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1 #ifndef _LINUX_ELEVATOR_H |
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2 #define _LINUX_ELEVATOR_H |
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3 |
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4 #include <linux/percpu.h> |
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5 |
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6 #ifdef CONFIG_BLOCK |
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7 |
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8 typedef int (elevator_merge_fn) (struct request_queue *, struct request **, |
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9 struct bio *); |
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10 |
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11 typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *); |
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12 |
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13 typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int); |
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14 |
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15 typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *); |
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16 |
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17 typedef int (elevator_dispatch_fn) (struct request_queue *, int); |
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18 |
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19 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *); |
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20 typedef int (elevator_queue_empty_fn) (struct request_queue *); |
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21 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *); |
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22 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *); |
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23 typedef int (elevator_may_queue_fn) (struct request_queue *, int); |
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24 |
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25 typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t); |
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26 typedef void (elevator_put_req_fn) (struct request *); |
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27 typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *); |
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28 typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *); |
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29 |
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30 typedef void *(elevator_init_fn) (struct request_queue *); |
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31 typedef void (elevator_exit_fn) (elevator_t *); |
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32 |
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33 struct elevator_ops |
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34 { |
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35 elevator_merge_fn *elevator_merge_fn; |
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36 elevator_merged_fn *elevator_merged_fn; |
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37 elevator_merge_req_fn *elevator_merge_req_fn; |
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38 elevator_allow_merge_fn *elevator_allow_merge_fn; |
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39 |
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40 elevator_dispatch_fn *elevator_dispatch_fn; |
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41 elevator_add_req_fn *elevator_add_req_fn; |
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42 elevator_activate_req_fn *elevator_activate_req_fn; |
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43 elevator_deactivate_req_fn *elevator_deactivate_req_fn; |
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44 |
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45 elevator_queue_empty_fn *elevator_queue_empty_fn; |
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46 elevator_completed_req_fn *elevator_completed_req_fn; |
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47 |
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48 elevator_request_list_fn *elevator_former_req_fn; |
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49 elevator_request_list_fn *elevator_latter_req_fn; |
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50 |
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51 elevator_set_req_fn *elevator_set_req_fn; |
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52 elevator_put_req_fn *elevator_put_req_fn; |
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53 |
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54 elevator_may_queue_fn *elevator_may_queue_fn; |
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55 |
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56 elevator_init_fn *elevator_init_fn; |
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57 elevator_exit_fn *elevator_exit_fn; |
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58 void (*trim)(struct io_context *); |
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59 }; |
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60 |
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61 #define ELV_NAME_MAX (16) |
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62 |
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63 struct elv_fs_entry { |
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64 struct attribute attr; |
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65 ssize_t (*show)(elevator_t *, char *); |
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66 ssize_t (*store)(elevator_t *, const char *, size_t); |
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67 }; |
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68 |
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69 /* |
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70 * identifies an elevator type, such as AS or deadline |
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71 */ |
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72 struct elevator_type |
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73 { |
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74 struct list_head list; |
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75 struct elevator_ops ops; |
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76 struct elv_fs_entry *elevator_attrs; |
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77 char elevator_name[ELV_NAME_MAX]; |
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78 struct module *elevator_owner; |
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79 }; |
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80 |
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81 /* |
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82 * each queue has an elevator_queue associated with it |
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83 */ |
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84 struct elevator_queue |
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85 { |
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86 struct elevator_ops *ops; |
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87 void *elevator_data; |
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88 struct kobject kobj; |
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89 struct elevator_type *elevator_type; |
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90 struct mutex sysfs_lock; |
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91 struct hlist_head *hash; |
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92 }; |
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93 |
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94 /* |
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95 * block elevator interface |
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96 */ |
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97 extern void elv_dispatch_sort(struct request_queue *, struct request *); |
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98 extern void elv_dispatch_add_tail(struct request_queue *, struct request *); |
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99 extern void elv_add_request(struct request_queue *, struct request *, int, int); |
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100 extern void __elv_add_request(struct request_queue *, struct request *, int, int); |
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101 extern void elv_insert(struct request_queue *, struct request *, int); |
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102 extern int elv_merge(struct request_queue *, struct request **, struct bio *); |
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103 extern void elv_merge_requests(struct request_queue *, struct request *, |
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104 struct request *); |
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105 extern void elv_merged_request(struct request_queue *, struct request *, int); |
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106 extern void elv_dequeue_request(struct request_queue *, struct request *); |
