When working on the patch of adding the data=nojournal mount option,
I start to wonder whether this mount option is actually needed.
When we mount a filesystem that was mkfs'ed with journal, using the
"noload" mount option
can help specify we do not load the journal.
When we mount a filesystem that was mkfs'ed without journal, we simply
go into the
nojournal mode.
That said, I do not really feel this data=nojournal option is necessary.
But I am still working on the patch to print appropriate messages when
people mount a filesystem
created without a journal but explicitly specify the "data=" option.
Any comments?
Thanks,
Xiang
On Mon, Jul 6, 2009 at 9:21 AM, Xiang Wang<xiangw@xxxxxxxxxx> wrote:
> On Sun, Jul 5, 2009 at 8:41 PM, Theodore Tso<tytso@xxxxxxx> wrote:
>> On Thu, Jul 02, 2009 at 12:01:30AM +0530, Aneesh Kumar K.V wrote:
>>>
>>> I looked at the patch in detail and I guess we should instead force
>>> a data=writeback mode if the filesystem is created without a journal.
>>> I am not sure what whould be the meaning of data=ordered/data=journal
>>> without a journal. So if we find that file system doesn't have a journal
>>> then either we should update the default mount option in the filesystem
>>> to be of data=writeback.
>>
>> Here's a patch which takes your approach to solving the problem. What
>> do you think?
>>
>> I haven't messed with dealing with the data= mount options in
>> fs/ext4/super.c. That's important from a UI point of view, but we
>> needed to fix ext4_jbd2.h since it was unconditionally returning 0 if
>> there was no journal for all of the ext4_should_*_data() functions.
>>
>> I believe this should DTRT with the -o nobh mount option, but I'd
>> appreciate another pair of eyes taking a look at this.
>
> This patch looks good to us.
>
> In the long run, we still think adding the data=nojournal mount option
> is useful and we are working on this patch.
>
> Thanks,
> Xiang
>
>>
>> - Ted
>>
>> commit 2a73eff8ba80095a871a6b402dfd24bc454e5bdc
>> Author: Theodore Ts'o <tytso@xxxxxxx>
>> Date: Sun Jul 5 23:37:13 2009 -0400
>>
>> ext4: fix no journal corruption with locale-gen
>>
>> If there is no journal, ext4_should_writeback_data() should return
>> TRUE. This will fix ext4_set_aops() to set ext4_da_ops in the case of
>> delayed allocation; otherwise ext4_journaled_aops gets used by
>> default, which doesn't handle delayed allocation properly.
>>
>> The advantage of using ext4_should_writeback_data() approach is that
>> it should handle nobh better as well.
>>
>> Thanks to Curt Wohlgemuth for investigating this problem, and Aneesh
>> Kumar for suggesting this approach.
>>
>> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
>>
>> diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
>> index be2f426..f800134 100644
>> --- a/fs/ext4/ext4_jbd2.h
>> +++ b/fs/ext4/ext4_jbd2.h
>> @@ -282,7 +282,7 @@ static inline int ext4_should_order_data(struct inode *inode)
>> static inline int ext4_should_writeback_data(struct inode *inode)
>> {
>> if (EXT4_JOURNAL(inode) == NULL)
>> - return 0;
>> + return 1;
>> if (!S_ISREG(inode->i_mode))
>> return 0;
>> if (EXT4_I(inode)->i_flags & EXT4_JOURNAL_DATA_FL)
>> --
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