[Ocfs2-devel] [PATCH 1/1] Ocfs2: Stop tracking a negative dentry after dentry_iput().

[Tristan Ye <tristan.ye@oracle.com>]

Joel Becker wrote:
> On Mon, Nov 15, 2010 at 09:39:09PM +0800, Tristan Ye wrote:
>> I suddenly hit the problem during 2.6.37-rc1 regression test, which was
>> introduced by commit '5e98d492406818e6a94c0ba54c61f59d40cefa4a'(Track
>> negative entries v3), following scenario reproduces the issue easily:
>>
>> Node A			Node B
>> ================	============
>> $touch 	testfile	
>> 			$ls testfile
>> $rm -rf testfile
>> $touch 	testfile	
>> 			$ls testfile
>> 			ls: cannot access testfile: No such file or directory
>>
>> This patch stops tracking the dentry which was negativated by a inode deletion,
>> so as to force the revaliation in next lookup, in case we'll touch the inode
>> again in the same node.
>>
>> It didn't hurt the performance of multiple lookup for none-existed files anyway,
>> while regresses a bit in the first try after a file deletion.
>
> 	I'm going to take this fix for now, because it is clearing the
> problem.  However, it looks like the original code _should_ work.  If we
> have created a file, the directory's generation should have been
> updated.  Thus, the pgen shouldn't match the generation set when the old
> inode was deleted.  Right?

Yep,

Original code did work of course, goldwyn's patch just tries to improve 
the performance by
reducing the possibility of calling revalidation for negative dentries 
on multiple lookups
on none-existed files.

If we created a file, the directory's generation only changes in the 
ocfs2_data_convert_worker,
which only happens when a node doing lock conversion, it means the pgen 
will not change if a node
creates the node without a dlmlock being converted.


Tristan.
>
> Joel
>
>