BLKRRPART bug + fix in mtd_blkdevs-24.c in mtd-snapshot-20040914.tar.bz2

["Frantisek Rysanek" <Frantisek.Rysanek@post.cz>]

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Dear Mr. Woodhouse,

I've found a bug in the functions serving the BLKRRPART 
ioctl() in the 2.4 branch of MTD blkdevs. See the attached 
patch, I believe it contains a fix.

My DiskOnChip was detected just fine, but when I flushed the 
original partition and issued a BLKRRPART, the device would 
report half its original size. If I did it again, it would
report a quarter size... etc.

Seems like the driver would re-init device size to a size 
denominated in 1k blocks, rather than sectors (512B).

Attached are two simple proggies that I'm using in my 
partitioning scripts.


Otherwise the driver seems to work just fine.
Actually I also had to insert 

#ifndef CONFIG_MTD_CFI_GEOMETRY
#define CONFIG_MTD_MAP_BANK_WIDTH_1
#endif

at the beginning of $KERNEL/include/linux/mtd/map.h

to make it compile. Seems like a dependency mismatch between 
drivers/mtd/chips/Config.in and the headers/code. I don't have 
a CFI MTD, but I do need drivers/mtd/chips/chipreg.o even for 
my DiskOnChip (now a generic NFTL device).


Thanks for the great job you're doing on MTD :-)

Frank Rysanek


[-- Attachment #2: Text from file 'mtd_blkdevs-24.c.patch' --]
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--- mtd_blkdevs-24.old.c	2004-09-16 12:51:08.000000000 +0200
+++ mtd_blkdevs-24.c	2004-09-16 12:54:38.000000000 +0200
@@ -315,7 +315,7 @@
 	}
 
 	grok_partitions(gd, minor, 1 << tr->part_bits, 
-			tr->blkcore_priv->sizes[minor]);
+			dev->size);
 	up(&mtd_table_mutex);
 
 	return 0;

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   ---- File information -----------
     File:  reset_disk.c
     Date:  16 Sep 2004, 13:23
     Size:  989 bytes.
     Type:  Program-source

[-- Attachment #4: reset_disk.c --]
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#include <stdio.h>         // general I/O
#include <fcntl.h>         // options for open()
#define O_LARGEFILE    0100000
#include <sys/ioctl.h>     // provides ioctl()
#include <linux/fs.h>      // BLKRRPART

int main(int argc, char** argv, char** env)
{
 int fd = -1;
 int err = 0;
 char* filename = NULL;

   if (argc > 1)
   {
      filename = argv[1];
   } 
   else
   {
      printf("Usage example: reset_disk /dev/hda\n");
      printf("Calls the BLKRRPART ioctl() to make kernel re-read and re-interpret partition table.\n");
      printf("This only works if no devices (filesystems) are currently mounted off that disk.\n");
      exit(1);
   }

   fd = open(filename, O_RDONLY|O_LARGEFILE);
   if (fd <= 0)
   {
      printf("Unable to open %s. Exiting\n", filename);
      exit(1);
   }

   err = ioctl(3, BLKRRPART, NULL);
   if (err)
   {
      printf("Error re-reading partition tables using the BLKRRPART ioctl().\n");
      exit(1);
   }

   close(fd);
   
   return(0);
}

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   ---- File information -----------
     File:  geom.c
     Date:  16 Sep 2004, 13:23
     Size:  1569 bytes.
     Type:  Program-source

[-- Attachment #6: geom.c --]
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#include <stdio.h>         // general I/O
#include <fcntl.h>         // options for open()
#define O_LARGEFILE    0100000
#include <sys/ioctl.h>     // provides ioctl()
#include <linux/fs.h>      // BLKGETSIZE
#include <linux/hdreg.h>   // HDIO_GETGEO_BIG

int main(int argc, char** argv, char** env)
{
 int fd = -1;
 int err = 0;
 struct hd_big_geometry big_geom;   // unsigned int cyls
 struct hd_geometry geom;           // unsigned short cyls
 unsigned int size = 0;
 char* filename = NULL;

   if (argc > 1)
   {
      filename = argv[1];
   } 
   else
   {
      printf("Usage example: geom /dev/hda\n");
      printf("Output:  Cylinders/Heads/Sectors_per_track/Capacity   (in sectors)\n");
      exit(1);
   }

      
   fd = open(filename, O_RDONLY|O_LARGEFILE);
   if (fd <= 0)
   {
      printf("Unable to open %s. Exiting\n", filename);
      exit(1);
   }

   err = ioctl(3, BLKGETSIZE, &size);
   if (err)
   {
      printf("Error getting capacity using BLKGETSIZE\n");
      exit(1);
   }

   geom.cylinders = 0;
   geom.heads = 0;
   geom.sectors = 0;
   err = ioctl(3, HDIO_GETGEO_BIG, &big_geom);
   if (err)
   {
      err = ioctl(3, HDIO_GETGEO, &geom);
      if (err)
      {
         printf("Error retrieving geometry - both HDIO_GETGEO_BIG and HDIO_GETGEO failed.\n");
         exit(1);
      }
      else
      {
         printf("%u/%u/%u/%u\n",geom.cylinders, geom.heads, geom.sectors, size);
      }
   }
   else
   {
      printf("%u/%u/%u/%u\n",big_geom.cylinders, big_geom.heads, big_geom.sectors, size);
   }

   close(fd);
   return(0);
}