diff options
Diffstat (limited to 'block/blk-core.c')
| -rw-r--r-- | block/blk-core.c | 3978 |
1 files changed, 3978 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c new file mode 100644 index 000000000..80f3e729f --- /dev/null +++ b/block/blk-core.c @@ -0,0 +1,3978 @@ +/* + * Copyright (C) 1991, 1992 Linus Torvalds + * Copyright (C) 1994, Karl Keyte: Added support for disk statistics + * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE + * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> + * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> + * - July2000 + * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 + */ + +/* + * This handles all read/write requests to block devices + */ +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/backing-dev.h> +#include <linux/bio.h> +#include <linux/blkdev.h> +#include <linux/blk-mq.h> +#include <linux/highmem.h> +#include <linux/mm.h> +#include <linux/kernel_stat.h> +#include <linux/string.h> +#include <linux/init.h> +#include <linux/completion.h> +#include <linux/slab.h> +#include <linux/swap.h> +#include <linux/writeback.h> +#include <linux/task_io_accounting_ops.h> +#include <linux/fault-inject.h> +#include <linux/list_sort.h> +#include <linux/delay.h> +#include <linux/ratelimit.h> +#include <linux/pm_runtime.h> +#include <linux/blk-cgroup.h> +#include <linux/debugfs.h> +#include <linux/bpf.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/block.h> + +#include "blk.h" +#include "blk-mq.h" +#include "blk-mq-sched.h" +#include "blk-rq-qos.h" + +#ifdef CONFIG_DEBUG_FS +struct dentry *blk_debugfs_root; +#endif + +EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); +EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); +EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); +EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); +EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); + +DEFINE_IDA(blk_queue_ida); + +/* + * For the allocated request tables + */ +struct kmem_cache *request_cachep; + +/* + * For queue allocation + */ +struct kmem_cache *blk_requestq_cachep; + +/* + * Controlling structure to kblockd + */ +static struct workqueue_struct *kblockd_workqueue; + +/** + * blk_queue_flag_set - atomically set a queue flag + * @flag: flag to be set + * @q: request queue + */ +void blk_queue_flag_set(unsigned int flag, struct request_queue *q) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + queue_flag_set(flag, q); + spin_unlock_irqrestore(q->queue_lock, flags); +} +EXPORT_SYMBOL(blk_queue_flag_set); + +/** + * blk_queue_flag_clear - atomically clear a queue flag + * @flag: flag to be cleared + * @q: request queue + */ +void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + queue_flag_clear(flag, q); + spin_unlock_irqrestore(q->queue_lock, flags); +} +EXPORT_SYMBOL(blk_queue_flag_clear); + +/** + * blk_queue_flag_test_and_set - atomically test and set a queue flag + * @flag: flag to be set + * @q: request queue + * + * Returns the previous value of @flag - 0 if the flag was not set and 1 if + * the flag was already set. + */ +bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q) +{ + unsigned long flags; + bool res; + + spin_lock_irqsave(q->queue_lock, flags); + res = queue_flag_test_and_set(flag, q); + spin_unlock_irqrestore(q->queue_lock, flags); + + return res; +} +EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set); + +/** + * blk_queue_flag_test_and_clear - atomically test and clear a queue flag + * @flag: flag to be cleared + * @q: request queue + * + * Returns the previous value of @flag - 0 if the flag was not set and 1 if + * the flag was set. + */ +bool blk_queue_flag_test_and_clear(unsigned int flag, struct request_queue *q) +{ + unsigned long flags; + bool res; + + spin_lock_irqsave(q->queue_lock, flags); + res = queue_flag_test_and_clear(flag, q); + spin_unlock_irqrestore(q->queue_lock, flags); + + return res; +} +EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_clear); + +static void blk_clear_congested(struct request_list *rl, int sync) +{ +#ifdef CONFIG_CGROUP_WRITEBACK + clear_wb_congested(rl->blkg->wb_congested, sync); +#else + /* + * If !CGROUP_WRITEBACK, all blkg's map to bdi->wb and we shouldn't + * flip its congestion state for events on other blkcgs. + */ + if (rl == &rl->q->root_rl) + clear_wb_congested(rl->q->backing_dev_info->wb.congested, sync); +#endif +} + +static void blk_set_congested(struct request_list *rl, int sync) +{ +#ifdef CONFIG_CGROUP_WRITEBACK + set_wb_congested(rl->blkg->wb_congested, sync); +#else + /* see blk_clear_congested() */ + if (rl == &rl->q->root_rl) + set_wb_congested(rl->q->backing_dev_info->wb.congested, sync); +#endif +} + +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; +} + +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->tag = -1; + rq->internal_tag = -1; + rq->start_time_ns = ktime_get_ns(); + rq->part = NULL; + refcount_set(&rq->ref, 1); +} +EXPORT_SYMBOL(blk_rq_init); + +static const struct { + int errno; + const char *name; +} blk_errors[] = { + [BLK_STS_OK] = { 0, "" }, + [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, + [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, + [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, + [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, + [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, + [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, + [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, + [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, + [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, + [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, + [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, + + /* device mapper special case, should not leak out: */ + [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, + + /* everything else not covered above: */ + [BLK_STS_IOERR] = { -EIO, "I/O" }, +}; + +blk_status_t errno_to_blk_status(int errno) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { + if (blk_errors[i].errno == errno) + return (__force blk_status_t)i; + } + + return BLK_STS_IOERR; +} +EXPORT_SYMBOL_GPL(errno_to_blk_status); + +int blk_status_to_errno(blk_status_t status) +{ + int idx = (__force int)status; + + if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) + return -EIO; + return blk_errors[idx].errno; +} +EXPORT_SYMBOL_GPL(blk_status_to_errno); + +static void print_req_error(struct request *req, blk_status_t status) +{ + int idx = (__force int)status; + + if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) + return; + + printk_ratelimited(KERN_ERR "%s: %s error, dev %s, sector %llu\n", + __func__, blk_errors[idx].name, req->rq_disk ? + req->rq_disk->disk_name : "?", + (unsigned long long)blk_rq_pos(req)); +} + +static void req_bio_endio(struct request *rq, struct bio *bio, + unsigned int nbytes, blk_status_t error) +{ + if (error) + bio->bi_status = error; + + if (unlikely(rq->rq_flags & RQF_QUIET)) + bio_set_flag(bio, BIO_QUIET); + + bio_advance(bio, nbytes); + + /* don't actually finish bio if it's part of flush sequence */ + if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ)) + bio_endio(bio); +} + +void blk_dump_rq_flags(struct request *rq, char *msg) +{ + printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg, + rq->rq_disk ? rq->rq_disk->disk_name : "?", + (unsigned long long) rq->cmd_flags); + + printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n", + (unsigned long long)blk_rq_pos(rq), + blk_rq_sectors(rq), blk_rq_cur_sectors(rq)); + printk(KERN_INFO " bio %p, biotail %p, len %u\n", + rq->bio, rq->biotail, blk_rq_bytes(rq)); +} +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) +{ + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + if (likely(!blk_queue_dead(q))) + queue_delayed_work(kblockd_workqueue, &q->delay_work, + msecs_to_jiffies(msecs)); +} +EXPORT_SYMBOL(blk_delay_queue); + +/** + * blk_start_queue_async - asynchronously restart a previously stopped queue + * @q: The &struct request_queue in question + * + * Description: + * blk_start_queue_async() will clear the stop flag on the queue, and + * ensure that the request_fn for the queue is run from an async + * context. + **/ +void blk_start_queue_async(struct request_queue *q) +{ + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + queue_flag_clear(QUEUE_FLAG_STOPPED, q); + blk_run_queue_async(q); +} +EXPORT_SYMBOL(blk_start_queue_async); + +/** + * 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(). + **/ +void blk_start_queue(struct request_queue *q) +{ + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + 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. + **/ +void blk_stop_queue(struct request_queue *q) +{ + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + cancel_delayed_work(&q->delay_work); + queue_flag_set(QUEUE_FLAG_STOPPED, q); +} +EXPORT_SYMBOL(blk_stop_queue); + +/** + * blk_sync_queue - cancel any pending callbacks on a queue + * @q: the queue + * + * Description: + * The block layer may perform asynchronous callback activity + * on a queue, such as calling the unplug function after a timeout. + * A block device may call blk_sync_queue to ensure that any + * such activity is cancelled, thus allowing it to release resources + * that the callbacks might use. The caller must already have made sure + * that its ->make_request_fn will not re-add plugging prior to calling + * this function. + * + * This function does not cancel any asynchronous activity arising + * out of elevator or throttling code. That would require elevator_exit() + * and blkcg_exit_queue() to be called with queue lock initialized. + * + */ +void blk_sync_queue(struct request_queue *q) +{ + del_timer_sync(&q->timeout); + cancel_work_sync(&q->timeout_work); + + if (q->mq_ops) { + struct blk_mq_hw_ctx *hctx; + int i; + + queue_for_each_hw_ctx(q, hctx, i) + cancel_delayed_work_sync(&hctx->run_work); + } else { + cancel_delayed_work_sync(&q->delay_work); + } +} +EXPORT_SYMBOL(blk_sync_queue); + +/** + * blk_set_pm_only - increment pm_only counter + * @q: request queue pointer + */ +void blk_set_pm_only(struct request_queue *q) +{ + atomic_inc(&q->pm_only); +} +EXPORT_SYMBOL_GPL(blk_set_pm_only); + +void blk_clear_pm_only(struct request_queue *q) +{ + int pm_only; + + pm_only = atomic_dec_return(&q->pm_only); + WARN_ON_ONCE(pm_only < 0); + if (pm_only == 0) + wake_up_all(&q->mq_freeze_wq); +} +EXPORT_SYMBOL_GPL(blk_clear_pm_only); + +/** + * __blk_run_queue_uncond - run a queue whether or not it has been stopped + * @q: The queue to run + * + * Description: + * Invoke request handling on a queue if there are any pending requests. + * May be used to restart request handling after a request has completed. + * This variant runs the queue whether or not the queue has been + * stopped. Must be called with the queue lock held and interrupts + * disabled. See also @blk_run_queue. + */ +inline void __blk_run_queue_uncond(struct request_queue *q) +{ + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + if (unlikely(blk_queue_dead(q))) + return; + + /* + * Some request_fn implementations, e.g. scsi_request_fn(), unlock + * the queue lock internally. As a result multiple threads may be + * running such a request function concurrently. Keep track of the + * number of active request_fn invocations such that blk_drain_queue() + * can wait until all these request_fn calls have finished. + */ + q->request_fn_active++; + q->request_fn(q); + q->request_fn_active--; +} +EXPORT_SYMBOL_GPL(__blk_run_queue_uncond); + +/** + * __blk_run_queue - run a single device queue + * @q: The queue to run + * + * Description: + * See @blk_run_queue. + */ +void __blk_run_queue(struct