kernel/blk_drv/blk.h

/* */
This source file includes following definitions.
unlock_buffer
end_request
   1 #ifndef _BLK_H
   2 #define _BLK_H
   3 
   4 #define NR_BLK_DEV      7
   5 /*
   6  * NR_REQUEST is the number of entries in the request-queue.
   7  * NOTE that writes may use only the low 2/3 of these: reads
   8  * take precedence.
   9  *
  10  * 32 seems to be a reasonable number: enough to get some benefit
  11  * from the elevator-mechanism, but not so much as to lock a lot of
  12  * buffers when they are in the queue. 64 seems to be too many (easily
  13  * long pauses in reading when heavy writing/syncing is going on)
  14  */
  15 #define NR_REQUEST      32
  16 
  17 /*
  18  * Ok, this is an expanded form so that we can use the same
  19  * request for paging requests when that is implemented. In
  20  * paging, 'bh' is NULL, and 'waiting' is used to wait for
  21  * read/write completion.
  22  */
  23 struct request {
  24         int dev;                /* -1 if no request */
  25         int cmd;                /* READ or WRITE */
  26         int errors;
  27         unsigned long sector;
  28         unsigned long nr_sectors;
  29         char * buffer;
  30         struct task_struct * waiting;
  31         struct buffer_head * bh;
  32         struct request * next;
  33 };
  34 
  35 /*
  36  * This is used in the elevator algorithm: Note that
  37  * reads always go before writes. This is natural: reads
  38  * are much more time-critical than writes.
  39  */
  40 #define IN_ORDER(s1,s2) \
  41 ((s1)->cmd<(s2)->cmd || (s1)->cmd==(s2)->cmd && \
  42 ((s1)->dev < (s2)->dev || ((s1)->dev == (s2)->dev && \
  43 (s1)->sector < (s2)->sector)))
  44 
  45 struct blk_dev_struct {
  46         void (*request_fn)(void);
  47         struct request * current_request;
  48 };
  49 
  50 extern struct blk_dev_struct blk_dev[NR_BLK_DEV];
  51 extern struct request request[NR_REQUEST];
  52 extern struct task_struct * wait_for_request;
  53 
  54 #ifdef MAJOR_NR
  55 
  56 /*
  57  * Add entries as needed. Currently the only block devices
  58  * supported are hard-disks and floppies.
  59  */
  60 
  61 #if (MAJOR_NR == 1)
  62 /* ram disk */
  63 #define DEVICE_NAME "ramdisk"
  64 #define DEVICE_REQUEST do_rd_request
  65 #define DEVICE_NR(device) ((device) & 7)
  66 #define DEVICE_ON(device) 
  67 #define DEVICE_OFF(device)
  68 
  69 #elif (MAJOR_NR == 2)
  70 /* floppy */
  71 #define DEVICE_NAME "floppy"
  72 #define DEVICE_INTR do_floppy
  73 #define DEVICE_REQUEST do_fd_request
  74 #define DEVICE_NR(device) ((device) & 3)
  75 #define DEVICE_ON(device) floppy_on(DEVICE_NR(device))
  76 #define DEVICE_OFF(device) floppy_off(DEVICE_NR(device))
  77 
  78 #elif (MAJOR_NR == 3)
  79 /* harddisk */
  80 #define DEVICE_NAME "harddisk"
  81 #define DEVICE_INTR do_hd
  82 #define DEVICE_REQUEST do_hd_request
  83 #define DEVICE_NR(device) (MINOR(device)/5)
  84 #define DEVICE_ON(device)
  85 #define DEVICE_OFF(device)
  86 
  87 #elif
  88 /* unknown blk device */
  89 #error "unknown blk device"
  90 
  91 #endif
  92 
  93 #define CURRENT (blk_dev[MAJOR_NR].current_request)
  94 #define CURRENT_DEV DEVICE_NR(CURRENT->dev)
  95 
  96 #ifdef DEVICE_INTR
  97 void (*DEVICE_INTR)(void) = NULL;
  98 #endif
  99 static void (DEVICE_REQUEST)(void);
 100 
 101 extern inline void unlock_buffer(struct buffer_head * bh)
     /*  */
 102 {
 103         if (!bh->b_lock)
 104                 printk(DEVICE_NAME ": free buffer being unlocked\n");
 105         bh->b_lock=0;
 106         wake_up(&bh->b_wait);
 107 }
 108 
 109 extern inline void end_request(int uptodate)
     /*  */
 110 {
 111         DEVICE_OFF(CURRENT->dev);
 112         if (CURRENT->bh) {
 113                 CURRENT->bh->b_uptodate = uptodate;
 114                 unlock_buffer(CURRENT->bh);
 115         }
 116         if (!uptodate) {
 117                 printk(DEVICE_NAME " I/O error\n\r");
 118                 printk("dev %04x, block %d\n\r",CURRENT->dev,
 119                         CURRENT->bh->b_blocknr);
 120         }
 121         wake_up(&CURRENT->waiting);
 122         wake_up(&wait_for_request);
 123         CURRENT->dev = -1;
 124         CURRENT = CURRENT->next;
 125 }
 126 
 127 #define INIT_REQUEST \
 128 repeat: \
 129         if (!CURRENT) \
 130                 return; \
 131         if (MAJOR(CURRENT->dev) != MAJOR_NR) \
 132                 panic(DEVICE_NAME ": request list destroyed"); \
 133         if (CURRENT->bh) { \
 134                 if (!CURRENT->bh->b_lock) \
 135                         panic(DEVICE_NAME ": block not locked"); \
 136         }
 137 
 138 #endif
 139 
 140 #endif
/* */
root/kernel/blk_drv/blk.h

INCLUDED FROM

DEFINITIONS
