[Ocfs2-devel] [PATCH] ocfs2: Try to free truncate log when meeting ENOSPC in write.
Tao Ma
tao.ma at oracle.com
Wed Nov 3 22:38:41 PDT 2010
On 11/04/2010 09:46 AM, Joel Becker wrote:
> On Tue, Oct 26, 2010 at 03:29:08PM +0800, Tao Ma wrote:
>> Recently, one of our colleagues meet with a problem that if we
>> write/delete a 32mb files repeatly, we will get an ENOSPC in
>> the end. And the corresponding bug is 1288.
>> http://oss.oracle.com/bugzilla/show_bug.cgi?id=1288
>>
>> The real problem is that although we have freed the clusters,
>> they are in truncate log and they will be summed up so that
>> we can free them once in a whole.
>>
>> So this patch just try to resolve it. In case we see -ENOSPC
>> in ocfs2_write_begin_no_lock, we will check whether the truncate
>> log has enough clusters for our need, if yes, we will try to
>> flush the truncate log at that point and try again. This method
>> is inspired by Mark Fasheh<mfasheh at suse.com>. Thanks.
>
> Ok, this is more like what I was thinking about. I guess I wish
> we could do it inside the allocation routines, but I think we have too
> many locks at that point.
yeah, the locks are really the biggest problem for us.
> This patch doesn't help any place that
> allocates other than write() and mmap(). Is this something that could
> be added to extending truncate and unwritten allocation?
I haven't tried in other cases. but in general it could be possible
since all the work is done in ocfs2_try_to_free_truncate_log. We may try
it in other place after thinking carefully of the lock there. But I
guess we can let it in first to see how it works. If it is right and
robust, I can generate another patch for them later. :)
> I agree that we only care to have one pass. Have you run it
> against the test case from
> http://oss.oracle.com/bugzilla/show_bug.cgi?id=1288? If so, modulo
> any cleanups you did after others commented, I'm happy ;-)
yes, I have run the test case overnight and didn't hit ENOSPC any more.
So do you think of accepting it? If yes, I will regenerate the patch for
your merge.
>
>> diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
>> index d840821..de06558 100644
>> --- a/fs/ocfs2/ocfs2.h
>> +++ b/fs/ocfs2/ocfs2.h
>> @@ -439,6 +439,8 @@ struct ocfs2_super
>> /* rb tree root for refcount lock. */
>> struct rb_root osb_rf_lock_tree;
>> struct ocfs2_refcount_tree *osb_ref_tree_lru;
>> +
>> + unsigned int truncated_clusters;
>
> Make sure you comment what lock is needed to access
> truncated_clusters.
OK, I will add comment for it.
Regards,
Tao
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