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A kernel crash is observed when a mounted ext3/ext4 filesystem is physically removed. The problem is that blk_cleanup_queue() frees up some resources eg by calling elevator_exit(), which are not checked for in normal operation. So we should rather move these calls to the destructor function blk_release_queue() as at that point all remaining references are gone. However, in doing so we have to ensure that any externally supplied queue_lock is disconnected as the driver might free up the lock after the call of blk_cleanup_queue(), Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2798 lines
74 KiB
C
2798 lines
74 KiB
C
/*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright (C) 1994, Karl Keyte: Added support for disk statistics
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* Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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* Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
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* kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au>
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* - July2000
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* bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
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*/
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/*
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* This handles all read/write requests to block devices
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/backing-dev.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/highmem.h>
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#include <linux/mm.h>
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#include <linux/kernel_stat.h>
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#include <linux/string.h>
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#include <linux/init.h>
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#include <linux/completion.h>
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#include <linux/slab.h>
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#include <linux/swap.h>
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#include <linux/writeback.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/fault-inject.h>
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#include <linux/list_sort.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/block.h>
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#include "blk.h"
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EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
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EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
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EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
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static int __make_request(struct request_queue *q, struct bio *bio);
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/*
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* For the allocated request tables
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*/
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static struct kmem_cache *request_cachep;
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/*
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* For queue allocation
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*/
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struct kmem_cache *blk_requestq_cachep;
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/*
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* Controlling structure to kblockd
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*/
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static struct workqueue_struct *kblockd_workqueue;
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static void drive_stat_acct(struct request *rq, int new_io)
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{
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struct hd_struct *part;
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int rw = rq_data_dir(rq);
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int cpu;
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if (!blk_do_io_stat(rq))
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return;
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cpu = part_stat_lock();
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if (!new_io) {
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part = rq->part;
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part_stat_inc(cpu, part, merges[rw]);
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} else {
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part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
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if (!hd_struct_try_get(part)) {
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/*
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* The partition is already being removed,
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* the request will be accounted on the disk only
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*
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* We take a reference on disk->part0 although that
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* partition will never be deleted, so we can treat
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* it as any other partition.
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*/
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part = &rq->rq_disk->part0;
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hd_struct_get(part);
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}
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part_round_stats(cpu, part);
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part_inc_in_flight(part, rw);
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rq->part = part;
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}
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part_stat_unlock();
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}
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void blk_queue_congestion_threshold(struct request_queue *q)
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{
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int nr;
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nr = q->nr_requests - (q->nr_requests / 8) + 1;
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if (nr > q->nr_requests)
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nr = q->nr_requests;
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q->nr_congestion_on = nr;
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nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
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if (nr < 1)
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nr = 1;
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q->nr_congestion_off = nr;
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}
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/**
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* blk_get_backing_dev_info - get the address of a queue's backing_dev_info
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* @bdev: device
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*
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* Locates the passed device's request queue and returns the address of its
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* backing_dev_info
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*
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* Will return NULL if the request queue cannot be located.
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*/
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struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
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{
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struct backing_dev_info *ret = NULL;
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struct request_queue *q = bdev_get_queue(bdev);
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if (q)
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ret = &q->backing_dev_info;
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return ret;
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}
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EXPORT_SYMBOL(blk_get_backing_dev_info);
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void blk_rq_init(struct request_queue *q, struct request *rq)
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{
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memset(rq, 0, sizeof(*rq));
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INIT_LIST_HEAD(&rq->queuelist);
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INIT_LIST_HEAD(&rq->timeout_list);
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rq->cpu = -1;
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rq->q = q;
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rq->__sector = (sector_t) -1;
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INIT_HLIST_NODE(&rq->hash);
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RB_CLEAR_NODE(&rq->rb_node);
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rq->cmd = rq->__cmd;
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rq->cmd_len = BLK_MAX_CDB;
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rq->tag = -1;
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rq->ref_count = 1;
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rq->start_time = jiffies;
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set_start_time_ns(rq);
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rq->part = NULL;
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}
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EXPORT_SYMBOL(blk_rq_init);
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static void req_bio_endio(struct request *rq, struct bio *bio,
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unsigned int nbytes, int error)
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{
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if (error)
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clear_bit(BIO_UPTODATE, &bio->bi_flags);
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else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
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error = -EIO;
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if (unlikely(nbytes > bio->bi_size)) {
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printk(KERN_ERR "%s: want %u bytes done, %u left\n",
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__func__, nbytes, bio->bi_size);
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nbytes = bio->bi_size;
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}
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if (unlikely(rq->cmd_flags & REQ_QUIET))
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set_bit(BIO_QUIET, &bio->bi_flags);
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bio->bi_size -= nbytes;
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bio->bi_sector += (nbytes >> 9);
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if (bio_integrity(bio))
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bio_integrity_advance(bio, nbytes);
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/* don't actually finish bio if it's part of flush sequence */
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if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
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bio_endio(bio, error);
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}
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void blk_dump_rq_flags(struct request *rq, char *msg)
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{
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int bit;
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printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg,
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rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
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rq->cmd_flags);
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printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
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(unsigned long long)blk_rq_pos(rq),
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blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
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printk(KERN_INFO " bio %p, biotail %p, buffer %p, len %u\n",
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rq->bio, rq->biotail, rq->buffer, blk_rq_bytes(rq));
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if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
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printk(KERN_INFO " cdb: ");
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for (bit = 0; bit < BLK_MAX_CDB; bit++)
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printk("%02x ", rq->cmd[bit]);
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printk("\n");
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}
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}
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EXPORT_SYMBOL(blk_dump_rq_flags);
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static void blk_delay_work(struct work_struct *work)
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{
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struct request_queue *q;
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q = container_of(work, struct request_queue, delay_work.work);
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spin_lock_irq(q->queue_lock);
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__blk_run_queue(q);
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spin_unlock_irq(q->queue_lock);
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}
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/**
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* blk_delay_queue - restart queueing after defined interval
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* @q: The &struct request_queue in question
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* @msecs: Delay in msecs
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*
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* Description:
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* Sometimes queueing needs to be postponed for a little while, to allow
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* resources to come back. This function will make sure that queueing is
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* restarted around the specified time.
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*/
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void blk_delay_queue(struct request_queue *q, unsigned long msecs)
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{
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queue_delayed_work(kblockd_workqueue, &q->delay_work,
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msecs_to_jiffies(msecs));
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}
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EXPORT_SYMBOL(blk_delay_queue);
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/**
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* blk_start_queue - restart a previously stopped queue
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* @q: The &struct request_queue in question
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*
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* Description:
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* blk_start_queue() will clear the stop flag on the queue, and call
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* the request_fn for the queue if it was in a stopped state when
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* entered. Also see blk_stop_queue(). Queue lock must be held.
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**/
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void blk_start_queue(struct request_queue *q)
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{
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WARN_ON(!irqs_disabled());
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queue_flag_clear(QUEUE_FLAG_STOPPED, q);
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__blk_run_queue(q);
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}
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EXPORT_SYMBOL(blk_start_queue);
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/**
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* blk_stop_queue - stop a queue
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* @q: The &struct request_queue in question
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*
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* Description:
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* The Linux block layer assumes that a block driver will consume all
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* entries on the request queue when the request_fn strategy is called.
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* Often this will not happen, because of hardware limitations (queue
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* depth settings). If a device driver gets a 'queue full' response,
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* or if it simply chooses not to queue more I/O at one point, it can
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* call this function to prevent the request_fn from being called until
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* the driver has signalled it's ready to go again. This happens by calling
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* blk_start_queue() to restart queue operations. Queue lock must be held.
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**/
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void blk_stop_queue(struct request_queue *q)
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{
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__cancel_delayed_work(&q->delay_work);
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queue_flag_set(QUEUE_FLAG_STOPPED, q);
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}
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EXPORT_SYMBOL(blk_stop_queue);
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/**
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* blk_sync_queue - cancel any pending callbacks on a queue
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* @q: the queue
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*
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* Description:
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* The block layer may perform asynchronous callback activity
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* on a queue, such as calling the unplug function after a timeout.
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* A block device may call blk_sync_queue to ensure that any
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* such activity is cancelled, thus allowing it to release resources
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* that the callbacks might use. The caller must already have made sure
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* that its ->make_request_fn will not re-add plugging prior to calling
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* this function.
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*
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* This function does not cancel any asynchronous activity arising
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* out of elevator or throttling code. That would require elevaotor_exit()
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* and blk_throtl_exit() to be called with queue lock initialized.
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*
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*/
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void blk_sync_queue(struct request_queue *q)
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{
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del_timer_sync(&q->timeout);
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cancel_delayed_work_sync(&q->delay_work);
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}
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EXPORT_SYMBOL(blk_sync_queue);
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/**
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* __blk_run_queue - run a single device queue
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* @q: The queue to run
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*
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* Description:
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* See @blk_run_queue. This variant must be called with the queue lock
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* held and interrupts disabled.
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*/
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void __blk_run_queue(struct request_queue *q)
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{
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if (unlikely(blk_queue_stopped(q)))
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return;
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q->request_fn(q);
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}
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EXPORT_SYMBOL(__blk_run_queue);
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/**
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* blk_run_queue_async - run a single device queue in workqueue context
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* @q: The queue to run
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*
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* Description:
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* Tells kblockd to perform the equivalent of @blk_run_queue on behalf
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* of us.
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*/
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void blk_run_queue_async(struct request_queue *q)
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{
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if (likely(!blk_queue_stopped(q))) {
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__cancel_delayed_work(&q->delay_work);
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queue_delayed_work(kblockd_workqueue, &q->delay_work, 0);
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}
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}
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EXPORT_SYMBOL(blk_run_queue_async);
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/**
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* blk_run_queue - run a single device queue
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* @q: The queue to run
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*
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* Description:
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* Invoke request handling on this queue, if it has pending work to do.
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* May be used to restart queueing when a request has completed.
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*/
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void blk_run_queue(struct request_queue *q)
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{
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unsigned long flags;
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spin_lock_irqsave(q->queue_lock, flags);
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__blk_run_queue(q);
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spin_unlock_irqrestore(q->queue_lock, flags);
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}
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EXPORT_SYMBOL(blk_run_queue);
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void blk_put_queue(struct request_queue *q)
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{
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kobject_put(&q->kobj);
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}
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EXPORT_SYMBOL(blk_put_queue);
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/*
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* Note: If a driver supplied the queue lock, it is disconnected
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* by this function. The actual state of the lock doesn't matter
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* here as the request_queue isn't accessible after this point
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* (QUEUE_FLAG_DEAD is set) and no other requests will be queued.
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*/
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void blk_cleanup_queue(struct request_queue *q)
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{
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/*
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* We know we have process context here, so we can be a little
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* cautious and ensure that pending block actions on this device
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* are done before moving on. Going into this function, we should
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* not have processes doing IO to this device.