request_queue *q) +{ + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + if (unlikely(blk_queue_stopped(q))) + return; + + __blk_run_queue_uncond(q); +} +EXPORT_SYMBOL(__blk_run_queue); + +/** + * blk_run_queue_async - run a single device queue in workqueue context + * @q: The queue to run + * + * Description: + * Tells kblockd to perform the equivalent of @blk_run_queue on behalf + * of us. + * + * Note: + * Since it is not allowed to run q->delay_work after blk_cleanup_queue() + * has canceled q->delay_work, callers must hold the queue lock to avoid + * race conditions between blk_cleanup_queue() and blk_run_queue_async(). + */ +void blk_run_queue_async(struct request_queue *q) +{ + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + if (likely(!blk_queue_stopped(q) && !blk_queue_dead(q))) + mod_delayed_work(kblockd_workqueue, &q->delay_work, 0); +} +EXPORT_SYMBOL(blk_run_queue_async); + +/** + * blk_run_queue - run a single device queue + * @q: The queue to run + * + * Description: + * Invoke request handling on this queue, if it has pending work to do. + * May be used to restart queueing when a request has completed. + */ +void blk_run_queue(struct request_queue *q) +{ + unsigned long flags; + + WARN_ON_ONCE(q->mq_ops); + + spin_lock_irqsave(q->queue_lock, flags); + __blk_run_queue(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} +EXPORT_SYMBOL(blk_run_queue); + +void blk_put_queue(struct request_queue *q) +{ + kobject_put(&q->kobj); +} +EXPORT_SYMBOL(blk_put_queue); + +/** + * __blk_drain_queue - drain requests from request_queue + * @q: queue to drain + * @drain_all: whether to drain all requests or only the ones w/ ELVPRIV + * + * Drain requests from @q. If @drain_all is set, all requests are drained. + * If not, only ELVPRIV requests are drained. The caller is responsible + * for ensuring that no new requests which need to be drained are queued. + */ +static void __blk_drain_queue(struct request_queue *q, bool drain_all) + __releases(q->queue_lock) + __acquires(q->queue_lock) +{ + int i; + + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + while (true) { + bool drain = false; + + /* + * The caller might be trying to drain @q before its + * elevator is initialized. + */ + if (q->elevator) + elv_drain_elevator(q); + + blkcg_drain_queue(q); + + /* + * This function might be called on a queue which failed + * driver init after queue creation or is not yet fully + * active yet. Some drivers (e.g. fd and loop) get unhappy + * in such cases. Kick queue iff dispatch queue has + * something on it and @q has request_fn set. + */ + if (!list_empty(&q->queue_head) && q->request_fn) + __blk_run_queue(q); + + drain |= q->nr_rqs_elvpriv; + drain |= q->request_fn_active; + + /* + * Unfortunately, requests are queued at and tracked from + * multiple places and there's no single counter which can + * be drained. Check all the queues and counters. + */ + if (drain_all) { + struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL); + drain |= !list_empty(&q->queue_head); + for (i = 0; i < 2; i++) { + drain |= q->nr_rqs[i]; + drain |= q->in_flight[i]; + if (fq) + drain |= !list_empty(&fq->flush_queue[i]); + } + } + + if (!drain) + break; + + spin_unlock_irq(q->queue_lock); + + msleep(10); + + spin_lock_irq(q->queue_lock); + } + + /* + * With queue marked dead, any woken up waiter will fail the + * allocation path, so the wakeup chaining is lost and we're + * left with hung waiters. We need to wake up those waiters. + */ + if (q->request_fn) { + struct request_list *rl; + + blk_queue_for_each_rl(rl, q) + for (i = 0; i < ARRAY_SIZE(rl->wait); i++) + wake_up_all(&rl->wait[i]); + } +} + +void blk_drain_queue(struct request_queue *q) +{ + spin_lock_irq(q->queue_lock); + __blk_drain_queue(q, true); + spin_unlock_irq(q->queue_lock); +} + +/** + * 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) +{ + WARN_ON_ONCE(q->mq_ops); + + spin_lock_irq(q->queue_lock); + q->bypass_depth++; + queue_flag_set(QUEUE_FLAG_BYPASS, q); + spin_unlock_irq(q->queue_lock); + + /* + * Queues start drained. Skip actual draining till init is + * complete. This avoids lenghty delays during queue init which + * can happen many times during boot. + */ + if (blk_queue_init_done(q)) { + spin_lock_irq(q->queue_lock); + __blk_drain_queue(q, false); + spin_unlock_irq(q->queue_lock); + + /* ensure blk_queue_bypass() is %true inside RCU read lock */ + synchronize_rcu(); + } +} +EXPORT_SYMBOL_GPL(blk_queue_bypass_start); + +/** + * blk_queue_bypass_end - leave queue bypass mode + * @q: queue of interest + * + * Leave bypass mode and restore the normal queueing behavior. + * + * Note: although blk_queue_bypass_start() is only called for blk-sq queues, + * this function is called for both blk-sq and blk-mq queues. + */ +void blk_queue_bypass_end(struct request_queue *q) +{ + spin_lock_irq(q->queue_lock); + if (!--q->bypass_depth) + queue_flag_clear(QUEUE_FLAG_BYPASS, q); + WARN_ON_ONCE(q->bypass_depth < 0); + spin_unlock_irq(q->queue_lock); +} +EXPORT_SYMBOL_GPL(blk_queue_bypass_end); + +void blk_set_queue_dying(struct request_queue *q) +{ + blk_queue_flag_set(QUEUE_FLAG_DYING, q); + + /* + * When queue DYING flag is set, we need to block new req + * entering queue, so we call blk_freeze_queue_start() to + * prevent I/O from crossing blk_queue_enter(). + */ + blk_freeze_queue_start(q); + + if (q->mq_ops) + blk_mq_wake_waiters(q); + else { + struct request_list *rl; + + spin_lock_irq(q->queue_lock); + blk_queue_for_each_rl(rl, q) { + if (rl->rq_pool) { + wake_up_all(&rl->wait[BLK_RW_SYNC]); + wake_up_all(&rl->wait[BLK_RW_ASYNC]); + } + } + spin_unlock_irq(q->queue_lock); + } + + /* Make blk_queue_enter() reexamine the DYING flag. */ + wake_up_all(&q->mq_freeze_wq); +} +EXPORT_SYMBOL_GPL(blk_set_queue_dying); + +/* Unconfigure the I/O scheduler and dissociate from the cgroup controller. */ +void blk_exit_queue(struct request_queue *q) +{ + /* + * Since the I/O scheduler exit code may access cgroup information, + * perform I/O scheduler exit before disassociating from the block + * cgroup controller. + */ + if (q->elevator) { + ioc_clear_queue(q); + elevator_exit(q, q->elevator); + q->elevator = NULL; + } + + /* + * Remove all references to @q from the block cgroup controller before + * restoring @q->queue_lock to avoid that restoring this pointer causes + * e.g. blkcg_print_blkgs() to crash. + */ + blkcg_exit_queue(q); + + /* + * Since the cgroup code may dereference the @q->backing_dev_info + * pointer, only decrease its reference count after having removed the + * association with the block cgroup controller. + */ + bdi_put(q->backing_dev_info); +} + +/** + * blk_cleanup_queue - shutdown a request queue + * @q: request queue to shutdown + * + * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and + * put it. All future requests will be failed immediately with -ENODEV. + */ +void blk_cleanup_queue(struct request_queue *q) +{ + spinlock_t *lock = q->queue_lock; + + /* mark @q DYING, no new request or merges will be allowed afterwards */ + mutex_lock(&q->sysfs_lock); + blk_set_queue_dying(q); + spin_lock_irq(lock); + + /* + * A dying queue is permanently in bypass mode till released. Note + * that, unlike blk_queue_bypass_start(), we aren't performing + * synchronize_rcu() after entering bypass mode to avoid the delay + * as some drivers create and destroy a lot of queues while + * probing. This is still safe because blk_release_queue() will be + * called only after the queue refcnt drops to zero and nothing, + * RCU or not, would be traversing the queue by then. + */ + q->bypass_depth++; + queue_flag_set(QUEUE_FLAG_BYPASS, q); + + queue_flag_set(QUEUE_FLAG_NOMERGES, q); + queue_flag_set(QUEUE_FLAG_NOXMERGES, q); + queue_flag_set(QUEUE_FLAG_DYING, q); + spin_unlock_irq(lock); + mutex_unlock(&q->sysfs_lock); + + /* + * Drain all requests queued before DYING marking. Set DEAD flag to + * prevent that q->request_fn() gets invoked after draining finished. + */ + blk_freeze_queue(q); + + rq_qos_exit(q); + + spin_lock_irq(lock); + queue_flag_set(QUEUE_FLAG_DEAD, q); + spin_unlock_irq(lock); + + /* + * make sure all in-progress dispatch are completed because + * blk_freeze_queue() can only complete all requests, and + * dispatch may still be in-progress since we dispatch requests + * from more than one contexts. + * + * We rely on driver to deal with the race in case that queue + * initialization isn't done. + */ + if (q->mq_ops && blk_queue_init_done(q)) + blk_mq_quiesce_queue(q); + + /* for synchronous bio-based driver finish in-flight integrity i/o */ + blk_flush_integrity(); + + /* @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); + + /* + * I/O scheduler exit is only safe after the sysfs scheduler attribute + * has been removed. + */ + WARN_ON_ONCE(q->kobj.state_in_sysfs); + + blk_exit_queue(q); + + if (q->mq_ops) + blk_mq_exit_queue(q); + + percpu_ref_exit(&q->q_usage_counter); + + spin_lock_irq(lock); + if (q->queue_lock != &q->__queue_lock) + q->queue_lock = &q->__queue_lock; + spin_unlock_irq(lock); + + /* @q is and will stay empty, shutdown and put */ + blk_put_queue(q); +} +EXPORT_SYMBOL(blk_cleanup_queue); + +/* Allocate memory local to the request queue */ +static void *alloc_request_simple(gfp_t gfp_mask, void *data) +{ + struct request_queue *q = data; + + return kmem_cache_alloc_node(request_cachep, gfp_mask, q->node); +} + +static void free_request_simple(void *element, void *data) +{ + kmem_cache_free(request_cachep, element); +} + +static void *alloc_request_size(gfp_t gfp_mask, void *data) +{ + struct request_queue *q = data; + struct request *rq; + + rq = kmalloc_node(sizeof(struct request) + q->cmd_size, gfp_mask, + q->node); + if (rq && q->init_rq_fn && q->init_rq_fn(q, rq, gfp_mask) < 0) { + kfree(rq); + rq = NULL; + } + return rq; +} + +static void free_request_size(void *element, void *data) +{ + struct request_queue *q = data; + + if (q->exit_rq_fn) + q->exit_rq_fn(q, element); + kfree(element); +} + +int blk_init_rl(struct request_list *rl, struct request_queue *q, + gfp_t gfp_mask) +{ + if (unlikely(rl->rq_pool) || q->mq_ops) + return 0; + + rl->q = q; + rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0; + rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0; + init_waitqueue_head(&rl->wait[BLK_RW_SYNC]); + init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]); + + if (q->cmd_size) { + rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, + alloc_request_size, free_request_size, + q, gfp_mask, q->node); + } else { + rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, + alloc_request_simple, free_request_simple, + q, gfp_mask, q->node); + } + if (!rl->rq_pool) + return -ENOMEM; + + if (rl != &q->root_rl) + WARN_ON_ONCE(!blk_get_queue(q)); + + return 0; +} + +void blk_exit_rl(struct request_queue *q, struct request_list *rl) +{ + if (rl->rq_pool) { + mempool_destroy(rl->rq_pool); + if (rl != &q->root_rl) + blk_put_queue(q); + } +} + +struct request_queue *blk_alloc_queue(gfp_t gfp_mask) +{ + return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE, NULL); +} +EXPORT_SYMBOL(blk_alloc_queue); + +/** + * blk_queue_enter() - try to increase q->q_usage_counter + * @q: request queue pointer + * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT + */ +int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) +{ + const bool pm = flags & BLK_MQ_REQ_PREEMPT; + + while (true) { + bool success = false; + + rcu_read_lock(); + if (percpu_ref_tryget_live(&q->q_usage_counter)) { + /* + * The code that increments the pm_only counter is + * responsible for ensuring that that counter is + * globally visible before the queue is unfrozen. + */ + if (pm || !blk_queue_pm_only(q)) { + success = true; + } else { + percpu_ref_put(&q->q_usage_counter); + } + } + rcu_read_unlock(); + + if (success) + return 0; + + if (flags & BLK_MQ_REQ_NOWAIT) + return -EBUSY; + + /* + * read pair of barrier in blk_freeze_queue_start(), + * we need to order reading __PERCPU_REF_DEAD flag of + * .q_usage_counter and reading .mq_freeze_depth or + * queue dying flag, otherwise the following wait may + * never return if the two reads are reordered. + */ + smp_rmb(); + + wait_event(q->mq_freeze_wq, + (atomic_read(&q->mq_freeze_depth) == 0 && + (pm || !blk_queue_pm_only(q))) || + blk_queue_dying(q)); + if (blk_queue_dying(q)) + return -ENODEV; + } +} + +void blk_queue_exit(struct request_queue *q) +{ + percpu_ref_put(&q->q_usage_counter); +} + +static void blk_queue_usage_counter_release(struct percpu_ref *ref) +{ + struct request_queue *q = + container_of(ref, struct request_queue, q_usage_counter); + + wake_up_all(&q->mq_freeze_wq); +} + +static void blk_rq_timed_out_timer(struct timer_list *t) +{ + struct request_queue *q = from_timer(q, t, timeout); + + kblockd_schedule_work(&q->timeout_work); +} + +static void blk_timeout_work_dummy(struct work_struct *work) +{ +} + +/** + * blk_alloc_queue_node - allocate a request queue + * @gfp_mask: memory allocation flags + * @node_id: NUMA node to allocate memory from + * @lock: For legacy queues, pointer to a spinlock that will be used to e.g. + * serialize calls to the legacy .request_fn() callback. Ignored for + * blk-mq request queues. + * + * Note: pass the queue lock as the third argument to this function instead of + * setting the queue lock pointer explicitly to avoid triggering a sporadic + * crash in the blkcg code. This function namely calls blkcg_init_queue() and + * the queue lock pointer must be set before blkcg_init_queue() is called. + */ +struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id, + spinlock_t *lock) +{ + struct request_queue *q; + int ret; + + q = kmem_cache_alloc_node(blk_requestq_cachep, + gfp_mask | __GFP_ZERO, node_id); + if (!q) + return NULL; + + INIT_LIST_HEAD(&q->queue_head); + q->last_merge = NULL; + q->end_sector = 0; + q->boundary_rq = NULL; + + q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask); + if (q->id < 0) + goto fail_q; + + ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS); + if (ret) + goto fail_id; + + q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id); + if (!q->backing_dev_info) + goto fail_split; + + q->stats = blk_alloc_queue_stats(); + if (!q->stats) + goto fail_stats; + + q->backing_dev_info->ra_pages = + (VM_MAX_READAHEAD * 1024) / PAGE_SIZE; + q->backing_dev_info->io_pages = + (VM_MAX_READAHEAD * 1024) / PAGE_SIZE; + q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; + q->backing_dev_info->name = "block"; + q->node = node_id; + + timer_setup(&q->backing_dev_info->laptop_mode_wb_timer, + laptop_mode_timer_fn, 0); + timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); + INIT_WORK(&q->timeout_work, blk_timeout_work_dummy); + INIT_LIST_HEAD(&q->timeout_list); + INIT_LIST_HEAD(&q->icq_list); +#ifdef CONFIG_BLK_CGROUP + INIT_LIST_HEAD(&q->blkg_list); +#endif + INIT_DELAYED_WORK(&q->delay_work, blk_delay_work); + + kobject_init(&q->kobj, &blk_queue_ktype); + +#ifdef CONFIG_BLK_DEV_IO_TRACE + mutex_init(&q->blk_trace_mutex); +#endif + mutex_init(&q->sysfs_lock); + mutex_init(&q->sysfs_dir_lock); + spin_lock_init(&q->__queue_lock); + + if (!q->mq_ops) + q->queue_lock = lock ? : &q->__queue_lock; + + /* + * A queue starts its life with bypass turned on to avoid + * unnecessary bypass on/off overhead and nasty surprises during + * init. The initial bypass will be finished when the queue is + * registered by blk_register_queue(). + */ + q->bypass_depth = 1; + queue_flag_set_unlocked(QUEUE_FLAG_BYPASS, q); + + init_waitqueue_head(&q->mq_freeze_wq); + + /* + * Init percpu_ref in atomic mode so that it's faster to shutdown. + * See blk_register_queue() for details. + */ + if (percpu_ref_init(&q->q_usage_counter, + blk_queue_usage_counter_release, + PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) + goto fail_bdi; + + if (blkcg_init_queue(q)) + goto fail_ref; + + return q; + +fail_ref: + percpu_ref_exit(&q->q_usage_counter); +fail_bdi: + blk_free_queue_stats(q->stats); +fail_stats: + bdi_put(q->backing_dev_info); +fail_split: + bioset_exit(&q->bio_split); +fail_id: + ida_simple_remove(&blk_queue_ida, q->id); +fail_q: + kmem_cache_free(blk_requestq_cachep, q); + return NULL; +} +EXPORT_SYMBOL(blk_alloc_queue_node); + +/** + * blk_init_queue - prepare a request queue for use with a block device + * @rfn: The function to be called to process requests that have been + * placed on the queue. + * @lock: Request queue spin lock + * + * Description: + * If a block device wishes to use the standard request handling procedures, + * which sorts requests and coalesces adjacent requests, then it must + * call blk_init_queue(). The function @rfn will be called when there + * are requests on the queue that need to be processed. If the device + * supports plugging, then @rfn may not be called immediately when requests + * are available on the queue, but may be called at some time later instead. + * Plugged queues are generally unplugged when a buffer belonging to one + * of the requests on the queue is needed, or due to memory pressure. + * + * @rfn is not required, or even expected, to remove all requests off the + * queue, but only as many as it can handle at a time. If it does leave + * requests on the queue, it is responsible for arranging that the requests + * get dealt with eventually. + * + * The queue spin lock must be held while manipulating the requests on the + * request queue; this lock will be taken also from interrupt context, so irq + * disabling is needed for it. + * + * Function returns a pointer to the initialized request queue, or %NULL if + * it didn't succeed. + * + * Note: + * blk_init_queue() must be paired with a blk_cleanup_queue() call + * when the block device is deactivated (such as at module unload). + **/ + +struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) +{ + return blk_init_queue_node(rfn, lock, NUMA_NO_NODE); +} +EXPORT_SYMBOL(blk_init_queue); + +struct request_queue * +blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) +{ + struct request_queue *q; + + q = blk_alloc_queue_node(GFP_KERNEL, node_id, lock); + if (!q) + return NULL; + + q->request_fn = rfn; + if (blk_init_allocated_queue(q) < 0) { + blk_cleanup_queue(q); + return NULL; + } + + return q; +} +EXPORT_SYMBOL(blk_init_queue_node); + +static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio); + + +int blk_init_allocated_queue(struct request_queue *q) +{ + WARN_ON_ONCE(q->mq_ops); + + q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, q->cmd_size, GFP_KERNEL); + if (!q->fq) + return -ENOMEM; + + if (q->init_rq_fn && q->init_rq_fn(q, q->fq->flush_rq, GFP_KERNEL)) + goto out_free_flush_queue; + + if (blk_init_rl(&q->root_rl, q, GFP_KERNEL)) + goto out_exit_flush_rq; + + INIT_WORK(&q->timeout_work, blk_timeout_work); + q->queue_flags |= QUEUE_FLAG_DEFAULT; + + /* + * This also sets hw/phys segments, boundary and size + */ + blk_queue_make_request(q, blk_queue_bio); + + q->sg_reserved_size = INT_MAX; + + if (elevator_init(q)) + goto out_exit_flush_rq; + return 0; + +out_exit_flush_rq: + if (q->exit_rq_fn) + q->exit_rq_fn(q, q->fq->flush_rq); +out_free_flush_queue: + blk_free_flush_queue(q->fq); + q->fq = NULL; + return -ENOMEM; +} +EXPORT_SYMBOL(blk_init_allocated_queue); + +bool blk_get_queue(struct request_queue *q) +{ + if (likely(!blk_queue_dying(q))) { + __blk_get_queue(q); + return true; + } + + return false; +} +EXPORT_SYMBOL(blk_get_queue); + +static inline void blk_free_request(struct request_list *rl, struct request *rq) +{ + if (rq->rq_flags & RQF_ELVPRIV) { + elv_put_request(rl->q, rq); + if (rq->elv.icq) + put_io_context(rq->elv.icq->ioc); + } + + mempool_free(rq, rl->rq_pool); +} + +/* + * ioc_batching returns true if the ioc is a valid batching request and + * should be given priority access to a request. + */ +static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) +{ + if (!ioc) + return 0; + + /* + * Make sure the process is able to allocate at least 1 request + * even if the batch times out, otherwise we could theoretically + * lose wakeups. + */ + return ioc->nr_batch_requests == q->nr_batching || + (ioc->nr_batch_requests > 0 + && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); +} + +/* + * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This + * will cause the process to be a "batcher" on all queues in the system. This + * is the behaviour we want though - once it gets a wakeup it should be given + * a nice run. + */ +static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) +{ + if (!ioc || ioc_batching(q, ioc)) + return; + + ioc->nr_batch_requests = q->nr_batching; + ioc->last_waited = jiffies; +} + +static void __freed_request(struct request_list *rl, int sync) +{ + struct request_queue *q = rl->q; + + if (rl->count[sync] < queue_congestion_off_threshold(q)) + blk_clear_congested(rl, sync); + + if (rl->count[sync] + 1 <= q->nr_requests) { + if (waitqueue_active(&rl->wait[sync])) + wake_up(&rl->wait[sync]); + + blk_clear_rl_full(rl, sync); + } +} + +/* + * A request has just been released. Account for it, update the full and + * congestion status, wake up any waiters. Called under q->queue_lock. + */ +static void freed_request(struct request_list *rl, bool sync, + req_flags_t rq_flags) +{ + struct request_queue *q = rl->q; + + q->nr_rqs[sync]--; + rl->count[sync]--; + if (rq_flags & RQF_ELVPRIV) + q->nr_rqs_elvpriv--; + + __freed_request(rl, sync); + + if (unlikely(rl->starved[sync ^ 1])) + __freed_request(rl, sync ^ 1); +} + +int blk_update_nr_requests(struct request_queue *q, unsigned int nr) +{ + struct request_list *rl; + int on_thresh, off_thresh; + + WARN_ON_ONCE(q->mq_ops); + + spin_lock_irq(q->queue_lock); + q->nr_requests = nr; + blk_queue_congestion_threshold(q); + on_thresh = queue_congestion_on_threshold(q); + off_thresh = queue_congestion_off_threshold(q); + + blk_queue_for_each_rl(rl, q) { + if (rl->count[BLK_RW_SYNC] >= on_thresh) + blk_set_congested(rl, BLK_RW_SYNC); + else if (rl->count[BLK_RW_SYNC] < off_thresh) + blk_clear_congested(rl, BLK_RW_SYNC); + + if (rl->count[BLK_RW_ASYNC] >= on_thresh) + blk_set_congested(rl, BLK_RW_ASYNC); + else if (rl->count[BLK_RW_ASYNC] < off_thresh) + blk_clear_congested(rl, BLK_RW_ASYNC); + + if (rl->count[BLK_RW_SYNC] >= q->nr_requests) { + blk_set_rl_full(rl, BLK_RW_SYNC); + } else { + blk_clear_rl_full(rl, BLK_RW_SYNC); + wake_up(&rl->wait[BLK_RW_SYNC]); + } + + if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) { + blk_set_rl_full(rl, BLK_RW_ASYNC); + } else { + blk_clear_rl_full(rl, BLK_RW_ASYNC); + wake_up(&rl->wait[BLK_RW_ASYNC]); + } + } + + spin_unlock_irq(q->queue_lock); + return 0; +} + +/** + * __get_request - get a free request + * @rl: request list to allocate from + * @op: operation and flags + * @bio: bio to allocate request for (can be %NULL) + * @flags: BLQ_MQ_REQ_* flags + * @gfp_mask: allocator flags + * + * Get a free request from @q. This function may fail under memory + * pressure or if @q is dead. + * + * Must be called with @q->queue_lock held and, + * Returns ERR_PTR on failure, with @q->queue_lock held. + * Returns request pointer on success, with @q->queue_lock *not held*. + */ +static struct request *__get_request(struct request_list *rl, unsigned int op, + struct bio *bio, blk_mq_req_flags_t flags, gfp_t gfp_mask) +{ + struct request_queue *q = rl->q; + struct