mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 05:48:40 +00:00
![Tejun Heo](/assets/img/avatar_default.png)
request_queue is refcounted but actually depdends on lifetime management from the queue owner - on blk_cleanup_queue(), block layer expects that there's no request passing through request_queue and no new one will. This is fundamentally broken. The queue owner (e.g. SCSI layer) doesn't have a way to know whether there are other active users before calling blk_cleanup_queue() and other users (e.g. bsg) don't have any guarantee that the queue is and would stay valid while it's holding a reference. With delay added in blk_queue_bio() before queue_lock is grabbed, the following oops can be easily triggered when a device is removed with in-flight IOs. sd 0:0:1:0: [sdb] Stopping disk ata1.01: disabled general protection fault: 0000 [#1] PREEMPT SMP CPU 2 Modules linked in: Pid: 648, comm: test_rawio Not tainted 3.1.0-rc3-work+ #56 Bochs Bochs RIP: 0010:[<ffffffff8137d651>] [<ffffffff8137d651>] elv_rqhash_find+0x61/0x100 ... Process test_rawio (pid: 648, threadinfo ffff880019efa000, task ffff880019ef8a80) ... Call Trace: [<ffffffff8137d774>] elv_merge+0x84/0xe0 [<ffffffff81385b54>] blk_queue_bio+0xf4/0x400 [<ffffffff813838ea>] generic_make_request+0xca/0x100 [<ffffffff81383994>] submit_bio+0x74/0x100 [<ffffffff811c53ec>] dio_bio_submit+0xbc/0xc0 [<ffffffff811c610e>] __blockdev_direct_IO+0x92e/0xb40 [<ffffffff811c39f7>] blkdev_direct_IO+0x57/0x60 [<ffffffff8113b1c5>] generic_file_aio_read+0x6d5/0x760 [<ffffffff8118c1ca>] do_sync_read+0xda/0x120 [<ffffffff8118ce55>] vfs_read+0xc5/0x180 [<ffffffff8118cfaa>] sys_pread64+0x9a/0xb0 [<ffffffff81afaf6b>] system_call_fastpath+0x16/0x1b This happens because blk_queue_cleanup() destroys the queue and elevator whether IOs are in progress or not and DEAD tests are sprinkled in the request processing path without proper synchronization. Similar problem exists for blk-throtl. On queue cleanup, blk-throtl is shutdown whether it has requests in it or not. Depending on timing, it either oopses or throttled bios are lost putting tasks which are waiting for bio completion into eternal D state. The way it should work is having the usual clear distinction between shutdown and release. Shutdown drains all currently pending requests, marks the queue dead, and performs partial teardown of the now unnecessary part of the queue. Even after shutdown is complete, reference holders are still allowed to issue requests to the queue although they will be immmediately failed. The rest of teardown happens on release. This patch makes the following changes to make blk_queue_cleanup() behave as proper shutdown. * QUEUE_FLAG_DEAD is now set while holding both q->exit_mutex and queue_lock. * Unsynchronized DEAD check in generic_make_request_checks() removed. This couldn't make any meaningful difference as the queue could die after the check. * blk_drain_queue() updated such that it can drain all requests and is now called during cleanup. * blk_throtl updated such that it checks DEAD on grabbing queue_lock, drains all throttled bios during cleanup and free td when queue is released. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
1101 lines
24 KiB
C
1101 lines
24 KiB
C
/*
|
|
* Block device elevator/IO-scheduler.
