Ocfs2 devel - Nov 2015 - [PATCH v2 4/4] ocfs2: check/fix inode block for online file check

Hello Junxiao,

See my comments inline.

>>> 
> Hi Gang,
> 
> This is not like a right patch.
> First, online file check only checks inode's block number, valid flag,
> fs generation value, and meta ecc. I never see a real corruption
> happened only on this field, if these fields are corrupted, that means
> something bad may happen on other place. So fix this field may not help
> and even cause corruption more hard.
This online file check/fix feature is used to check/fix some light file meta
block corruption, instead of turning a file system off and using fsck.ocfs2.
e.g. meta ecc error, we really need not to use fsck.ocfs2. 
of course, this feature does not replace fsck.ocfs2 and touch some complicated
meta block problems, if there is some potential problem in some areas, we can
discuss them one by one.


> Second, the repair way is wrong. In
> ocfs2_filecheck_repair_inode_block(), if these fields in disk don't
> match the ones in memory, the ones in memory are used to update the disk
> fields. The question is how do you know these field in memory are
> right(they may be the real corrupted ones)?
Here, if the inode block was corrupted, the file system is not able to load it
into the memory.
ocfs2_filecheck_repair_inode_block() will able to load it into the memory, since
it try to fix these light-level problem before loading.
if the fix is OK, the changed meta-block can pass the block-validate function
and load into the memory as a inode object.
Since the file system is under a cluster environment, we have to use some
existing function and code path to keep these block operation under a cluster
lock.


Thanks
Gang
> 
> Thanks,
> Junxiao.
> On 10/28/2015 02:26 PM, Gang He wrote:
>> +static int ocfs2_filecheck_repair_inode_block(struct super_block *sb,
>> +			       struct buffer_head *bh)
>> +{
>> +	int rc;
>> +	int changed = 0;
>> +	struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
>> +
>> +	rc = ocfs2_filecheck_validate_inode_block(sb, bh);
>> +	/* Can't fix invalid inode block */
>> +	if (!rc || rc == -OCFS2_FILECHECK_ERR_INVALIDINO)
>> +		return rc;
>> +
>> +	trace_ocfs2_filecheck_repair_inode_block(
>> +		(unsigned long long)bh->b_blocknr);
>> +
>> +	if (ocfs2_is_hard_readonly(OCFS2_SB(sb)) ||
>> +		ocfs2_is_soft_readonly(OCFS2_SB(sb))) {
>> +		mlog(ML_ERROR,
>> +			"Filecheck: try to repair dinode #%llu on readonly
filesystem\n",
>> +			(unsigned long long)bh->b_blocknr);
>> +		return -OCFS2_FILECHECK_ERR_READONLY;
>> +	}
>> +
>> +	if (le64_to_cpu(di->i_blkno) != bh->b_blocknr) {
>> +		di->i_blkno = cpu_to_le64(bh->b_blocknr);
>> +		changed = 1;
>> +		mlog(ML_ERROR,
>> +			"Filecheck: reset dinode #%llu: i_blkno to %llu\n",
>> +			(unsigned long long)bh->b_blocknr,
>> +			(unsigned long long)le64_to_cpu(di->i_blkno));
>> +	}
>> +
>> +	if (!(di->i_flags & cpu_to_le32(OCFS2_VALID_FL))) {
>> +		di->i_flags |= cpu_to_le32(OCFS2_VALID_FL);
>> +		changed = 1;
>> +		mlog(ML_ERROR,
>> +			"Filecheck: reset dinode #%llu: OCFS2_VALID_FL is set\n",
>> +			(unsigned long long)bh->b_blocknr);
>> +	}
>> +
>> +	if (le32_to_cpu(di->i_fs_generation) !>> +	   
OCFS2_SB(sb)->fs_generation) {
>> +		di->i_fs_generation =
cpu_to_le32(OCFS2_SB(sb)->fs_generation);
>> +		changed = 1;
>> +		mlog(ML_ERROR,
>> +			"Filecheck: reset dinode #%llu: fs_generation to %u\n",
>> +			(unsigned long long)bh->b_blocknr,
>> +			le32_to_cpu(di->i_fs_generation));
>> +	}
>> +
>> +	if (changed ||
>> +		ocfs2_validate_meta_ecc(sb, bh->b_data, &di->i_check)) {
>> +		ocfs2_compute_meta_ecc(sb, bh->b_data, &di->i_check);
>> +		mark_buffer_dirty(bh);
>> +		mlog(ML_ERROR,
>> +			"Filecheck: reset dinode #%llu: compute meta ecc\n",
>> +			(unsigned long long)bh->b_blocknr);
>> +	}
>> +
>> +	return 0;
>> +}

