elevator: make elevator_init_fn() return 0/-errno

[sfrench/cifs-2.6.git] / include / linux / elevator.h

diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 1d0f7a2ff73b22c0dc38a2a88a11081980e5a5be..97fb2557a18ca27ee15c0781cfae6e8e6e51adca 100644 (file)
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -5,6 +5,8 @@
 
 #ifdef CONFIG_BLOCK
 
+struct io_cq;
+
 typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
                                 struct bio *);
 
@@ -24,12 +26,14 @@ typedef struct request *(elevator_request_list_fn) (struct request_queue *, stru
 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
 typedef int (elevator_may_queue_fn) (struct request_queue *, 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 *, 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 void *(elevator_init_fn) (struct request_queue *);
+typedef int (elevator_init_fn) (struct request_queue *);
 typedef void (elevator_exit_fn) (struct elevator_queue *);
 
 struct elevator_ops
@@ -38,12 +42,6 @@ struct elevator_ops
        elevator_merged_fn *elevator_merged_fn;
        elevator_merge_req_fn *elevator_merge_req_fn;
        elevator_allow_merge_fn *elevator_allow_merge_fn;
-
-       /*
-        * Used for both plugged list and elevator merging and in the
-        * former case called without queue_lock.  Read comment on top of
-        * attempt_plug_merge() for details.
-        */
        elevator_bio_merged_fn *elevator_bio_merged_fn;
 
        elevator_dispatch_fn *elevator_dispatch_fn;
@@ -56,6 +54,9 @@ struct elevator_ops
        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;
 
@@ -63,7 +64,6 @@ struct elevator_ops
 
        elevator_init_fn *elevator_init_fn;
        elevator_exit_fn *elevator_exit_fn;
-       void (*trim)(struct io_context *);
 };
 
 #define ELV_NAME_MAX   (16)
@@ -79,11 +79,20 @@ struct elv_fs_entry {
  */
 struct elevator_type
 {
-       struct list_head list;
+       /* managed by elevator core */
+       struct kmem_cache *icq_cache;
+
+       /* fields provided by elevator implementation */
        struct elevator_ops 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;
+
+       /* managed by elevator core */
+       char icq_cache_name[ELV_NAME_MAX + 5];  /* elvname + "_io_cq" */
+       struct list_head list;
 };
 
 /*
@@ -91,10 +100,9 @@ struct elevator_type
  */
 struct elevator_queue
 {
-       struct elevator_ops *ops;
+       struct elevator_type *type;
        void *elevator_data;
        struct kobject kobj;
-       struct elevator_type *elevator_type;
        struct mutex sysfs_lock;
        struct hlist_head *hash;
        unsigned int registered:1;
@@ -108,7 +116,6 @@ 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 int elv_merge(struct request_queue *, struct request **, struct bio *);
-extern int elv_try_merge(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 *, int);
@@ -129,7 +136,7 @@ extern void elv_drain_elevator(struct request_queue *);
 /*
  * io scheduler registration
  */
-extern void elv_register(struct elevator_type *);
+extern int elv_register(struct elevator_type *);
 extern void elv_unregister(struct elevator_type *);
 
 /*
@@ -141,7 +148,7 @@ 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 elevator_queue *);
 extern int elevator_change(struct request_queue *, const char *);
-extern int elv_rq_merge_ok(struct request *, struct bio *);
+extern bool elv_rq_merge_ok(struct request *, struct bio *);
 
 /*
  * Helper functions.
@@ -197,22 +204,5 @@ enum {
        INIT_LIST_HEAD(&(rq)->csd.list);        \
        } while (0)
 
-/*
- * io context count accounting
- */
-#define elv_ioc_count_mod(name, __val) this_cpu_add(name, __val)
-#define elv_ioc_count_inc(name)        this_cpu_inc(name)
-#define elv_ioc_count_dec(name)        this_cpu_dec(name)
-
-#define elv_ioc_count_read(name)                               \
-({                                                             \
-       unsigned long __val = 0;                                \
-       int __cpu;                                              \
-       smp_wmb();                                              \
-       for_each_possible_cpu(__cpu)                            \
-               __val += per_cpu(name, __cpu);                  \
-       __val;                                                  \
-})
-
 #endif /* CONFIG_BLOCK */
 #endif