|
|
*
|
|
* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
|
|
*
|
|
* 30042000 Jens Axboe <axboe@kernel.dk> :
|
|
*
|
|
* Split the elevator a bit so that it is possible to choose a different
|
|
* one or even write a new "plug in". There are three pieces:
|
|
* - elevator_fn, inserts a new request in the queue list
|
|
* - elevator_merge_fn, decides whether a new buffer can be merged with
|
|
* an existing request
|
|
* - elevator_dequeue_fn, called when a request is taken off the active list
|
|
*
|
|
* 20082000 Dave Jones <davej@suse.de> :
|
|
* Removed tests for max-bomb-segments, which was breaking elvtune
|
|
* when run without -bN
|
|
*
|
|
* Jens:
|
|
* - Rework again to work with bio instead of buffer_heads
|
|
* - loose bi_dev comparisons, partition handling is right now
|
|
* - completely modularize elevator setup and teardown
|
|
*
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/blkdev.h>
|
|
#include <linux/elevator.h>
|
|
#include <linux/bio.h>
|
|
#include <linux/module.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/init.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/blktrace_api.h>
|
|
#include <linux/hash.h>
|
|
#include <linux/uaccess.h>
|
|
|
|
#include <trace/events/block.h>
|
|
|
|
#include "blk.h"
|
|
|
|
static DEFINE_SPINLOCK(elv_list_lock);
|
|
static LIST_HEAD(elv_list);
|
|
|
|
/*
|
|
* Merge hash stuff.
|
|
*/
|
|
static const int elv_hash_shift = 6;
|
|
#define ELV_HASH_BLOCK(sec) ((sec) >> 3)
|
|
#define ELV_HASH_FN(sec) \
|
|
(hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift))
|
|
#define ELV_HASH_ENTRIES (1 << elv_hash_shift)
|
|
#define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
|
|
|
|
/*
|
|
* Query io scheduler to see if the current process issuing bio may be
|
|
* merged with rq.
|
|
*/
|
|
static int elv_iosched_allow_merge(struct request *rq, struct bio *bio)
|
|
{
|
|
struct request_queue *q = rq->q;
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->ops->elevator_allow_merge_fn)
|
|
return e->ops->elevator_allow_merge_fn(q, rq, bio);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* can we safely merge with this request?
|
|
*/
|
|
int elv_rq_merge_ok(struct request *rq, struct bio *bio)
|
|
{
|
|
if (!rq_mergeable(rq))
|
|
return 0;
|
|
|
|
/*
|
|
* Don't merge file system requests and discard requests
|
|
*/
|
|
if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
|
|
return 0;
|
|
|
|
/*
|
|
* Don't merge discard requests and secure discard requests
|
|
*/
|
|
if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
|
|
return 0;
|
|
|
|
/*
|
|
* different data direction or already started, don't merge
|
|
*/
|
|
if (bio_data_dir(bio) != rq_data_dir(rq))
|
|
return 0;
|
|
|
|
/*
|
|
* must be same device and not a special request
|
|
*/
|
|
if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
|
|
return 0;
|
|
|
|
/*
|
|
* only merge integrity protected bio into ditto rq
|
|
*/
|
|
if (bio_integrity(bio) != blk_integrity_rq(rq))
|
|
return 0;
|
|
|
|
if (!elv_iosched_allow_merge(rq, bio))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(elv_rq_merge_ok);
|
|
|
|
int elv_try_merge(struct request *__rq, struct bio *bio)
|
|
{
|
|
int ret = ELEVATOR_NO_MERGE;
|
|
|
|
/*
|
|
* we can merge and sequence is ok, check if it's possible
|
|
*/
|
|
if (elv_rq_merge_ok(__rq, bio)) {
|
|
if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector)
|
|
ret = ELEVATOR_BACK_MERGE;
|
|
else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector)
|
|
ret = ELEVATOR_FRONT_MERGE;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static struct elevator_type *elevator_find(const char *name)
|
|
{
|
|
struct elevator_type *e;
|
|
|
|
list_for_each_entry(e, &elv_list, list) {
|
|
if (!strcmp(e->elevator_name, name))
|
|
return e;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static void elevator_put(struct elevator_type *e)
|
|
{
|
|
module_put(e->elevator_owner);
|
|
}
|
|
|
|
static struct elevator_type *elevator_get(const char *name)
|
|
{
|
|
struct elevator_type *e;
|
|
|
|
spin_lock(&elv_list_lock);
|
|
|
|
e = elevator_find(name);
|
|
if (!e) {
|
|
spin_unlock(&elv_list_lock);
|
|
request_module("%s-iosched", name);
|
|
spin_lock(&elv_list_lock);
|
|
e = elevator_find(name);
|
|
}
|
|
|
|
if (e && !try_module_get(e->elevator_owner))
|
|
e = NULL;
|
|
|
|
spin_unlock(&elv_list_lock);
|
|
|
|
return e;
|
|
}
|
|
|
|
static void *elevator_init_queue(struct request_queue *q,
|
|
struct elevator_queue *eq)
|
|
{
|
|
return eq->ops->elevator_init_fn(q);
|
|
}
|
|
|
|
static void elevator_attach(struct request_queue *q, struct elevator_queue *eq,
|
|
void *data)
|
|
{
|
|
q->elevator = eq;
|
|
eq->elevator_data = data;
|
|
}
|
|
|
|
static char chosen_elevator[ELV_NAME_MAX];
|
|
|
|
static int __init elevator_setup(char *str)
|
|
{
|
|
/*
|
|
* Be backwards-compatible with previous kernels, so users
|
|
* won't get the wrong elevator.
