Re: [PATCH] fs/jbd2: t_updates should increase when start_this_handle() failed in jbd2__journal_restart()

[Younger Liu <younger.liu@huawei.com>]

I will check and test the pacth.

I only merge the patch about " jbd2: invalidate handle if 
jbd2_journal_restart() fails" int my source. But I do not 
merge the patch about "jbd2: Transaction reservation support...".

Does it affect the test?

On 2013/6/24 1:36, Theodore Ts'o wrote:
> On Fri, Jun 21, 2013 at 09:29:31PM +0800, Younger Liu wrote:
>>
>> This bug was triggered by the following scenario:
>> In ocfs2 file system, allocate a very large disk space for a small file
>> with ocfs2_fallocate(), while the journal file size is 32M. 
>>
>> Because there are much many journal blocks needed by jbd2_journal_restart(), 
>> so that nblocks is greater than journal->j_max_transaction_buffers 
>> in start_this_handle(), and then return -ENOSPC.
> 
> Ah, I see.  I have a patch that should prevent the kernel from
> crashing in this situation, and which adds some additional checks to
> make sure no one tries to use the handle after jbd2_journal_restart()
> fails in this circumstance.
> 
> However, you may want to further pursue a fix in ocfs2 so you don't
> actually return ENOSPC to userspace, since it is a very misleading
> error message --- it's not that the file system is out of space, but
> that the journal is too small for the amount of space that you are
> trying to allocate using fallocate().
> 
> I would think a better way of handling this situation would be to log
> a warning message that the journal is probably too small, and then to
> break up the fallocate into smaller chunks, so that it can
> successfully complete despite the fact that the journal was
> unfortunately missized.
> 
> I'll be sending the proposed fix in a moment; could you check and see
> if the patch prevents ocfs2/jbd2 from tripping over the assertion
> given your test case?
> 
> Thanks,
> 
> 					- Ted
> 
> .
>