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linux_dsm_epyc7002/include/linux/elevator.h
Omar Sandoval 54d5329d42 blk-mq-sched: fix crash in switch error path 
In elevator_switch(), if blk_mq_init_sched() fails, we attempt to fall
back to the original scheduler. However, at this point, we've already
torn down the original scheduler's tags, so this causes a crash. Doing
the fallback like the legacy elevator path is much harder for mq, so fix
it by just falling back to none, instead.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07 08:56:48 -06:00

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#ifndef _LINUX_ELEVATOR_H
#define _LINUX_ELEVATOR_H
#include <linux/percpu.h>
#include <linux/hashtable.h>
#ifdef CONFIG_BLOCK
struct io_cq;
struct elevator_type;
/*
* Return values from elevator merger
*/
enum elv_merge {
ELEVATOR_NO_MERGE = 0,
ELEVATOR_FRONT_MERGE = 1,
ELEVATOR_BACK_MERGE = 2,
ELEVATOR_DISCARD_MERGE = 3,
};
typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
struct bio *);
typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
struct request *, struct bio *);
typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
struct request *, struct request *);
typedef void (elevator_bio_merged_fn) (struct request_queue *,
struct request *, struct bio *);
typedef int (elevator_dispatch_fn) (struct request_queue *, int);
typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
typedef int (elevator_may_queue_fn) (struct request_queue *, unsigned int);
typedef void (elevator_init_icq_fn) (struct io_cq *);
typedef void (elevator_exit_icq_fn) (struct io_cq *);
typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
struct bio *, gfp_t);
typedef void (elevator_put_req_fn) (struct request *);
typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
typedef int (elevator_init_fn) (struct request_queue *,
struct elevator_type *e);
typedef void (elevator_exit_fn) (struct elevator_queue *);
typedef void (elevator_registered_fn) (struct request_queue *);
struct elevator_ops
{
elevator_merge_fn *elevator_merge_fn;
elevator_merged_fn *elevator_merged_fn;
elevator_merge_req_fn *elevator_merge_req_fn;
elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
elevator_bio_merged_fn *elevator_bio_merged_fn;
elevator_dispatch_fn *elevator_dispatch_fn;
elevator_add_req_fn *elevator_add_req_fn;
elevator_activate_req_fn *elevator_activate_req_fn;
elevator_deactivate_req_fn *elevator_deactivate_req_fn;
elevator_completed_req_fn *elevator_completed_req_fn;
elevator_request_list_fn *elevator_former_req_fn;
elevator_request_list_fn *elevator_latter_req_fn;
elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
elevator_set_req_fn *elevator_set_req_fn;
elevator_put_req_fn *elevator_put_req_fn;
elevator_may_queue_fn *elevator_may_queue_fn;
elevator_init_fn *elevator_init_fn;
elevator_exit_fn *elevator_exit_fn;
elevator_registered_fn *elevator_registered_fn;
};
struct blk_mq_alloc_data;
struct blk_mq_hw_ctx;
struct elevator_mq_ops {
int (*init_sched)(struct request_queue *, struct elevator_type *);
void (*exit_sched)(struct elevator_queue *);
bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
void (*requests_merged)(struct request_queue *, struct request *, struct request *);
struct request *(*get_request)(struct request_queue *, unsigned int, struct blk_mq_alloc_data *);
void (*put_request)(struct request *);
void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
bool (*has_work)(struct blk_mq_hw_ctx *);
void (*completed_request)(struct blk_mq_hw_ctx *, struct request *);
void (*started_request)(struct request *);
void (*requeue_request)(struct request *);
struct request *(*former_request)(struct request_queue *, struct request *);
struct request *(*next_request)(struct request_queue *, struct request *);
int (*get_rq_priv)(struct request_queue *, struct request *, struct bio *);
void (*put_rq_priv)(struct request_queue *, struct request *);
void (*init_icq)(struct io_cq *);
void (*exit_icq)(struct io_cq *);
};
#define ELV_NAME_MAX (16)
struct elv_fs_entry {
struct attribute attr;
ssize_t (*show)(struct elevator_queue *, char *);
