1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
#ifndef _LINUX_BLKDEV_H
#define _LINUX_BLKDEV_H
#include <linux/major.h>
#include <linux/sched.h>
#include <linux/genhd.h>
#include <linux/tqueue.h>
#include <linux/list.h>
struct request_queue;
typedef struct request_queue request_queue_t;
struct elevator_s;
typedef struct elevator_s elevator_t;
/*
* Ok, this is an expanded form so that we can use the same
* request for paging requests when that is implemented. In
* paging, 'bh' is NULL, and the semaphore is used to wait
* for read/write completion.
*/
struct request {
struct list_head queue;
int elevator_sequence;
struct list_head table;
struct list_head *free_list;
volatile int rq_status; /* should split this into a few status bits */
#define RQ_INACTIVE (-1)
#define RQ_ACTIVE 1
#define RQ_SCSI_BUSY 0xffff
#define RQ_SCSI_DONE 0xfffe
#define RQ_SCSI_DISCONNECTING 0xffe0
kdev_t rq_dev;
int cmd; /* READ or WRITE */
int errors;
unsigned long sector;
unsigned long nr_sectors;
unsigned long hard_sector, hard_nr_sectors;
unsigned int nr_segments;
unsigned int nr_hw_segments;
unsigned long current_nr_sectors;
void * special;
char * buffer;
struct semaphore * sem;
struct buffer_head * bh;
struct buffer_head * bhtail;
request_queue_t *q;
elevator_t *e;
};
#include <linux/elevator.h>
typedef int (merge_request_fn) (request_queue_t *q,
struct request *req,
struct buffer_head *bh,
int);
typedef int (merge_requests_fn) (request_queue_t *q,
struct request *req,
struct request *req2,
int);
typedef void (request_fn_proc) (request_queue_t *q);
typedef request_queue_t * (queue_proc) (kdev_t dev);
typedef int (make_request_fn) (request_queue_t *q, int rw, struct buffer_head *bh);
typedef void (plug_device_fn) (request_queue_t *q, kdev_t device);
typedef void (unplug_device_fn) (void *q);
/*
* Default nr free requests per queue
*/
#define QUEUE_NR_REQUESTS 256
struct request_queue
{
/*
* the queue request freelist, one for reads and one for writes
*/
struct list_head request_freelist[2];
/*
* Together with queue_head for cacheline sharing
*/
struct list_head queue_head;
elevator_t elevator;
request_fn_proc * request_fn;
merge_request_fn * back_merge_fn;
merge_request_fn * front_merge_fn;
merge_requests_fn * merge_requests_fn;
make_request_fn * make_request_fn;
plug_device_fn * plug_device_fn;
/*
* The queue owner gets to use this for whatever they like.
* ll_rw_blk doesn't touch it.
*/
void * queuedata;
/*
* This is used to remove the plug when tq_disk runs.
*/
struct tq_struct plug_tq;
/*
* Boolean that indicates whether this queue is plugged or not.
*/
char plugged;
/*
* Boolean that indicates whether current_request is active or
* not.
*/
char head_active;
/*
* Is meant to protect the queue in the future instead of
* io_request_lock
*/
spinlock_t request_lock;
/*
* Tasks wait here for free request
*/
wait_queue_head_t wait_for_request;
};
struct blk_dev_struct {
/*
* queue_proc has to be atomic
*/
request_queue_t request_queue;
queue_proc *queue;
void *data;
};
struct sec_size {
unsigned block_size;
unsigned block_size_bits;
};
/*
* Used to indicate the default queue for drivers that don't bother
* to implement multiple queues. We have this access macro here
* so as to eliminate the need for each and every block device
* driver to know about the internal structure of blk_dev[].
*/
#define BLK_DEFAULT_QUEUE(_MAJOR) &blk_dev[_MAJOR].request_queue
extern struct sec_size * blk_sec[MAX_BLKDEV];
extern struct blk_dev_struct blk_dev[MAX_BLKDEV];
extern void grok_partitions(struct gendisk *dev, int drive, unsigned minors, long size);
extern void register_disk(struct gendisk *dev, kdev_t first, unsigned minors, struct block_device_operations *ops, long size);
extern void generic_make_request(request_queue_t *q, int rw,
struct buffer_head * bh);
extern request_queue_t *blk_get_queue(kdev_t dev);
extern void blkdev_release_request(struct request *);
/*
* Access functions for manipulating queue properties
*/
extern void blk_init_queue(request_queue_t *, request_fn_proc *);
extern void blk_cleanup_queue(request_queue_t *);
extern void blk_queue_headactive(request_queue_t *, int);
extern void blk_queue_pluggable(request_queue_t *, plug_device_fn *);
extern void blk_queue_make_request(request_queue_t *, make_request_fn *);
extern int * blk_size[MAX_BLKDEV];
extern int * blksize_size[MAX_BLKDEV];
extern int * hardsect_size[MAX_BLKDEV];
extern int * max_readahead[MAX_BLKDEV];
extern int * max_sectors[MAX_BLKDEV];
extern int * max_segments[MAX_BLKDEV];
#define MAX_SECTORS 254
#define MAX_SEGMENTS MAX_SECTORS
#define PageAlignSize(size) (((size) + PAGE_SIZE -1) & PAGE_MASK)
/* read-ahead in pages.. */
#define MAX_READAHEAD 31
#define MIN_READAHEAD 3
#define blkdev_entry_to_request(entry) list_entry((entry), struct request, queue)
#define blkdev_entry_next_request(entry) blkdev_entry_to_request((entry)->next)
#define blkdev_entry_prev_request(entry) blkdev_entry_to_request((entry)->prev)
#define blkdev_next_request(req) blkdev_entry_to_request((req)->queue.next)
#define blkdev_prev_request(req) blkdev_entry_to_request((req)->queue.prev)
extern void drive_stat_acct (kdev_t dev, int rw,
unsigned long nr_sectors, int new_io);
static inline int get_hardsect_size(kdev_t dev)
{
extern int *hardsect_size[];
if (hardsect_size[MAJOR(dev)] != NULL)
return hardsect_size[MAJOR(dev)][MINOR(dev)];
else
return 512;
}
#endif
|