|
|
*/
|
|
strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
|
|
return 1;
|
|
}
|
|
|
|
__setup("elevator=", elevator_setup);
|
|
|
|
static struct kobj_type elv_ktype;
|
|
|
|
static struct elevator_queue *elevator_alloc(struct request_queue *q,
|
|
struct elevator_type *e)
|
|
{
|
|
struct elevator_queue *eq;
|
|
int i;
|
|
|
|
eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node);
|
|
if (unlikely(!eq))
|
|
goto err;
|
|
|
|
eq->ops = &e->ops;
|
|
eq->elevator_type = e;
|
|
kobject_init(&eq->kobj, &elv_ktype);
|
|
mutex_init(&eq->sysfs_lock);
|
|
|
|
eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES,
|
|
GFP_KERNEL, q->node);
|
|
if (!eq->hash)
|
|
goto err;
|
|
|
|
for (i = 0; i < ELV_HASH_ENTRIES; i++)
|
|
INIT_HLIST_HEAD(&eq->hash[i]);
|
|
|
|
return eq;
|
|
err:
|
|
kfree(eq);
|
|
elevator_put(e);
|
|
return NULL;
|
|
}
|
|
|
|
static void elevator_release(struct kobject *kobj)
|
|
{
|
|
struct elevator_queue *e;
|
|
|
|
e = container_of(kobj, struct elevator_queue, kobj);
|
|
elevator_put(e->elevator_type);
|
|
kfree(e->hash);
|
|
kfree(e);
|
|
}
|
|
|
|
int elevator_init(struct request_queue *q, char *name)
|
|
{
|
|
struct elevator_type *e = NULL;
|
|
struct elevator_queue *eq;
|
|
void *data;
|
|
|
|
if (unlikely(q->elevator))
|
|
return 0;
|
|
|
|
INIT_LIST_HEAD(&q->queue_head);
|
|
q->last_merge = NULL;
|
|
q->end_sector = 0;
|
|
q->boundary_rq = NULL;
|
|
|
|
if (name) {
|
|
e = elevator_get(name);
|
|
if (!e)
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (!e && *chosen_elevator) {
|
|
e = elevator_get(chosen_elevator);
|
|
if (!e)
|
|
printk(KERN_ERR "I/O scheduler %s not found\n",
|
|
chosen_elevator);
|
|
}
|
|
|
|
if (!e) {
|
|
e = elevator_get(CONFIG_DEFAULT_IOSCHED);
|
|
if (!e) {
|
|
printk(KERN_ERR
|
|
"Default I/O scheduler not found. " \
|
|
"Using noop.\n");
|
|
e = elevator_get("noop");
|
|
}
|
|
}
|
|
|
|
eq = elevator_alloc(q, e);
|
|
if (!eq)
|
|
return -ENOMEM;
|
|
|
|
data = elevator_init_queue(q, eq);
|
|
if (!data) {
|
|
kobject_put(&eq->kobj);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
elevator_attach(q, eq, data);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(elevator_init);
|
|
|
|
void elevator_exit(struct elevator_queue *e)
|
|
{
|
|
mutex_lock(&e->sysfs_lock);
|
|
if (e->ops->elevator_exit_fn)
|
|
e->ops->elevator_exit_fn(e);
|
|
e->ops = NULL;
|
|
mutex_unlock(&e->sysfs_lock);
|
|
|
|
kobject_put(&e->kobj);
|
|
}
|
|
EXPORT_SYMBOL(elevator_exit);
