bypass mode and drains all requests which were * throttled or issued before. On return, it's guaranteed that no request * is being throttled or has ELVPRIV set and blk_queue_bypass() %true * inside queue or RCU read lock. */ void blk_queue_bypass_start(struct request_queue *q) { bool drain; spin_lock_irq(q->queue_lock); drain = !q->bypass_depth++; queue_flag_set(QUEUE_FLAG_BYPASS, q); spin_unlock_irq(q->queue_lock); if (drain) { blk_drain_queue(q, false); /* ensure blk_queue_bypass() is %true inside RCU read lock */ synchronize_rcu(); } } EXPORT_SYMBOL_GPL(blk_queue_bypass_start); /** * blk_queue_bypass_end - leave queue bypass mode * @q: queue of interest * * Leave bypass mode and restore the normal queueing behavior. */ void blk_queue_bypass_end(struct request_queue *q) { spin_lock_irq(q->queue_lock); if (!--q->bypass_depth) queue_flag_clear(QUEUE_FLAG_BYPASS, q); WARN_ON_ONCE(q->bypass_depth < 0); spin_unlock_irq(q->queue_lock); } EXPORT_SYMBOL_GPL(blk_queue_bypass_end); /** * 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); /* * Dead queue is permanently in bypass mode till released. Note * that, unlike blk_queue_bypass_start(), we aren't performing * synchronize_rcu() after entering bypass mode to avoid the delay * as some drivers create and destroy a lot of queues while * probing. This is still safe because blk_release_queue() will be * called only after the queue refcnt drops to zero and nothing, * RCU or not, would be traversing the queue by then. */ q->bypass_depth++; queue_flag_set(QUEUE_FLAG_BYPASS, q); queue_flag_set(QUEUE_FLAG_NOMERGES, q); queue_flag_set(QUEUE_FLAG_NOXMERGES, q); queue_flag_set(QUEUE_FLAG_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);