ext2resize-devel

Re: [ext2resize] Patches for ext2resize?

[<sh...@tn...>]

Hi,

>> Hi,
>> 
>> I had gone out for three days so the reply to you was delayed.
>> 
>>> Can you explain why the rest of the patch is needed?  This is the
>>> patch updated to the current CVS version.
>> 
>> OK, I described comments below.

I found a bug in my patch which you applied to CVS.

ext2_block_iterate():
------------------------------------------------------------------------
	/* Double indirect blocks for next 2^16/2^18/2^20 1k/2k/4k blocks */
	for (i = 0; i < fs->u32perblock; i++) {
		
			:				:

		if (!udata[i])
			continue;
		if(udata[i] == block){
			ext2_brelse(bh, 0);
			return 1;
		}
***		if(((block - gdb_offset)%fs->u32perblock) != i)
			continue;
------------------------------------------------------------------------
The "block" should be stored to the double indirect block whose
block number should be got from the offset(block - gdb_offset)%fs->s_blocks_per_group)
in the single indirect block.

However, actually the target double indirect block number is got from 
the offset(block - gdb_offset)%fs->u32perblock) as the above code marked
with "***".  So ext2_block_iterate() cannot find the target double
indirect block number and returns -1(error).

We should fix the above code as below.
-------------------------------------------------------------------------
-		if(((block - gdb_offset)%fs->u32perblock) != i)
+		if(((block - gdb_offset)%fs->sb.s_blocks_per_group) != i)
-------------------------------------------------------------------------

Cheers, sho

Re: [ext2resize] Patches for ext2resize?

[Petter R. <pe...@hu...>]

> I found a bug in my patch which you applied to CVS.

If I understand you correctly, you suggest this change.  How can I
test if the change work or not?  How can I reproduce the error it is
fixing?

Index: src/ext2.c
===================================================================
RCS file: /cvsroot/ext2resize/ext2resize/src/ext2.c,v
retrieving revision 1.35
diff -u -3 -p -r1.35 ext2.c
--- src/ext2.c  11 Jun 2006 08:30:07 -0000      1.35
+++ src/ext2.c  21 Jun 2006 13:42:23 -0000
@@ -382,7 +382,7 @@ int ext2_block_iterate(struct ext2_fs *f
                        ext2_brelse(bh, 0);
                        return 1;
                }
-               if(((block - gdb_offset)%fs->u32perblock) != i)
+               if(((block - gdb_offset)%fs->sb.s_blocks_per_group) != i)
                        continue;

                bh2 = ext2_bread(fs, udata[i]);

Friendly,
-- 
Petter Reinholdtsen

Re: [ext2resize] Patches for ext2resize?

[Takashi S. <sh...@tn...>]

Hi,

> 
>> I found a bug in my patch which you applied to CVS.
> 
> If I understand you correctly, you suggest this change.  How can I
> test if the change work or not?  How can I reproduce the error it is
> fixing?

This change works only when ext2prepare adds reserved group 
descriptor blocks.

This is reproduced by the following procedure.

#mke2fs /dev/XXX -j -b 16384 3294967295
#ext2prepare /dev/XXX 4294967295

In case 4KB blocksize, this problem doesn't occur because
fs->sb.s_blocks_per_group is set to 32768, which is a multiple of
1024(fs->u32perblock), and both the following two cases give
the same result.

> -               if(((block - gdb_offset)%fs->u32perblock) != i)
> +               if(((block - gdb_offset)%fs->sb.s_blocks_per_group) != i)

While in case 16KB blocksize,  fs->sb.s_blocks_per_group seems
to be set to 65528, which is not a multiple of 4096(fs->u32perblock),
so this problem occurs.

> Index: src/ext2.c
> ===================================================================
> RCS file: /cvsroot/ext2resize/ext2resize/src/ext2.c,v
> retrieving revision 1.35
> diff -u -3 -p -r1.35 ext2.c
> --- src/ext2.c  11 Jun 2006 08:30:07 -0000      1.35
> +++ src/ext2.c  21 Jun 2006 13:42:23 -0000
> @@ -382,7 +382,7 @@ int ext2_block_iterate(struct ext2_fs *f
>                        ext2_brelse(bh, 0);
>                        return 1;
>                }
> -               if(((block - gdb_offset)%fs->u32perblock) != i)
> +               if(((block - gdb_offset)%fs->sb.s_blocks_per_group) != i)
>                        continue;
> 
>                bh2 = ext2_bread(fs, udata[i]);
> 
> Friendly,
> -- 
> Petter Reinholdtsen

Cheers, sho