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*/
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blk_sync_queue(q);
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del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
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mutex_lock(&q->sysfs_lock);
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queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
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mutex_unlock(&q->sysfs_lock);
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if (q->queue_lock != &q->__queue_lock)
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q->queue_lock = &q->__queue_lock;
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blk_put_queue(q);
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}
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EXPORT_SYMBOL(blk_cleanup_queue);
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static int blk_init_free_list(struct request_queue *q)
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{
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struct request_list *rl = &q->rq;
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if (unlikely(rl->rq_pool))
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return 0;
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rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
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rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
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rl->elvpriv = 0;
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init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
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init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
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rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
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mempool_free_slab, request_cachep, q->node);
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if (!rl->rq_pool)
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return -ENOMEM;
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return 0;
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}
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struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
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{
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return blk_alloc_queue_node(gfp_mask, -1);
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}
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EXPORT_SYMBOL(blk_alloc_queue);
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struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
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{
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struct request_queue *q;
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int err;
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q = kmem_cache_alloc_node(blk_requestq_cachep,
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gfp_mask | __GFP_ZERO, node_id);
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if (!q)
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return NULL;
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q->backing_dev_info.ra_pages =
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(VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
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q->backing_dev_info.state = 0;
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q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
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q->backing_dev_info.name = "block";
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err = bdi_init(&q->backing_dev_info);
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if (err) {
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kmem_cache_free(blk_requestq_cachep, q);
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return NULL;
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}
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if (blk_throtl_init(q)) {
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kmem_cache_free(blk_requestq_cachep, q);
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return NULL;
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}
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setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
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laptop_mode_timer_fn, (unsigned long) q);
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setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
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INIT_LIST_HEAD(&q->timeout_list);
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INIT_LIST_HEAD(&q->flush_queue[0]);
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INIT_LIST_HEAD(&q->flush_queue[1]);
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INIT_LIST_HEAD(&q->flush_data_in_flight);
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INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
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kobject_init(&q->kobj, &blk_queue_ktype);
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mutex_init(&q->sysfs_lock);
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spin_lock_init(&q->__queue_lock);
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/*
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* By default initialize queue_lock to internal lock and driver can
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* override it later if need be.
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*/
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q->queue_lock = &q->__queue_lock;
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return q;
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}
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EXPORT_SYMBOL(blk_alloc_queue_node);
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|
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/**
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|
* blk_init_queue - prepare a request queue for use with a block device
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|
* @rfn: The function to be called to process requests that have been
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* placed on the queue.
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* @lock: Request queue spin lock
|
|
*
|
|
* Description:
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* If a block device wishes to use the standard request handling procedures,
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* which sorts requests and coalesces adjacent requests, then it must
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* call blk_init_queue(). The function @rfn will be called when there
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* are requests on the queue that need to be processed. If the device
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* supports plugging, then @rfn may not be called immediately when requests
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* are available on the queue, but may be called at some time later instead.
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* Plugged queues are generally unplugged when a buffer belonging to one
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* of the requests on the queue is needed, or due to memory pressure.
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*
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* @rfn is not required, or even expected, to remove all requests off the
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* queue, but only as many as it can handle at a time. If it does leave
|
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* requests on the queue, it is responsible for arranging that the requests
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* get dealt with eventually.
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*
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* The queue spin lock must be held while manipulating the requests on the
|
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* request queue; this lock will be taken also from interrupt context, so irq
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* disabling is needed for it.
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*
|
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* Function returns a pointer to the initialized request queue, or %NULL if
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* it didn't succeed.
|
|
*
|
|
* Note:
|
|
* blk_init_queue() must be paired with a blk_cleanup_queue() call
|
|
* when the block device is deactivated (such as at module unload).
|
|
**/
|
|
|
|
struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
|
|
{
|
|
return blk_init_queue_node(rfn, lock, -1);
|
|
}
|
|
EXPORT_SYMBOL(blk_init_queue);
|
|
|
|
struct request_queue *
|
|
blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
|
|
{
|
|
struct request_queue *uninit_q, *q;
|
|
|
|
uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
|
|
if (!uninit_q)
|
|
return NULL;
|
|
|
|
q = blk_init_allocated_queue_node(uninit_q, rfn, lock, node_id);
|
|
if (!q)
|
|
blk_cleanup_queue(uninit_q);
|
|
|
|
return q;
|
|
}
|
|
EXPORT_SYMBOL(blk_init_queue_node);
|
|
|
|
struct request_queue *
|
|
blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
|
|
spinlock_t *lock)
|
|
{
|
|
return blk_init_allocated_queue_node(q, rfn, lock, -1);
|
|
}
|
|
EXPORT_SYMBOL(blk_init_allocated_queue);
|
|
|
|
struct request_queue *
|
|
blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn,
|
|
spinlock_t *lock, int node_id)
|
|
{
|
|
if (!q)
|
|
return NULL;
|
|
|
|
q->node = node_id;
|
|
if (blk_init_free_list(q))
|
|
return NULL;
|
|
|
|
q->request_fn = rfn;
|
|
q->prep_rq_fn = NULL;
|
|
q->unprep_rq_fn = NULL;
|
|
q->queue_flags = QUEUE_FLAG_DEFAULT;
|
|
|
|
/* Override internal queue lock with supplied lock pointer */
|
|
if (lock)
|
|
q->queue_lock = lock;
|
|
|
|
/*
|
|
* This also sets hw/phys segments, boundary and size
|
|
*/
|
|
blk_queue_make_request(q, __make_request);
|
|
|
|
q->sg_reserved_size = INT_MAX;
|
|
|
|
/*
|
|
* all done
|
|
*/
|
|
if (!elevator_init(q, NULL)) {
|
|
blk_queue_congestion_threshold(q);
|
|
return q;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(blk_init_allocated_queue_node);
|
|
|
|
int blk_get_queue(struct request_queue *q)
|
|
{
|
|
if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
|
|
kobject_get(&q->kobj);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(blk_get_queue);
|
|
|
|
static inline void blk_free_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
if (rq->cmd_flags & REQ_ELVPRIV)
|
|
elv_put_request(q, rq);
|
|
mempool_free(rq, q->rq.rq_pool);
|
|
}
|
|
|
|
static struct request *
|
|
blk_alloc_request(struct request_queue *q, int flags, int priv, gfp_t gfp_mask)
|
|
{
|
|
struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
|
|
|
|
if (!rq)
|
|
return NULL;
|
|
|
|
blk_rq_init(q, rq);
|
|
|
|
rq->cmd_flags = flags | REQ_ALLOCED;
|
|
|
|
if (priv) {
|
|
if (unlikely(elv_set_request(q, rq, gfp_mask))) {
|
|
mempool_free(rq, q->rq.rq_pool);
|
|
return NULL;
|
|
}
|
|
rq->cmd_flags |= REQ_ELVPRIV;
|
|
}
|
|
|
|
return rq;
|
|
}
|
|
|
|
/*
|
|
* ioc_batching returns true if the ioc is a valid batching request and
|
|
* should be given priority access to a request.
|
|
*/
|
|
static inline int ioc_batching(struct request_queue *q, struct io_context *ioc)
|
|
{
|
|
if (!ioc)
|
|
return 0;
|
|
|
|
/*
|
|
* Make sure the process is able to allocate at least 1 request
|
|
* even if the batch times out, otherwise we could theoretically
|
|
* lose wakeups.
|
|
*/
|
|
return ioc->nr_batch_requests == q->nr_batching ||
|
|
(ioc->nr_batch_requests > 0
|
|
&& time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
|
|
}
|
|
|
|
/*
|
|
* ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
|
|
* will cause the process to be a "batcher" on all queues in the system. This
|
|
* is the behaviour we want though - once it gets a wakeup it should be given
|
|
* a nice run.
|
|
*/
|
|
static void ioc_set_batching(struct request_queue *q, struct io_context *ioc)
|
|
{
|
|
if (!ioc || ioc_batching(q, ioc))
|
|
return;
|
|
|
|
ioc->nr_batch_requests = q->nr_batching;
|
|
ioc->last_waited = jiffies;
|
|
}
|
|
|
|
static void __freed_request(struct request_queue *q, int sync)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
|
|
if (rl->count[sync] < queue_congestion_off_threshold(q))
|
|
blk_clear_queue_congested(q, sync);
|
|
|
|
if (rl->count[sync] + 1 <= q->nr_requests) {
|
|
if (waitqueue_active(&rl->wait[sync]))
|
|
wake_up(&rl->wait[sync]);
|
|
|
|
blk_clear_queue_full(q, sync);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* A request has just been released. Account for it, update the full and
|
|
* congestion status, wake up any waiters. Called under q->queue_lock.
|
|
*/
|
|
static void freed_request(struct request_queue *q, int sync, int priv)
|
|
{
|
|
struct request_list *rl = &q->rq;
|
|
|
|
rl->count[sync]--;
|
|
if (priv)
|
|
rl->elvpriv--;
|
|
|
|
__freed_request(q, sync);
|
|
|
|
if (unlikely(rl->starved[sync ^ 1]))
|
|
__freed_request(q, sync ^ 1);
|
|
}
|
|
|
|
/*
|
|
* Determine if elevator data should be initialized when allocating the
|
|
* request associated with @bio.
|
|
*/
|
|
static bool blk_rq_should_init_elevator(struct bio *bio)
|
|
{
|
|
if (!bio)
|
|
return true;
|
|
|
|
/*
|
|
* Flush requests do not use the elevator so skip initialization.
|
|
* This allows a request to share the flush and elevator data.
|
|
*/
|
|
if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Get a free request, queue_lock must be held.
|
|
* Returns NULL on failure, with queue_lock held.
|
|
* Returns !NULL on success, with queue_lock *not held*.
|
|
*/
|
|
static struct request *get_request(struct request_queue *q, int rw_flags,
|
|
struct bio *bio, gfp_t gfp_mask)
|
|
{
|
|
struct request *rq = NULL;
|
|
struct request_list *rl = &q->rq;
|
|
struct io_context *ioc = NULL;
|
|
const bool is_sync = rw_is_sync(rw_flags) != 0;
|
|
int may_queue, priv = 0;
|
|
|
|
may_queue = elv_may_queue(q, rw_flags);
|
|
if (may_queue == ELV_MQUEUE_NO)
|
|
goto rq_starved;
|
|
|
|
if (rl->count[is_sync]+1 >= queue_congestion_on_threshold(q)) {
|
|
if (rl->count[is_sync]+1 >= q->nr_requests) {
|
|
ioc = current_io_context(GFP_ATOMIC, q->node);
|
|
/*
|
|
* The queue will fill after this allocation, so set
|
|
* it as full, and mark this process as "batching".
|
|
* This process will be allowed to complete a batch of
|
|
* requests, others will be blocked.
|
|
*/
|
|
if (!blk_queue_full(q, is_sync)) {
|
|
ioc_set_batching(q, ioc);
|
|
blk_set_queue_full(q, is_sync);
|
|
} else {
|
|
if (may_queue != ELV_MQUEUE_MUST
|
|
&& !ioc_batching(q, ioc)) {
|
|
/*
|
|
* The queue is full and the allocating
|
|
* process is not a "batcher", and not
|
|
* exempted by the IO scheduler
|
|
*/
|
|
goto out;
|
|
}
|
|
}
|
|
}
|
|
blk_set_queue_congested(q, is_sync);
|
|
}
|
|
|
|
/*
|
|
* Only allow batching queuers to allocate up to 50% over the defined
|
|
* limit of requests, otherwise we could have thousands of requests
|
|
* allocated with any setting of ->nr_requests
|
|
*/
|
|
if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
|
|
goto out;
|
|
|
|
rl->count[is_sync]++;
|
|
rl->starved[is_sync] = 0;
|
|
|
|
if (blk_rq_should_init_elevator(bio)) {
|
|
priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
|
|
if (priv)
|
|
rl->elvpriv++;
|
|
}
|
|
|
|
if (blk_queue_io_stat(q))
|
|
rw_flags |= REQ_IO_STAT;
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
rq = blk_alloc_request(q, rw_flags, priv, gfp_mask);
|
|
if (unlikely(!rq)) {
|
|
/*
|
|
* Allocation failed presumably due to memory. Undo anything
|
|
* we might have messed up.
|
|
*
|
|
* Allocating task should really be put onto the front of the
|
|
* wait queue, but this is pretty rare.
