Re: REVIEW: Fix for incore extent corruption.

[Lachlan McIlroy <lachlan@sgi.com>]

Eric Sandeen wrote:
> Lachlan McIlroy wrote:
>> Eric Sandeen wrote:
>>> Lachlan McIlroy wrote:
>>>> Russell, this fixes xfs_iext_irec_compact_full().  If we don't move
>>>> all the records from the next page into the current page then we need
>>>> to update the er_extoff of the modified page as we move the remaining
>>>> extents up.  Would you mind giving it a go?
>>>>
>>>> --- a/fs/xfs/xfs_inode.c	2008-09-18 18:48:46.000000000 +1000
>>>> +++ b/fs/xfs/xfs_inode.c	2008-09-18 18:57:18.000000000 +1000
>>>> @@ -4623,6 +4623,7 @@ xfs_iext_irec_compact_full(
>>>>  					(XFS_LINEAR_EXTS -
>>>>  						erp_next->er_extcount) *
>>>>  					sizeof(xfs_bmbt_rec_t));
>>>> +				erp_next->er_extoff += ext_diff;
>>>>  			}
>>>>  		}
>>> Lachlan, I concur.  I spent way too long last night looking at this and
>>> arrived at the same conclusion about the root cause of the problem, but
>>> didn't hae *quite* the right solution.  I blame it on 2am ;)  Your fix
>>> looks right.
>>>
>>> (though I'd probably move the erp_next changes into the else clause? 
>>> Otherwise you're changing it then freeing it.)
>> I don't understand what you mean by that.  Could you elaborate?
> 
> Sorry I mis-read where the above hunk went... that makes sense as-is above.
> 
> For clarity having the erp_next->er_extoff and er_extcount adjustments
> together *might* make sense but no big deal.

That did occur to me.  I thought if I put it with the er_extcount adjustment
then it might look like the er_extoff line was missing from
xfs_iext_irec_compact_pages() because it does the er_extcount adjustment too
but never needs to adjust er_extoff.  Doesn't really matter if we get rid of
xfs_iext_irec_compact_full().