Re: overlayfs patches for ovl_copy_up & ovl_rename

[Miklos Szeredi <miklos@szeredi.hu>]

Jordi Pujol <jordipujolp@gmail.com> writes:

> A Dimarts 17 Maig 2011 20:07:13, vàreu escriure:
>> Jordi, what about the original bug you reported:
>> >>>- a few days ago we talked about an error when repetitive sed
>> >>>instructions were executed, also it happens in other processes,
>> >>>like mantaining list of installed files for actual packages, that
>> >>>is solved in ovl_rename issuing a dget for the old-dentry and
>> >>>parent dentries. (This code is inspired on rename.c from unionfs)
>> 
>> Is this still happening?  Does the debug patch make any difference?
>
> my patch adds some dget/dput operations that minimize the problem, it
> occurs less times, but it happens.  I suppose that those extra
> operations add an execution delay before processing the main routine;

Probably timing related, yes.

> a deduction is that locking dentries is required to synchronize a rename to 
> not be executed until another rename operation has finished.

Already done by the VFS.  The locks used actually provide stronger
guarantees than your code.  See

  Documentation/filesystems/directory-locking

for all the gory details.

So, is there a minimal test case that I can try to replicate the bad
behavior?

Thanks,
Miklos
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