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
freed_request(q, is_sync, priv);
|
|
|
|
/*
|
|
* in the very unlikely event that allocation failed and no
|
|
* requests for this direction was pending, mark us starved
|
|
* so that freeing of a request in the other direction will
|
|
* notice us. another possible fix would be to split the
|
|
* rq mempool into READ and WRITE
|
|
*/
|
|
rq_starved:
|
|
if (unlikely(rl->count[is_sync] == 0))
|
|
rl->starved[is_sync] = 1;
|
|
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* ioc may be NULL here, and ioc_batching will be false. That's
|
|
* OK, if the queue is under the request limit then requests need
|
|
* not count toward the nr_batch_requests limit. There will always
|
|
* be some limit enforced by BLK_BATCH_TIME.
|
|
*/
|
|
if (ioc_batching(q, ioc))
|
|
ioc->nr_batch_requests--;
|
|
|
|
trace_block_getrq(q, bio, rw_flags & 1);
|
|
out:
|
|
return rq;
|
|
}
|
|
|
|
/*
|
|
* No available requests for this queue, wait for some requests to become
|
|
* available.
|
|
*
|
|
* Called with q->queue_lock held, and returns with it unlocked.
|
|
*/
|
|
static struct request *get_request_wait(struct request_queue *q, int rw_flags,
|
|
struct bio *bio)
|
|
{
|
|
const bool is_sync = rw_is_sync(rw_flags) != 0;
|
|
struct request *rq;
|
|
|
|
rq = get_request(q, rw_flags, bio, GFP_NOIO);
|
|
while (!rq) {
|
|
DEFINE_WAIT(wait);
|
|
struct io_context *ioc;
|
|
struct request_list *rl = &q->rq;
|
|
|
|
prepare_to_wait_exclusive(&rl->wait[is_sync], &wait,
|
|
TASK_UNINTERRUPTIBLE);
|
|
|
|
trace_block_sleeprq(q, bio, rw_flags & 1);
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
io_schedule();
|
|
|
|
/*
|
|
* After sleeping, we become a "batching" process and
|
|
* will be able to allocate at least one request, and
|
|
* up to a big batch of them for a small period time.
|
|
* See ioc_batching, ioc_set_batching
|
|
*/
|
|
ioc = current_io_context(GFP_NOIO, q->node);
|
|
ioc_set_batching(q, ioc);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
finish_wait(&rl->wait[is_sync], &wait);
|
|
|
|
rq = get_request(q, rw_flags, bio, GFP_NOIO);
|
|
};
|
|
|
|
return rq;
|
|
}
|
|
|
|
struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
|
|
{
|
|
struct request *rq;
|
|
|
|
if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
|
|
return NULL;
|
|
|
|
BUG_ON(rw != READ && rw != WRITE);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
if (gfp_mask & __GFP_WAIT) {
|
|
rq = get_request_wait(q, rw, NULL);
|
|
} else {
|
|
rq = get_request(q, rw, NULL, gfp_mask);
|
|
if (!rq)
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
/* q->queue_lock is unlocked at this point */
|
|
|
|
return rq;
|
|
}
|
|
EXPORT_SYMBOL(blk_get_request);
|
|
|
|
/**
|
|
* blk_make_request - given a bio, allocate a corresponding struct request.
|
|
* @q: target request queue
|
|
* @bio: The bio describing the memory mappings that will be submitted for IO.
|
|
* It may be a chained-bio properly constructed by block/bio layer.
|
|
* @gfp_mask: gfp flags to be used for memory allocation
|
|
*
|
|
* blk_make_request is the parallel of generic_make_request for BLOCK_PC
|
|
* type commands. Where the struct request needs to be farther initialized by
|
|
* the caller. It is passed a &struct bio, which describes the memory info of
|
|
* the I/O transfer.
|
|
*
|
|
* The caller of blk_make_request must make sure that bi_io_vec
|
|
* are set to describe the memory buffers. That bio_data_dir() will return
|
|
* the needed direction of the request. (And all bio's in the passed bio-chain
|
|
* are properly set accordingly)
|
|
*
|
|
* If called under none-sleepable conditions, mapped bio buffers must not
|
|
* need bouncing, by calling the appropriate masked or flagged allocator,
|
|
* suitable for the target device. Otherwise the call to blk_queue_bounce will
|
|
* BUG.
|
|
*
|
|
* WARNING: When allocating/cloning a bio-chain, careful consideration should be
|
|
* given to how you allocate bios. In particular, you cannot use __GFP_WAIT for
|
|
* anything but the first bio in the chain. Otherwise you risk waiting for IO
|
|
* completion of a bio that hasn't been submitted yet, thus resulting in a
|
|
* deadlock. Alternatively bios should be allocated using bio_kmalloc() instead
|
|
* of bio_alloc(), as that avoids the mempool deadlock.
|
|
* If possible a big IO should be split into smaller parts when allocation
|
|
* fails. Partial allocation should not be an error, or you risk a live-lock.
|
|
*/
|
|
struct request *blk_make_request(struct request_queue *q, struct bio *bio,
|
|
gfp_t gfp_mask)
|
|
{
|
|
struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
|
|
|
|
if (unlikely(!rq))
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
for_each_bio(bio) {
|
|
struct bio *bounce_bio = bio;
|
|
int ret;
|
|
|
|
blk_queue_bounce(q, &bounce_bio);
|
|
ret = blk_rq_append_bio(q, rq, bounce_bio);
|
|
if (unlikely(ret)) {
|
|
blk_put_request(rq);
|
|
return ERR_PTR(ret);
|
|
}
|
|
}
|
|
|
|
return rq;
|
|
}
|
|
EXPORT_SYMBOL(blk_make_request);
|
|
|
|
/**
|
|
* blk_requeue_request - put a request back on queue
|
|
* @q: request queue where request should be inserted
|
|
* @rq: request to be inserted
|
|
*
|
|
* Description:
|
|
* Drivers often keep queueing requests until the hardware cannot accept
|
|
* more, when that condition happens we need to put the request back
|
|
* on the queue. Must be called with queue lock held.
|
|
*/
|
|
void blk_requeue_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
blk_delete_timer(rq);
|
|
blk_clear_rq_complete(rq);
|
|
trace_block_rq_requeue(q, rq);
|
|
|
|
if (blk_rq_tagged(rq))
|
|
blk_queue_end_tag(q, rq);
|
|
|
|
BUG_ON(blk_queued_rq(rq));
|
|
|
|
elv_requeue_request(q, rq);
|
|
}
|
|
EXPORT_SYMBOL(blk_requeue_request);
|
|
|
|
static void add_acct_request(struct request_queue *q, struct request *rq,
|
|
int where)
|
|
{
|
|
drive_stat_acct(rq, 1);
|
|
__elv_add_request(q, rq, where);
|
|
}
|
|
|
|
/**
|
|
* blk_insert_request - insert a special request into a request queue
|
|
* @q: request queue where request should be inserted
|
|
* @rq: request to be inserted
|
|
* @at_head: insert request at head or tail of queue
|
|
* @data: private data
|
|
*
|
|
* Description:
|
|
* Many block devices need to execute commands asynchronously, so they don't
|
|
* block the whole kernel from preemption during request execution. This is
|
|
* accomplished normally by inserting aritficial requests tagged as
|
|
* REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them
|
|
* be scheduled for actual execution by the request queue.
|
|
*
|
|
* We have the option of inserting the head or the tail of the queue.
|
|
* Typically we use the tail for new ioctls and so forth. We use the head
|
|
* of the queue for things like a QUEUE_FULL message from a device, or a
|
|
* host that is unable to accept a particular command.
|
|
*/
|
|
void blk_insert_request(struct request_queue *q, struct request *rq,
|
|
int at_head, void *data)
|
|
{
|
|
int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* tell I/O scheduler that this isn't a regular read/write (ie it
|
|
* must not attempt merges on this) and that it acts as a soft
|
|
* barrier
|
|
*/
|
|
rq->cmd_type = REQ_TYPE_SPECIAL;
|
|
|
|
rq->special = data;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
/*
|
|
* If command is tagged, release the tag
|
|
*/
|
|
if (blk_rq_tagged(rq))
|
|
blk_queue_end_tag(q, rq);
|
|
|
|
add_acct_request(q, rq, where);
|
|
__blk_run_queue(q);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(blk_insert_request);
|
|
|
|
static void part_round_stats_single(int cpu, struct hd_struct *part,
|
|
unsigned long now)
|
|
{
|
|
if (now == part->stamp)
|
|
return;
|
|
|
|
if (part_in_flight(part)) {
|
|
__part_stat_add(cpu, part, time_in_queue,
|
|
part_in_flight(part) * (now - part->stamp));
|
|
__part_stat_add(cpu, part, io_ticks, (now - part->stamp));
|
|
}
|
|
part->stamp = now;
|
|
}
|
|
|
|
/**
|
|
* part_round_stats() - Round off the performance stats on a struct disk_stats.
|
|
* @cpu: cpu number for stats access
|
|
* @part: target partition
|
|
*
|
|
* The average IO queue length and utilisation statistics are maintained
|
|
* by observing the current state of the queue length and the amount of
|
|
* time it has been in this state for.
|
|
*
|
|
* Normally, that accounting is done on IO completion, but that can result
|
|
* in more than a second's worth of IO being accounted for within any one
|
|
* second, leading to >100% utilisation. To deal with that, we call this
|
|
* function to do a round-off before returning the results when reading
|
|
* /proc/diskstats. This accounts immediately for all queue usage up to
|
|
* the current jiffies and restarts the counters again.
|
|
*/
|
|
void part_round_stats(int cpu, struct hd_struct *part)
|
|
{
|
|
unsigned long now = jiffies;
|
|
|
|
if (part->partno)
|
|
part_round_stats_single(cpu, &part_to_disk(part)->part0, now);
|
|
part_round_stats_single(cpu, part, now);
|
|
}
|
|
EXPORT_SYMBOL_GPL(part_round_stats);
|
|
|
|
/*
|
|
* queue lock must be held
|
|
*/
|
|
void __blk_put_request(struct request_queue *q, struct request *req)
|
|
{
|
|
if (unlikely(!q))
|
|
return;
|
|
if (unlikely(--req->ref_count))
|
|
return;
|
|
|
|
elv_completed_request(q, req);
|
|
|
|
/* this is a bio leak */
|
|
WARN_ON(req->bio != NULL);
|
|
|
|
/*
|
|
* Request may not have originated from ll_rw_blk. if not,
|
|
* it didn't come out of our reserved rq pools
|
|
*/
|
|
if (req->cmd_flags & REQ_ALLOCED) {
|
|
int is_sync = rq_is_sync(req) != 0;
|
|
int priv = req->cmd_flags & REQ_ELVPRIV;
|
|
|
|
BUG_ON(!list_empty(&req->queuelist));
|
|
BUG_ON(!hlist_unhashed(&req->hash));
|
|
|
|
blk_free_request(q, req);
|
|
freed_request(q, is_sync, priv);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(__blk_put_request);
|
|
|
|
void blk_put_request(struct request *req)
|
|
{
|
|
unsigned long flags;
|
|
struct request_queue *q = req->q;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
__blk_put_request(q, req);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(blk_put_request);
|
|
|
|
/**
|
|
* blk_add_request_payload - add a payload to a request
|
|
* @rq: request to update
|
|
* @page: page backing the payload
|
|
* @len: length of the payload.
|
|
*
|
|
* This allows to later add a payload to an already submitted request by
|
|
* a block driver. The driver needs to take care of freeing the payload
|
|
* itself.
|
|
*
|
|
* Note that this is a quite horrible hack and nothing but handling of
|
|
* discard requests should ever use it.
