root/drivers/block/blk.h

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INCLUDED FROM


DEFINITIONS

This source file includes following definitions.
  1. end_request

   1 #ifndef _BLK_H
   2 #define _BLK_H
   3 
   4 #include <linux/major.h>
   5 #include <linux/sched.h>
   6 #include <linux/locks.h>
   7 #include <linux/genhd.h>
   8 
   9 /*
  10  * NR_REQUEST is the number of entries in the request-queue.
  11  * NOTE that writes may use only the low 2/3 of these: reads
  12  * take precedence.
  13  *
  14  * 32 seems to be a reasonable number: enough to get some benefit
  15  * from the elevator-mechanism, but not so much as to lock a lot of
  16  * buffers when they are in the queue. 64 seems to be too many (easily
  17  * long pauses in reading when heavy writing/syncing is going on)
  18  */
  19 #define NR_REQUEST      64
  20 
  21 /*
  22  * Ok, this is an expanded form so that we can use the same
  23  * request for paging requests when that is implemented. In
  24  * paging, 'bh' is NULL, and 'waiting' is used to wait for
  25  * read/write completion.
  26  */
  27 struct request {
  28         int dev;                /* -1 if no request */
  29         int cmd;                /* READ or WRITE */
  30         int errors;
  31         unsigned long sector;
  32         unsigned long nr_sectors;
  33         unsigned long current_nr_sectors;
  34         char * buffer;
  35         struct task_struct * waiting;
  36         struct buffer_head * bh;
  37         struct buffer_head * bhtail;
  38         struct request * next;
  39 };
  40 
  41 /*
  42  * This is used in the elevator algorithm: Note that
  43  * reads always go before writes. This is natural: reads
  44  * are much more time-critical than writes.
  45  *
  46  * Update: trying with writes being preferred due to test
  47  * by Alessandro Rubini..
  48  */
  49 #define IN_ORDER(s1,s2) \
  50 ((s1)->cmd > (s2)->cmd || ((s1)->cmd == (s2)->cmd && \
  51 ((s1)->dev < (s2)->dev || (((s1)->dev == (s2)->dev && \
  52 (s1)->sector < (s2)->sector)))))
  53 
  54 struct blk_dev_struct {
  55         void (*request_fn)(void);
  56         struct request * current_request;
  57 };
  58 
  59 
  60 struct sec_size {
  61         unsigned block_size;
  62         unsigned block_size_bits;
  63 };
  64 
  65 /*
  66  * These will have to be changed to be aware of different buffer
  67  * sizes etc.. It actually needs a major cleanup.
  68  */
  69 #define SECTOR_MASK (blksize_size[MAJOR_NR] &&     \
  70         blksize_size[MAJOR_NR][MINOR(CURRENT->dev)] ? \
  71         ((blksize_size[MAJOR_NR][MINOR(CURRENT->dev)] >> 9) - 1) :  \
  72         ((BLOCK_SIZE >> 9)  -  1))
  73 
  74 #define SUBSECTOR(block) (CURRENT->current_nr_sectors > 0)
  75 
  76 extern struct sec_size * blk_sec[MAX_BLKDEV];
  77 extern struct blk_dev_struct blk_dev[MAX_BLKDEV];
  78 extern struct wait_queue * wait_for_request;
  79 extern void resetup_one_dev(struct gendisk *dev, int drive);
  80 
  81 extern int * blk_size[MAX_BLKDEV];
  82 
  83 extern int * blksize_size[MAX_BLKDEV];
  84 
  85 extern unsigned long hd_init(unsigned long mem_start, unsigned long mem_end);
  86 extern unsigned long cdu31a_init(unsigned long mem_start, unsigned long mem_end);
  87 extern unsigned long mcd_init(unsigned long mem_start, unsigned long mem_end);
  88 extern int is_read_only(int dev);
  89 extern void set_device_ro(int dev,int flag);
  90 
  91 extern void rd_load(void);
  92 extern long rd_init(long mem_start, int length);
