linux - Why is the kernel using the default block driver instead of my driver's code? -


I wrote a block driver program that creates a dummy block device ( sbd0 ). I registered all device operations for that block device: (see include / linux / blkdev.h in the 2.6.32 kernel source) 

  static structure block_device_operations sbd_ops = {.owner = THIS_MODULE, .open = sbd_open, .octl = sbd_ioctl, .getgeo = sbd_getgeo, .locked_ioctl = sbd_locked_ioctl, .compat_ioctl = sbd_compat_ioctl, .direct_access = sbd_direct_access, .media_changed = sbd_media_changed, .revalidate_disk = sbd_revalidate_disk};   
 I compiled the driver program, I put the module and created the  / dev / sbd0 . Now I want to test my driver code. So I wrote an application below.  
  fd = open ("/ dev / sbd0", O_RDONLY); Retvl = IOCLL (FD, BLKBSZ, and Blocks); Trying to get the logical block size   
 Output is:  4096   
 I'm surprised: I did not have the  For ioctl has not implemented BLKBSZGET . This did not implement my  sbd_ioctl , instead it used the default driver and gave me results. It has been executed for  open ,  off  calls  sbd_open  and  sbd_close  (which I have applied). And then I tried:  
  retval = ioctl (fd, hdio_getGEO, and geoinfo);   
 has implemented this  sbd_getgeo  but I thought it would call  sbd_ioctl .  
 These are my questions:  
     
  1.  I implemented a driver and made a device. If I do any work on that device, then he has to invite my driver's application. But how does it use some of my driver's actions and some default driver functions?  
  2.   ioctl (fd, hdio_getGEO, ..)   did not invoke. .ctl call , but it has been applied to  .getgeo . How is this possible?    
     
     
      ioctl  sending is handled  blkdev_ioctl By the  function, which will process directly on some ioctls without calling a specific routine of your driver.  
      for HDIO_GETGEO , it calls your driver  getgeo  function directly (3.13.6 from kernel, much later than 2.6.32 Change does not appear):  
      [...] / * * First we need to set startect, driver * wants to override it. * / Mameset (and ground, 0, size (ground)); Geo.start = get_start_sect (bdev); Rate = disk-> FPS-> Getgeo (BDV, and Geo);  block_size (bdev)) , which for  BLKBSZGET  and [...]   
     simply  bdev- & gt; Bd_block_size .  
     You will find the  blkdev_ioctl  in the  block / ioctl.c  if you need to know what happens to other ioctls.

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