linux-ext4 - Re: [PATCH 15/15][e2fsprogs] 64-bit mke2fs cleanup

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Date:	Wed, 16 Jul 2008 15:52:01 +0200
From:	Goswin von Brederlow <goswin-v-b@....de>
To:	Goswin von Brederlow <goswin-v-b@....de>
Cc:	"Jose R. Santos" <jrs@...ibm.com>, "Theodore Ts'o" <tytso@....edu>,
	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 15/15][e2fsprogs] 64-bit mke2fs cleanup

Goswin von Brederlow <goswin-v-b@....de> writes:

> "Jose R. Santos" <jrs@...ibm.com> writes:
>
>> diff --git a/misc/mke2fs.c b/misc/mke2fs.c
>> index 7171990..817be56 100644
>> --- a/misc/mke2fs.c
>> +++ b/misc/mke2fs.c
>> @@ -1402,12 +1402,12 @@ static void PRS(int argc, char *argv[])
>>  
>>  	fs_param.s_log_frag_size = fs_param.s_log_block_size;
>>  
>> -	if (noaction && fs_param.s_blocks_count) {
>> -		dev_size = fs_param.s_blocks_count;
>> +	if (noaction && ext2fs_blocks_count(&fs_param)) {
>> +		dev_size = ext2fs_blocks_count(&fs_param);
>>  		retval = 0;
>>  	} else {
>>  	retry:
>> -		retval = ext2fs_get_device_size(device_name,
>> +		retval = ext2fs_get_device_size2(device_name,
>>  						EXT2_BLOCK_SIZE(&fs_param),
>>  						&dev_size);
>>  		if ((retval == EFBIG) &&
>
> You should not assume that ext2fs_get_device_size2() will return EFBIG
> if the size exceed 2^32 blocks. The point of ext2fs_get_device_size2()
> was to be able to support more than 2^32 blocks and the library
> function will certainly change to return larger numbers in the future.
>
> So you need something like
>
> if ((retval == EFBIG || dev_size >= (1ULL << 32)) &&
>
> MfG
>         Goswin

Actualy that is already a problem. The ext2fs_get_device_size2() only
returns EFBIG if sizeof(dev_size) < sizeof(unsigned long long), which
was the case for blk_t but no longer.

As a result mke2fs no longer stops with the right error on devices >
16TiB. My test device is exactly 32 TiB large and gives the following:

root@...-13:~# LD_LIBRARY_PATH=/tmpa/ext4 /tmpa/ext4/mke2fs -T ext4dev
-j -m0 /dev/mapper/ext4
mke2fs 1.41.0 (10-Jul-2008)
mke2fs: inode_size (256) * inodes_count (0) too big for a
        filesystem with 0 blocks, specify higher inode_ratio (-i)
        or lower inode count (-N).

I'm guessing somewhere along the line it converts to 32bit choping of
the higher bits.

MfG
        Goswin
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