Conference decwet::advfs_support

1013.0. "Problem with ADVFS representation on 4.0b" by MDR01::ARANCHA (MCS Madrid) Wed Mar 05 1997 03:11

    *****************
    I posted this note on DECC_BUG, but I think the problem is ADVFS on
    4.0a or 4.0b. Because I do it on Dunix 3.2c/3.2f and it's working 
    O.K. on advfs and ufs.
    *****************
Hi,
My customer has reported the following error on Digital UNIX 4.0B.

 This program osftest.c uses only system calls, it creates a file veria.bdf
of 18944 bytes,  fills the first blocks with 1.1 and then writes from 
address 6656 on 12000 bytes (representing 3000 floating point values going 
from 0.0 to 29.99 in steps of 0.01).

All system calls execute successfully. But when you do

	> od -f veria.bdf


you see that the last value written is only: 2.4309999e+01.

This happens on a directory which is set up with DEC's advanced file system.

If I do the same in a directory set up with DEC's UFS the program
works o.k. (last value = 2.9990000e+01)

This is very critical for the application customer.
Has anybody  any idea ??
Thanks in the advance,
Arancha

*************************

Program : OSFTEST.C                                                   

#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>

/*
#define O_write         (O_WRONLY | O_CREAT)
*/

#define O_write         O_RDWR

/*
*/


long oskseek(fid, address)
/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.PURPOSE moves the file pointer.
         The argument fid is the file identification
         obtained from osdopen. The address defines
         the pointer position in bytes relative to:
         start of the file, current position or end of the file as
         defined by the variable mode (FILE_START, FILE_CURRENT, FILE_END).
         (see midas/osparms.h). (i.e. : an address=0 and OS_START set means
         first byte of the file).
.RETURNS Upon successful completion, the resulting pointer position
.RETURNS measured in bytes is returned, in case of error -1L.
.REMARKS System dependencies:
 -- UNIX: lseek(2)
------------------------------------------------------------*/
int fid;                        /* file identification */
long address;                   /* file pointer */
{
int  mode;
off_t ret;

mode = SEEK_SET;

if ((ret = lseek(fid, (off_t)address, mode)) == (off_t)-1)
   printf("oskseek: error...\n");
else
   printf("oskseek: addr = %ld, retpntr = %ld\n",address,(long)ret);

return((long)ret);
}


/*
*/


main()

{
char    *mypntr;
char    *cbuf;

int size, status, kk;
int  fid, nr, n, allbytes;
long int addr;

float *fpntr, fbuf[512];


for (nr=0; nr<512; nr++) fbuf[nr] = 1.1;
cbuf = (char *)fbuf;

/* create file on disk with size = 18944 bytes */

fid = creat("veria.bdf",0666);
if (fid < 0)
   printf("creat: problems with creat...\n");
n = 18944;
addr = n - 1;				/* move to last byte */
status = oskseek(fid,addr);
if (status != -1)
   {
   char  c;

   c = ' ';
   n = 1;				/* write 1 byte */
   if ((kk = write(fid,&c,(unsigned int)n)) == -1) 
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }
if (close(fid) < 0) printf("'roblems with close...\n");


fid = open("veria.bdf",O_write,0666);


allbytes = 12000;

mypntr = (char *) malloc((size_t) allbytes);
printf("mypntr = %x\n",mypntr);

fpntr = (float *) mypntr;
for (nr=0; nr<3000; nr++)
   {
   *fpntr++ = 0.01 * nr;
   }



addr = 0;
n = 512;
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,cbuf,(unsigned int)n)) == -1) 
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }

addr += 512;				/* 512 */
n = 2048;
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,cbuf,(unsigned int)n)) == -1)
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }

addr +=2048;				/* 2560 */
n = 2048;
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,cbuf,(unsigned int)n)) == -1)
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }

addr +=2048;				/* 4608 */
n = 2048;
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,cbuf,(unsigned int)n)) == -1)
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",n,kk);
   }

addr +=2048;				/* 6656 */
status = oskseek(fid,addr);
if (status != -1)
   {
   if ((kk = write(fid,mypntr,(unsigned int)allbytes)) == -1) 
      printf("write failed...\n");
   else
      printf("write: nobyt = %d, ret = %d\n",allbytes,kk);
   }

close(fid);

}

 

This is a known problem in AdvFS.  It has been fixed in the releases 
currently under development but to my knowledge a patch has not yet been
created for 4.0, 4.0A, and 4.0B.  The problem was originally reported as 
QAR 50226.  A new QAR requesting that this fix be backported to 4.0,
4.0A, and 4.0B has been filed.  It is QAR 51304.  I will check on its status
today.

By the way, this is the second report we've seen of this.  The first was from
Germany.  This one is from Spain.  What application is hitting this problem?
[Posted by WWW Notes gateway]

    The application and source code is the same on Germany and Spain. 
    The customer doesn't tell me about the application, but it must be 
    of astrophic.
    I'm waiting for your news over QAR.
    Do I open an IMPT case ?
    
    Thanks,
    Arancha

I think that if you opened an IPMT case you would probably speed up the
process of getting a patch.  Mention in the IPMT case that this is a 
serious data corruption problem in AdvFS.  That should get some attention.
[Posted by WWW Notes gateway]

I got mail from the patch-creation manager who said there was just one other
filesystems bug ahead of it in the patch-creation queue.  She said she would
raise the priority of creating a patch for this bug.
[Posted by WWW Notes gateway]