|
|
*/
|
|
void blk_add_request_payload(struct request *rq, struct page *page,
|
|
unsigned int len)
|
|
{
|
|
struct bio *bio = rq->bio;
|
|
|
|
bio->bi_io_vec->bv_page = page;
|
|
bio->bi_io_vec->bv_offset = 0;
|
|
bio->bi_io_vec->bv_len = len;
|
|
|
|
bio->bi_size = len;
|
|
bio->bi_vcnt = 1;
|
|
bio->bi_phys_segments = 1;
|
|
|
|
rq->__data_len = rq->resid_len = len;
|
|
rq->nr_phys_segments = 1;
|
|
rq->buffer = bio_data(bio);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_add_request_payload);
|
|
|
|
static bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
|
|
struct bio *bio)
|
|
{
|
|
const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
|
|
|
|
if (!ll_back_merge_fn(q, req, bio))
|
|
return false;
|
|
|
|
trace_block_bio_backmerge(q, bio);
|
|
|
|
if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
|
|
blk_rq_set_mixed_merge(req);
|
|
|
|
req->biotail->bi_next = bio;
|
|
req->biotail = bio;
|
|
req->__data_len += bio->bi_size;
|
|
req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
|
|
|
|
drive_stat_acct(req, 0);
|
|
elv_bio_merged(q, req, bio);
|
|
return true;
|
|
}
|
|
|
|
static bool bio_attempt_front_merge(struct request_queue *q,
|
|
struct request *req, struct bio *bio)
|
|
{
|
|
const int ff = bio->bi_rw & REQ_FAILFAST_MASK;
|
|
|
|
if (!ll_front_merge_fn(q, req, bio))
|
|
return false;
|
|
|
|
trace_block_bio_frontmerge(q, bio);
|
|
|
|
if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
|
|
blk_rq_set_mixed_merge(req);
|
|
|
|
bio->bi_next = req->bio;
|
|
req->bio = bio;
|
|
|
|
/*
|
|
* may not be valid. if the low level driver said
|
|
* it didn't need a bounce buffer then it better
|
|
* not touch req->buffer either...
|
|
*/
|
|
req->buffer = bio_data(bio);
|
|
req->__sector = bio->bi_sector;
|
|
req->__data_len += bio->bi_size;
|
|
req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
|
|
|
|
drive_stat_acct(req, 0);
|
|
elv_bio_merged(q, req, bio);
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Attempts to merge with the plugged list in the current process. Returns
|
|
* true if merge was successful, otherwise false.
|
|
*/
|
|
static bool attempt_plug_merge(struct task_struct *tsk, struct request_queue *q,
|
|
struct bio *bio, unsigned int *request_count)
|
|
{
|
|
struct blk_plug *plug;
|
|
struct request *rq;
|
|
bool ret = false;
|
|
|
|
plug = tsk->plug;
|
|
if (!plug)
|
|
goto out;
|
|
*request_count = 0;
|
|
|
|
list_for_each_entry_reverse(rq, &plug->list, queuelist) {
|
|
int el_ret;
|
|
|
|
(*request_count)++;
|
|
|
|
if (rq->q != q)
|
|
continue;
|
|
|
|
el_ret = elv_try_merge(rq, bio);
|
|
if (el_ret == ELEVATOR_BACK_MERGE) {
|
|
ret = bio_attempt_back_merge(q, rq, bio);
|
|
if (ret)
|
|
break;
|
|
} else if (el_ret == ELEVATOR_FRONT_MERGE) {
|
|
ret = bio_attempt_front_merge(q, rq, bio);
|
|
if (ret)
|
|
break;
|
|
}
|
|
}
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
void init_request_from_bio(struct request *req, struct bio *bio)
|
|
{
|
|
req->cpu = bio->bi_comp_cpu;
|
|
req->cmd_type = REQ_TYPE_FS;
|
|
|
|
req->cmd_flags |= bio->bi_rw & REQ_COMMON_MASK;
|
|
if (bio->bi_rw & REQ_RAHEAD)
|
|
req->cmd_flags |= REQ_FAILFAST_MASK;
|
|
|
|
req->errors = 0;
|
|
req->__sector = bio->bi_sector;
|
|
req->ioprio = bio_prio(bio);
|
|
blk_rq_bio_prep(req->q, req, bio);
|
|
}
|
|
|
|
static int __make_request(struct request_queue *q, struct bio *bio)
|
|
{
|
|
const bool sync = !!(bio->bi_rw & REQ_SYNC);
|
|
struct blk_plug *plug;
|
|
int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT;
|
|
struct request *req;
|
|
unsigned int request_count = 0;
|
|
|
|
/*
|
|
* low level driver can indicate that it wants pages above a
|
|
* certain limit bounced to low memory (ie for highmem, or even
|
|
* ISA dma in theory)
|
|
*/
|
|
blk_queue_bounce(q, &bio);
|
|
|
|
if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
|
|
spin_lock_irq(q->queue_lock);
|
|
where = ELEVATOR_INSERT_FLUSH;
|
|
goto get_rq;
|
|
}
|
|
|
|
/*
|
|
* Check if we can merge with the plugged list before grabbing
|
|
* any locks.
|
|
*/
|
|
if (attempt_plug_merge(current, q, bio, &request_count))
|
|
goto out;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
|
|
el_ret = elv_merge(q, &req, bio);
|
|
if (el_ret == ELEVATOR_BACK_MERGE) {
|
|
if (bio_attempt_back_merge(q, req, bio)) {
|
|
if (!attempt_back_merge(q, req))
|
|
elv_merged_request(q, req, el_ret);
|
|
goto out_unlock;
|
|
}
|
|
} else if (el_ret == ELEVATOR_FRONT_MERGE) {
|
|
if (bio_attempt_front_merge(q, req, bio)) {
|
|
if (!attempt_front_merge(q, req))
|
|
elv_merged_request(q, req, el_ret);
|
|
goto out_unlock;
|
|
}
|
|
}
|
|
|
|
get_rq:
|
|
/*
|
|
* This sync check and mask will be re-done in init_request_from_bio(),
|
|
* but we need to set it earlier to expose the sync flag to the
|
|
* rq allocator and io schedulers.
|
|
*/
|
|
rw_flags = bio_data_dir(bio);
|
|
if (sync)
|
|
rw_flags |= REQ_SYNC;
|
|
|
|
/*
|
|
* Grab a free request. This is might sleep but can not fail.
|
|
* Returns with the queue unlocked.
|
|
*/
|
|
req = get_request_wait(q, rw_flags, bio);
|
|
|
|
/*
|
|
* After dropping the lock and possibly sleeping here, our request
|
|
* may now be mergeable after it had proven unmergeable (above).
|
|
* We don't worry about that case for efficiency. It won't happen
|
|
* often, and the elevators are able to handle it.
|
|
*/
|
|
init_request_from_bio(req, bio);
|
|
|
|
if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) ||
|
|
bio_flagged(bio, BIO_CPU_AFFINE))
|
|
req->cpu = raw_smp_processor_id();
|
|
|
|
plug = current->plug;
|
|
if (plug) {
|
|
/*
|
|
* If this is the first request added after a plug, fire
|
|
* of a plug trace. If others have been added before, check
|
|
* if we have multiple devices in this plug. If so, make a
|
|
* note to sort the list before dispatch.
|
|
*/
|
|
if (list_empty(&plug->list))
|
|
trace_block_plug(q);
|
|
else if (!plug->should_sort) {
|
|
struct request *__rq;
|
|
|
|
__rq = list_entry_rq(plug->list.prev);
|
|
if (__rq->q != q)
|
|
plug->should_sort = 1;
|
|
}
|
|
if (request_count >= BLK_MAX_REQUEST_COUNT)
|
|
blk_flush_plug_list(plug, false);
|
|
list_add_tail(&req->queuelist, &plug->list);
|
|
drive_stat_acct(req, 1);
|
|
} else {
|
|
spin_lock_irq(q->queue_lock);
|
|
add_acct_request(q, req, where);
|
|
__blk_run_queue(q);
|
|
out_unlock:
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
out:
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If bio->bi_dev is a partition, remap the location
|
|
*/
|
|
static inline void blk_partition_remap(struct bio *bio)
|
|
{
|
|
struct block_device *bdev = bio->bi_bdev;
|
|
|
|
if (bio_sectors(bio) && bdev != bdev->bd_contains) {
|
|
struct hd_struct *p = bdev->bd_part;
|
|
|
|
bio->bi_sector += p->start_sect;
|
|
bio->bi_bdev = bdev->bd_contains;
|
|
|
|
trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), bio,
|
|
bdev->bd_dev,
|
|
bio->bi_sector - p->start_sect);
|
|
}
|
|
}
|
|
|
|
static void handle_bad_sector(struct bio *bio)
|
|
{
|
|
char b[BDEVNAME_SIZE];
|
|
|
|
printk(KERN_INFO "attempt to access beyond end of device\n");
|
|
printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
|
|
bdevname(bio->bi_bdev, b),
|
|
bio->bi_rw,
|
|
(unsigned long long)bio->bi_sector + bio_sectors(bio),
|
|
(long long)(i_size_read(bio->bi_bdev->bd_inode) >> 9));
|
|
|
|
set_bit(BIO_EOF, &bio->bi_flags);
|
|
}
|
|
|
|
#ifdef CONFIG_FAIL_MAKE_REQUEST
|
|
|
|
static DECLARE_FAULT_ATTR(fail_make_request);
|
|
|
|
static int __init setup_fail_make_request(char *str)
|
|
{
|
|
return setup_fault_attr(&fail_make_request, str);
|
|
}
|
|
__setup("fail_make_request=", setup_fail_make_request);
|
|
|
|
static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
|
|
{
|
|
return part->make_it_fail && should_fail(&fail_make_request, bytes);
|
|
}
|
|
|
|
static int __init fail_make_request_debugfs(void)
|
|
{
|
|
struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
|
|
NULL, &fail_make_request);
|
|
|
|
return IS_ERR(dir) ? PTR_ERR(dir) : 0;
|
|
}
|
|
|
|
late_initcall(fail_make_request_debugfs);
|
|
|
|
#else /* CONFIG_FAIL_MAKE_REQUEST */
|
|
|
|
static inline bool should_fail_request(struct hd_struct *part,
|
|
unsigned int bytes)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
#endif /* CONFIG_FAIL_MAKE_REQUEST */
|
|
|
|
/*
|
|
* Check whether this bio extends beyond the end of the device.
|
|
*/
|
|
static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
|
|
{
|
|
sector_t maxsector;
|
|
|
|
if (!nr_sectors)
|
|
return 0;
|
|
|
|
/* Test device or partition size, when known. */
|
|
maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
|
|
if (maxsector) {
|
|
sector_t sector = bio->bi_sector;
|
|
|
|
if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
|
|
/*
|
|
* This may well happen - the kernel calls bread()
|
|
* without checking the size of the device, e.g., when
|
|
* mounting a device.
|
|
*/
|
|
handle_bad_sector(bio);
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* generic_make_request - hand a buffer to its device driver for I/O
|
|
* @bio: The bio describing the location in memory and on the device.
|
|
*
|
|
* generic_make_request() is used to make I/O requests of block
|
|
* devices. It is passed a &struct bio, which describes the I/O that needs
|
|
* to be done.
|
|
*
|
|
* generic_make_request() does not return any status. The
|
|
* success/failure status of the request, along with notification of
|
|
* completion, is delivered asynchronously through the bio->bi_end_io
|
|
* function described (one day) else where.
|
|
*
|
|
* The caller of generic_make_request must make sure that bi_io_vec
|
|
* are set to describe the memory buffer, and that bi_dev and bi_sector are
|
|
* set to describe the device address, and the
|
|
* bi_end_io and optionally bi_private are set to describe how
|
|
* completion notification should be signaled.
|
|
*
|
|
* generic_make_request and the drivers it calls may use bi_next if this
|
|
* bio happens to be merged with someone else, and may change bi_dev and
|
|
* bi_sector for remaps as it sees fit. So the values of these fields
|
|
* should NOT be depended on after the call to generic_make_request.
