Revision 96dc89d526ef77604376f06220e3d2931a0bfd58 authored by Michael Neuling on 25 September 2018, 09:36:47 UTC, committed by Michael Ellerman on 25 September 2018, 12:51:32 UTC
Current we store the userspace r1 to PACATMSCRATCH before finally saving it to the thread struct. In theory an exception could be taken here (like a machine check or SLB miss) that could write PACATMSCRATCH and hence corrupt the userspace r1. The SLB fault currently doesn't touch PACATMSCRATCH, but others do. We've never actually seen this happen but it's theoretically possible. Either way, the code is fragile as it is. This patch saves r1 to the kernel stack (which can't fault) before we turn MSR[RI] back on. PACATMSCRATCH is still used but only with MSR[RI] off. We then copy r1 from the kernel stack to the thread struct once we have MSR[RI] back on. Suggested-by: Breno Leitao <leitao@debian.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
1 parent cf13435
blk-core.c
/*
* 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;
}
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;
cancel_delayed_work_sync(&q->requeue_work);
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_preempt_only - set QUEUE_FLAG_PREEMPT_ONLY
* @q: request queue pointer
*
* Returns the previous value of the PREEMPT_ONLY flag - 0 if the flag was not
* set and 1 if the flag was already set.
*/
int blk_set_preempt_only(struct request_queue *q)
{
return blk_queue_flag_test_and_set(QUEUE_FLAG_PREEMPT_ONLY, q);
}
EXPORT_SYMBOL_GPL(blk_set_preempt_only);
void blk_clear_preempt_only(struct request_queue *q)
{
blk_queue_flag_clear(QUEUE_FLAG_PREEMPT_ONLY, q);
wake_up_all(&q->mq_freeze_wq);
}
EXPORT_SYMBOL_GPL(blk_clear_preempt_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);
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.
*
* No need to quiesce queue if it isn't initialized yet since
* blk_freeze_queue() should be enough for cases of passthrough
* request.
*/
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_free_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 preempt = 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 sets the PREEMPT_ONLY flag is
* responsible for ensuring that that flag is globally
* visible before the queue is unfrozen.
*/
if (preempt || !blk_queue_preempt_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 &&
(preempt || !blk_queue_preempt_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);
}
/**
* 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->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, NULL);
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);
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);
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;
q = NULL;
}
}
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);
}
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)) {
unsigned long duration;
const int sgrp = op_stat_group(req_op(req));
struct hd_struct *part;
int cpu;
duration = nsecs_to_jiffies(now - req->start_time_ns);
cpu = part_stat_lock();
part = req->part;
part_stat_inc(cpu, part, ios[sgrp]);
part_stat_add(cpu, part, ticks[sgrp], duration);
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;
}
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