request *rq; + struct elevator_type *et = q->elevator->type; + struct io_context *ioc = rq_ioc(bio); + struct io_cq *icq = NULL; + const bool is_sync = op_is_sync(op); + int may_queue; + req_flags_t rq_flags = RQF_ALLOCED; + + lockdep_assert_held(q->queue_lock); + + if (unlikely(blk_queue_dying(q))) + return ERR_PTR(-ENODEV); + + may_queue = elv_may_queue(q, op); + if (may_queue == ELV_MQUEUE_NO) + goto rq_starved; + + if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) { + if (rl->count[is_sync]+1 >= q->nr_requests) { + /* + * The queue will fill after this allocation, so set + * it as full, and mark this process as "batching". + * This process will be allowed to complete a batch of + * requests, others will be blocked. + */ + if (!blk_rl_full(rl, is_sync)) { + ioc_set_batching(q, ioc); + blk_set_rl_full(rl, is_sync); + } else { + if (may_queue != ELV_MQUEUE_MUST + && !ioc_batching(q, ioc)) { + /* + * The queue is full and the allocating + * process is not a "batcher", and not + * exempted by the IO scheduler + */ + return ERR_PTR(-ENOMEM); + } + } + } + blk_set_congested(rl, is_sync); + } + + /* + * Only allow batching queuers to allocate up to 50% over the defined + * limit of requests, otherwise we could have thousands of requests + * allocated with any setting of ->nr_requests + */ + if (rl->count[is_sync] >= (3 * q->nr_requests / 2)) + return ERR_PTR(-ENOMEM); + + q->nr_rqs[is_sync]++; + rl->count[is_sync]++; + rl->starved[is_sync] = 0; + + /* + * Decide whether the new request will be managed by elevator. If + * so, mark @rq_flags and increment elvpriv. Non-zero elvpriv will + * prevent the current elevator from being destroyed until the new + * request is freed. This guarantees icq's won't be destroyed and + * makes creating new ones safe. + * + * Flush requests do not use the elevator so skip initialization. + * This allows a request to share the flush and elevator data. + * + * Also, lookup icq while holding queue_lock. If it doesn't exist, + * it will be created after releasing queue_lock. + */ + if (!op_is_flush(op) && !blk_queue_bypass(q)) { + rq_flags |= RQF_ELVPRIV; + q->nr_rqs_elvpriv++; + if (et->icq_cache && ioc) + icq = ioc_lookup_icq(ioc, q); + } + + if (blk_queue_io_stat(q)) + rq_flags |= RQF_IO_STAT; + spin_unlock_irq(q->queue_lock); + + /* allocate and init request */ + rq = mempool_alloc(rl->rq_pool, gfp_mask); + if (!rq) + goto fail_alloc; + + blk_rq_init(q, rq); + blk_rq_set_rl(rq, rl); + rq->cmd_flags = op; + rq->rq_flags = rq_flags; + if (flags & BLK_MQ_REQ_PREEMPT) + rq->rq_flags |= RQF_PREEMPT; + + /* init elvpriv */ + if (rq_flags & RQF_ELVPRIV) { + if (unlikely(et->icq_cache && !icq)) { + if (ioc) + icq = ioc_create_icq(ioc, q, gfp_mask); + if (!icq) + goto fail_elvpriv; + } + + rq->elv.icq = icq; + if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) + goto fail_elvpriv; + + /* @rq->elv.icq holds io_context until @rq is freed */ + if (icq) + get_io_context(icq->ioc); + } +out: + /* + * ioc may be NULL here, and ioc_batching will be false. That's + * OK, if the queue is under the request limit then requests need + * not count toward the nr_batch_requests limit. There will always + * be some limit enforced by BLK_BATCH_TIME. + */ + if (ioc_batching(q, ioc)) + ioc->nr_batch_requests--; + + trace_block_getrq(q, bio, op); + return rq; + +fail_elvpriv: + /* + * elvpriv init failed. ioc, icq and elvpriv aren't mempool backed + * and may fail indefinitely under memory pressure and thus + * shouldn't stall IO. Treat this request as !elvpriv. This will + * disturb iosched and blkcg but weird is bettern than dead. + */ + printk_ratelimited(KERN_WARNING "%s: dev %s: request aux data allocation failed, iosched may be disturbed\n", + __func__, dev_name(q->backing_dev_info->dev)); + + rq->rq_flags &= ~RQF_ELVPRIV; + rq->elv.icq = NULL; + + spin_lock_irq(q->queue_lock); + q->nr_rqs_elvpriv--; + spin_unlock_irq(q->queue_lock); + goto out; + +fail_alloc: + /* + * Allocation failed presumably due to memory. Undo anything we + * might have messed up. + * + * Allocating task should really be put onto the front of the wait + * queue, but this is pretty rare. + */ + spin_lock_irq(q->queue_lock); + freed_request(rl, is_sync, rq_flags); + + /* + * in the very unlikely event that allocation failed and no + * requests for this direction was pending, mark us starved so that + * freeing of a request in the other direction will notice + * us. another possible fix would be to split the rq mempool into + * READ and WRITE + */ +rq_starved: + if (unlikely(rl->count[is_sync] == 0)) + rl->starved[is_sync] = 1; + return ERR_PTR(-ENOMEM); +} + +/** + * get_request - get a free request + * @q: request_queue to allocate request from + * @op: operation and flags + * @bio: bio to allocate request for (can be %NULL) + * @flags: BLK_MQ_REQ_* flags. + * @gfp: allocator flags + * + * Get a free request from @q. If %BLK_MQ_REQ_NOWAIT is set in @flags, + * this function keeps retrying under memory pressure and fails iff @q is dead. + * + * Must be called with @q->queue_lock held and, + * Returns ERR_PTR on failure, with @q->queue_lock held. + * Returns request pointer on success, with @q->queue_lock *not held*. + */ +static struct request *get_request(struct request_queue *q, unsigned int op, + struct bio *bio, blk_mq_req_flags_t flags, gfp_t gfp) +{ + const bool is_sync = op_is_sync(op); + DEFINE_WAIT(wait); + struct request_list *rl; + struct request *rq; + + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + rl = blk_get_rl(q, bio); /* transferred to @rq on success */ +retry: + rq = __get_request(rl, op, bio, flags, gfp); + if (!IS_ERR(rq)) + return rq; + + if (op & REQ_NOWAIT) { + blk_put_rl(rl); + return ERR_PTR(-EAGAIN); + } + + if ((flags & BLK_MQ_REQ_NOWAIT) || unlikely(blk_queue_dying(q))) { + blk_put_rl(rl); + return rq; + } + + /* wait on @rl and retry */ + prepare_to_wait_exclusive(&rl->wait[is_sync], &wait, + TASK_UNINTERRUPTIBLE); + + trace_block_sleeprq(q, bio, op); + + spin_unlock_irq(q->queue_lock); + io_schedule(); + + /* + * After sleeping, we become a "batching" process and will be able + * to allocate at least one request, and up to a big batch of them + * for a small period time. See ioc_batching, ioc_set_batching + */ + ioc_set_batching(q, current->io_context); + + spin_lock_irq(q->queue_lock); + finish_wait(&rl->wait[is_sync], &wait); + + goto retry; +} + +/* flags: BLK_MQ_REQ_PREEMPT and/or BLK_MQ_REQ_NOWAIT. */ +static struct request *blk_old_get_request(struct request_queue *q, + unsigned int op, blk_mq_req_flags_t flags) +{ + struct request *rq; + gfp_t gfp_mask = flags & BLK_MQ_REQ_NOWAIT ? GFP_ATOMIC : GFP_NOIO; + int ret = 0; + + WARN_ON_ONCE(q->mq_ops); + + /* create ioc upfront */ + create_io_context(gfp_mask, q->node); + + ret = blk_queue_enter(q, flags); + if (ret) + return ERR_PTR(ret); + spin_lock_irq(q->queue_lock); + rq = get_request(q, op, NULL, flags, gfp_mask); + if (IS_ERR(rq)) { + spin_unlock_irq(q->queue_lock); + blk_queue_exit(q); + return rq; + } + + /* q->queue_lock is unlocked at this point */ + rq->__data_len = 0; + rq->__sector = (sector_t) -1; + rq->bio = rq->biotail = NULL; + return rq; +} + +/** + * blk_get_request - allocate a request + * @q: request queue to allocate a request for + * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC. + * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT. + */ +struct request *blk_get_request(struct request_queue *q, unsigned int op, + blk_mq_req_flags_t flags) +{ + struct request *req; + + WARN_ON_ONCE(op & REQ_NOWAIT); + WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT)); + + if (q->mq_ops) { + req = blk_mq_alloc_request(q, op, flags); + if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn) + q->mq_ops->initialize_rq_fn(req); + } else { + req = blk_old_get_request(q, op, flags); + if (!IS_ERR(req) && q->initialize_rq_fn) + q->initialize_rq_fn(req); + } + + return req; +} +EXPORT_SYMBOL(blk_get_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) +{ + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + blk_delete_timer(rq); + blk_clear_rq_complete(rq); + trace_block_rq_requeue(q, rq); + rq_qos_requeue(q, rq); + + if (rq->rq_flags & RQF_QUEUED) + blk_queue_end_tag(q, rq); + + BUG_ON(blk_queued_rq(rq)); + + elv_requeue_request(q, rq); +} +EXPORT_SYMBOL(blk_requeue_request); + +static void add_acct_request(struct request_queue *q, struct request *rq, + int where) +{ + blk_account_io_start(rq, true); + __elv_add_request(q, rq, where); +} + +static void part_round_stats_single(struct request_queue *q, int cpu, + struct hd_struct *part, unsigned long now, + unsigned int inflight) +{ + if (inflight) { + __part_stat_add(cpu, part, time_in_queue, + inflight * (now - part->stamp)); + __part_stat_add(cpu, part, io_ticks, (now - part->stamp)); + } + part->stamp = now; +} + +/** + * part_round_stats() - Round off the performance stats on a struct disk_stats. + * @q: target block queue + * @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(struct request_queue *q, int cpu, struct hd_struct *part) +{ + struct hd_struct *part2 = NULL; + unsigned long now = jiffies; + unsigned int inflight[2]; + int stats = 0; + + if (part->stamp != now) + stats |= 1; + + if (part->partno) { + part2 = &part_to_disk(part)->part0; + if (part2->stamp != now) + stats |= 2; + } + + if (!stats) + return; + + part_in_flight(q, part, inflight); + + if (stats & 2) + part_round_stats_single(q, cpu, part2, now, inflight[1]); + if (stats & 1) + part_round_stats_single(q, cpu, part, now, inflight[0]); +} +EXPORT_SYMBOL_GPL(part_round_stats); + +#ifdef CONFIG_PM +static void blk_pm_put_request(struct request *rq) +{ + if (rq->q->dev && !(rq->rq_flags & RQF_PM) && !--rq->q->nr_pending) + pm_runtime_mark_last_busy(rq->q->dev); +} +#else +static inline void blk_pm_put_request(struct request *rq) {} +#endif + +void __blk_put_request(struct request_queue *q, struct request *req) +{ + req_flags_t rq_flags = req->rq_flags; + + if (unlikely(!q)) + return; + + if (q->mq_ops) { + blk_mq_free_request(req); + return; + } + + lockdep_assert_held(q->queue_lock); + + blk_req_zone_write_unlock(req); + blk_pm_put_request(req); + + elv_completed_request(q, req); + + /* this is a bio leak */ + WARN_ON(req->bio != NULL); + + rq_qos_done(q, req); + + /* + * Request may not have originated from ll_rw_blk. if not, + * it didn't come out of our reserved rq pools + */ + if (rq_flags & RQF_ALLOCED) { + struct request_list *rl = blk_rq_rl(req); + bool sync = op_is_sync(req->cmd_flags); + + BUG_ON(!list_empty(&req->queuelist)); + BUG_ON(ELV_ON_HASH(req)); + + blk_free_request(rl, req); + freed_request(rl, sync, rq_flags); + blk_put_rl(rl); + blk_queue_exit(q); + } +} +EXPORT_SYMBOL_GPL(__blk_put_request); + +void blk_put_request(struct request *req) +{ + struct request_queue *q = req->q; + + if (q->mq_ops) + blk_mq_free_request(req); + else { + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + __blk_put_request(q, req); + spin_unlock_irqrestore(q->queue_lock, flags); + } +} +EXPORT_SYMBOL(blk_put_request); + +bool bio_attempt_back_merge(struct request_queue *q, struct request *req, + struct bio *bio) +{ + const int ff = bio->bi_opf & REQ_FAILFAST_MASK; + + if (!ll_back_merge_fn(q, req, bio)) + return false; + + trace_block_bio_backmerge(q, req, bio); + + if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) + blk_rq_set_mixed_merge(req); + + req->biotail->bi_next = bio; + req->biotail = bio; + req->__data_len += bio->bi_iter.bi_size; + req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); + + blk_account_io_start(req, false); + return true; +} + +bool bio_attempt_front_merge(struct request_queue *q, struct request *req, + struct bio *bio) +{ + const int ff = bio->bi_opf & REQ_FAILFAST_MASK; + + if (!ll_front_merge_fn(q, req, bio)) + return false; + + trace_block_bio_frontmerge(q, req, bio); + + if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) + blk_rq_set_mixed_merge(req); + + bio->bi_next = req->bio; + req->bio = bio; + + req->__sector = bio->bi_iter.bi_sector; + req->__data_len += bio->bi_iter.bi_size; + req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); + + blk_account_io_start(req, false); + return true; +} + +bool bio_attempt_discard_merge(struct request_queue *q, struct request *req, + struct bio *bio) +{ + unsigned short segments = blk_rq_nr_discard_segments(req); + + if (segments >= queue_max_discard_segments(q)) + goto no_merge; + if (blk_rq_sectors(req) + bio_sectors(bio) > + blk_rq_get_max_sectors(req, blk_rq_pos(req))) + goto no_merge; + + req->biotail->bi_next = bio; + req->biotail = bio; + req->__data_len += bio->bi_iter.bi_size; + req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); + req->nr_phys_segments = segments + 1; + + blk_account_io_start(req, false); + return true; +no_merge: + req_set_nomerge(q, req); + return false; +} + +/** + * blk_attempt_plug_merge - try to merge with %current's plugged list + * @q: request_queue new bio is being queued at + * @bio: new bio being queued + * @request_count: out parameter for number of traversed plugged requests + * @same_queue_rq: pointer to &struct request that gets filled in when + * another request associated with @q is found on the plug list + * (optional, may be %NULL) + * + * Determine whether @bio being queued on @q can be merged with a request + * on %current's plugged list. Returns %true if merge was successful, + * otherwise %false. + * + * Plugging coalesces IOs from the same issuer for the same purpose without + * going through @q->queue_lock. As such it's more of an issuing mechanism + * than scheduling, and the request, while may have elvpriv data, is not + * added on the elevator at this point. In addition, we don't have + * reliable access to the elevator outside queue lock. Only check basic + * merging parameters without querying the elevator. + * + * Caller must ensure !blk_queue_nomerges(q) beforehand. + */ +bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, + unsigned int *request_count, + struct request **same_queue_rq) +{ + struct blk_plug *plug; + struct request *rq; + struct list_head *plug_list; + + plug = current->plug; + if (!plug) + return false; + *request_count = 0; + + if (q->mq_ops) + plug_list = &plug->mq_list; + else + plug_list = &plug->list; + + list_for_each_entry_reverse(rq, plug_list, queuelist) { + bool merged = false; + + if (rq->q == q) { + (*request_count)++; + /* + * Only blk-mq multiple hardware queues case checks the + * rq in the same queue, there should be only one such + * rq in a queue + **/ + if (same_queue_rq) + *same_queue_rq = rq; + } + + if (rq->q != q || !blk_rq_merge_ok(rq, bio)) + continue; + + switch (blk_try_merge(rq, bio)) { + case ELEVATOR_BACK_MERGE: + merged = bio_attempt_back_merge(q, rq, bio); + break; + case ELEVATOR_FRONT_MERGE: + merged = bio_attempt_front_merge(q, rq, bio); + break; + case ELEVATOR_DISCARD_MERGE: + merged = bio_attempt_discard_merge(q, rq, bio); + break; + default: + break; + } + + if (merged) + return true; + } + + return false; +} + +unsigned int blk_plug_queued_count(struct request_queue *q) +{ + struct blk_plug *plug; + struct request *rq; + struct list_head *plug_list; + unsigned int ret = 0; + + plug = current->plug; + if (!plug) + goto out; + + if (q->mq_ops) + plug_list = &plug->mq_list; + else + plug_list = &plug->list; + + list_for_each_entry(rq, plug_list, queuelist) { + if (rq->q == q) + ret++; + } +out: + return ret; +} + +void blk_init_request_from_bio(struct request *req, struct bio *bio) +{ + struct io_context *ioc = rq_ioc(bio); + + if (bio->bi_opf & REQ_RAHEAD) + req->cmd_flags |= REQ_FAILFAST_MASK; + + req->__sector = bio->bi_iter.bi_sector; + if (ioprio_valid(bio_prio(bio))) + req->ioprio = bio_prio(bio); + else if (ioc) + req->ioprio = ioc->ioprio; + else + req->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); + req->write_hint = bio->bi_write_hint; + blk_rq_bio_prep(req->q, req, bio); +} +EXPORT_SYMBOL_GPL(blk_init_request_from_bio); + +static blk_qc_t blk_queue_bio(struct request_queue *q, struct bio *bio) +{ + struct blk_plug *plug; + int where = ELEVATOR_INSERT_SORT; + struct request *req, *free; + 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); + + blk_queue_split(q, &bio); + + if (!bio_integrity_prep(bio)) + return BLK_QC_T_NONE; + + if (op_is_flush(bio->bi_opf)) { + spin_lock_irq(q->queue_lock); + where = ELEVATOR_INSERT_FLUSH; + goto get_rq; + } + + /* + * Check if we can merge with the plugged list before grabbing + * any locks. + */ + if (!blk_queue_nomerges(q)) { + if (blk_attempt_plug_merge(q, bio, &request_count, NULL)) + return BLK_QC_T_NONE; + } else + request_count = blk_plug_queued_count(q); + + spin_lock_irq(q->queue_lock); + + switch (elv_merge(q, &req, bio)) { + case ELEVATOR_BACK_MERGE: + if (!bio_attempt_back_merge(q, req, bio)) + break; + elv_bio_merged(q, req, bio); + free = attempt_back_merge(q, req); + if (free) + __blk_put_request(q, free); + else + elv_merged_request(q, req, ELEVATOR_BACK_MERGE); + goto out_unlock; + case ELEVATOR_FRONT_MERGE: + if (!bio_attempt_front_merge(q, req, bio)) + break; + elv_bio_merged(q, req, bio); + free = attempt_front_merge(q, req); + if (free) + __blk_put_request(q, free); + else + elv_merged_request(q, req, ELEVATOR_FRONT_MERGE); + goto out_unlock; + default: + break; + } + +get_rq: + rq_qos_throttle(q, bio, q->queue_lock); + + /* + * Grab a free request. This is might sleep but can not fail. + * Returns with the queue unlocked. + */ + blk_queue_enter_live(q); + req = get_request(q, bio->bi_opf, bio, 0, GFP_NOIO); + if (IS_ERR(req)) { + blk_queue_exit(q); + rq_qos_cleanup(q, bio); + if (PTR_ERR(req) == -ENOMEM) + bio->bi_status = BLK_STS_RESOURCE; + else + bio->bi_status = BLK_STS_IOERR; + bio_endio(bio); + goto out_unlock; + } + + rq_qos_track(q, req, bio); + + /* + * After dropping the lock and possibly sleeping here, our request + * may now be mergeable after it had proven unmergeable (above). + * We don't worry about that case for efficiency. It won't happen + * often, and the elevators are able to handle it. + */ + blk_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. + * + * @request_count may become stale because of schedule + * out, so check plug list again. + */ + if (!request_count || list_empty(&plug->list)) + trace_block_plug(q); + else { + struct request *last = list_entry_rq(plug->list.prev); + if (request_count >= BLK_MAX_REQUEST_COUNT || + blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE) { + blk_flush_plug_list(plug, false); + trace_block_plug(q); + } + } + list_add_tail(&req->queuelist, &plug->list); + blk_account_io_start(req, true); + } else { + spin_lock_irq(q->queue_lock); + add_acct_request(q, req, where); + __blk_run_queue(q); +out_unlock: + spin_unlock_irq(q->queue_lock); + } + + return BLK_QC_T_NONE; +} + +static void handle_bad_sector(struct bio *bio, sector_t maxsector) +{ + char b[BDEVNAME_SIZE]; + + printk(KERN_INFO "attempt to access beyond end of device\n"); + printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n", + bio_devname(bio, b), bio->bi_opf, + (unsigned long long)bio_end_sector(bio), + (long long)maxsector); +} + +#ifdef CONFIG_FAIL_MAKE_REQUEST + +static DECLARE_FAULT_ATTR(fail_make_request); + +static int __init setup_fail_make_request(char *str) +{ + return setup_fault_attr(&fail_make_request, str); +} +__setup("fail_make_request=", setup_fail_make_request); + +static bool should_fail_request(struct hd_struct *part, unsigned int bytes) +{ + return part->make_it_fail && should_fail(&fail_make_request, bytes); +} + +static int __init fail_make_request_debugfs(void) +{ + struct dentry *dir = fault_create_debugfs_attr("fail_make_request", + NULL, &fail_make_request); + + return PTR_ERR_OR_ZERO(dir); +} + +late_initcall(fail_make_request_debugfs); + +#else /* CONFIG_FAIL_MAKE_REQUEST */ + +static inline bool should_fail_request(struct hd_struct *part, + unsigned int bytes) +{ + return false; +} + +#endif /* CONFIG_FAIL_MAKE_REQUEST */ + +static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part) +{ + const int op = bio_op(bio); + + if (part->policy && op_is_write(op)) { + char b[BDEVNAME_SIZE]; + + if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) + return false; + + WARN_ONCE(1, + "generic_make_request: Trying to write " + "to read-only block-device %s (partno %d)\n", + bio_devname(bio, b), part->partno); + /* Older lvm-tools actually trigger this */ + return false; + } + + return false; +} + +static noinline int should_fail_bio(struct bio *bio) +{ + if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size)) + return -EIO; + return 0; +} +ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); + +/* + * Check whether this bio extends beyond the end of the device or partition. + * This may well happen - the kernel calls bread() without checking the size of + * the device, e.g., when mounting a file system. + */ +static inline int bio_check_eod(struct bio *bio, sector_t maxsector) +{ + unsigned int nr_sectors = bio_sectors(bio); + + if (nr_sectors && maxsector && + (nr_sectors > maxsector || + bio->bi_iter.bi_sector > maxsector - nr_sectors)) { + handle_bad_sector(bio, maxsector); + return -EIO; + } + return 0; +} + +/* + * Remap block n of partition p to block n+start(p) of the disk. + */ +static inline int blk_partition_remap(struct bio *bio) +{ + struct hd_struct *p; + int ret = -EIO; + + rcu_read_lock(); + p = __disk_get_part(bio->bi_disk, bio->bi_partno); + if (unlikely(!p)) + goto out; + if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) + goto out; + if (unlikely(bio_check_ro(bio, p))) + goto out; + + /* + * Zone reset does not include bi_size so bio_sectors() is always 0. + * Include a test for the reset op code and perform the remap if needed. + */ + if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) { + if (bio_check_eod(bio, part_nr_sects_read(p))) + goto out; + bio->bi_iter.bi_sector += p->start_sect; + trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p), + bio->bi_iter.bi_sector - p->start_sect); + } + bio->bi_partno = 0; + ret = 0; +out: + rcu_read_unlock(); + return ret; +} + +static noinline_for_stack bool +generic_make_request_checks(struct bio *bio) +{ + struct request_queue *q; + int nr_sectors = bio_sectors(bio); + blk_status_t status = BLK_STS_IOERR; + char b[BDEVNAME_SIZE]; + + might_sleep(); + + q = bio->bi_disk->queue; + if (unlikely(!q)) { + printk(KERN_ERR + "generic_make_request: Trying to access " + "nonexistent block-device %s (%Lu)\n", + bio_devname(bio, b), (long long)bio->bi_iter.bi_sector); + goto end_io; + } + + /* + * For a REQ_NOWAIT based request, return -EOPNOTSUPP + * if queue is not a request based queue. + */ + if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q)) + goto not_supported; + + if (should_fail_bio(bio)) + goto end_io; + + if (bio->bi_partno) { + if (unlikely(blk_partition_remap(bio))) + goto end_io; + } else { + if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0))) + goto end_io; + if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk)))) + 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 (op_is_flush(bio->bi_opf) && + !