Your CVS fix 1.109 to union_vnops.c

Takanori Watanabe takawata at
Sun Oct 3 23:08:14 PDT 2004

In message <20041004053106.GQ88303 at>, Boris Popov wrote:
>On Sun, Oct 03, 2004 at 11:06:42PM +0200, Uwe Doering wrote:
>> >
>> >That isn't the issue.  The issue is that an application might open
>> >the vnode in the unionfs mount, and another application might
>> >modify the same file in the underlying file system.  If the kernel
>> >doesn't understand that it is really the same file, then cache
>> >incoherencies will occur.  I'm actually not sure to what extent
>> >this is a problem already; John Heidemann's Phd thesis had a way
>> >of dealing with it, but FreeBSD doesn't do things that way AFAIK.
>> Okay, but that's a different matter.  What I was addressing at the start
>> of this discussion is an ambiguity issue with meta data, that is,
>> information that ends up in stat(2) and friends.
>	Exactly, one never knows what parts of metadata used by applications.
>I can confirm that ino are ought to be unique inside filesystem, otherwise
>some programs will fail in a very obscure ways.

Ok, the issue Uwe says is when underlying filesystem and 
wrapping filesystem are diffent and if there are two files
with same identifier exists. 
And the issue I want to fix is when underlying filesystem and
wrapping filesystem are same so getcwd routine failed to distinguish 
the mount point.

So it can be solved by translating fsid if the fsid of a file is same as
that of mountpoint. True?

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