7b6d91daee
Remove the current bio flags and reuse the request flags for the bio, too. This allows to more easily trace the type of I/O from the filesystem down to the block driver. There were two flags in the bio that were missing in the requests: BIO_RW_UNPLUG and BIO_RW_AHEAD. Also I've renamed two request flags that had a superflous RW in them. Note that the flags are in bio.h despite having the REQ_ name - as blkdev.h includes bio.h that is the only way to go for now. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
1145 lines
25 KiB
C
1145 lines
25 KiB
C
/*
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* Block device elevator/IO-scheduler.
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*
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* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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*
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* 30042000 Jens Axboe <axboe@kernel.dk> :
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*
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* Split the elevator a bit so that it is possible to choose a different
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* one or even write a new "plug in". There are three pieces:
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* - elevator_fn, inserts a new request in the queue list
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* - elevator_merge_fn, decides whether a new buffer can be merged with
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* an existing request
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* - elevator_dequeue_fn, called when a request is taken off the active list
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*
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* 20082000 Dave Jones <davej@suse.de> :
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* Removed tests for max-bomb-segments, which was breaking elvtune
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* when run without -bN
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*
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* Jens:
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* - Rework again to work with bio instead of buffer_heads
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* - loose bi_dev comparisons, partition handling is right now
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* - completely modularize elevator setup and teardown
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*
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*/
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#include <linux/bio.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/compiler.h>
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#include <linux/delay.h>
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#include <linux/blktrace_api.h>
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#include <linux/hash.h>
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#include <linux/uaccess.h>
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#include <trace/events/block.h>
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#include "blk.h"
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static DEFINE_SPINLOCK(elv_list_lock);
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static LIST_HEAD(elv_list);
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/*
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* Merge hash stuff.
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*/
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static const int elv_hash_shift = 6;
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#define ELV_HASH_BLOCK(sec) ((sec) >> 3)
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#define ELV_HASH_FN(sec) \
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(hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift))
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#define ELV_HASH_ENTRIES (1 << elv_hash_shift)
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#define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
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/*
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* Query io scheduler to see if the current process issuing bio may be
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* merged with rq.
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*/
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static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
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{
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struct request_queue *q = rq->q;
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struct elevator_queue *e = q->elevator;
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if (e->ops->elevator_allow_merge_fn)
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return e->ops->elevator_allow_merge_fn(q, rq, bio);
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return 1;
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}
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/*
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* can we safely merge with this request?
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*/
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int elv_rq_merge_ok(struct request *rq, struct bio *bio)
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{
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if (!rq_mergeable(rq))
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return 0;
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/*
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* Don't merge file system requests and discard requests
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*/
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if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
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return 0;
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/*
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* different data direction or already started, don't merge
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*/
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if (bio_data_dir(bio) != rq_data_dir(rq))
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return 0;
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/*
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* must be same device and not a special request
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*/
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if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
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return 0;
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/*
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* only merge integrity protected bio into ditto rq
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*/
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if (bio_integrity(bio) != blk_integrity_rq(rq))
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return 0;
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if (!elv_iosched_allow_merge(rq, bio))
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return 0;
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return 1;
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}
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EXPORT_SYMBOL(elv_rq_merge_ok);
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static inline int elv_try_merge(struct request *__rq, struct bio *bio)
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{
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int ret = ELEVATOR_NO_MERGE;
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/*
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* we can merge and sequence is ok, check if it's possible
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*/
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if (elv_rq_merge_ok(__rq, bio)) {
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if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector)
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ret = ELEVATOR_BACK_MERGE;
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else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector)
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ret = ELEVATOR_FRONT_MERGE;
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}
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return ret;
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}
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static struct elevator_type *elevator_find(const char *name)
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{
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struct elevator_type *e;
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list_for_each_entry(e, &elv_list, list) {
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if (!strcmp(e->elevator_name, name))
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return e;
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}
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return NULL;
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}
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static void elevator_put(struct elevator_type *e)
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{
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module_put(e->elevator_owner);
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}
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static struct elevator_type *elevator_get(const char *name)
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{
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struct elevator_type *e;
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spin_lock(&elv_list_lock);
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e = elevator_find(name);
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if (!e) {
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char elv[ELV_NAME_MAX + strlen("-iosched")];
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spin_unlock(&elv_list_lock);
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snprintf(elv, sizeof(elv), "%s-iosched", name);
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request_module("%s", elv);
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spin_lock(&elv_list_lock);
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e = elevator_find(name);
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}
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if (e && !try_module_get(e->elevator_owner))
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e = NULL;
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spin_unlock(&elv_list_lock);
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return e;
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}
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static void *elevator_init_queue(struct request_queue *q,
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struct elevator_queue *eq)
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{
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return eq->ops->elevator_init_fn(q);
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}
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static void elevator_attach(struct request_queue *q, struct elevator_queue *eq,
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void *data)
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{
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q->elevator = eq;
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eq->elevator_data = data;
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}
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static char chosen_elevator[16];
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static int __init elevator_setup(char *str)
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{
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/*
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* Be backwards-compatible with previous kernels, so users
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* won't get the wrong elevator.
