include/linux/blkdev.h

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