|
|
|
|
static inline void __elv_rqhash_del(struct request *rq)
|
|
{
|
|
hlist_del_init(&rq->hash);
|
|
}
|
|
|
|
static void elv_rqhash_del(struct request_queue *q, struct request *rq)
|
|
{
|
|
if (ELV_ON_HASH(rq))
|
|
__elv_rqhash_del(rq);
|
|
}
|
|
|
|
static void elv_rqhash_add(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
BUG_ON(ELV_ON_HASH(rq));
|
|
hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]);
|
|
}
|
|
|
|
static void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
|
|
{
|
|
__elv_rqhash_del(rq);
|
|
elv_rqhash_add(q, rq);
|
|
}
|
|
|
|
static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)];
|
|
struct hlist_node *entry, *next;
|
|
struct request *rq;
|
|
|
|
hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) {
|
|
BUG_ON(!ELV_ON_HASH(rq));
|
|
|
|
if (unlikely(!rq_mergeable(rq))) {
|
|
__elv_rqhash_del(rq);
|
|
continue;
|
|
}
|
|
|
|
if (rq_hash_key(rq) == offset)
|
|
return rq;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* RB-tree support functions for inserting/lookup/removal of requests
|
|
* in a sorted RB tree.
|
|
*/
|
|
void elv_rb_add(struct rb_root *root, struct request *rq)
|
|
{
|
|
struct rb_node **p = &root->rb_node;
|
|
struct rb_node *parent = NULL;
|
|
struct request *__rq;
|
|
|
|
while (*p) {
|
|
parent = *p;
|
|
__rq = rb_entry(parent, struct request, rb_node);
|
|
|
|
if (blk_rq_pos(rq) < blk_rq_pos(__rq))
|
|
p = &(*p)->rb_left;
|
|
else if (blk_rq_pos(rq) >= blk_rq_pos(__rq))
|
|
p = &(*p)->rb_right;
|
|
}
|
|
|
|
rb_link_node(&rq->rb_node, parent, p);
|
|
rb_insert_color(&rq->rb_node, root);
|
|
}
|
|
EXPORT_SYMBOL(elv_rb_add);
|
|
|
|
void elv_rb_del(struct rb_root *root, struct request *rq)
|
|
{
|
|
BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
|
|
rb_erase(&rq->rb_node, root);
|
|
RB_CLEAR_NODE(&rq->rb_node);
|
|
}
|
|
EXPORT_SYMBOL(elv_rb_del);
|
|
|
|
struct request *elv_rb_find(struct rb_root *root, sector_t sector)
|
|
{
|
|
struct rb_node *n = root->rb_node;
|
|
struct request *rq;
|
|
|
|
while (n) {
|
|
rq = rb_entry(n, struct request, rb_node);
|
|
|
|
if (sector < blk_rq_pos(rq))
|
|
n = n->rb_left;
|
|
else if (sector > blk_rq_pos(rq))
|
|
n = n->rb_right;
|
|
else
|
|
return rq;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(elv_rb_find);
|
|
|
|
/*
|
|
* Insert rq into dispatch queue of q. Queue lock must be held on
|
|
* entry. rq is sort instead into the dispatch queue. To be used by
|
|
* specific elevators.