On 11/03/2015 04:15 PM, Gang He wrote:
> Hello Junxiao,
> 
> See my comments inline.
> 
> 
>>>>
>> Hi Gang,
>>
>> This is not like a right patch.
>> First, online file check only checks inode's block number, valid
flag,
>> fs generation value, and meta ecc. I never see a real corruption
>> happened only on this field, if these fields are corrupted, that means
>> something bad may happen on other place. So fix this field may not help
>> and even cause corruption more hard.
> This online file check/fix feature is used to check/fix some light file
meta block corruption, instead of turning a file system off and using
fsck.ocfs2.
What's light meta block corruption? Do you have a case about
it?
> e.g. meta ecc error, we really need not to use fsck.ocfs2. 
> of course, this feature does not replace fsck.ocfs2 and touch some
complicated meta block problems, if there is some potential problem in some
areas, we can discuss them one by one.
> 
> 
> 
>> Second, the repair way is wrong. In
>> ocfs2_filecheck_repair_inode_block(), if these fields in disk don't
>> match the ones in memory, the ones in memory are used to update the
disk
>> fields. The question is how do you know these field in memory are
>> right(they may be the real corrupted ones)?
> Here, if the inode block was corrupted, the file system is not able to load
it into the memory.
How do you know inode block corrupted? If bh for inode block is
overwritten, i mean bh corrupted, the repair will corrupted a good inode
block.

Thanks,
Junxiao.
> ocfs2_filecheck_repair_inode_block() will able to load it into the memory,
since it try to fix these light-level problem before loading.
> if the fix is OK, the changed meta-block can pass the block-validate
function and load into the memory as a inode object.
> Since the file system is under a cluster environment, we have to use some
existing function and code path to keep these block operation under a cluster
lock.
> 
> 
> Thanks
> Gang
> 
>>
>> Thanks,
>> Junxiao.
>> On 10/28/2015 02:26 PM, Gang He wrote:
>>> +static int ocfs2_filecheck_repair_inode_block(struct super_block
*sb,
>>> +			       struct buffer_head *bh)
>>> +{
>>> +	int rc;
>>> +	int changed = 0;
>>> +	struct ocfs2_dinode *di = (struct ocfs2_dinode *)bh->b_data;
>>> +
>>> +	rc = ocfs2_filecheck_validate_inode_block(sb, bh);
>>> +	/* Can't fix invalid inode block */
>>> +	if (!rc || rc == -OCFS2_FILECHECK_ERR_INVALIDINO)
>>> +		return rc;
>>> +
>>> +	trace_ocfs2_filecheck_repair_inode_block(
>>> +		(unsigned long long)bh->b_blocknr);
>>> +
>>> +	if (ocfs2_is_hard_readonly(OCFS2_SB(sb)) ||
>>> +		ocfs2_is_soft_readonly(OCFS2_SB(sb))) {
>>> +		mlog(ML_ERROR,
>>> +			"Filecheck: try to repair dinode #%llu on readonly
filesystem\n",
>>> +			(unsigned long long)bh->b_blocknr);
>>> +		return -OCFS2_FILECHECK_ERR_READONLY;
>>> +	}
>>> +
>>> +	if (le64_to_cpu(di->i_blkno) != bh->b_blocknr) {
>>> +		di->i_blkno = cpu_to_le64(bh->b_blocknr);
>>> +		changed = 1;
>>> +		mlog(ML_ERROR,
>>> +			"Filecheck: reset dinode #%llu: i_blkno to %llu\n",
>>> +			(unsigned long long)bh->b_blocknr,
>>> +			(unsigned long long)le64_to_cpu(di->i_blkno));
>>> +	}
>>> +
>>> +	if (!(di->i_flags & cpu_to_le32(OCFS2_VALID_FL))) {
>>> +		di->i_flags |= cpu_to_le32(OCFS2_VALID_FL);
>>> +		changed = 1;
>>> +		mlog(ML_ERROR,
>>> +			"Filecheck: reset dinode #%llu: OCFS2_VALID_FL is
set\n",
>>> +			(unsigned long long)bh->b_blocknr);
>>> +	}
>>> +
>>> +	if (le32_to_cpu(di->i_fs_generation) !>>> +	   
OCFS2_SB(sb)->fs_generation) {
>>> +		di->i_fs_generation =
cpu_to_le32(OCFS2_SB(sb)->fs_generation);
>>> +		changed = 1;
>>> +		mlog(ML_ERROR,
>>> +			"Filecheck: reset dinode #%llu: fs_generation to
%u\n",
>>> +			(unsigned long long)bh->b_blocknr,
>>> +			le32_to_cpu(di->i_fs_generation));
>>> +	}
>>> +
>>> +	if (changed ||
>>> +		ocfs2_validate_meta_ecc(sb, bh->b_data, &di->i_check))
{
>>> +		ocfs2_compute_meta_ecc(sb, bh->b_data, &di->i_check);
>>> +		mark_buffer_dirty(bh);
>>> +		mlog(ML_ERROR,
>>> +			"Filecheck: reset dinode #%llu: compute meta ecc\n",
>>> +			(unsigned long long)bh->b_blocknr);
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>