Re: 2.6.9 VFS Issues

[Jeff V. Merkey]

Jeff V. Merkey wrote:

> I have noticed one change from 2.4 to 2.6 which although esoteric, is 
> bothersome.  Did the dache assign static inode identities to
> the "." and ".." directories for 2.6 differnt than the behavior in 
> 2.4?  I notice that the root of ext based filesystems is now always "2"
> for the root (although readdir commands pass "0" during passes through 
> the readdir function calls into the VFS).  I have noticed that
> the user space libs always fix "2" as the value of the inode for the 
> root directory.  I am having trouble getting the . and .. entries to show
> up under 2.6, although, they seem to work just fine when you type cd 
> .. and cd ., etc.
>
> I am using my DSFS file system and I am generating inode numbers 
> dynamically for captured data, but I am seeing problems with readdir 
> calls
> from a program I wrote called "dir.c" (ATTACHED) I am using to debug.  
> Anyone know what changed in 2.6.9 and later
> kernels that is causing this, and is there some assummption I need to 
> make?  I also have noted that the . and .. entries are no longer
> passed (or at least do not appear to be getting passed) through to the 
> VFS layer from the dcache.  The DSFS works just fine but this
> issue is somewhat bothersome and I would like to know what is wrong 
> here as it may be exposing some other problem in the VFS
> (apart from wetware issues).
>
> Here's what dir.c outputs from user space for ext3 FS's:
>
> . type-4 len-16 ino-00000002 off-0000000C
> .. type-4 len-16 ino-00000002 off-00000018
> lost+found type-4 len-24 ino-0000000B off-0000002C
> grub type-4 len-16 ino-00000FC1 off-00000038
> initrd-2.6.5-1.358.img type-8 len-40 ino-0000001D off-00000058
> bzImage type-8 len-24 ino-00000010 off-00000078
> boot.b type-8 len-24 ino-00000011 off-00000088
> chain.b type-8 len-24 ino-0000000E off-00000098
> os2_d.b type-8 len-24 ino-0000000F off-000000A8
> vmlinuz-2.6.9 type-8 len-32 ino-00000012 off-00000150
> kernel.h type-8 len-24 ino-00000019 off-000001FC
> System.map-2.6.5-1.358 type-8 len-40 ino-0000000C off-0000021C
> config-2.6.5-1.358 type-8 len-32 ino-0000000D off-00000238
> vmlinuz-2.6.5-1.358 type-8 len-32 ino-0000001C off-00000400
>
>
>
> Here's what dir.c outputs from user space for DSFS (I assign inode 
> numbers dynamically, however, the data files are fixed in the FS 
> beneath).  The . and .. entries are always missing.
>
> stats type-4 len-24 ino-00008001 off-00000003
> slots type-4 len-24 ino-00008002 off-00000004
> slice type-4 len-24 ino-00008003 off-00000005
> merge type-4 len-24 ino-00008004 off-00000006
> create type-4 len-24 ino-00008005 off-00000007
> 1-lo type-8 len-16 ino-10000005 off-0000000B
> 5-eth0 type-8 len-24 ino-10000009 off-00000027
> 1-lo-slice type-8 len-24 ino-20000025 off-0000002B
> 5-eth0-slice type-8 len-24 ino-20000029 off-00000046
>
>
>
> Here's the dir.c source code I wrote to test this:
>
> #include <unistd.h>
> #include <dirent.h>
>
> int main(int argc, char *argv[])
> {
>     register struct dirent *entry;
>     DIR *local_dir;
>
>         if (argc < 2)
>         {
>               printf("USAGE:  dir <directory>\n");
>               return 1;
>         }
>
>         if ((local_dir = opendir(argv[1])) == NULL)
>             return 1;
>
>         while ((entry = readdir(local_dir)) != NULL)
>        {
>             printf("%s type-%d len-%d ino-%08X off-%08X\n",
>                    entry->d_name,                        
> (int)entry->d_type,                       (int)entry->d_reclen,     
>                   (unsigned)entry->d_ino,                       
> (unsigned)entry->d_off);
>         }
>         closedir(local_dir);
>
>         return 0;
> }
>
> Any ideas?
>
> Jeff
And here's the readdir code I use in DSFS to create the entries:

int solera_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
   register ULONG i, count = 0, retCode;
   struct inode *inode = filp->f_dentry->d_inode;
   struct dentry *dentry = filp->f_dentry;
#if LINUX_26
   register DISK_SPACE_RECORD *d =
            (DISK_SPACE_RECORD *) inode->i_sb->s_fs_info;
#else
   register DISK_SPACE_RECORD *d =
            (DISK_SPACE_RECORD *) inode->i_sb->u.generic_sbp;
#endif
   BYTE name[MAX_NAME_LENGTH];
   ULONG ino = 0, namelen = 0, type = DT_UNKNOWN;

#if VERBOSE   
   P_Print("readdir called\n");
#endif

   if (!inode || !S_ISDIR(inode->i_mode))
      return -ENOTDIR;

   i = filp->f_pos;
   switch (i)
   {
      case 0:
     if (filldir(dirent, ".",  1, 0, inode->i_ino, DT_DIR) < 0)
        goto readdir_end;
     filp->f_pos = 1;
         count++;

      case 1:
     if (filldir(dirent, "..", 2, 1, parent_ino(dentry), DT_DIR) < 0)
        goto readdir_end;
     filp->f_pos = 2;
         count++;

      default:
         while (1)
         {
            name[0] = '\0';
            retCode = get_directory_entry(d, inode->i_ino, (filp->f_pos 
- 2),
                                    name, &namelen, &ino, &type);
            if (retCode == -2) 
            {
               filp->f_pos++;
               continue;
            }

#if FS_VERBOSE
            P_Print("%s (%d) ino-%u count=%d pos1-%d pos2-%d\n",
                   name, (int)namelen, (unsigned int)ino,
                   (int)count, (int)i, (int)filp->f_pos);
#endif

            if (retCode)
               break;

            if (filldir(dirent, name, namelen, filp->f_pos,
                        ino, type) < 0)
           goto readdir_end;

            filp->f_pos++;
        count++;
         }
         break;
   }

readdir_end:;

#if FS_VERBOSE
   P_Print("readdir count=%d pos1-%d pos2-%d\n", (int)count,
            (int)i, (int)filp->f_pos);
#endif

   return count;
}


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