|
|
*/
|
|
void elv_dispatch_sort(struct request_queue *q, struct request *rq)
|
|
{
|
|
sector_t boundary;
|
|
struct list_head *entry;
|
|
int stop_flags;
|
|
|
|
if (q->last_merge == rq)
|
|
q->last_merge = NULL;
|
|
|
|
elv_rqhash_del(q, rq);
|
|
|
|
q->nr_sorted--;
|
|
|
|
boundary = q->end_sector;
|
|
stop_flags = REQ_SOFTBARRIER | REQ_STARTED;
|
|
list_for_each_prev(entry, &q->queue_head) {
|
|
struct request *pos = list_entry_rq(entry);
|
|
|
|
if ((rq->cmd_flags & REQ_DISCARD) !=
|
|
(pos->cmd_flags & REQ_DISCARD))
|
|
break;
|
|
if (rq_data_dir(rq) != rq_data_dir(pos))
|
|
break;
|
|
if (pos->cmd_flags & stop_flags)
|
|
break;
|
|
if (blk_rq_pos(rq) >= boundary) {
|
|
if (blk_rq_pos(pos) < boundary)
|
|
continue;
|
|
} else {
|
|
if (blk_rq_pos(pos) >= boundary)
|
|
break;
|
|
}
|
|
if (blk_rq_pos(rq) >= blk_rq_pos(pos))
|
|
break;
|
|
}
|
|
|
|
list_add(&rq->queuelist, entry);
|
|
}
|
|
EXPORT_SYMBOL(elv_dispatch_sort);
|
|
|
|
/*
|
|
* Insert rq into dispatch queue of q. Queue lock must be held on
|
|
* entry. rq is added to the back of the dispatch queue. To be used by
|
|
* specific elevators.
|
|
*/
|
|
void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
|
|
{
|
|
if (q->last_merge == rq)
|
|
q->last_merge = NULL;
|
|
|
|
elv_rqhash_del(q, rq);
|
|
|
|
q->nr_sorted--;
|
|
|
|
q->end_sector = rq_end_sector(rq);
|
|
q->boundary_rq = rq;
|
|
list_add_tail(&rq->queuelist, &q->queue_head);
|
|
}
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* Attempt to do an insertion back merge. Only check for the case where
|
|
* we can append 'rq' to an existing request, so we can throw 'rq' away
|
|
* afterwards.
|
|
*
|
|
* Returns true if we merged, false otherwise
|
|
*/
|
|
static bool elv_attempt_insert_merge(struct request_queue *q,
|
|
struct request *rq)
|
|
{
|
|
struct request *__rq;
|
|
|
|
if (blk_queue_nomerges(q))
|
|
return false;
|
|
|
|
/*
|
|
* First try one-hit cache.
|
|
*/
|
|
if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq))
|
|
return true;
|
|
|
|
if (blk_queue_noxmerges(q))
|
|
return false;
|
|
|
|
/*
|
|
* See if our hash lookup can find a potential backmerge.
|
|
*/
|
|
__rq = elv_rqhash_find(q, blk_rq_pos(rq));
|
|
if (__rq && blk_attempt_req_merge(q, __rq, rq))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
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;
|
|
const int next_sorted = next->cmd_flags & REQ_SORTED;
|
|
|
|
if (next_sorted && e->ops->elevator_merge_req_fn)
|
|
e->ops->elevator_merge_req_fn(q, rq, next);
|
|
|
|
elv_rqhash_reposition(q, rq);
|
|
|
|
if (next_sorted) {
|
|
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_add_request(q, rq, ELEVATOR_INSERT_REQUEUE);
|
|
}
|
|
|
|
void elv_drain_elevator(struct request_queue *q)
|
|
{
|
|
static int printed;
|
|
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
while (q->elevator->ops->elevator_dispatch_fn(q, 1))
|
|
;
|
|
if (q->nr_sorted && 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);
|
|
}
|
|
}
|
|
|
|
void elv_quiesce_start(struct request_queue *q)
|
|
{
|
|
if (!q->elevator)
|
|
return;
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
queue_flag_set(QUEUE_FLAG_ELVSWITCH, q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
blk_drain_queue(q, false);
|
|
}
|
|
|
|
void elv_quiesce_end(struct request_queue *q)
|
|
{
|
|
spin_lock_irq(q->queue_lock);
|
|
queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
|
|
void __elv_add_request(struct request_queue *q, struct request *rq, int where)
|
|
{
|
|
trace_block_rq_insert(q, rq);
|
|
|
|
rq->q = q;
|
|
|
|
if (rq->cmd_flags & REQ_SOFTBARRIER) {
|
|
/* barriers are 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_SORT_MERGE))
|
|
where = ELEVATOR_INSERT_BACK;
|
|
|
|
switch (where) {
|
|
case ELEVATOR_INSERT_REQUEUE:
|
|
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_MERGE:
|
|
/*
|
|
* If we succeed in merging this request with one in the
|
|
* queue already, we are done - rq has now been freed,
|
|
* so no need to do anything further.