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { + bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); + if (!nr_sectors) { + status = BLK_STS_OK; + goto end_io; + } + } + + switch (bio_op(bio)) { + case REQ_OP_DISCARD: + if (!blk_queue_discard(q)) + goto not_supported; + break; + case REQ_OP_SECURE_ERASE: + if (!blk_queue_secure_erase(q)) + goto not_supported; + break; + case REQ_OP_WRITE_SAME: + if (!q->limits.max_write_same_sectors) + goto not_supported; + break; + case REQ_OP_ZONE_REPORT: + case REQ_OP_ZONE_RESET: + if (!blk_queue_is_zoned(q)) + goto not_supported; + break; + case REQ_OP_WRITE_ZEROES: + if (!q->limits.max_write_zeroes_sectors) + goto not_supported; + break; + default: + break; + } + + /* + * Various block parts want %current->io_context and lazy ioc + * allocation ends up trading a lot of pain for a small amount of + * memory. Just allocate it upfront. This may fail and block + * layer knows how to live with it. + */ + create_io_context(GFP_ATOMIC, q->node); + + if (!blkcg_bio_issue_check(q, bio)) + return false; + + if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { + trace_block_bio_queue(q, bio); + /* Now that enqueuing has been traced, we need to trace + * completion as well. + */ + bio_set_flag(bio, BIO_TRACE_COMPLETION); + } + return true; + +not_supported: + status = BLK_STS_NOTSUPP; +end_io: + bio->bi_status = status; + bio_endio(bio); + 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. + */ +blk_qc_t generic_make_request(struct bio *bio) +{ + /* + * bio_list_on_stack[0] contains bios submitted by the current + * make_request_fn. + * bio_list_on_stack[1] contains bios that were submitted before + * the current make_request_fn, but that haven't been processed + * yet. + */ + struct bio_list bio_list_on_stack[2]; + blk_mq_req_flags_t flags = 0; + struct request_queue *q = bio->bi_disk->queue; + blk_qc_t ret = BLK_QC_T_NONE; + + if (bio->bi_opf & REQ_NOWAIT) + flags = BLK_MQ_REQ_NOWAIT; + if (bio_flagged(bio, BIO_QUEUE_ENTERED)) + blk_queue_enter_live(q); + else if (blk_queue_enter(q, flags) < 0) { + if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT)) + bio_wouldblock_error(bio); + else + bio_io_error(bio); + return ret; + } + + if (!generic_make_request_checks(bio)) + goto out; + + /* + * 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(¤t->bio_list[0], bio); + goto out; + } + + /* 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[0]); + current->bio_list = bio_list_on_stack; + do { + bool enter_succeeded = true; + + if (unlikely(q != bio->bi_disk->queue)) { + if (q) + blk_queue_exit(q); + q = bio->bi_disk->queue; + flags = 0; + if (bio->bi_opf & REQ_NOWAIT) + flags = BLK_MQ_REQ_NOWAIT; + if (blk_queue_enter(q, flags) < 0) + enter_succeeded = false; + } + + if (enter_succeeded) { + struct bio_list lower, same; + + /* Create a fresh bio_list for all subordinate requests */ + bio_list_on_stack[1] = bio_list_on_stack[0]; + bio_list_init(&bio_list_on_stack[0]); + ret = q->make_request_fn(q, bio); + + /* sort new bios into those for a lower level + * and those for the same level + */ + bio_list_init(&lower); + bio_list_init(&same); + while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) + if (q == bio->bi_disk->queue) + bio_list_add(&same, bio); + else + bio_list_add(&lower, bio); + /* now assemble so we handle the lowest level first */ + bio_list_merge(&bio_list_on_stack[0], &lower); + bio_list_merge(&bio_list_on_stack[0], &same); + bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); + } else { + if (unlikely(!blk_queue_dying(q) && + (bio->bi_opf & REQ_NOWAIT))) + bio_wouldblock_error(bio); + else + bio_io_error(bio); + q = NULL; + } + bio = bio_list_pop(&bio_list_on_stack[0]); + } while (bio); + current->bio_list = NULL; /* deactivate */ + +out: + if (q) + blk_queue_exit(q); + return ret; +} +EXPORT_SYMBOL(generic_make_request); + +/** + * direct_make_request - hand a buffer directly to its device driver for I/O + * @bio: The bio describing the location in memory and on the device. + * + * This function behaves like generic_make_request(), but does not protect + * against recursion. Must only be used if the called driver is known + * to not call generic_make_request (or direct_make_request) again from + * its make_request function. (Calling direct_make_request again from + * a workqueue is perfectly fine as that doesn't recurse). + */ +blk_qc_t direct_make_request(struct bio *bio) +{ + struct request_queue *q = bio->bi_disk->queue; + bool nowait = bio->bi_opf & REQ_NOWAIT; + blk_qc_t ret; + + if (!generic_make_request_checks(bio)) + return BLK_QC_T_NONE; + + if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) { + if (nowait && !blk_queue_dying(q)) + bio->bi_status = BLK_STS_AGAIN; + else + bio->bi_status = BLK_STS_IOERR; + bio_endio(bio); + return BLK_QC_T_NONE; + } + + ret = q->make_request_fn(q, bio); + blk_queue_exit(q); + return ret; +} +EXPORT_SYMBOL_GPL(direct_make_request); + +/** + * submit_bio - submit a bio to the block device layer for I/O + * @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. + * + */ +blk_qc_t submit_bio(struct bio *bio) +{ + /* + * If it's a regular read/write or a barrier with data attached, + * go through the normal accounting stuff before submission. + */ + if (bio_has_data(bio)) { + unsigned int count; + + if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) + count = queue_logical_block_size(bio->bi_disk->queue) >> 9; + else + count = bio_sectors(bio); + + if (op_is_write(bio_op(bio))) { + count_vm_events(PGPGOUT, count); + } else { + task_io_account_read(bio->bi_iter.bi_size); + count_vm_events(PGPGIN, count); + } + + if (unlikely(block_dump)) { + char b[BDEVNAME_SIZE]; + printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n", + current->comm, task_pid_nr(current), + op_is_write(bio_op(bio)) ? "WRITE" : "READ", + (unsigned long long)bio->bi_iter.bi_sector, + bio_devname(bio, b), count); + } + } + + return generic_make_request(bio); +} +EXPORT_SYMBOL(submit_bio); + +bool blk_poll(struct request_queue *q, blk_qc_t cookie) +{ + if (!q->poll_fn || !blk_qc_t_valid(cookie)) + return false; + + if (current->plug) + blk_flush_plug_list(current->plug, false); + return q->poll_fn(q, cookie); +} +EXPORT_SYMBOL_GPL(blk_poll); + +/** + * blk_cloned_rq_check_limits - Helper function to check a cloned request + * for new the queue limits + * @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. + * + * Request stacking drivers like request-based dm may change the queue + * limits when retrying requests on other queues. Those requests need + * to be checked against the new queue limits again during dispatch. + */ +static int blk_cloned_rq_check_limits(struct request_queue *q, + struct request *rq) +{ + if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) { + 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; +} + +/** + * blk_insert_cloned_request - Helper for stacking drivers to submit a request + * @q: the queue to submit the request + * @rq: the request being queued + */ +blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq) +{ + unsigned long flags; + int where = ELEVATOR_INSERT_BACK; + + if (blk_cloned_rq_check_limits(q, rq)) + return BLK_STS_IOERR; + + if (rq->rq_disk && + should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq))) + return BLK_STS_IOERR; + + if (q->mq_ops) { + if (blk_queue_io_stat(q)) + blk_account_io_start(rq, true); + /* + * Since we have a scheduler attached on the top device, + * bypass a potential scheduler on the bottom device for + * insert. + */ + return blk_mq_request_issue_directly(rq); + } + + spin_lock_irqsave(q->queue_lock, flags); + if (unlikely(blk_queue_dying(q))) { + spin_unlock_irqrestore(q->queue_lock, flags); + return BLK_STS_IOERR; + } + + /* + * 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 (op_is_flush(rq->cmd_flags)) + where = ELEVATOR_INSERT_FLUSH; + + add_acct_request(q, rq, where); + if (where == ELEVATOR_INSERT_FLUSH) + __blk_run_queue(q); + spin_unlock_irqrestore(q->queue_lock, flags); + + return BLK_STS_OK; +} +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. + */ +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->rq_flags & RQF_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_opf & ff) != ff) + break; + bytes += bio->bi_iter.bi_size; + } + + /* this could lead to infinite loop */ + BUG_ON(blk_rq_bytes(rq) && !bytes); + return bytes; +} +EXPORT_SYMBOL_GPL(blk_rq_err_bytes); + +void blk_account_io_completion(struct request *req, unsigned int bytes) +{ + if (blk_do_io_stat(req)) { + const int sgrp = op_stat_group(req_op(req)); + struct hd_struct *part; + int cpu; + + cpu = part_stat_lock(); + part = req->part; + part_stat_add(cpu, part, sectors[sgrp], bytes >> 9); + part_stat_unlock(); + } +} + +void blk_account_io_done(struct request *req, u64 now) +{ + /* + * 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->rq_flags & RQF_FLUSH_SEQ)) { + const int sgrp = op_stat_group(req_op(req)); + struct hd_struct *part; + int cpu; + + cpu = part_stat_lock(); + part = req->part; + + part_stat_inc(cpu, part, ios[sgrp]); + part_stat_add(cpu, part, nsecs[sgrp], now - req->start_time_ns); + part_round_stats(req->q, cpu, part); + part_dec_in_flight(req->q, part, rq_data_dir(req)); + + hd_struct_put(part); + part_stat_unlock(); + } +} + +#ifdef CONFIG_PM +/* + * Don't process normal requests when queue is suspended + * or in the process of suspending/resuming + */ +static bool blk_pm_allow_request(struct request *rq) +{ + switch (rq->q->rpm_status) { + case RPM_RESUMING: + case RPM_SUSPENDING: + return rq->rq_flags & RQF_PM; + case RPM_SUSPENDED: + return false; + default: + return true; + } +} +#else +static bool blk_pm_allow_request(struct request *rq) +{ + return true; +} +#endif + +void blk_account_io_start(struct request *rq, bool new_io) +{ + struct hd_struct *part; + int rw = rq_data_dir(rq); + int cpu; + + if (!blk_do_io_stat(rq)) + return; + + cpu = part_stat_lock(); + + if (!new_io) { + part = rq->part; + part_stat_inc(cpu, part, merges[rw]); + } else { + part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); + if (!hd_struct_try_get(part)) { + /* + * The partition is already being removed, + * the request will be accounted on the disk only + * + * We take a reference on disk->part0 although that + * partition will never be deleted, so we can treat + * it as any other partition. + */ + part = &rq->rq_disk->part0; + hd_struct_get(part); + } + part_round_stats(rq->q, cpu, part); + part_inc_in_flight(rq->q, part, rw); + rq->part = part; + } + + part_stat_unlock(); +} + +static struct request *elv_next_request(struct request_queue *q) +{ + struct request *rq; + struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL); + + WARN_ON_ONCE(q->mq_ops); + + while (1) { + list_for_each_entry(rq, &q->queue_head, queuelist) { + if (blk_pm_allow_request(rq)) + return rq; + + if (rq->rq_flags & RQF_SOFTBARRIER) + break; + } + + /* + * Flush request is running and flush request isn't queueable + * in the drive, we can hold the queue till flush request is + * finished. Even we don't do this, driver can't dispatch next + * requests and will requeue them. And this can improve + * throughput too. For example, we have request flush1, write1, + * flush 2. flush1 is dispatched, then queue is hold, write1 + * isn't inserted to queue. After flush1 is finished, flush2 + * will be dispatched. Since disk cache is already clean, + * flush2 will be finished very soon, so looks like flush2 is + * folded to flush1. + * Since the queue is hold, a flag is set to indicate the queue + * should be restarted later. Please see flush_end_io() for + * details. + */ + if (fq->flush_pending_idx != fq->flush_running_idx && + !queue_flush_queueable(q)) { + fq->flush_queue_delayed = 1; + return NULL; + } + if (unlikely(blk_queue_bypass(q)) || + !q->elevator->type->ops.sq.elevator_dispatch_fn(q, 0)) + return NULL; + } +} + +/** + * 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. + */ +struct request *blk_peek_request(struct request_queue *q) +{ + struct request *rq; + int ret; + + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + while ((rq = elv_next_request(q)) != NULL) { + if (!