|
|
*/
|
|
static inline void __generic_make_request(struct bio *bio)
|
|
{
|
|
struct request_queue *q;
|
|
sector_t old_sector;
|
|
int ret, nr_sectors = bio_sectors(bio);
|
|
dev_t old_dev;
|
|
int err = -EIO;
|
|
|
|
might_sleep();
|
|
|
|
if (bio_check_eod(bio, nr_sectors))
|
|
goto end_io;
|
|
|
|
/*
|
|
* Resolve the mapping until finished. (drivers are
|
|
* still free to implement/resolve their own stacking
|
|
* by explicitly returning 0)
|
|
*
|
|
* NOTE: we don't repeat the blk_size check for each new device.
|
|
* Stacking drivers are expected to know what they are doing.
|
|
*/
|
|
old_sector = -1;
|
|
old_dev = 0;
|
|
do {
|
|
char b[BDEVNAME_SIZE];
|
|
struct hd_struct *part;
|
|
|
|
q = bdev_get_queue(bio->bi_bdev);
|
|
if (unlikely(!q)) {
|
|
printk(KERN_ERR
|
|
"generic_make_request: Trying to access "
|
|
"nonexistent block-device %s (%Lu)\n",
|
|
bdevname(bio->bi_bdev, b),
|
|
(long long) bio->bi_sector);
|
|
goto end_io;
|
|
}
|
|
|
|
if (unlikely(!(bio->bi_rw & REQ_DISCARD) &&
|
|
nr_sectors > queue_max_hw_sectors(q))) {
|
|
printk(KERN_ERR "bio too big device %s (%u > %u)\n",
|
|
bdevname(bio->bi_bdev, b),
|
|
bio_sectors(bio),
|
|
queue_max_hw_sectors(q));
|
|
goto end_io;
|
|
}
|
|
|
|
if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
|
|
goto end_io;
|
|
|
|
part = bio->bi_bdev->bd_part;
|
|
if (should_fail_request(part, bio->bi_size) ||
|
|
should_fail_request(&part_to_disk(part)->part0,
|
|
bio->bi_size))
|
|
goto end_io;
|
|
|
|
/*
|
|
* If this device has partitions, remap block n
|
|
* of partition p to block n+start(p) of the disk.
|
|
*/
|
|
blk_partition_remap(bio);
|
|
|
|
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio))
|
|
goto end_io;
|
|
|
|
if (old_sector != -1)
|
|
trace_block_bio_remap(q, bio, old_dev, old_sector);
|
|
|
|
old_sector = bio->bi_sector;
|
|
old_dev = bio->bi_bdev->bd_dev;
|
|
|
|
if (bio_check_eod(bio, nr_sectors))
|
|
goto end_io;
|
|
|
|
/*
|
|
* Filter flush bio's early so that make_request based
|
|
* drivers without flush support don't have to worry
|
|
* about them.
|
|
*/
|
|
if ((bio->bi_rw & (REQ_FLUSH | REQ_FUA)) && !q->flush_flags) {
|
|
bio->bi_rw &= ~(REQ_FLUSH | REQ_FUA);
|
|
if (!nr_sectors) {
|
|
err = 0;
|
|
goto end_io;
|
|
}
|
|
}
|
|
|
|
if ((bio->bi_rw & REQ_DISCARD) &&
|
|
(!blk_queue_discard(q) ||
|
|
((bio->bi_rw & REQ_SECURE) &&
|
|
!blk_queue_secdiscard(q)))) {
|
|
err = -EOPNOTSUPP;
|
|
goto end_io;
|
|
}
|
|
|
|
if (blk_throtl_bio(q, &bio))
|
|
goto end_io;
|
|
|
|
/*
|
|
* If bio = NULL, bio has been throttled and will be submitted
|
|
* later.
|
|
*/
|
|
if (!bio)
|
|
break;
|
|
|
|
trace_block_bio_queue(q, bio);
|
|
|
|
ret = q->make_request_fn(q, bio);
|
|
} while (ret);
|
|
|
|
return;
|
|
|
|
end_io:
|
|
bio_endio(bio, err);
|
|
}
|
|
|
|
/*
|
|
* 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
|
|
*/
|
|
void generic_make_request(struct bio *bio)
|
|
{
|
|
struct bio_list bio_list_on_stack;
|
|
|
|
if (current->bio_list) {
|
|
/* make_request is active */
|
|
bio_list_add(current->bio_list, bio);
|
|
return;
|
|
}
|
|
/* following loop may be a bit non-obvious, and so deserves some
|
|
* explanation.
|
|
* Before entering the loop, bio->bi_next is NULL (as all callers
|
|
* ensure that) so we have a list with a single bio.
|
|
* We pretend that we have just taken it off a longer list, so
|
|
* we assign bio_list to a pointer to the bio_list_on_stack,
|
|
* thus initialising the bio_list of new bios to be
|
|
* added. __generic_make_request may indeed add some more bios
|
|
* through a recursive call to generic_make_request. If it
|
|
* did, we find a non-NULL value in bio_list and re-enter the loop
|
|
* from the top. In this case we really did just take the bio
|
|
* of the top of the list (no pretending) and so remove it from
|
|
* bio_list, and call into __generic_make_request again.
|
|
*
|
|
* The loop was structured like this to make only one call to
|
|
* __generic_make_request (which is important as it is large and
|
|
* inlined) and to keep the structure simple.
|
|
*/
|
|
BUG_ON(bio->bi_next);
|
|
bio_list_init(&bio_list_on_stack);
|
|
current->bio_list = &bio_list_on_stack;
|
|
do {
|
|
__generic_make_request(bio);
|
|
bio = bio_list_pop(current->bio_list);
|
|
} while (bio);
|
|
current->bio_list = NULL; /* deactivate */
|
|
}
|
|
EXPORT_SYMBOL(generic_make_request);
|
|
|
|
/**
|
|
* submit_bio - submit a bio to the block device layer for I/O
|
|
* @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
|
|
* @bio: The &struct bio which describes the I/O
|
|
*
|
|
* submit_bio() is very similar in purpose to generic_make_request(), and
|
|
* uses that function to do most of the work. Both are fairly rough
|
|
* interfaces; @bio must be presetup and ready for I/O.
|
|
*
|
|
*/
|
|
void submit_bio(int rw, struct bio *bio)
|
|
{
|
|
int count = bio_sectors(bio);
|
|
|
|
bio->bi_rw |= rw;
|
|
|
|
/*
|
|
* If it's a regular read/write or a barrier with data attached,
|
|
* go through the normal accounting stuff before submission.
|
|
*/
|
|
if (bio_has_data(bio) && !(rw & REQ_DISCARD)) {
|
|
if (rw & WRITE) {
|
|
count_vm_events(PGPGOUT, count);
|
|
} else {
|
|
task_io_account_read(bio->bi_size);
|
|
count_vm_events(PGPGIN, count);
|
|
}
|
|
|
|
if (unlikely(block_dump)) {
|
|
char b[BDEVNAME_SIZE];
|
|
printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
|
|
current->comm, task_pid_nr(current),
|
|
(rw & WRITE) ? "WRITE" : "READ",
|
|
(unsigned long long)bio->bi_sector,
|
|
bdevname(bio->bi_bdev, b),
|
|
count);
|
|
}
|
|
}
|
|
|
|
generic_make_request(bio);
|
|
}
|
|
EXPORT_SYMBOL(submit_bio);
|
|
|
|
/**
|
|
* blk_rq_check_limits - Helper function to check a request for the queue limit
|
|
* @q: the queue
|
|
* @rq: the request being checked
|
|
*
|
|
* Description:
|
|
* @rq may have been made based on weaker limitations of upper-level queues
|
|
* in request stacking drivers, and it may violate the limitation of @q.
|
|
* Since the block layer and the underlying device driver trust @rq
|
|
* after it is inserted to @q, it should be checked against @q before
|
|
* the insertion using this generic function.
|
|
*
|
|
* This function should also be useful for request stacking drivers
|
|
* in some cases below, so export this function.
|
|
* Request stacking drivers like request-based dm may change the queue
|
|
* limits while requests are in the queue (e.g. dm's table swapping).
|
|
* Such request stacking drivers should check those requests agaist
|
|
* the new queue limits again when they dispatch those requests,
|
|
* although such checkings are also done against the old queue limits
|
|
* when submitting requests.
|
|
*/
|
|
int blk_rq_check_limits(struct request_queue *q, struct request *rq)
|
|
{
|
|
if (rq->cmd_flags & REQ_DISCARD)
|
|
return 0;
|
|
|
|
if (blk_rq_sectors(rq) > queue_max_sectors(q) ||
|
|
blk_rq_bytes(rq) > queue_max_hw_sectors(q) << 9) {
|
|
printk(KERN_ERR "%s: over max size limit.\n", __func__);
|
|
return -EIO;
|
|
}
|
|
|
|
/*
|
|
* queue's settings related to segment counting like q->bounce_pfn
|
|
* may differ from that of other stacking queues.
|
|
* Recalculate it to check the request correctly on this queue's
|
|
* limitation.
|
|
*/
|
|
blk_recalc_rq_segments(rq);
|
|
if (rq->nr_phys_segments > queue_max_segments(q)) {
|
|
printk(KERN_ERR "%s: over max segments limit.\n", __func__);
|
|
return -EIO;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_rq_check_limits);
|
|
|
|
/**
|
|
* blk_insert_cloned_request - Helper for stacking drivers to submit a request
|
|
* @q: the queue to submit the request
|
|
* @rq: the request being queued
|
|
*/
|
|
int blk_insert_cloned_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
unsigned long flags;
|
|
int where = ELEVATOR_INSERT_BACK;
|
|
|
|
if (blk_rq_check_limits(q, rq))
|
|
return -EIO;
|
|
|
|
if (rq->rq_disk &&
|
|
should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
|
|
return -EIO;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
|
|
/*
|
|
* Submitting request must be dequeued before calling this function
|
|
* because it will be linked to another request_queue
|
|
*/
|
|
BUG_ON(blk_queued_rq(rq));
|
|
|
|
if (rq->cmd_flags & (REQ_FLUSH|REQ_FUA))
|
|
where = ELEVATOR_INSERT_FLUSH;
|
|
|
|
add_acct_request(q, rq, where);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
|
|
|
|
/**
|
|
* blk_rq_err_bytes - determine number of bytes till the next failure boundary
|
|
* @rq: request to examine
|
|
*
|
|
* Description:
|
|
* A request could be merge of IOs which require different failure
|
|
* handling. This function determines the number of bytes which
|
|
* can be failed from the beginning of the request without
|
|
* crossing into area which need to be retried further.
|
|
*
|
|
* Return:
|
|
* The number of bytes to fail.
|
|
*
|
|
* Context:
|
|
* queue_lock must be held.
|
|
*/
|
|
unsigned int blk_rq_err_bytes(const struct request *rq)
|
|
{
|
|
unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
|
|
unsigned int bytes = 0;
|
|
struct bio *bio;
|
|
|
|
if (!(rq->cmd_flags & REQ_MIXED_MERGE))
|
|
return blk_rq_bytes(rq);
|
|
|
|
/*
|
|
* Currently the only 'mixing' which can happen is between
|
|
* different fastfail types. We can safely fail portions
|
|
* which have all the failfast bits that the first one has -
|
|
* the ones which are at least as eager to fail as the first
|
|
* one.