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*/
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strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
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return 1;
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}
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__setup("elevator=", elevator_setup);
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static struct kobj_type elv_ktype;
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static struct elevator_queue *elevator_alloc(struct request_queue *q,
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struct elevator_type *e)
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{
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struct elevator_queue *eq;
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int i;
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eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node);
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if (unlikely(!eq))
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goto err;
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eq->ops = &e->ops;
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eq->elevator_type = e;
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kobject_init(&eq->kobj, &elv_ktype);
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mutex_init(&eq->sysfs_lock);
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eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES,
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GFP_KERNEL, q->node);
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if (!eq->hash)
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goto err;
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for (i = 0; i < ELV_HASH_ENTRIES; i++)
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INIT_HLIST_HEAD(&eq->hash[i]);
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return eq;
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err:
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kfree(eq);
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elevator_put(e);
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return NULL;
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}
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static void elevator_release(struct kobject *kobj)
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{
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struct elevator_queue *e;
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e = container_of(kobj, struct elevator_queue, kobj);
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elevator_put(e->elevator_type);
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kfree(e->hash);
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kfree(e);
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}
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int elevator_init(struct request_queue *q, char *name)
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{
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struct elevator_type *e = NULL;
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struct elevator_queue *eq;
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void *data;
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if (unlikely(q->elevator))
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return 0;
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INIT_LIST_HEAD(&q->queue_head);
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q->last_merge = NULL;
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q->end_sector = 0;
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q->boundary_rq = NULL;
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if (name) {
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e = elevator_get(name);
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if (!e)
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return -EINVAL;
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}
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if (!e && *chosen_elevator) {
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e = elevator_get(chosen_elevator);
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if (!e)
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printk(KERN_ERR "I/O scheduler %s not found\n",
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chosen_elevator);
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}
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if (!e) {
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e = elevator_get(CONFIG_DEFAULT_IOSCHED);
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if (!e) {
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printk(KERN_ERR
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"Default I/O scheduler not found. " \
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"Using noop.\n");
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e = elevator_get("noop");
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}
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}
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eq = elevator_alloc(q, e);
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if (!eq)
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return -ENOMEM;
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data = elevator_init_queue(q, eq);
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if (!data) {
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kobject_put(&eq->kobj);
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return -ENOMEM;
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}
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elevator_attach(q, eq, data);
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return 0;
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}
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EXPORT_SYMBOL(elevator_init);
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void elevator_exit(struct elevator_queue *e)
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{
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mutex_lock(&e->sysfs_lock);
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if (e->ops->elevator_exit_fn)
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e->ops->elevator_exit_fn(e);
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e->ops = NULL;
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mutex_unlock(&e->sysfs_lock);
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kobject_put(&e->kobj);
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}
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EXPORT_SYMBOL(elevator_exit);
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static inline void __elv_rqhash_del(struct request *rq)
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{
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hlist_del_init(&rq->hash);
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}
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static void elv_rqhash_del(struct request_queue *q, struct request *rq)
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{
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if (ELV_ON_HASH(rq))
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__elv_rqhash_del(rq);
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}
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static void elv_rqhash_add(struct request_queue *q, struct request *rq)
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{
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struct elevator_queue *e = q->elevator;
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BUG_ON(ELV_ON_HASH(rq));
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hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]);
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}
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static void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
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{
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__elv_rqhash_del(rq);
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elv_rqhash_add(q, rq);
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}
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static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
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{
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struct elevator_queue *e = q->elevator;
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struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)];
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struct hlist_node *entry, *next;
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struct request *rq;
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hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) {
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BUG_ON(!ELV_ON_HASH(rq));
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if (unlikely(!rq_mergeable(rq))) {
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__elv_rqhash_del(rq);
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continue;
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}
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if (rq_hash_key(rq) == offset)
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return rq;
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}
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return NULL;
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}
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/*
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* RB-tree support functions for inserting/lookup/removal of requests
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* in a sorted RB tree.
