Re: [PATCH 2/3] jbd2 : Fix journal start by passing a parameter to specify if the caller can deal with ENOMEM

[Manish Katiyar <mkatiyar@gmail.com>]

On Wed, May 25, 2011 at 7:22 PM, Ted Ts'o <tytso@mit.edu> wrote:
> On Wed, May 25, 2011 at 10:13:33AM +0200, Jan Kara wrote:
>> >
>> >    ok.. I will do it as a separate patch.
>>   Well, patch 2/3 does not really make too much sense without it (errok
>> parameter isn't used) so there's no reason to do it as a separate patch.
>> Just add it to this patch please.
>
> Agreed; right now this whole patch series is a no-op, since errok
> isn't getting used for anything.  So fixing errok so it's passed to
> start_this_handle() seems to be more in the category of "fix the
> patch" more than anything else.
>
> One more thing; perhaps we should be passing in a integer so we can
> pass in a flag word.  That way you don't need to have a fail_ok
> variant.  It's a lot more obvious if you have a call:
>
>          handle = ext4_journal_start(inode, 1, JBD2_FAIL_OK);
>
> What we can also do is this:
>
>          handle = ext4_journal_start(inode, 1, JBD2_FAIL_OK | JBD2_TOPLEVEL);
>
> What JBD2_TOPLEVEL means is that caller is from a top-level file
> system function, such as ext4_symlink() or ext4_chmod(), such that
> start_this_handle() can use GFP_KERNEL instead of GFP_NOFS.  GFP_NOFS
> is needed for any function that might get called by the direct reclaim
> path (i.e., the writepage() function).  But for the top-level
> symlink() or chmod() function, it's actually OK to allocate memory
> using GFP_KERNEL, since there's no potential recursion problem.

Hi Ted/Jan,

Will it be more desirable to have the patch fixed as JBD2_FAIL_OK as
you suggested above ? I have already
fixed the patch to pass errok to start_this_handle() and then retry or
not based on that, and was planning to send
it. But if this needs to be fixed this way, then I will rework it then send.

Thanks -
Manish

>
>                                                       - Ted
>



-- 
Thanks -
Manish
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