(rq->rq_flags & RQF_STARTED)) { + /* + * This is the first time the device driver + * sees this request (possibly after + * requeueing). Notify IO scheduler. + */ + if (rq->rq_flags & RQF_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->rq_flags |= RQF_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->rq_flags & RQF_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. RQF_STARTED will + * prevent other fs requests from passing this one. + */ + if (q->dma_drain_size && blk_rq_bytes(rq) && + !(rq->rq_flags & RQF_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 || ret == BLKPREP_INVALID) { + rq->rq_flags |= RQF_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, ret == BLKPREP_INVALID ? + BLK_STS_TARGET : BLK_STS_IOERR); + } else { + printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); + break; + } + } + + return rq; +} +EXPORT_SYMBOL(blk_peek_request); + +static 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)]++; +} + +/** + * 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. + */ +void blk_start_request(struct request *req) +{ + lockdep_assert_held(req->q->queue_lock); + WARN_ON_ONCE(req->q->mq_ops); + + blk_dequeue_request(req); + + if (test_bit(QUEUE_FLAG_STATS, &req->q->queue_flags)) { + req->io_start_time_ns = ktime_get_ns(); +#ifdef CONFIG_BLK_DEV_THROTTLING_LOW + req->throtl_size = blk_rq_sectors(req); +#endif + req->rq_flags |= RQF_STATS; + rq_qos_issue(req->q, req); + } + + BUG_ON(blk_rq_is_complete(req)); + 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. + */ +struct request *blk_fetch_request(struct request_queue *q) +{ + struct request *rq; + + lockdep_assert_held(q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + rq = blk_peek_request(q); + if (rq) + blk_start_request(rq); + return rq; +} +EXPORT_SYMBOL(blk_fetch_request); + +/* + * Steal bios from a request and add them to a bio list. + * The request must not have been partially completed before. + */ +void blk_steal_bios(struct bio_list *list, struct request *rq) +{ + if (rq->bio) { + if (list->tail) + list->tail->bi_next = rq->bio; + else + list->head = rq->bio; + list->tail = rq->biotail; + + rq->bio = NULL; + rq->biotail = NULL; + } + + rq->__data_len = 0; +} +EXPORT_SYMBOL_GPL(blk_steal_bios); + +/** + * blk_update_request - Special helper function for request stacking drivers + * @req: the request being processed + * @error: block status code + * @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. + * + * Note: + * The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both + * blk_rq_bytes() and in blk_update_request(). + * + * Return: + * %false - this request doesn't have any more data + * %true - this request has more data + **/ +bool blk_update_request(struct request *req, blk_status_t error, + unsigned int nr_bytes) +{ + int total_bytes; + + trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes); + + if (!req->bio) + return false; + + if (unlikely(error && !blk_rq_is_passthrough(req) && + !(req->rq_flags & RQF_QUIET))) + print_req_error(req, error); + + blk_account_io_completion(req, nr_bytes); + + total_bytes = 0; + while (req->bio) { + struct bio *bio = req->bio; + unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes); + + if (bio_bytes == bio->bi_iter.bi_size) + req->bio = bio->bi_next; + + /* Completion has already been traced */ + bio_clear_flag(bio, BIO_TRACE_COMPLETION); + req_bio_endio(req, bio, bio_bytes, error); + + total_bytes += bio_bytes; + nr_bytes -= bio_bytes; + + if (!nr_bytes) + break; + } + + /* + * completely done + */ + if (!req->bio) { + /* + * Reset counters so that the request stacking driver + * can find how many bytes remain in the request + * later. + */ + req->__data_len = 0; + return false; + } + + req->__data_len -= total_bytes; + + /* update sector only for requests with clear definition of sector */ + if (!blk_rq_is_passthrough(req)) + req->__sector += total_bytes >> 9; + + /* mixed attributes always follow the first bio */ + if (req->rq_flags & RQF_MIXED_MERGE) { + req->cmd_flags &= ~REQ_FAILFAST_MASK; + req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK; + } + + if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) { + /* + * 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, blk_status_t 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->rq_flags &= ~RQF_DONTPREP; + if (q->unprep_rq_fn) + q->unprep_rq_fn(q, req); +} +EXPORT_SYMBOL_GPL(blk_unprep_request); + +void blk_finish_request(struct request *req, blk_status_t error) +{ + struct request_queue *q = req->q; + u64 now = ktime_get_ns(); + + lockdep_assert_held(req->q->queue_lock); + WARN_ON_ONCE(q->mq_ops); + + if (req->rq_flags & RQF_STATS) + blk_stat_add(req, now); + + if (req->rq_flags & RQF_QUEUED) + blk_queue_end_tag(q, req); + + BUG_ON(blk_queued_rq(req)); + + if (unlikely(laptop_mode) && !blk_rq_is_passthrough(req)) + laptop_io_completion(req->q->backing_dev_info); + + blk_delete_timer(req); + + if (req->rq_flags & RQF_DONTPREP) + blk_unprep_request(req); + + blk_account_io_done(req, now); + + if (req->end_io) { + rq_qos_done(q, req); + req->end_io(req, error); + } else { + if (blk_bidi_rq(req)) + __blk_put_request(req->next_rq->q, req->next_rq); + + __blk_put_request(q, req); + } +} +EXPORT_SYMBOL(blk_finish_request); + +/** + * blk_end_bidi_request - Complete a bidi request + * @rq: the request to complete + * @error: block status code + * @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, blk_status_t error, + unsigned int nr_bytes, unsigned int bidi_bytes) +{ + struct request_queue *q = rq->q; + unsigned long flags; + + WARN_ON_ONCE(q->mq_ops); + + 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: block status code + * @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 + **/ +static bool __blk_end_bidi_request(struct request *rq, blk_status_t error, + unsigned int nr_bytes, unsigned int bidi_bytes) +{ + lockdep_assert_held(rq->q->queue_lock); + WARN_ON_ONCE(rq->q->mq_ops); + + 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: block status code + * @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, blk_status_t error, + unsigned int nr_bytes) +{ + WARN_ON_ONCE(rq->q->mq_ops); + 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: block status code + * + * Description: + * Completely finish @rq. + */ +void blk_end_request_all(struct request *rq, blk_status_t 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 - Helper function for drivers to complete the request. + * @rq: the request being processed + * @error: block status code + * @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, blk_status_t error, + unsigned int nr_bytes) +{ + lockdep_assert_held(rq->q->queue_lock); + WARN_ON_ONCE(rq->q->mq_ops); + + 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: block status code + * + * Description: + * Completely finish @rq. Must be called with queue lock held. + */ +void __blk_end_request_all(struct request *rq, blk_status_t error) +{ + bool pending; + unsigned int bidi_bytes = 0; + + lockdep_assert_held(rq->q->queue_lock); + WARN_ON_ONCE(rq->q->mq_ops); + + 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: block status code + * + * 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, blk_status_t error) +{ + return __blk_end_request(rq, error, blk_rq_cur_bytes(rq)); +} +EXPORT_SYMBOL(__blk_end_request_cur); + +void blk_rq_bio_prep(struct request_queue *q, struct request *rq, + struct bio *bio) +{ + if (bio_has_data(bio)) + rq->nr_phys_segments = bio_phys_segments(q, bio); + else if (bio_op(bio) == REQ_OP_DISCARD) + rq->nr_phys_segments = 1; + + rq->__data_len = bio->bi_iter.bi_size; + rq->bio = rq->biotail = bio; + + if (bio->bi_disk) + rq->rq_disk = bio->bi_disk; +} + +#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE +/** + * rq_flush_dcache_pages - Helper function to flush all pages in a request + * @rq: the request to be flushed + * + * Description: + * Flush all pages in @rq. + */ +void rq_flush_dcache_pages(struct request *rq) +{ + struct req_iterator iter; + struct bio_vec bvec; + + rq_for_each_segment(bvec, rq, iter) + flush_dcache_page(bvec.bv_page); +} +EXPORT_SYMBOL_GPL(rq_flush_dcache_pages); +#endif + +/** + * blk_lld_busy - Check if underlying low-level drivers of a device are busy + * @q : the queue of the device being checked + * + * Description: + * Check if underlying low-level drivers of a device are busy. + * If the drivers want to export their busy state, they must set own + * exporting function using blk_queue_lld_busy() first. + * + * Basically, this function is used only by request stacking drivers + * to stop dispatching requests to underlying devices when underlying + * devices are busy. This behavior helps more I/O merging on the queue + * of the request stacking driver and prevents I/O throughput regression + * on burst I/O load. + * + * Return: + * 0 - Not busy (The request stacking driver should dispatch request) + * 1 - Busy (The request stacking driver should stop dispatching request) + */ +int blk_lld_busy(struct request_queue *q) +{ + if (q->lld_busy_fn) + return q->lld_busy_fn(q); + + return 0; +} +EXPORT_SYMBOL_GPL(blk_lld_busy); + +/** + * blk_rq_unprep_clone - Helper function to free all bios in a cloned request + * @rq: the clone request to be cleaned up + * + * Description: + * Free all bios in @rq for a cloned request. + */ +void blk_rq_unprep_clone(struct request *rq) +{ + struct bio *bio; + + while ((bio = rq->bio) != NULL) { + rq->bio = bio->bi_next; + + bio_put(bio); + } +} +EXPORT_SYMBOL_GPL(blk_rq_unprep_clone); + +/* + * Copy attributes of the original request to the clone request. + * The actual data parts (e.g. ->cmd, ->sense) are not copied. + */ +static void __blk_rq_prep_clone(struct request *dst, struct request *src) +{ + dst->cpu = src->cpu; + dst->__sector = blk_rq_pos(src); + dst->__data_len = blk_rq_bytes(src); + if (src->rq_flags & RQF_SPECIAL_PAYLOAD) { + dst->rq_flags |= RQF_SPECIAL_PAYLOAD; + dst->special_vec = src->special_vec; + } + dst->nr_phys_segments = src->nr_phys_segments; + dst->ioprio = src->ioprio; + dst->extra_len = src->extra_len; +} + +/** + * blk_rq_prep_clone - Helper function to setup clone request + * @rq: the request to be setup + * @rq_src: original request to be cloned + * @bs: bio_set that bios for clone are allocated from + * @gfp_mask: memory allocation mask for bio + * @bio_ctr: setup function to be called for each clone bio. + * Returns %0 for success, non %0 for failure. + * @data: private data to be passed to @bio_ctr + * + * Description: + * Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq. + * The actual data parts of @rq_src (e.g. ->cmd, ->sense) + * are not copied, and copying such parts is the caller's responsibility. + * Also, pages which the original bios are pointing to are not copied + * and the cloned bios just point same pages. + * So cloned bios must be completed before original bios, which means + * the caller must complete @rq before @rq_src. + */ +int blk_rq_prep_clone(struct request *rq, struct request *rq_src, + struct bio_set *bs, gfp_t gfp_mask, + int (*bio_ctr)(struct bio *, struct bio *, void *), + void *data) +{ + struct bio *bio, *bio_src; + + if (!bs) + bs = &fs_bio_set; + + __rq_for_each_bio(bio_src, rq_src) { + bio = bio_clone_fast(bio_src, gfp_mask, bs); + if (!bio) + goto free_and_out; + + if (bio_ctr && bio_ctr(bio, bio_src, data)) + goto free_and_out; + + if (rq->bio) { + rq->biotail->bi_next = bio; + rq->biotail = bio; + } else + rq->bio = rq->biotail = bio; + } + + __blk_rq_prep_clone(rq, rq_src); + + return 0; + +free_and_out: + if (bio) + bio_put(bio); + blk_rq_unprep_clone(rq); + + return -ENOMEM; +} +EXPORT_SYMBOL_GPL(blk_rq_prep_clone); + +int kblockd_schedule_work(struct work_struct *work) +{ + return queue_work(kblockd_workqueue, work); +} +EXPORT_SYMBOL(kblockd_schedule_work); + +int kblockd_schedule_work_on(int cpu, struct work_struct *work) +{ + return queue_work_on(cpu, kblockd_workqueue, work); +} +EXPORT_SYMBOL(kblockd_schedule_work_on); + +int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, + unsigned long delay) +{ + return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); +} +EXPORT_SYMBOL(kblockd_mod_delayed_work_on); + +/** + * blk_start_plug - initialize blk_plug and track it inside the task_struct + * @plug: The &struct blk_plug that needs to be initialized + * + * Description: + * Tracking blk_plug inside the task_struct will help with auto-flushing the + * pending I/O should the task end up blocking between blk_start_plug() and + * blk_finish_plug(). This is important from a performance perspective, but + * also ensures that we don't deadlock. For instance, if the task is blocking + * for a memory allocation, memory reclaim could end up wanting to free a + * page belonging to that request that is currently residing in our private + * plug. By flushing the pending I/O when the process goes to sleep, we avoid + * this kind of deadlock. + */ +void blk_start_plug(struct blk_plug *plug) +{ + struct task_struct *tsk = current; + + /* + * If this is a nested plug, don't actually assign it. + */ + if (tsk->plug) + return; + + INIT_LIST_HEAD(&plug->list); + INIT_LIST_HEAD(&plug->mq_list); + INIT_LIST_HEAD(&plug->cb_list); + /* + * Store ordering should not be needed here, since a potential + * preempt will imply a full memory barrier + */ + tsk->plug = plug; +} +EXPORT_SYMBOL(blk_start_plug); + +static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) +{ + struct request *rqa = container_of(a, struct request, queuelist); + struct request *rqb = container_of(b, struct request, queuelist); + + return !(rqa->q < rqb->q || + (rqa->q == rqb->q && blk_rq_pos(rqa) < blk_rq_pos(rqb))); +} + +/* + * If 'from_schedule' is true, then postpone the dispatch of requests + * until a safe kblockd context. We due this to avoid accidental big + * additional stack usage in driver dispatch, in places where the originally + * plugger did not intend it. + */ +static void queue_unplugged(struct request_queue *q, unsigned int depth, + bool from_schedule) + __releases(q->queue_lock) +{ + lockdep_assert_held(q->queue_lock); + + trace_block_unplug(q, depth, !from_schedule); + + if (from_schedule) + blk_run_queue_async(q); + else + __blk_run_queue(q); + spin_unlock_irq(q->queue_lock); +} + +static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) +{ + LIST_HEAD(callbacks); + + while (!list_empty(&plug->cb_list)) { + list_splice_init(&plug->cb_list, &callbacks); + + while (!list_empty(&callbacks)) { + struct blk_plug_cb *cb = list_first_entry(&callbacks, + struct blk_plug_cb, + list); + list_del(&cb->list); + cb->callback(cb, from_schedule); + } + } +} + +struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, + int size) +{ + struct blk_plug *plug = current->plug; + struct blk_plug_cb *cb; + + if (!plug) + return NULL; + + list_for_each_entry(cb, &plug->cb_list, list) + if (cb->callback == unplug && cb->data == data) + return cb; + + /* Not currently on the callback list */ + BUG_ON(size < sizeof(*cb)); + cb = kzalloc(size, GFP_ATOMIC); + if (cb) { + cb->data = data; + cb->callback = unplug; + list_add(&cb->list, &plug->cb_list); + } + return cb; +} +EXPORT_SYMBOL(blk_check_plugged); + +void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule) +{ + struct request_queue *q; + struct request *rq; + LIST_HEAD(list); + unsigned int depth; + + flush_plug_callbacks(plug, from_schedule); + + if (!list_empty(&plug->mq_list)) + blk_mq_flush_plug_list(plug, from_schedule); + + if (list_empty(&plug->list)) + return; + + list_splice_init(&plug->list, &list); + + list_sort(NULL, &list, plug_rq_cmp); + + q = NULL; + depth = 0; + + while (!list_empty(&list)) { + rq = list_entry_rq(list.next); + list_del_init(&rq->queuelist); + BUG_ON(!rq->q); + if (rq->q != q) { + /* + * This drops the queue lock + */ + if (q) + queue_unplugged(q, depth, from_schedule); + q = rq->q; + depth = 0; + spin_lock_irq(q->queue_lock); + } + + /* + * Short-circuit if @q is dead + */ + if (unlikely(blk_queue_dying(q))) { + __blk_end_request_all(rq, BLK_STS_IOERR); + continue; + } + + /* + * rq is already accounted, so use raw insert + */ + if (op_is_flush(rq->cmd_flags)) + __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH); + else + __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE); + + depth++; + } + + /* + * This drops the queue lock + */ + if (q) + queue_unplugged(q, depth, from_schedule); +} + +void blk_finish_plug(struct blk_plug *plug) +{ + if (plug != current->plug) + return; + blk_flush_plug_list(plug, false); + + current->plug = NULL; +} +EXPORT_SYMBOL(blk_finish_plug); + +#ifdef CONFIG_PM +/** + * blk_pm_runtime_init - Block layer runtime PM initialization routine + * @q: the queue of the device + * @dev: the device the queue belongs to + * + * Description: + * Initialize runtime-PM-related fields for @q and start auto suspend for + * @dev. Drivers that want to take advantage of request-based runtime PM + * should call this function after @dev has been initialized, and its + * request queue @q has been allocated, and runtime PM for it can not happen + * yet(either due to disabled/forbidden or its usage_count > 0). In most + * cases, driver should call this function before any I/O has taken place. + * + * This function takes care of setting up using auto suspend for the device, + * the autosuspend delay is set to -1 to make runtime suspend impossible + * until an updated value is either set by user or by driver. Drivers do + * not need to touch other autosuspend settings. + * + * The block layer runtime PM is request based, so only works for drivers + * that use request as their IO unit instead of those directly use bio's. + */ +void blk_pm_runtime_init(struct request_queue *q, struct device *dev) +{ + /* Don't enable runtime PM for blk-mq until it is ready */ + if (q->mq_ops) { + pm_runtime_disable(dev); + return; + } + + q->dev = dev; + q->rpm_status = RPM_ACTIVE; + pm_runtime_set_autosuspend_delay(q->dev, -1); + pm_runtime_use_autosuspend(q->dev); +} +EXPORT_SYMBOL(blk_pm_runtime_init); + +/** + * blk_pre_runtime_suspend - Pre runtime suspend check + * @q: the queue of the device + * + * Description: + * This function will check if runtime suspend is allowed for the device + * by examining if there are any requests pending in the queue. If there + * are requests pending, the device can not be runtime suspended; otherwise, + * the queue's status will be updated to SUSPENDING and the driver can + * proceed to suspend the device. + * + * For the not allowed case, we mark last busy for the device so that + * runtime PM core will try to autosuspend it some time later. + * + * This function should be called near the start of the device's + * runtime_suspend callback. + * + * Return: + * 0 - OK to runtime suspend the device + * -EBUSY - Device should not be runtime suspended + */ +int blk_pre_runtime_suspend(struct request_queue *q) +{ + int ret = 0; + + if (!q->dev) + return ret; + + spin_lock_irq(q->queue_lock); + if (q->nr_pending) { + ret = -EBUSY; + pm_runtime_mark_last_busy(q->dev); + } else { + q->rpm_status = RPM_SUSPENDING; + } + spin_unlock_irq(q->queue_lock); + return ret; +} +EXPORT_SYMBOL(blk_pre_runtime_suspend); + +/** + * blk_post_runtime_suspend - Post runtime suspend processing + * @q: the queue of the device + * @err: return value of the device's runtime_suspend function + * + * Description: + * Update the queue's runtime status according to the return value of the + * device's runtime suspend function and mark last busy for the device so + * that PM core will try to auto suspend the device at a later time. + * + * This function should be called near the end of the device's + * runtime_suspend callback. + */ +void blk_post_runtime_suspend(struct request_queue *q, int err) +{ + if (!q->dev) + return; + + spin_lock_irq(q->queue_lock); + if (!err) { + q->rpm_status = RPM_SUSPENDED; + } else { + q->rpm_status = RPM_ACTIVE; + pm_runtime_mark_last_busy(q->dev); + } + spin_unlock_irq(q->queue_lock); +} +EXPORT_SYMBOL(blk_post_runtime_suspend); + +/** + * blk_pre_runtime_resume - Pre runtime resume processing + * @q: the queue of the device + * + * Description: + * Update the queue's runtime status to RESUMING in preparation for the + * runtime resume of the device. + * + * This function should be called near the start of the device's + * runtime_resume callback. + */ +void blk_pre_runtime_resume(struct request_queue *q) +{ + if (!q->dev) + return; + + spin_lock_irq(q->queue_lock); + q->rpm_status = RPM_RESUMING; + spin_unlock_irq(q->queue_lock); +} +EXPORT_SYMBOL(blk_pre_runtime_resume); + +/** + * blk_post_runtime_resume - Post runtime resume processing + * @q: the queue of the device + * @err: return value of the device's runtime_resume function + * + * Description: + * Update the queue's runtime status according to the return value of the + * device's runtime_resume function. If it is successfully resumed, process + * the requests that are queued into the device's queue when it is resuming + * and then mark last busy and initiate autosuspend for it. + * + * This function should be called near the end of the device's + * runtime_resume callback. + */ +void blk_post_runtime_resume(struct request_queue *q, int err) +{ + if (!q->dev) + return; + + spin_lock_irq(q->queue_lock); + if (!err) { + q->rpm_status = RPM_ACTIVE; + __blk_run_queue(q); + pm_runtime_mark_last_busy(q->dev); + pm_request_autosuspend(q->dev); + } else { + q->rpm_status = RPM_SUSPENDED; + } + spin_unlock_irq(q->queue_lock); +} +EXPORT_SYMBOL(blk_post_runtime_resume); + +/** + * blk_set_runtime_active - Force runtime status of the queue to be active + * @q: the queue of the device + * + * If the device is left runtime suspended during system suspend the resume + * hook typically resumes the device and corrects runtime status + * accordingly. However, that does not affect the queue runtime PM status + * which is still "suspended". This prevents processing requests from the + * queue. + * + * This function can be used in driver's resume hook to correct queue + * runtime PM status and re-enable peeking requests from the queue. It + * should be called before first request is added to the queue. + */ +void blk_set_runtime_active(struct request_queue *q) +{ + spin_lock_irq(q->queue_lock); + q->rpm_status = RPM_ACTIVE; + pm_runtime_mark_last_busy(q->dev); + pm_request_autosuspend(q->dev); + spin_unlock_irq(q->queue_lock); +} +EXPORT_SYMBOL(blk_set_runtime_active); +#endif + +int __init blk_dev_init(void) +{ + BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); + BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * + FIELD_SIZEOF(struct request, cmd_flags)); + BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * + FIELD_SIZEOF(struct bio, bi_opf)); + + /* 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("request_queue", + sizeof(struct request_queue), 0, SLAB_PANIC, NULL); + +#ifdef CONFIG_DEBUG_FS + blk_debugfs_root = debugfs_create_dir("block", NULL); +#endif + + return 0; +} |