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*/
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struct request *elv_rb_add(struct rb_root *root, struct request *rq)
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{
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struct rb_node **p = &root->rb_node;
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struct rb_node *parent = NULL;
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struct request *__rq;
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while (*p) {
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parent = *p;
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__rq = rb_entry(parent, struct request, rb_node);
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if (blk_rq_pos(rq) < blk_rq_pos(__rq))
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p = &(*p)->rb_left;
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else if (blk_rq_pos(rq) > blk_rq_pos(__rq))
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p = &(*p)->rb_right;
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else
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return __rq;
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}
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rb_link_node(&rq->rb_node, parent, p);
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rb_insert_color(&rq->rb_node, root);
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return NULL;
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}
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EXPORT_SYMBOL(elv_rb_add);
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void elv_rb_del(struct rb_root *root, struct request *rq)
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{
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BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
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rb_erase(&rq->rb_node, root);
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RB_CLEAR_NODE(&rq->rb_node);
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}
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EXPORT_SYMBOL(elv_rb_del);
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struct request *elv_rb_find(struct rb_root *root, sector_t sector)
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{
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struct rb_node *n = root->rb_node;
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struct request *rq;
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while (n) {
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rq = rb_entry(n, struct request, rb_node);
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if (sector < blk_rq_pos(rq))
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n = n->rb_left;
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else if (sector > blk_rq_pos(rq))
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n = n->rb_right;
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else
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return rq;
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}
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return NULL;
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}
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EXPORT_SYMBOL(elv_rb_find);
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|
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/*
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* Insert rq into dispatch queue of q. Queue lock must be held on
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* entry. rq is sort instead into the dispatch queue. To be used by
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* specific elevators.
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*/
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void elv_dispatch_sort(struct request_queue *q, struct request *rq)
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{
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sector_t boundary;
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struct list_head *entry;
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int stop_flags;
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if (q->last_merge == rq)
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q->last_merge = NULL;
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elv_rqhash_del(q, rq);
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q->nr_sorted--;
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boundary = q->end_sector;
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stop_flags = REQ_SOFTBARRIER | REQ_HARDBARRIER | REQ_STARTED;
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list_for_each_prev(entry, &q->queue_head) {
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struct request *pos = list_entry_rq(entry);
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if ((rq->cmd_flags & REQ_DISCARD) !=
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(pos->cmd_flags & REQ_DISCARD))
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break;
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if (rq_data_dir(rq) != rq_data_dir(pos))
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break;
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if (pos->cmd_flags & stop_flags)
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break;
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if (blk_rq_pos(rq) >= boundary) {
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if (blk_rq_pos(pos) < boundary)
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continue;
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} else {
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if (blk_rq_pos(pos) >= boundary)
|
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break;
|
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}
|
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if (blk_rq_pos(rq) >= blk_rq_pos(pos))
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break;
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}
|
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|
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list_add(&rq->queuelist, entry);
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}
|
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EXPORT_SYMBOL(elv_dispatch_sort);
|
|
|
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/*
|
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* Insert rq into dispatch queue of q. Queue lock must be held on
|
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* entry. rq is added to the back of the dispatch queue. To be used by
|
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* specific elevators.