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107 extern void elv_requeue_request(struct request_queue *, struct request *); |
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108 extern int elv_queue_empty(struct request_queue *); |
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109 extern struct request *elv_next_request(struct request_queue *q); |
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110 extern struct request *elv_former_request(struct request_queue *, struct request *); |
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111 extern struct request *elv_latter_request(struct request_queue *, struct request *); |
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112 extern int elv_register_queue(struct request_queue *q); |
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113 extern void elv_unregister_queue(struct request_queue *q); |
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114 extern int elv_may_queue(struct request_queue *, int); |
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115 extern void elv_abort_queue(struct request_queue *); |
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116 extern void elv_completed_request(struct request_queue *, struct request *); |
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117 extern int elv_set_request(struct request_queue *, struct request *, gfp_t); |
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118 extern void elv_put_request(struct request_queue *, struct request *); |
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119 |
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120 /* |
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121 * io scheduler registration |
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122 */ |
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123 extern void elv_register(struct elevator_type *); |
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124 extern void elv_unregister(struct elevator_type *); |
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125 |
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126 /* |
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127 * io scheduler sysfs switching |
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128 */ |
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129 extern ssize_t elv_iosched_show(struct request_queue *, char *); |
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130 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t); |
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131 |
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132 extern int elevator_init(struct request_queue *, char *); |
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133 extern void elevator_exit(elevator_t *); |
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134 extern int elv_rq_merge_ok(struct request *, struct bio *); |
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135 |
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136 /* |
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137 * Helper functions. |
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138 */ |
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139 extern struct request *elv_rb_former_request(struct request_queue *, struct request *); |
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140 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *); |
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141 |
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142 /* |
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143 * rb support functions. |
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144 */ |
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145 extern struct request *elv_rb_add(struct rb_root *, struct request *); |
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146 extern void elv_rb_del(struct rb_root *, struct request *); |
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147 extern struct request *elv_rb_find(struct rb_root *, sector_t); |
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148 |
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149 /* |
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150 * Return values from elevator merger |
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151 */ |
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152 #define ELEVATOR_NO_MERGE 0 |
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153 #define ELEVATOR_FRONT_MERGE 1 |
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154 #define ELEVATOR_BACK_MERGE 2 |
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155 |
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156 /* |
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157 * Insertion selection |
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158 */ |
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159 #define ELEVATOR_INSERT_FRONT 1 |
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160 #define ELEVATOR_INSERT_BACK 2 |
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161 #define ELEVATOR_INSERT_SORT 3 |
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162 #define ELEVATOR_INSERT_REQUEUE 4 |
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163 |
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164 /* |
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165 * return values from elevator_may_queue_fn |
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166 */ |
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167 enum { |
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168 ELV_MQUEUE_MAY, |
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169 ELV_MQUEUE_NO, |
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170 ELV_MQUEUE_MUST, |
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171 }; |
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172 |
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173 #define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors) |
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174 #define rb_entry_rq(node) rb_entry((node), struct request, rb_node) |
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175 |
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176 /* |
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177 * Hack to reuse the csd.list list_head as the fifo time holder while |
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178 * the request is in the io scheduler. Saves an unsigned long in rq. |
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179 */ |
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180 #define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next) |
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181 #define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp)) |
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182 #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) |
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183 #define rq_fifo_clear(rq) do { \ |
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184 list_del_init(&(rq)->queuelist); \ |
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185 INIT_LIST_HEAD(&(rq)->csd.list); \ |
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186 } while (0) |
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187 |
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188 /* |
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189 * io context count accounting |
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190 */ |
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191 #define elv_ioc_count_mod(name, __val) \ |
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192 do { \ |
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193 preempt_disable(); \ |
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194 __get_cpu_var(name) += (__val); \ |
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195 preempt_enable(); \ |
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196 } while (0) |
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197 |
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198 #define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1) |
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199 #define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1) |
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200 |
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201 #define elv_ioc_count_read(name) \ |
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202 ({ \ |
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203 unsigned long __val = 0; \ |
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204 int __cpu; \ |
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205 smp_wmb(); \ |
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206 for_each_possible_cpu(__cpu) \ |
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207 __val += per_cpu(name, __cpu); \ |
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208 __val; \ |
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209 }) |
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210 |
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211 #endif /* CONFIG_BLOCK */ |
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212 #endif |