Re: REVIEW: Fix for incore extent corruption.

[Lachlan McIlroy <lachlan@sgi.com>]

Eric Sandeen wrote:
> Lachlan McIlroy wrote:
>> Here's a patch to remove xfs_iext_irec_compact_full() like Russell
>> did in his original patch - are you guys happy with this?
>>
>> I'm putting it through it's paces now and so far it looks good.
> 
> I'll have to think more about it, honestly.  Probably fine, but I've not
> looked at all the surrounding code, I was so far just looking for the
> original bug.
> 
> (FWIW, compact_full *does* get called reasonably frequently, but the
> memmove case is what's hard to hit...)
xfs_iext_irec_compact_full() is probably getting called frequently from
xfs_iext_indirect_to_direct() which we only ever call when the number of
extents will fit into one extent buffer so we will never need the memmove
case in xfs_iext_irec_compact_full() and we can safely call
xfs_iext_irec_compact_pages() instead.

I wonder why xfs_iext_irec_compact_pages() is doing a memmove() instead
of a memcpy().

> 
> -Eric
> 
>> --- a/fs/xfs/xfs_inode.c	2008-09-19 13:08:08.000000000 +1000
>> +++ b/fs/xfs/xfs_inode.c	2008-09-19 13:16:34.000000000 +1000
>> @@ -4157,7 +4166,7 @@ xfs_iext_indirect_to_direct(
>>  	ASSERT(nextents <= XFS_LINEAR_EXTS);
>>  	size = nextents * sizeof(xfs_bmbt_rec_t);
>>  
>> -	xfs_iext_irec_compact_full(ifp);
>> +	xfs_iext_irec_compact_pages(ifp);
>>  	ASSERT(ifp->if_real_bytes == XFS_IEXT_BUFSZ);
>>  
>>  	ep = ifp->if_u1.if_ext_irec->er_extbuf;
> 
> ...
>