|
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*/
|
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void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
|
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{
|
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if (q->last_merge == rq)
|
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q->last_merge = NULL;
|
|
|
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elv_rqhash_del(q, rq);
|
|
|
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q->nr_sorted--;
|
|
|
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q->end_sector = rq_end_sector(rq);
|
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q->boundary_rq = rq;
|
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list_add_tail(&rq->queuelist, &q->queue_head);
|
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}
|
|
EXPORT_SYMBOL(elv_dispatch_add_tail);
|
|
|
|
int elv_merge(struct request_queue *q, struct request **req, struct bio *bio)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
struct request *__rq;
|
|
int ret;
|
|
|
|
/*
|
|
* Levels of merges:
|
|
* nomerges: No merges at all attempted
|
|
* noxmerges: Only simple one-hit cache try
|
|
* merges: All merge tries attempted
|
|
*/
|
|
if (blk_queue_nomerges(q))
|
|
return ELEVATOR_NO_MERGE;
|
|
|
|
/*
|
|
* First try one-hit cache.
|
|
*/
|
|
if (q->last_merge) {
|
|
ret = elv_try_merge(q->last_merge, bio);
|
|
if (ret != ELEVATOR_NO_MERGE) {
|
|
*req = q->last_merge;
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
if (blk_queue_noxmerges(q))
|
|
return ELEVATOR_NO_MERGE;
|
|
|
|
/*
|
|
* See if our hash lookup can find a potential backmerge.
|
|
*/
|
|
__rq = elv_rqhash_find(q, bio->bi_sector);
|
|
if (__rq && elv_rq_merge_ok(__rq, bio)) {
|
|
*req = __rq;
|
|
return ELEVATOR_BACK_MERGE;
|
|
}
|
|
|
|
if (e->ops->elevator_merge_fn)
|
|
return e->ops->elevator_merge_fn(q, req, bio);
|
|
|
|
return ELEVATOR_NO_MERGE;
|
|
}
|
|
|
|
void elv_merged_request(struct request_queue *q, struct request *rq, int type)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_merged_fn)
|
|
e->ops->elevator_merged_fn(q, rq, type);
|
|
|
|
if (type == ELEVATOR_BACK_MERGE)
|
|
elv_rqhash_reposition(q, rq);
|
|
|
|
q->last_merge = rq;
|
|
}
|
|
|
|
void elv_merge_requests(struct request_queue *q, struct request *rq,
|
|
struct request *next)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_merge_req_fn)
|
|
e->ops->elevator_merge_req_fn(q, rq, next);
|
|
|
|
elv_rqhash_reposition(q, rq);
|
|
elv_rqhash_del(q, next);
|
|
|
|
q->nr_sorted--;
|
|
q->last_merge = rq;
|
|
}
|
|
|
|
void elv_bio_merged(struct request_queue *q, struct request *rq,
|
|
struct bio *bio)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_bio_merged_fn)
|
|
e->ops->elevator_bio_merged_fn(q, rq, bio);
|
|
}
|
|
|
|
void elv_requeue_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
/*
|
|
* it already went through dequeue, we need to decrement the
|
|
* in_flight count again
|
|
*/
|
|
if (blk_account_rq(rq)) {
|
|
q->in_flight[rq_is_sync(rq)]--;
|
|
if (rq->cmd_flags & REQ_SORTED)
|
|
elv_deactivate_rq(q, rq);
|
|
}
|
|
|
|
rq->cmd_flags &= ~REQ_STARTED;
|
|
|
|
elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
|
|
}
|
|
|
|
void elv_drain_elevator(struct request_queue *q)
|
|
{
|
|
static int printed;
|
|
while (q->elevator->ops->elevator_dispatch_fn(q, 1))
|
|
;
|
|
if (q->nr_sorted == 0)
|
|
return;
|
|
if (printed++ < 10) {
|
|
printk(KERN_ERR "%s: forced dispatching is broken "
|
|
"(nr_sorted=%u), please report this\n",
|
|
q->elevator->elevator_type->elevator_name, q->nr_sorted);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Call with queue lock held, interrupts disabled
|
|
*/
|
|
void elv_quiesce_start(struct request_queue *q)
|
|
{
|
|
if (!q->elevator)
|
|
return;
|
|
|
|
queue_flag_set(QUEUE_FLAG_ELVSWITCH, q);
|
|
|
|
/*
|
|
* make sure we don't have any requests in flight
|
|
*/
|
|
elv_drain_elevator(q);
|
|
while (q->rq.elvpriv) {
|
|
__blk_run_queue(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
msleep(10);
|
|
spin_lock_irq(q->queue_lock);
|
|
elv_drain_elevator(q);
|
|
}
|
|
}
|
|
|
|
void elv_quiesce_end(struct request_queue *q)
|
|
{
|
|
queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
|
|
}
|
|
|
|
void elv_insert(struct request_queue *q, struct request *rq, int where)
|
|
{
|
|
struct list_head *pos;
|
|
unsigned ordseq;
|
|
int unplug_it = 1;
|
|
|
|
trace_block_rq_insert(q, rq);
|
|
|
|
rq->q = q;
|
|
|
|
switch (where) {
|
|
case ELEVATOR_INSERT_FRONT:
|
|
rq->cmd_flags |= REQ_SOFTBARRIER;
|
|
|
|
list_add(&rq->queuelist, &q->queue_head);
|
|
break;
|
|
|
|
case ELEVATOR_INSERT_BACK:
|
|
rq->cmd_flags |= REQ_SOFTBARRIER;
|
|
elv_drain_elevator(q);
|
|
list_add_tail(&rq->queuelist, &q->queue_head);
|
|
/*
|
|
* We kick the queue here for the following reasons.
