Re: [PATCH v2 1/7] Adding support to freeze and unfreeze a journal

[Eric Sandeen <sandeen@redhat.com>]

On 1/10/12 3:31 PM, Jan Kara wrote:
> On Tue 10-01-12 14:20:23, Eric Sandeen wrote:

<snip>

>> Hrm let me think through this a little more; we actually do:
>>
>> t16) ext4_journal_start()
>>   t17) ext4_journal_start_sb()
>>     t18) handle = ext4_journal_current_handle();
>>     t19) if (!handle) vfs_check_frozen()
>>     t20) ... jbd2_journal_start()
>   Ah, right. I forgot.
> 
>> So actually we *do* block new handles, but let *existing* ones
>> continue (see commits 6b0310fbf087ad6e9e3b8392adca97cd77184084
>> and be4f27d324e8ddd57cc0d4d604fe85ee0425cba9)
>>
>> So your assertion that a new handle is started is incorrect
>> in general, isn't it?  So then does the fix seem necessary?
>> Or, at least, in the fashion below - maybe we need to just make
>> sure all started handles complete before the unlock_updates?
>> Or am I missing something...?
>   Well, the problem with running operations and freezing is more
> fundamental I believe. See my email
> http://marc.info/?l=linux-fsdevel&m=132585911925796&w=2
> 
> So I believe we'll need some better exclusion mechanism already in VFS.
> 
> 								Honza
> 

Yep, saw it, just wasn't sure if this patchset was still under active consideration.

Thanks,
-Eric