  93 extern int ramdisk_size;
  94 
  95 extern unsigned long xd_init(unsigned long mem_start, unsigned long mem_end);
  96 
  97 #define RO_IOCTLS(dev,where) \
  98   case BLKROSET: if (!suser()) return -EPERM; \
  99                  set_device_ro((dev),get_fs_long((long *) (where))); return 0; \
 100   case BLKROGET: { int __err = verify_area(VERIFY_WRITE, (void *) (where), sizeof(long)); \
 101                    if (!__err) put_fs_long(is_read_only(dev),(long *) (where)); return __err; }
 102                  
 103 #ifdef MAJOR_NR
 104 
 105 /*
 106  * Add entries as needed. Currently the only block devices
 107  * supported are hard-disks and floppies.
 108  */
 109 
 110 #if (MAJOR_NR == MEM_MAJOR)
 111 
 112 /* ram disk */
 113 #define DEVICE_NAME "ramdisk"
 114 #define DEVICE_REQUEST do_rd_request
 115 #define DEVICE_NR(device) ((device) & 7)
 116 #define DEVICE_ON(device) 
 117 #define DEVICE_OFF(device)
 118 
 119 #elif (MAJOR_NR == FLOPPY_MAJOR)
 120 
 121 static void floppy_on(unsigned int nr);
 122 static void floppy_off(unsigned int nr);
 123 
 124 #define DEVICE_NAME "floppy"
 125 #define DEVICE_INTR do_floppy
 126 #define DEVICE_REQUEST do_fd_request
 127 #define DEVICE_NR(device) ((device) & 3)
 128 #define DEVICE_ON(device) floppy_on(DEVICE_NR(device))
 129 #define DEVICE_OFF(device) floppy_off(DEVICE_NR(device))
 130 
 131 #elif (MAJOR_NR == HD_MAJOR)
 132 
 133 /* harddisk: timeout is 6 seconds.. */
 134 #define DEVICE_NAME "harddisk"
 135 #define DEVICE_INTR do_hd
 136 #define DEVICE_TIMEOUT HD_TIMER
 137 #define TIMEOUT_VALUE 600
 138 #define DEVICE_REQUEST do_hd_request
 139 #define DEVICE_NR(device) (MINOR(device)>>6)
 140 #define DEVICE_ON(device)
 141 #define DEVICE_OFF(device)
 142 
 143 #elif (MAJOR_NR == SCSI_DISK_MAJOR)
 144 
 145 #define DEVICE_NAME "scsidisk"
 146 #define DEVICE_INTR do_sd  
 147 #define TIMEOUT_VALUE 200
 148 #define DEVICE_REQUEST do_sd_request
 149 #define DEVICE_NR(device) (MINOR(device) >> 4)
 150 #define DEVICE_ON(device)
 151 #define DEVICE_OFF(device)
 152 
 153 #elif (MAJOR_NR == SCSI_TAPE_MAJOR)
 154 
 155 #define DEVICE_NAME "scsitape"
 156 #define DEVICE_INTR do_st  
 157 #define DEVICE_NR(device) (MINOR(device))
 158 #define DEVICE_ON(device)
 159 #define DEVICE_OFF(device)
 160 
 161 #elif (MAJOR_NR == SCSI_CDROM_MAJOR)
 162 
 163 #define DEVICE_NAME "CD-ROM"
 164 #define DEVICE_INTR do_sr
 165 #define DEVICE_REQUEST do_sr_request
 166 #define DEVICE_NR(device) (MINOR(device))
 167 #define DEVICE_ON(device)
 168 #define DEVICE_OFF(device)
 169 
 170 #elif (MAJOR_NR == XT_DISK_MAJOR)
 171 
 172 #define DEVICE_NAME "xt disk"
 173 #define DEVICE_REQUEST do_xd_request
 174 #define DEVICE_NR(device) (MINOR(device) >> 6)
 175 #define DEVICE_ON(device)
 176 #define DEVICE_OFF(device)
 177 
 178 #elif (MAJOR_NR == CDU31A_CDROM_MAJOR)
 179 
 180 #define DEVICE_NAME "CDU31A"
 181 #define DEVICE_REQUEST do_cdu31a_request
 182 #define DEVICE_NR(device) (MINOR(device))
 183 #define DEVICE_ON(device)
 184 #define DEVICE_OFF(device)
 185 
 186 #elif (MAJOR_NR == MITSUMI_CDROM_MAJOR)
 187 
 188 #define DEVICE_NAME "Mitsumi CD-ROM"
 189 /* #define DEVICE_INTR do_mcd */
 190 #define DEVICE_REQUEST do_mcd_request
 191 #define DEVICE_NR(device) (MINOR(device))
 192 #define DEVICE_ON(device)
 193 #define DEVICE_OFF(device)
 194 
 195 #elif (MAJOR_NR == MATSUSHITA_CDROM_MAJOR)
 196 
 197 #define DEVICE_NAME "Matsushita CD-ROM"
 198 #define DEVICE_REQUEST do_sbpcd_request
 199 #define DEVICE_NR(device) (MINOR(device))
 200 #define DEVICE_ON(device)