|
|
* - The elevator might have returned NULL previously
|
|
* to delay requests and returned them now. As the
|
|
* queue wasn't empty before this request, ll_rw_blk
|
|
* won't run the queue on return, resulting in hang.
|
|
* - Usually, back inserted requests won't be merged
|
|
* with anything. There's no point in delaying queue
|
|
* processing.
|
|
*/
|
|
__blk_run_queue(q);
|
|
break;
|
|
|
|
case ELEVATOR_INSERT_SORT:
|
|
BUG_ON(rq->cmd_type != REQ_TYPE_FS &&
|
|
!(rq->cmd_flags & REQ_DISCARD));
|
|
rq->cmd_flags |= REQ_SORTED;
|
|
q->nr_sorted++;
|
|
if (rq_mergeable(rq)) {
|
|
elv_rqhash_add(q, rq);
|
|
if (!q->last_merge)
|
|
q->last_merge = rq;
|
|
}
|
|
|
|
/*
|
|
* Some ioscheds (cfq) run q->request_fn directly, so
|
|
* rq cannot be accessed after calling
|
|
* elevator_add_req_fn.
|
|
*/
|
|
q->elevator->ops->elevator_add_req_fn(q, rq);
|
|
break;
|
|
|
|
case ELEVATOR_INSERT_REQUEUE:
|
|
/*
|
|
* If ordered flush isn't in progress, we do front
|
|
* insertion; otherwise, requests should be requeued
|
|
* in ordseq order.
|
|
*/
|
|
rq->cmd_flags |= REQ_SOFTBARRIER;
|
|
|
|
/*
|
|
* Most requeues happen because of a busy condition,
|
|
* don't force unplug of the queue for that case.
|
|
*/
|
|
unplug_it = 0;
|
|
|
|
if (q->ordseq == 0) {
|
|
list_add(&rq->queuelist, &q->queue_head);
|
|
break;
|
|
}
|
|
|
|
ordseq = blk_ordered_req_seq(rq);
|
|
|
|
list_for_each(pos, &q->queue_head) {
|
|
struct request *pos_rq = list_entry_rq(pos);
|
|
if (ordseq <= blk_ordered_req_seq(pos_rq))
|
|
break;
|
|
}
|
|
|
|
list_add_tail(&rq->queuelist, pos);
|
|
break;
|
|
|
|
default:
|
|
printk(KERN_ERR "%s: bad insertion point %d\n",
|
|
__func__, where);
|
|
BUG();
|
|
}
|
|
|
|
if (unplug_it && blk_queue_plugged(q)) {
|
|
int nrq = q->rq.count[BLK_RW_SYNC] + q->rq.count[BLK_RW_ASYNC]
|
|
- queue_in_flight(q);
|
|
|
|
if (nrq >= q->unplug_thresh)
|
|
__generic_unplug_device(q);
|
|
}
|
|
}
|
|
|
|
void __elv_add_request(struct request_queue *q, struct request *rq, int where,
|
|
int plug)
|
|
{
|
|
if (q->ordcolor)
|
|
rq->cmd_flags |= REQ_ORDERED_COLOR;
|
|
|
|
if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) {
|
|
/*
|
|
* toggle ordered color
|
|
*/
|
|
if (rq->cmd_flags & REQ_HARDBARRIER)
|
|
q->ordcolor ^= 1;
|
|
|
|
/*
|
|
* barriers implicitly indicate back insertion
|
|
*/
|
|
if (where == ELEVATOR_INSERT_SORT)
|
|
where = ELEVATOR_INSERT_BACK;
|
|
|
|
/*
|
|
* this request is scheduling boundary, update
|
|
* end_sector
|
|
*/
|
|
if (rq->cmd_type == REQ_TYPE_FS ||
|
|
(rq->cmd_flags & REQ_DISCARD)) {
|
|