|
|
*/
|
|
for (bio = rq->bio; bio; bio = bio->bi_next) {
|
|
if ((bio->bi_rw & ff) != ff)
|
|
break;
|
|
bytes += bio->bi_size;
|
|
}
|
|
|
|
/* this could lead to infinite loop */
|
|
BUG_ON(blk_rq_bytes(rq) && !bytes);
|
|
return bytes;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
|
|
|
|
static void blk_account_io_completion(struct request *req, unsigned int bytes)
|
|
{
|
|
if (blk_do_io_stat(req)) {
|
|
const int rw = rq_data_dir(req);
|
|
struct hd_struct *part;
|
|
int cpu;
|
|
|
|
cpu = part_stat_lock();
|
|
part = req->part;
|
|
part_stat_add(cpu, part, sectors[rw], bytes >> 9);
|
|
part_stat_unlock();
|
|
}
|
|
}
|
|
|
|
static void blk_account_io_done(struct request *req)
|
|
{
|
|
/*
|
|
* Account IO completion. flush_rq isn't accounted as a
|
|
* normal IO on queueing nor completion. Accounting the
|
|
* containing request is enough.
|
|
*/
|
|
if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
|
|
unsigned long duration = jiffies - req->start_time;
|
|
const int rw = rq_data_dir(req);
|
|
struct hd_struct *part;
|
|
int cpu;
|
|
|
|
cpu = part_stat_lock();
|
|
part = req->part;
|
|
|
|
part_stat_inc(cpu, part, ios[rw]);
|
|
part_stat_add(cpu, part, ticks[rw], duration);
|
|
part_round_stats(cpu, part);
|
|
part_dec_in_flight(part, rw);
|
|
|
|
hd_struct_put(part);
|
|
part_stat_unlock();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* blk_peek_request - peek at the top of a request queue
|
|
* @q: request queue to peek at
|
|
*
|
|
* Description:
|
|
* Return the request at the top of @q. The returned request
|
|
* should be started using blk_start_request() before LLD starts
|
|
* processing it.
|
|
*
|
|
* Return:
|
|
* Pointer to the request at the top of @q if available. Null
|
|
* otherwise.
|
|
*
|
|
* Context:
|
|
* queue_lock must be held.
|
|
*/
|
|
struct request *blk_peek_request(struct request_queue *q)
|
|
{
|
|
struct request *rq;
|
|
int ret;
|
|
|
|
while ((rq = __elv_next_request(q)) != NULL) {
|
|
if (!(rq->cmd_flags & REQ_STARTED)) {
|
|
/*
|
|
* This is the first time the device driver
|
|
* sees this request (possibly after
|
|
* requeueing). Notify IO scheduler.
|
|
*/
|
|
if (rq->cmd_flags & REQ_SORTED)
|
|
elv_activate_rq(q, rq);
|
|
|
|
/*
|
|
* just mark as started even if we don't start
|
|
* it, a request that has been delayed should
|
|
* not be passed by new incoming requests
|
|
*/
|
|
rq->cmd_flags |= REQ_STARTED;
|
|
trace_block_rq_issue(q, rq);
|
|
}
|
|
|
|
if (!q->boundary_rq || q->boundary_rq == rq) {
|
|
q->end_sector = rq_end_sector(rq);
|
|
q->boundary_rq = NULL;
|
|
}
|
|
|
|
if (rq->cmd_flags & REQ_DONTPREP)
|
|
break;
|
|
|
|
if (q->dma_drain_size && blk_rq_bytes(rq)) {
|
|
/*
|
|
* make sure space for the drain appears we
|
|
* know we can do this because max_hw_segments
|
|
* has been adjusted to be one fewer than the
|
|
* device can handle
|
|
*/
|
|
rq->nr_phys_segments++;
|
|
}
|
|
|
|
if (!q->prep_rq_fn)
|
|
break;
|
|
|
|
ret = q->prep_rq_fn(q, rq);
|
|
if (ret == BLKPREP_OK) {
|
|
break;
|
|
} else if (ret == BLKPREP_DEFER) {
|
|
/*
|
|
* the request may have been (partially) prepped.
|
|
* we need to keep this request in the front to
|
|
* avoid resource deadlock. REQ_STARTED will
|
|
* prevent other fs requests from passing this one.
|
|
*/
|
|
if (q->dma_drain_size && blk_rq_bytes(rq) &&
|
|
!(rq->cmd_flags & REQ_DONTPREP)) {
|
|
/*
|
|
* remove the space for the drain we added
|
|
* so that we don't add it again
|
|
*/
|
|
--rq->nr_phys_segments;
|
|
}
|
|
|
|
rq = NULL;
|
|
break;
|
|
} else if (ret == BLKPREP_KILL) {
|
|
rq->cmd_flags |= REQ_QUIET;
|
|
/*
|
|
* Mark this request as started so we don't trigger
|
|
* any debug logic in the end I/O path.
|
|
*/
|
|
blk_start_request(rq);
|
|
__blk_end_request_all(rq, -EIO);
|
|
} else {
|
|
printk(KERN_ERR "%s: bad return=%d\n", __func__, ret);
|
|
break;
|
|
}
|
|
}
|
|
|
|
return rq;
|
|
}
|
|
EXPORT_SYMBOL(blk_peek_request);
|
|
|
|
void blk_dequeue_request(struct request *rq)
|
|
{
|
|
struct request_queue *q = rq->q;
|
|
|
|
BUG_ON(list_empty(&rq->queuelist));
|
|
BUG_ON(ELV_ON_HASH(rq));
|
|
|
|
list_del_init(&rq->queuelist);
|
|
|
|
/*
|
|
* the time frame between a request being removed from the lists
|
|
* and to it is freed is accounted as io that is in progress at
|
|
* the driver side.
|
|
*/
|
|
if (blk_account_rq(rq)) {
|
|
q->in_flight[rq_is_sync(rq)]++;
|
|
set_io_start_time_ns(rq);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* blk_start_request - start request processing on the driver
|
|
* @req: request to dequeue
|
|
*
|
|
* Description:
|
|
* Dequeue @req and start timeout timer on it. This hands off the
|
|
* request to the driver.
|
|
*
|
|
* Block internal functions which don't want to start timer should
|
|
* call blk_dequeue_request().
|
|
*
|
|
* Context:
|
|
* queue_lock must be held.
|
|
*/
|
|
void blk_start_request(struct request *req)
|
|
{
|
|
blk_dequeue_request(req);
|
|
|
|
/*
|
|
* We are now handing the request to the hardware, initialize
|
|
* resid_len to full count and add the timeout handler.
|
|
*/
|
|
req->resid_len = blk_rq_bytes(req);
|
|
if (unlikely(blk_bidi_rq(req)))
|
|
req->next_rq->resid_len = blk_rq_bytes(req->next_rq);
|
|
|
|
blk_add_timer(req);
|
|
}
|
|
EXPORT_SYMBOL(blk_start_request);
|
|
|
|
/**
|
|
* blk_fetch_request - fetch a request from a request queue
|
|
* @q: request queue to fetch a request from
|
|
*
|
|
* Description:
|
|
* Return the request at the top of @q. The request is started on
|
|
* return and LLD can start processing it immediately.
|
|
*
|
|
* Return:
|
|
* Pointer to the request at the top of @q if available. Null
|
|
* otherwise.
|
|
*
|
|
* Context:
|
|
* queue_lock must be held.
|
|
*/
|
|
struct request *blk_fetch_request(struct request_queue *q)
|
|
{
|
|
struct request *rq;
|
|
|
|
rq = blk_peek_request(q);
|
|
if (rq)
|
|
blk_start_request(rq);
|
|
return rq;
|
|
}
|
|
EXPORT_SYMBOL(blk_fetch_request);
|
|
|
|
/**
|
|
* blk_update_request - Special helper function for request stacking drivers
|
|
* @req: the request being processed
|
|
* @error: %0 for success, < %0 for error
|
|
* @nr_bytes: number of bytes to complete @req
|
|
*
|
|
* Description:
|
|
* Ends I/O on a number of bytes attached to @req, but doesn't complete
|
|
* the request structure even if @req doesn't have leftover.
|
|
* If @req has leftover, sets it up for the next range of segments.
|
|
*
|
|
* This special helper function is only for request stacking drivers
|
|
* (e.g. request-based dm) so that they can handle partial completion.
|
|
* Actual device drivers should use blk_end_request instead.
|
|
*
|
|
* Passing the result of blk_rq_bytes() as @nr_bytes guarantees
|
|
* %false return from this function.
|
|
*
|
|
* Return:
|
|
* %false - this request doesn't have any more data
|
|
* %true - this request has more data
|
|
**/
|
|
bool blk_update_request(struct request *req, int error, unsigned int nr_bytes)
|
|
{
|
|
int total_bytes, bio_nbytes, next_idx = 0;
|
|
struct bio *bio;
|
|
|
|
if (!req->bio)
|
|
return false;
|
|
|
|
trace_block_rq_complete(req->q, req);
|
|
|
|
/*
|
|
* For fs requests, rq is just carrier of independent bio's
|
|
* and each partial completion should be handled separately.
|
|
* Reset per-request error on each partial completion.
|
|
*
|
|
* TODO: tj: This is too subtle. It would be better to let
|
|
* low level drivers do what they see fit.
|
|
*/
|
|
if (req->cmd_type == REQ_TYPE_FS)
|
|
req->errors = 0;
|
|
|
|
if (error && req->cmd_type == REQ_TYPE_FS &&
|
|
!(req->cmd_flags & REQ_QUIET)) {
|
|
char *error_type;
|
|
|
|
switch (error) {
|
|
case -ENOLINK:
|
|
error_type = "recoverable transport";
|
|
break;
|
|
case -EREMOTEIO:
|
|
error_type = "critical target";
|
|
break;
|
|
case -EBADE:
|
|
error_type = "critical nexus";
|
|
break;
|
|
case -EIO:
|
|
default:
|
|
error_type = "I/O";
|
|
break;
|
|
}
|
|
printk(KERN_ERR "end_request: %s error, dev %s, sector %llu\n",
|
|
error_type, req->rq_disk ? req->rq_disk->disk_name : "?",
|
|
(unsigned long long)blk_rq_pos(req));
|
|
}
|
|
|
|
blk_account_io_completion(req, nr_bytes);
|
|
|
|
total_bytes = bio_nbytes = 0;
|
|
while ((bio = req->bio) != NULL) {
|
|
int nbytes;
|
|
|
|
if (nr_bytes >= bio->bi_size) {
|
|
req->bio = bio->bi_next;
|
|
nbytes = bio->bi_size;
|
|
req_bio_endio(req, bio, nbytes, error);
|
|
next_idx = 0;
|
|
bio_nbytes = 0;
|
|
} else {
|
|
int idx = bio->bi_idx + next_idx;
|
|
|
|
if (unlikely(idx >= bio->bi_vcnt)) {
|
|
blk_dump_rq_flags(req, "__end_that");
|
|
printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n",
|
|
__func__, idx, bio->bi_vcnt);
|
|
break;
|
|
}
|
|
|
|
nbytes = bio_iovec_idx(bio, idx)->bv_len;
|
|
BIO_BUG_ON(nbytes > bio->bi_size);
|
|
|
|
/*
|
|
* not a complete bvec done
|
|
*/
|
|
if (unlikely(nbytes > nr_bytes)) {
|
|
bio_nbytes += nr_bytes;
|
|
total_bytes += nr_bytes;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* advance to the next vector
|
|
*/
|
|
next_idx++;
|
|
bio_nbytes += nbytes;
|
|
}
|
|
|
|
total_bytes += nbytes;
|
|
nr_bytes -= nbytes;
|
|
|
|
bio = req->bio;
|
|
if (bio) {
|
|
/*
|
|
* end more in this run, or just return 'not-done'
|
|
*/
|
|
if (unlikely(nr_bytes <= 0))
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* completely done
|
|
*/
|
|
if (!req->bio) {
|
|
/*
|
|
* Reset counters so that the request stacking driver
|
|
* can find how many bytes remain in the request
|
|
* later.
