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
   9 /*
  10  * Ok, this is an expanded form so that we can use the same
  11  * request for paging requests when that is implemented. In
  12  * paging, 'bh' is NULL, and the semaphore is used to wait
  13  * for read/write completion.
  14  */
  15 struct request {
  16         volatile int rq_status; /* should split this into a few status bits */
  17 #define RQ_INACTIVE             (-1)
  18 #define RQ_ACTIVE               1
  19 #define RQ_SCSI_BUSY            0xffff
  20 #define RQ_SCSI_DONE            0xfffe
  21 #define RQ_SCSI_DISCONNECTING   0xffe0
  22
  23         kdev_t rq_dev;
  24         int cmd;                /* READ or WRITE */
  25         int errors;
  26         unsigned long sector;
  27         unsigned long nr_sectors;
  28         unsigned long nr_segments;
  29         unsigned long current_nr_sectors;
  30         char * buffer;
  31         struct semaphore * sem;
  32         struct buffer_head * bh;
  33         struct buffer_head * bhtail;
  34         struct request * next;
  35 };
  36
  37 typedef void (request_fn_proc) (void);
  38 typedef struct request ** (queue_proc) (kdev_t dev);
  39
  40 struct blk_dev_struct {
  41         request_fn_proc         *request_fn;
  42         /*
  43          * queue_proc has to be atomic
  44          */
  45         queue_proc              *queue;
  46         void                    *data;
  47         struct request          *current_request;
  48         struct request   plug;
  49         struct tq_struct plug_tq;
  50 };
  51
  52 struct sec_size {
  53         unsigned block_size;
  54         unsigned block_size_bits;
  55 };
  56
  57 extern struct sec_size * blk_sec[MAX_BLKDEV];
  58 extern struct blk_dev_struct blk_dev[MAX_BLKDEV];
  59 extern wait_queue_head_t wait_for_request;
  60 extern void resetup_one_dev(struct gendisk *dev, int drive);
  61 extern void unplug_device(void * data);
  62 extern void make_request(int major,int rw, struct buffer_head * bh);
  63
  64 /* md needs this function to remap requests */
  65 extern int md_map (int minor, kdev_t *rdev, unsigned long *rsector, unsigned long size);
  66 extern int md_make_request (int minor, int rw, struct buffer_head * bh);
  67 extern int md_error (kdev_t mddev, kdev_t rdev);
  68
  69 extern int * blk_size[MAX_BLKDEV];
  70
  71 extern int * blksize_size[MAX_BLKDEV];
  72
  73 extern int * hardsect_size[MAX_BLKDEV];
  74
  75 extern int * max_readahead[MAX_BLKDEV];
  76
  77 extern int * max_sectors[MAX_BLKDEV];
  78
  79 extern int * max_segments[MAX_BLKDEV];
  80
  81 #define MAX_SECTORS 128
  82
  83 #define MAX_SEGMENTS MAX_SECTORS
  84
  85 #define PageAlignSize(size) (((size) + PAGE_SIZE -1) & PAGE_MASK)
  86 #if 0  /* small readahead */
  87 #define MAX_READAHEAD PageAlignSize(4096*7)
  88 #define MIN_READAHEAD PageAlignSize(4096*2)
  89 #else /* large readahead */
  90 #define MAX_READAHEAD PageAlignSize(4096*31)
  91 #define MIN_READAHEAD PageAlignSize(4096*3)
  92 #endif
  93
  94 #endif