q->end_sector = rq_end_sector(rq);
|
|
q->boundary_rq = rq;
|
|
}
|
|
} else if (!(rq->cmd_flags & REQ_ELVPRIV) &&
|
|
where == ELEVATOR_INSERT_SORT)
|
|
where = ELEVATOR_INSERT_BACK;
|
|
|
|
if (plug)
|
|
blk_plug_device(q);
|
|
|
|
elv_insert(q, rq, where);
|
|
}
|
|
EXPORT_SYMBOL(__elv_add_request);
|
|
|
|
void elv_add_request(struct request_queue *q, struct request *rq, int where,
|
|
int plug)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
__elv_add_request(q, rq, where, plug);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(elv_add_request);
|
|
|
|
int elv_queue_empty(struct request_queue *q)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (!list_empty(&q->queue_head))
|
|
return 0;
|
|
|
|
if (e->ops->elevator_queue_empty_fn)
|
|
return e->ops->elevator_queue_empty_fn(q);
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(elv_queue_empty);
|
|
|
|
struct request *elv_latter_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_latter_req_fn)
|
|
return e->ops->elevator_latter_req_fn(q, rq);
|
|
return NULL;
|
|
}
|
|
|
|
struct request *elv_former_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_former_req_fn)
|
|
return e->ops->elevator_former_req_fn(q, rq);
|
|
return NULL;
|
|
}
|
|
|
|
int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_set_req_fn)
|
|
return e->ops->elevator_set_req_fn(q, rq, gfp_mask);
|
|
|
|
rq->elevator_private = NULL;
|
|
return 0;
|
|
}
|
|
|
|
void elv_put_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_put_req_fn)
|
|
e->ops->elevator_put_req_fn(rq);
|
|
}
|
|
|
|
int elv_may_queue(struct request_queue *q, int rw)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_may_queue_fn)
|
|
return e->ops->elevator_may_queue_fn(q, rw);
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
void elv_abort_queue(struct request_queue *q)
|
|
{
|
|
struct request *rq;
|
|
|
|
while (!list_empty(&q->queue_head)) {
|
|
rq = list_entry_rq(q->queue_head.next);
|
|
rq->cmd_flags |= REQ_QUIET;
|
|
trace_block_rq_abort(q, rq);
|
|
/*
|
|
* 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);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(elv_abort_queue);
|
|
|
|
void elv_completed_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
/*
|
|
* request is released from the driver, io must be done
|
|
*/
|
|
if (blk_account_rq(rq)) {
|
|
q->in_flight[rq_is_sync(rq)]--;
|
|
if ((rq->cmd_flags & REQ_SORTED) &&
|
|
e->ops->elevator_completed_req_fn)
|
|
e->ops->elevator_completed_req_fn(q, rq);
|
|
}
|
|
|
|
/*
|
|
* Check if the queue is waiting for fs requests to be
|
|
* drained for flush sequence.