|
|
*/
|
|
req->__data_len = 0;
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* if the request wasn't completed, update state
|
|
*/
|
|
if (bio_nbytes) {
|
|
req_bio_endio(req, bio, bio_nbytes, error);
|
|
bio->bi_idx += next_idx;
|
|
bio_iovec(bio)->bv_offset += nr_bytes;
|
|
bio_iovec(bio)->bv_len -= nr_bytes;
|
|
}
|
|
|
|
req->__data_len -= total_bytes;
|
|
req->buffer = bio_data(req->bio);
|
|
|
|
/* update sector only for requests with clear definition of sector */
|
|
if (req->cmd_type == REQ_TYPE_FS || (req->cmd_flags & REQ_DISCARD))
|
|
req->__sector += total_bytes >> 9;
|
|
|
|
/* mixed attributes always follow the first bio */
|
|
if (req->cmd_flags & REQ_MIXED_MERGE) {
|
|
req->cmd_flags &= ~REQ_FAILFAST_MASK;
|
|
req->cmd_flags |= req->bio->bi_rw & REQ_FAILFAST_MASK;
|
|
}
|
|
|
|
/*
|
|
* If total number of sectors is less than the first segment
|
|
* size, something has gone terribly wrong.
|
|
*/
|
|
if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
|
|
blk_dump_rq_flags(req, "request botched");
|
|
req->__data_len = blk_rq_cur_bytes(req);
|
|
}
|
|
|
|
/* recalculate the number of segments */
|
|
blk_recalc_rq_segments(req);
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_update_request);
|
|
|
|
static bool blk_update_bidi_request(struct request *rq, int error,
|
|
unsigned int nr_bytes,
|
|
unsigned int bidi_bytes)
|
|
{
|
|
if (blk_update_request(rq, error, nr_bytes))
|
|
return true;
|
|
|
|
/* Bidi request must be completed as a whole */
|
|
if (unlikely(blk_bidi_rq(rq)) &&
|
|
blk_update_request(rq->next_rq, error, bidi_bytes))
|
|
return true;
|
|
|
|
if (blk_queue_add_random(rq->q))
|
|
add_disk_randomness(rq->rq_disk);
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* blk_unprep_request - unprepare a request
|
|
* @req: the request
|
|
*
|
|
* This function makes a request ready for complete resubmission (or
|
|
* completion). It happens only after all error handling is complete,
|
|
* so represents the appropriate moment to deallocate any resources
|
|
* that were allocated to the request in the prep_rq_fn. The queue
|
|
* lock is held when calling this.
|
|
*/
|
|
void blk_unprep_request(struct request *req)
|
|
{
|
|
struct request_queue *q = req->q;
|
|
|
|
req->cmd_flags &= ~REQ_DONTPREP;
|
|
if (q->unprep_rq_fn)
|
|
q->unprep_rq_fn(q, req);
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_unprep_request);
|
|
|
|
/*
|
|
* queue lock must be held
|
|
*/
|
|
static void blk_finish_request(struct request *req, int error)
|
|
{
|
|
if (blk_rq_tagged(req))
|
|
blk_queue_end_tag(req->q, req);
|
|
|
|
BUG_ON(blk_queued_rq(req));
|
|
|
|
if (unlikely(laptop_mode) && req->cmd_type == REQ_TYPE_FS)
|
|
laptop_io_completion(&req->q->backing_dev_info);
|
|
|
|
blk_delete_timer(req);
|
|
|
|
if (req->cmd_flags & REQ_DONTPREP)
|
|
blk_unprep_request(req);
|
|
|
|
|
|
blk_account_io_done(req);
|
|
|
|
if (req->end_io)
|
|
req->end_io(req, error);
|
|
else {
|
|
if (blk_bidi_rq(req))
|
|
__blk_put_request(req->next_rq->q, req->next_rq);
|
|
|
|
__blk_put_request(req->q, req);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* blk_end_bidi_request - Complete a bidi request
|
|
* @rq: the request to complete
|
|
* @error: %0 for success, < %0 for error
|
|
* @nr_bytes: number of bytes to complete @rq
|
|
* @bidi_bytes: number of bytes to complete @rq->next_rq
|
|
*
|
|
* Description:
|
|
* Ends I/O on a number of bytes attached to @rq and @rq->next_rq.
|
|
* Drivers that supports bidi can safely call this member for any
|
|
* type of request, bidi or uni. In the later case @bidi_bytes is
|
|
* just ignored.
|
|
*
|
|
* Return:
|
|
* %false - we are done with this request
|
|
* %true - still buffers pending for this request
|
|
**/
|
|
static bool blk_end_bidi_request(struct request *rq, int error,
|
|
unsigned int nr_bytes, unsigned int bidi_bytes)
|
|
{
|
|
struct request_queue *q = rq->q;
|
|
unsigned long flags;
|
|
|
|
if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
|
|
return true;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
blk_finish_request(rq, error);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* __blk_end_bidi_request - Complete a bidi request with queue lock held
|
|
* @rq: the request to complete
|
|
* @error: %0 for success, < %0 for error
|
|
* @nr_bytes: number of bytes to complete @rq
|
|
* @bidi_bytes: number of bytes to complete @rq->next_rq
|
|
*
|
|
* Description:
|
|
* Identical to blk_end_bidi_request() except that queue lock is
|
|
* assumed to be locked on entry and remains so on return.
|
|
*
|
|
* Return:
|
|
* %false - we are done with this request
|
|
* %true - still buffers pending for this request
|
|
**/
|
|
bool __blk_end_bidi_request(struct request *rq, int error,
|
|
unsigned int nr_bytes, unsigned int bidi_bytes)
|
|
{
|
|
if (blk_update_bidi_request(rq, error, nr_bytes, bidi_bytes))
|
|
return true;
|
|
|
|
blk_finish_request(rq, error);
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* blk_end_request - Helper function for drivers to complete the request.
|
|
* @rq: the request being processed
|
|
* @error: %0 for success, < %0 for error
|
|
* @nr_bytes: number of bytes to complete
|
|
*
|
|
* Description:
|
|
* Ends I/O on a number of bytes attached to @rq.
|
|
* If @rq has leftover, sets it up for the next range of segments.
|
|
*
|
|
* Return:
|
|
* %false - we are done with this request
|
|
* %true - still buffers pending for this request
|
|
**/
|
|
bool blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
|
|
{
|
|
return blk_end_bidi_request(rq, error, nr_bytes, 0);
|
|
}
|
|
EXPORT_SYMBOL(blk_end_request);
|
|
|
|
/**
|
|
* blk_end_request_all - Helper function for drives to finish the request.
|
|
* @rq: the request to finish
|
|
* @error: %0 for success, < %0 for error
|
|
*
|
|
* Description:
|
|
* Completely finish @rq.
|
|
*/
|
|
void blk_end_request_all(struct request *rq, int error)
|
|
{
|
|
bool pending;
|
|
unsigned int bidi_bytes = 0;
|
|
|
|
if (unlikely(blk_bidi_rq(rq)))
|
|
bidi_bytes = blk_rq_bytes(rq->next_rq);
|
|
|
|
pending = blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
|
|
BUG_ON(pending);
|
|
}
|
|
EXPORT_SYMBOL(blk_end_request_all);
|
|
|
|
/**
|
|
* blk_end_request_cur - Helper function to finish the current request chunk.
|
|
* @rq: the request to finish the current chunk for
|
|
* @error: %0 for success, < %0 for error
|
|
*
|
|
* Description:
|
|
* Complete the current consecutively mapped chunk from @rq.
|
|
*
|
|
* Return:
|
|
* %false - we are done with this request
|
|
* %true - still buffers pending for this request
|
|
*/
|
|
bool blk_end_request_cur(struct request *rq, int error)
|
|
{
|
|
return blk_end_request(rq, error, blk_rq_cur_bytes(rq));
|
|
}
|
|
EXPORT_SYMBOL(blk_end_request_cur);
|
|
|
|
/**
|
|
* blk_end_request_err - Finish a request till the next failure boundary.
|
|
* @rq: the request to finish till the next failure boundary for
|
|
* @error: must be negative errno
|
|
*
|
|
* Description:
|
|
* Complete @rq till the next failure boundary.
|
|
*
|
|
* Return:
|
|
* %false - we are done with this request
|
|
* %true - still buffers pending for this request
|
|
*/
|
|
bool blk_end_request_err(struct request *rq, int error)
|
|
{
|
|
WARN_ON(error >= 0);
|
|
return blk_end_request(rq, error, blk_rq_err_bytes(rq));
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_end_request_err);
|
|
|
|
/**
|
|
* __blk_end_request - Helper function for drivers to complete the request.
|
|
* @rq: the request being processed
|
|
* @error: %0 for success, < %0 for error
|
|
* @nr_bytes: number of bytes to complete
|
|
*
|
|
* Description:
|
|
* Must be called with queue lock held unlike blk_end_request().
|
|
*
|
|
* Return:
|
|
* %false - we are done with this request
|
|
* %true - still buffers pending for this request
|
|
**/
|
|
bool __blk_end_request(struct request *rq, int error, unsigned int nr_bytes)
|
|
{
|
|
return __blk_end_bidi_request(rq, error, nr_bytes, 0);
|
|
}
|
|
EXPORT_SYMBOL(__blk_end_request);
|
|
|
|
/**
|
|
* __blk_end_request_all - Helper function for drives to finish the request.
|
|
* @rq: the request to finish
|
|
* @error: %0 for success, < %0 for error
|
|
*
|
|
* Description:
|
|
* Completely finish @rq. Must be called with queue lock held.
|
|
*/
|
|
void __blk_end_request_all(struct request *rq, int error)
|
|
{
|
|
bool pending;
|
|
unsigned int bidi_bytes = 0;
|
|
|
|
if (unlikely(blk_bidi_rq(rq)))
|
|
bidi_bytes = blk_rq_bytes(rq->next_rq);
|
|
|
|
pending = __blk_end_bidi_request(rq, error, blk_rq_bytes(rq), bidi_bytes);
|
|
BUG_ON(pending);
|
|
}
|
|
EXPORT_SYMBOL(__blk_end_request_all);
|
|
|
|
/**
|
|
* __blk_end_request_cur - Helper function to finish the current request chunk.
|
|
* @rq: the request to finish the current chunk for
|
|
* @error: %0 for success, < %0 for error
|
|
*
|
|
* Description:
|
|
* Complete the current consecutively mapped chunk from @rq. Must
|
|
* be called with queue lock held.
|
|
*
|
|
* Return:
|
|
* %false - we are done with this request
|
|
* %true - still buffers pending for this request
|
|
*/
|
|
bool __blk_end_request_cur(struct request *rq, int error)
|
|
{
|
|
return __blk_end_request(rq, error, blk_rq_cur_bytes(rq));
|
|
}
|
|
EXPORT_SYMBOL(__blk_end_request_cur);
|
|
|
|
/**
|
|
* __blk_end_request_err - Finish a request till the next failure boundary.
|
|
* @rq: the request to finish till the next failure boundary for
|
|
* @error: must be negative errno
|
|
*
|
|
* Description:
|
|
* Complete @rq till the next failure boundary. Must be called
|
|
* with queue lock held.
|
|
*
|
|
* Return:
|
|
* %false - we are done with this request
|
|
* %true - still buffers pending for this request
|
|
*/
|
|
bool __blk_end_request_err(struct request *rq, int error)
|
|
{
|
|
WARN_ON(error >= 0);
|
|
return __blk_end_request(rq, error, blk_rq_err_bytes(rq));
|
|
}
|
|
EXPORT_SYMBOL_GPL(__blk_end_request_err);
|
|
|
|
void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
|
|
struct bio *bio)
|
|
{
|
|
/* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw */
|
|
rq->cmd_flags |= bio->bi_rw & REQ_WRITE;
|
|
|
|
if (bio_has_data(bio)) {
|
|
rq->nr_phys_segments = bio_phys_segments(q, bio);
|
|
rq->buffer = bio_data(bio);
|
|
}
|
|
rq->__data_len = bio->bi_size;
|
|
rq->bio = rq->biotail = bio;
|
|
|
|
if (bio->bi_bdev)
|
|
rq->rq_disk = bio->bi_bdev->bd_disk;
|
|
}
|
|
|
|
#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
|
|
/**
|
|
* rq_flush_dcache_pages - Helper function to flush all pages in a request
|
|
* @rq: the request to be flushed
|
|
*
|
|
* Description:
|
|
* Flush all pages in @rq.