ssize_t (*store)(struct elevator_queue *, const char *, size_t);
};
/*
* identifies an elevator type, such as AS or deadline
*/
struct elevator_type
{
/* managed by elevator core */
struct kmem_cache *icq_cache;
/* fields provided by elevator implementation */
union {
struct elevator_ops sq;
struct elevator_mq_ops mq;
} ops;
size_t icq_size; /* see iocontext.h */
size_t icq_align; /* ditto */
struct elv_fs_entry *elevator_attrs;
char elevator_name[ELV_NAME_MAX];
struct module *elevator_owner;
bool uses_mq;
/* managed by elevator core */
char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
struct list_head list;
};
#define ELV_HASH_BITS 6
void elv_rqhash_del(struct request_queue *q, struct request *rq);
void elv_rqhash_add(struct request_queue *q, struct request *rq);
void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
/*
* each queue has an elevator_queue associated with it
*/
struct elevator_queue
{
struct elevator_type *type;
void *elevator_data;
struct kobject kobj;
struct mutex sysfs_lock;
unsigned int registered:1;
unsigned int uses_mq:1;
DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
};
/*
* block elevator interface
*/
extern void elv_dispatch_sort(struct request_queue *, struct request *);
extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
extern void elv_add_request(struct request_queue *, struct request *, int);
extern void __elv_add_request(struct request_queue *, struct request *, int);
extern enum elv_merge elv_merge(struct request_queue *, struct request **,
struct bio *);
extern void elv_merge_requests(struct request_queue *, struct request *,
struct request *);
extern void elv_merged_request(struct request_queue *, struct request *,
enum elv_merge);
extern void elv_bio_merged(struct request_queue *q, struct request *,
struct bio *);
extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
extern void elv_requeue_request(struct request_queue *, struct request *);
extern struct request *elv_former_request(struct request_queue *, struct request *);
extern struct request *elv_latter_request(struct request_queue *, struct request *);
extern int elv_register_queue(struct request_queue *q);
extern void elv_unregister_queue(struct request_queue *q);
extern int elv_may_queue(struct request_queue *, unsigned int);
extern void elv_completed_request(struct request_queue *, struct request *);
extern int elv_set_request(struct request_queue *q, struct request *rq,
struct bio *bio, gfp_t gfp_mask);
extern void elv_put_request(struct request_queue *, struct request *);
extern void elv_drain_elevator(struct request_queue *);
/*
* io scheduler registration
*/
extern void __init load_default_elevator_module(void);
extern int elv_register(struct elevator_type *);
extern void elv_unregister(struct elevator_type *);
/*
* io scheduler sysfs switching
*/
extern ssize_t elv_iosched_show(struct request_queue *, char *);
extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
extern int elevator_init(struct request_queue *, char *);
extern void elevator_exit(struct request_queue *, struct elevator_queue *);
extern int elevator_change(struct request_queue *, const char *);
extern bool elv_bio_merge_ok(struct request *, struct bio *);
extern struct elevator_queue *elevator_alloc(struct request_queue *,
struct elevator_type *);
/*
* Helper functions.
*/
extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
/*
* rb support functions.
*/
extern void elv_rb_add(struct rb_root *, struct request *);
extern void elv_rb_del(struct rb_root *, struct request *);
extern struct request *elv_rb_find(struct rb_root *, sector_t);
/*
* Insertion selection
*/
#define ELEVATOR_INSERT_FRONT 1
#define ELEVATOR_INSERT_BACK 2
#define ELEVATOR_INSERT_SORT 3
#define ELEVATOR_INSERT_REQUEUE 4
#define ELEVATOR_INSERT_FLUSH 5
#define ELEVATOR_INSERT_SORT_MERGE 6
/*
* return values from elevator_may_queue_fn
*/
enum {
ELV_MQUEUE_MAY,
ELV_MQUEUE_NO,
ELV_MQUEUE_MUST,
};
#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
#else /* CONFIG_BLOCK */
static inline void load_default_elevator_module(void) { }
#endif /* CONFIG_BLOCK */
#endif
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