|
|
*/
|
|
if (unlikely(q->ordseq)) {
|
|
struct request *next = NULL;
|
|
|
|
if (!list_empty(&q->queue_head))
|
|
next = list_entry_rq(q->queue_head.next);
|
|
|
|
if (!queue_in_flight(q) &&
|
|
blk_ordered_cur_seq(q) == QUEUE_ORDSEQ_DRAIN &&
|
|
(!next || blk_ordered_req_seq(next) > QUEUE_ORDSEQ_DRAIN)) {
|
|
blk_ordered_complete_seq(q, QUEUE_ORDSEQ_DRAIN, 0);
|
|
__blk_run_queue(q);
|
|
}
|
|
}
|
|
}
|
|
|
|
#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
|
|
|
|
static ssize_t
|
|
elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
|
|
{
|
|
struct elv_fs_entry *entry = to_elv(attr);
|
|
struct elevator_queue *e;
|
|
ssize_t error;
|
|
|
|
if (!entry->show)
|
|
return -EIO;
|
|
|
|
e = container_of(kobj, struct elevator_queue, kobj);
|
|
mutex_lock(&e->sysfs_lock);
|
|
error = e->ops ? entry->show(e, page) : -ENOENT;
|
|
mutex_unlock(&e->sysfs_lock);
|
|
return error;
|
|
}
|
|
|
|
static ssize_t
|
|
elv_attr_store(struct kobject *kobj, struct attribute *attr,
|
|
const char *page, size_t length)
|
|
{
|
|
struct elv_fs_entry *entry = to_elv(attr);
|
|
struct elevator_queue *e;
|
|
ssize_t error;
|
|
|
|
if (!entry->store)
|
|
return -EIO;
|
|
|
|
e = container_of(kobj, struct elevator_queue, kobj);
|
|
mutex_lock(&e->sysfs_lock);
|
|
error = e->ops ? entry->store(e, page, length) : -ENOENT;
|
|
mutex_unlock(&e->sysfs_lock);
|
|
return error;
|
|
}
|
|
|
|
static const struct sysfs_ops elv_sysfs_ops = {
|
|
.show = elv_attr_show,
|
|
.store = elv_attr_store,
|
|
};
|
|
|
|
static struct kobj_type elv_ktype = {
|
|
.sysfs_ops = &elv_sysfs_ops,
|
|
.release = elevator_release,
|
|
};
|
|
|
|
int elv_register_queue(struct request_queue *q)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
int error;
|
|
|
|
error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
|
|
if (!error) {
|
|
struct elv_fs_entry *attr = e->elevator_type->elevator_attrs;
|
|
if (attr) {
|
|
while (attr->attr.name) {
|
|
if (sysfs_create_file(&e->kobj, &attr->attr))
|
|
break;
|
|
attr++;
|
|
}
|
|
}
|
|
kobject_uevent(&e->kobj, KOBJ_ADD);
|
|
}
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(elv_register_queue);
|
|
|
|
static void __elv_unregister_queue(struct elevator_queue *e)
|
|
{
|
|
kobject_uevent(&e->kobj, KOBJ_REMOVE);
|
|
kobject_del(&e->kobj);
|
|
}
|
|
|
|
void elv_unregister_queue(struct request_queue *q)
|
|
{
|
|
if (q)
|
|
__elv_unregister_queue(q->elevator);
|
|
}
|
|
EXPORT_SYMBOL(elv_unregister_queue);
|
|
|
|
void elv_register(struct elevator_type *e)
|
|
{
|
|
char *def = "";
|
|
|
|
spin_lock(&elv_list_lock);
|
|
BUG_ON(elevator_find(e->elevator_name));
|
|
list_add_tail(&e->list, &elv_list);
|
|
spin_unlock(&elv_list_lock);
|
|
|
|
if (!strcmp(e->elevator_name, chosen_elevator) ||
|
|
(!*chosen_elevator &&
|
|
!strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
|
|
def = " (default)";
|
|
|
|
printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
|
|
def);
|
|
}
|
|
EXPORT_SYMBOL_GPL(elv_register);
|
|
|
|
void elv_unregister(struct elevator_type *e)
|
|
{
|
|
struct task_struct *g, *p;
|
|
|
|
/*
|
|
* Iterate every thread in the process to remove the io contexts.
|
|
*/
|
|
if (e->ops.trim) {
|
|
read_lock(&tasklist_lock);
|
|
do_each_thread(g, p) {
|
|
task_lock(p);
|
|
if (p->io_context)
|
|
e->ops.trim(p->io_context);
|
|
task_unlock(p);
|
|
} while_each_thread(g, p);
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
spin_lock(&elv_list_lock);
|
|
list_del_init(&e->list);
|
|
spin_unlock(&elv_list_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(elv_unregister);
|
|
|
|
/*
|
|
* switch to new_e io scheduler. be careful not to introduce deadlocks -
|
|
* we don't free the old io scheduler, before we have allocated what we
|
|
* need for the new one. this way we have a chance of going back to the old
|
|
* one, if the new one fails init for some reason.