|
|
*/
|
|
void rq_flush_dcache_pages(struct request *rq)
|
|
{
|
|
struct req_iterator iter;
|
|
struct bio_vec *bvec;
|
|
|
|
rq_for_each_segment(bvec, rq, iter)
|
|
flush_dcache_page(bvec->bv_page);
|
|
}
|
|
EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
|
|
#endif
|
|
|
|
/**
|
|
* blk_lld_busy - Check if underlying low-level drivers of a device are busy
|
|
* @q : the queue of the device being checked
|
|
*
|
|
* Description:
|
|
* Check if underlying low-level drivers of a device are busy.
|
|
* If the drivers want to export their busy state, they must set own
|
|
* exporting function using blk_queue_lld_busy() first.
|
|
*
|
|
* Basically, this function is used only by request stacking drivers
|
|
* to stop dispatching requests to underlying devices when underlying
|
|
* devices are busy. This behavior helps more I/O merging on the queue
|
|
* of the request stacking driver and prevents I/O throughput regression
|
|
* on burst I/O load.
|
|
*
|
|
* Return:
|
|
* 0 - Not busy (The request stacking driver should dispatch request)
|
|
* 1 - Busy (The request stacking driver should stop dispatching request)
|
|
*/
|
|
int blk_lld_busy(struct request_queue *q)
|
|
{
|
|
if (q->lld_busy_fn)
|
|
return q->lld_busy_fn(q);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_lld_busy);
|
|
|
|
/**
|
|
* blk_rq_unprep_clone - Helper function to free all bios in a cloned request
|
|
* @rq: the clone request to be cleaned up
|
|
*
|
|
* Description:
|
|
* Free all bios in @rq for a cloned request.
|
|
*/
|
|
void blk_rq_unprep_clone(struct request *rq)
|
|
{
|
|
struct bio *bio;
|
|
|
|
while ((bio = rq->bio) != NULL) {
|
|
rq->bio = bio->bi_next;
|
|
|
|
bio_put(bio);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
|
|
|
|
/*
|
|
* Copy attributes of the original request to the clone request.
|
|
* The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not copied.
|
|
*/
|
|
static void __blk_rq_prep_clone(struct request *dst, struct request *src)
|
|
{
|
|
dst->cpu = src->cpu;
|
|
dst->cmd_flags = (src->cmd_flags & REQ_CLONE_MASK) | REQ_NOMERGE;
|
|
dst->cmd_type = src->cmd_type;
|
|
dst->__sector = blk_rq_pos(src);
|
|
dst->__data_len = blk_rq_bytes(src);
|
|
dst->nr_phys_segments = src->nr_phys_segments;
|
|
dst->ioprio = src->ioprio;
|
|
dst->extra_len = src->extra_len;
|
|
}
|
|
|
|
/**
|
|
* blk_rq_prep_clone - Helper function to setup clone request
|
|
* @rq: the request to be setup
|
|
* @rq_src: original request to be cloned
|
|
* @bs: bio_set that bios for clone are allocated from
|
|
* @gfp_mask: memory allocation mask for bio
|
|
* @bio_ctr: setup function to be called for each clone bio.
|
|
* Returns %0 for success, non %0 for failure.
|
|
* @data: private data to be passed to @bio_ctr
|
|
*
|
|
* Description:
|
|
* Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
|
|
* The actual data parts of @rq_src (e.g. ->cmd, ->buffer, ->sense)
|
|
* are not copied, and copying such parts is the caller's responsibility.
|
|
* Also, pages which the original bios are pointing to are not copied
|
|
* and the cloned bios just point same pages.
|
|
* So cloned bios must be completed before original bios, which means
|
|
* the caller must complete @rq before @rq_src.
|
|
*/
|
|
int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
|
|
struct bio_set *bs, gfp_t gfp_mask,
|
|
int (*bio_ctr)(struct bio *, struct bio *, void *),
|
|
void *data)
|
|
{
|
|
struct bio *bio, *bio_src;
|
|
|
|
if (!bs)
|
|
bs = fs_bio_set;
|
|
|
|
blk_rq_init(NULL, rq);
|
|
|
|
__rq_for_each_bio(bio_src, rq_src) {
|
|
bio = bio_alloc_bioset(gfp_mask, bio_src->bi_max_vecs, bs);
|
|
if (!bio)
|
|
goto free_and_out;
|
|
|
|
__bio_clone(bio, bio_src);
|
|
|
|
if (bio_integrity(bio_src) &&
|
|
bio_integrity_clone(bio, bio_src, gfp_mask, bs))
|
|
goto free_and_out;
|
|
|
|
if (bio_ctr && bio_ctr(bio, bio_src, data))
|
|
goto free_and_out;
|
|
|
|
if (rq->bio) {
|
|
rq->biotail->bi_next = bio;
|
|
rq->biotail = bio;
|
|
} else
|
|
rq->bio = rq->biotail = bio;
|
|
}
|
|
|
|
__blk_rq_prep_clone(rq, rq_src);
|
|
|
|
return 0;
|
|
|
|
free_and_out:
|
|
if (bio)
|
|
bio_free(bio, bs);
|
|
blk_rq_unprep_clone(rq);
|
|
|
|
return -ENOMEM;
|
|
}
|
|
EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
|
|
|
|
int kblockd_schedule_work(struct request_queue *q, struct work_struct *work)
|
|
{
|
|
return queue_work(kblockd_workqueue, work);
|
|
}
|
|
EXPORT_SYMBOL(kblockd_schedule_work);
|
|
|
|
int kblockd_schedule_delayed_work(struct request_queue *q,
|
|
struct delayed_work *dwork, unsigned long delay)
|
|
{
|
|
return queue_delayed_work(kblockd_workqueue, dwork, delay);
|
|
}
|
|
EXPORT_SYMBOL(kblockd_schedule_delayed_work);
|
|
|
|
#define PLUG_MAGIC 0x91827364
|
|
|
|
void blk_start_plug(struct blk_plug *plug)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
|
|
plug->magic = PLUG_MAGIC;
|
|
INIT_LIST_HEAD(&plug->list);
|
|
INIT_LIST_HEAD(&plug->cb_list);
|
|
plug->should_sort = 0;
|
|
|
|
/*
|
|
* If this is a nested plug, don't actually assign it. It will be
|
|
* flushed on its own.
|
|
*/
|
|
if (!tsk->plug) {
|
|
/*
|
|
* Store ordering should not be needed here, since a potential
|
|
* preempt will imply a full memory barrier
|
|
*/
|
|
tsk->plug = plug;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(blk_start_plug);
|
|
|
|
static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
|
|
{
|
|
struct request *rqa = container_of(a, struct request, queuelist);
|
|
struct request *rqb = container_of(b, struct request, queuelist);
|
|
|
|
return !(rqa->q <= rqb->q);
|
|
}
|
|
|
|
/*
|
|
* If 'from_schedule' is true, then postpone the dispatch of requests
|
|
* until a safe kblockd context. We due this to avoid accidental big
|
|
* additional stack usage in driver dispatch, in places where the originally
|
|
* plugger did not intend it.
|
|
*/
|
|
static void queue_unplugged(struct request_queue *q, unsigned int depth,
|
|
bool from_schedule)
|
|
__releases(q->queue_lock)
|
|
{
|
|
trace_block_unplug(q, depth, !from_schedule);
|
|
|
|
/*
|
|
* If we are punting this to kblockd, then we can safely drop
|
|
* the queue_lock before waking kblockd (which needs to take
|
|
* this lock).
|
|
*/
|
|
if (from_schedule) {
|
|
spin_unlock(q->queue_lock);
|
|
blk_run_queue_async(q);
|
|
} else {
|
|
__blk_run_queue(q);
|
|
spin_unlock(q->queue_lock);
|
|
}
|
|
|
|
}
|
|
|
|
static void flush_plug_callbacks(struct blk_plug *plug)
|
|
{
|
|
LIST_HEAD(callbacks);
|
|
|
|
if (list_empty(&plug->cb_list))
|
|
return;
|
|
|
|
list_splice_init(&plug->cb_list, &callbacks);
|
|
|
|
while (!list_empty(&callbacks)) {
|
|
struct blk_plug_cb *cb = list_first_entry(&callbacks,
|
|
struct blk_plug_cb,
|
|
list);
|
|
list_del(&cb->list);
|
|
cb->callback(cb);
|
|
}
|
|
}
|
|
|
|
void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
|
|
{
|
|
struct request_queue *q;
|
|
unsigned long flags;
|
|
struct request *rq;
|
|
LIST_HEAD(list);
|
|
unsigned int depth;
|
|
|
|
BUG_ON(plug->magic != PLUG_MAGIC);
|
|
|
|
flush_plug_callbacks(plug);
|
|
if (list_empty(&plug->list))
|
|
return;
|
|
|
|
list_splice_init(&plug->list, &list);
|
|
|
|
if (plug->should_sort) {
|
|
list_sort(NULL, &list, plug_rq_cmp);
|
|
plug->should_sort = 0;
|
|
}
|
|
|
|
q = NULL;
|
|
depth = 0;
|
|
|
|
/*
|
|
* Save and disable interrupts here, to avoid doing it for every
|
|
* queue lock we have to take.
|
|
*/
|
|
local_irq_save(flags);
|
|
while (!list_empty(&list)) {
|
|
rq = list_entry_rq(list.next);
|
|
list_del_init(&rq->queuelist);
|
|
BUG_ON(!rq->q);
|
|
if (rq->q != q) {
|
|
/*
|
|
* This drops the queue lock
|
|
*/
|
|
if (q)
|
|
queue_unplugged(q, depth, from_schedule);
|
|
q = rq->q;
|
|
depth = 0;
|
|
spin_lock(q->queue_lock);
|
|
}
|
|
/*
|
|
* rq is already accounted, so use raw insert
|
|
*/
|
|
if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA))
|
|
__elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
|
|
else
|
|
__elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
|
|
|
|
depth++;
|
|
}
|
|
|
|
/*
|
|
* This drops the queue lock
|
|
*/
|
|
if (q)
|
|
queue_unplugged(q, depth, from_schedule);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
void blk_finish_plug(struct blk_plug *plug)
|
|
{
|
|
blk_flush_plug_list(plug, false);
|
|
|
|
if (plug == current->plug)
|
|
current->plug = NULL;
|
|
}
|
|
EXPORT_SYMBOL(blk_finish_plug);
|
|
|
|
int __init blk_dev_init(void)
|
|
{
|
|
BUILD_BUG_ON(__REQ_NR_BITS > 8 *
|
|
sizeof(((struct request *)0)->cmd_flags));
|
|
|
|
/* used for unplugging and affects IO latency/throughput - HIGHPRI */
|
|
kblockd_workqueue = alloc_workqueue("kblockd",
|
|
WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
|
|
if (!kblockd_workqueue)
|
|
panic("Failed to create kblockd\n");
|
|
|
|
request_cachep = kmem_cache_create("blkdev_requests",
|
|
sizeof(struct request), 0, SLAB_PANIC, NULL);
|
|
|
|
blk_requestq_cachep = kmem_cache_create("blkdev_queue",
|
|
sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
|
|
|
|
return 0;
|
|
}
|