linux-ext4 - Re: [PATCH v3 2/3] e2fsprogs/tune2fs: rewrite metadata checksums when resizing inode size

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Message-ID: <546955CB.5090101@cn.fujitsu.com>
Date:	Mon, 17 Nov 2014 09:56:27 +0800
From:	Xiaoguang Wang <wangxg.fnst@...fujitsu.com>
To:	"Darrick J. Wong" <darrick.wong@...cle.com>
CC:	<linux-ext4@...r.kernel.org>, <tytso@....edu>
Subject: Re: [PATCH v3 2/3] e2fsprogs/tune2fs: rewrite metadata checksums
 when resizing inode size

Hi,

On 11/15/2014 07:10 AM, Darrick J. Wong wrote:
> On Fri, Nov 14, 2014 at 05:15:36PM +0800, Xiaoguang Wang wrote:
>> When we use tune2fs -I new_ino_size to change inode size, if everything is OK,
>> the corresponding ext4_group_desc.bg_free_blocks_count will be decreased, so
>> obviously, we need to re-compute the group descriptor checksums, and the inode
>> 's size has also changed, we also need to recompute the checksums of inodes for
>> metadata_csum filesystem, so here we choose to call a rewrite_metadata_checksums(),
>> this will fix checksum issues.
>>
>> Meanwhile, the patch will trigger an existing memory write overflow, which will
>> casue segfault, please see the next patch.
>>
>> Signed-off-by: Xiaoguang Wang <wangxg.fnst@...fujitsu.com>
>> Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
>> ---
>>  misc/tune2fs.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/misc/tune2fs.c b/misc/tune2fs.c
>> index 065b483..91dc7c1 100644
>> --- a/misc/tune2fs.c
>> +++ b/misc/tune2fs.c
>> @@ -2908,8 +2908,7 @@ retry_open:
>>  				EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
>>  			rewrite_checksums = 1;
>>  	}
>> -	if (rewrite_checksums)
>> -		rewrite_metadata_checksums(fs);
>> +
>>  	if (I_flag) {
>>  		if (mount_flags & EXT2_MF_MOUNTED) {
>>  			fputs(_("The inode size may only be "
>> @@ -2935,6 +2934,7 @@ retry_open:
>>  		if (resize_inode(fs, new_inode_size) == 0) {
> 
> Come to think of it, if we're enabling metadata_csum /and/ resizing the inode,
> we have to set EXT2_FLAG_IGNORE_CSUM_ERRORS before calling resize_inode.  If we
> don't, the library calls that resize_inode() makes will try to verify the
> checksums (which haven't been set yet) and the operation will fail.

Aha, right, sorry!
> 
> Will send patch, but at this point I'm wondering if it doesn't make more sense
> for me to incorporate them into my patchbomb rather than let this series get
> lost in the blizzard...

OK, it would be better for you to incorporate them into your patchbomb, thanks!
Also I attached one filefrag's bug fix, please incorporate it too :)

Regards,
Xiaoguang Wang
> 
> --D
> 
>>  			printf(_("Setting inode size %lu\n"),
>>  							new_inode_size);
>> +			rewrite_checksums = 1;
>>  		} else {
>>  			printf("%s", _("Failed to change inode size\n"));
>>  			rc = 1;
>> @@ -2942,6 +2942,9 @@ retry_open:
>>  		}
>>  	}
>>  
>> +	if (rewrite_checksums)
>> +		rewrite_metadata_checksums(fs);
>> +
>>  	if (l_flag)
>>  		list_super(sb);
>>  	if (stride_set) {
>> -- 
>> 1.8.2.1
>>
>> --
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> .
> 


View attachment "0001-filefrag-fix-wrong-extent-count-calculation-when-usi.patch" of type "text/x-patch" (4247 bytes)