|
|
*/
|
|
if (elv_attempt_insert_merge(q, rq))
|
|
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_FLUSH:
|
|
rq->cmd_flags |= REQ_SOFTBARRIER;
|
|
blk_insert_flush(rq);
|
|
break;
|
|
default:
|
|
printk(KERN_ERR "%s: bad insertion point %d\n",
|
|
__func__, where);
|
|
BUG();
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(__elv_add_request);
|
|
|
|
void elv_add_request(struct request_queue *q, struct request *rq, int where)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
__elv_add_request(q, rq, where);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(elv_add_request);
|
|
|
|
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[0] = 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;
|
|
|
|
blk_abort_flushes(q);
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
#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);
|
|
e->registered = 1;
|
|
}
|
|
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);
|
|
e->registered = 0;
|
|
}
|
|
|
|
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;
|
|
int err;
|
|
|
|
/*
|
|
* Allocate new elevator
|
|
*/
|
|
e = elevator_alloc(q, new_e);
|
|
if (!e)
|
|
return -ENOMEM;
|
|
|
|
data = elevator_init_queue(q, e);
|
|
if (!data) {
|
|
kobject_put(&e->kobj);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* Turn on BYPASS and drain all requests w/ elevator private data
|
|
*/
|
|
elv_quiesce_start(q);
|
|
|
|
/*
|
|
* Remember old elevator.
|
|
*/
|
|
old_elevator = q->elevator;
|
|
|
|
/*
|
|
* attach and start new elevator
|
|
*/
|
|
spin_lock_irq(q->queue_lock);
|
|
elevator_attach(q, e, data);
|
|
spin_unlock_irq(q->queue_lock);
|
|
|
|
if (old_elevator->registered) {
|
|
__elv_unregister_queue(old_elevator);
|
|
|
|
err = elv_register_queue(q);
|
|
if (err)
|
|
goto fail_register;
|
|
}
|
|
|
|
/*
|
|
* finally exit old elevator and turn off BYPASS.
|
|
*/
|
|
elevator_exit(old_elevator);
|
|
elv_quiesce_end(q);
|
|
|
|
blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);
|
|
|
|
return 0;
|
|
|
|
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);
|
|
elv_quiesce_end(q);
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Switch this queue to the given IO scheduler.
|
|
*/
|
|
int elevator_change(struct request_queue *q, const char *name)
|
|
{
|
|
char elevator_name[ELV_NAME_MAX];
|
|
struct elevator_type *e;
|
|
|
|
if (!q->elevator)
|
|
return -ENXIO;
|
|
|
|
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 0;
|
|
}
|
|
|
|
return elevator_switch(q, e);
|
|
}
|
|
EXPORT_SYMBOL(elevator_change);
|
|
|
|
ssize_t elv_iosched_store(struct request_queue *q, const char *name,
|
|
size_t count)
|
|
{
|
|
int ret;
|
|
|
|
if (!q->elevator)
|
|
return count;
|
|
|
|
ret = elevator_change(q, name);
|
|
if (!ret)
|
|
return count;
|
|
|
|
printk(KERN_ERR "elevator: switch to %s failed\n", name);
|
|
return ret;
|
|
}
|
|
|
|
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);
|