|
|
*/
|
|
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
|
|
{
|
|
struct elevator_queue *old_elevator, *e;
|
|
void *data;
|
|
|
|
/*
|
|
* Allocate new elevator
|
|
*/
|
|
e = elevator_alloc(q, new_e);
|
|
if (!e)
|
|
return 0;
|
|
|
|
data = elevator_init_queue(q, e);
|
|
if (!data) {
|
|
kobject_put(&e->kobj);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Turn on BYPASS and drain all requests w/ elevator private data
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
elv_quiesce_start(q);
|
|
|
|
/*
|
|
* Remember old elevator.
|
|
*/
|
|
old_elevator = q->elevator;
|
|
|
|
/*
|
|
* attach and start new elevator
|
|
*/
|
|
elevator_attach(q, e, data);
|
|
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
__elv_unregister_queue(old_elevator);
|
|
|
|
if (elv_register_queue(q))
|
|
goto fail_register;
|
|
|
|
/*
|
|
* finally exit old elevator and turn off BYPASS.
|
|
*/
|
|
elevator_exit(old_elevator);
|
|
spin_lock_irq(q->queue_lock);
|
|
elv_quiesce_end(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);
|
|
|
|
return 1;
|
|
|
|
fail_register:
|
|
/*
|
|
* switch failed, exit the new io scheduler and reattach the old
|
|
* one again (along with re-adding the sysfs dir)
|
|
*/
|
|
elevator_exit(e);
|
|
q->elevator = old_elevator;
|
|
elv_register_queue(q);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
ssize_t elv_iosched_store(struct request_queue *q, const char *name,
|
|
size_t count)
|
|
{
|
|
char elevator_name[ELV_NAME_MAX];
|
|
struct elevator_type *e;
|
|
|
|
if (!q->elevator)
|
|
return count;
|
|
|
|
strlcpy(elevator_name, name, sizeof(elevator_name));
|
|
e = elevator_get(strstrip(elevator_name));
|
|
if (!e) {
|
|
printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
|
|
elevator_put(e);
|
|
return count;
|
|
}
|
|
|
|
if (!elevator_switch(q, e))
|
|
printk(KERN_ERR "elevator: switch to %s failed\n",
|
|
elevator_name);
|
|
return count;
|
|
}
|
|
|
|
ssize_t elv_iosched_show(struct request_queue *q, char *name)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
struct elevator_type *elv;
|
|
struct elevator_type *__e;
|
|
int len = 0;
|
|
|
|
if (!q->elevator || !blk_queue_stackable(q))
|
|
return sprintf(name, "none\n");
|
|
|
|
elv = e->elevator_type;
|
|
|
|
spin_lock(&elv_list_lock);
|
|
list_for_each_entry(__e, &elv_list, list) {
|
|
if (!strcmp(elv->elevator_name, __e->elevator_name))
|
|
len += sprintf(name+len, "[%s] ", elv->elevator_name);
|
|
else
|
|
len += sprintf(name+len, "%s ", __e->elevator_name);
|
|
}
|
|
spin_unlock(&elv_list_lock);
|
|
|
|
len += sprintf(len+name, "\n");
|
|
return len;
|
|
}
|
|
|
|
struct request *elv_rb_former_request(struct request_queue *q,
|
|
struct request *rq)
|
|
{
|
|
struct rb_node *rbprev = rb_prev(&rq->rb_node);
|
|
|
|
if (rbprev)
|
|
return rb_entry_rq(rbprev);
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(elv_rb_former_request);
|
|
|
|
struct request *elv_rb_latter_request(struct request_queue *q,
|
|
struct request *rq)
|
|
{
|
|
struct rb_node *rbnext = rb_next(&rq->rb_node);
|
|
|
|
if (rbnext)
|
|
return rb_entry_rq(rbnext);
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(elv_rb_latter_request);
|