 201 #define DEVICE_OFF(device)
 202 
 203 #else
 204 
 205 #error "unknown blk device"
 206 
 207 #endif
 208 
 209 #if (MAJOR_NR != SCSI_TAPE_MAJOR)
 210 
 211 #ifndef CURRENT
 212 #define CURRENT (blk_dev[MAJOR_NR].current_request)
 213 #endif
 214 
 215 #define CURRENT_DEV DEVICE_NR(CURRENT->dev)
 216 
 217 #ifdef DEVICE_INTR
 218 void (*DEVICE_INTR)(void) = NULL;
 219 #endif
 220 #ifdef DEVICE_TIMEOUT
 221 
 222 #define SET_TIMER \
 223 ((timer_table[DEVICE_TIMEOUT].expires = jiffies + TIMEOUT_VALUE), \
 224 (timer_active |= 1<<DEVICE_TIMEOUT))
 225 
 226 #define CLEAR_TIMER \
 227 timer_active &= ~(1<<DEVICE_TIMEOUT)
 228 
 229 #define SET_INTR(x) \
 230 if ((DEVICE_INTR = (x)) != NULL) \
 231         SET_TIMER; \
 232 else \
 233         CLEAR_TIMER;
 234 
 235 #else
 236 
 237 #define SET_INTR(x) (DEVICE_INTR = (x))
 238 
 239 #endif
 240 static void (DEVICE_REQUEST)(void);
 241 
 242 /* end_request() - SCSI devices have their own version */
 243 
 244 #if ! SCSI_MAJOR(MAJOR_NR)
 245 
 246 static void end_request(int uptodate)
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 247 {
 248         struct request * req;
 249         struct buffer_head * bh;
 250         struct task_struct * p;
 251 
 252         req = CURRENT;
 253         req->errors = 0;
 254         if (!uptodate) {
 255                 printk(DEVICE_NAME " I/O error\n");
 256                 printk("dev %04lX, sector %lu\n",
 257                        (unsigned long)req->dev, req->sector);
 258                 req->nr_sectors--;
 259                 req->nr_sectors &= ~SECTOR_MASK;
 260                 req->sector += (BLOCK_SIZE / 512);
 261                 req->sector &= ~SECTOR_MASK;            
 262         }
 263 
 264         if ((bh = req->bh) != NULL) {
 265                 req->bh = bh->b_reqnext;
 266                 bh->b_reqnext = NULL;
 267                 bh->b_uptodate = uptodate;
 268                 unlock_buffer(bh);
 269                 if ((bh = req->bh) != NULL) {
 270                         req->current_nr_sectors = bh->b_size >> 9;
 271                         if (req->nr_sectors < req->current_nr_sectors) {
 272                                 req->nr_sectors = req->current_nr_sectors;
 273                                 printk("end_request: buffer-list destroyed\n");
 274                         }
 275                         req->buffer = bh->b_data;
 276                         return;
 277                 }
 278         }
 279         DEVICE_OFF(req->dev);
 280         CURRENT = req->next;
 281         if ((p = req->waiting) != NULL) {
 282                 req->waiting = NULL;
 283                 p->state = TASK_RUNNING;
 284                 if (p->counter > current->counter)
 285                         need_resched = 1;
 286         }
 287         req->dev = -1;
 288         wake_up(&wait_for_request);
 289 }
 290 #endif
 291 
 292 #ifdef DEVICE_INTR
 293 #define CLEAR_INTR SET_INTR(NULL)
 294 #else
 295 #define CLEAR_INTR
 296 #endif
 297 
 298 #define INIT_REQUEST \
 299         if (!CURRENT) {\
 300                 CLEAR_INTR; \
 301                 return; \
 302         } \
 303         if (MAJOR(CURRENT->dev) != MAJOR_NR) \
 304                 panic(DEVICE_NAME ": request list destroyed"); \
 305         if (CURRENT->bh) { \
 306                 if (!CURRENT->bh->b_lock) \
 307                         panic(DEVICE_NAME ": block not locked"); \
 308         }
 309 
 310 #endif
 311 
 312 #endif
 313 #endif

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