Re: [PATCH v2 1/5] fat: allocate persistent inode numbers

From: OGAWA Hirofumi
Date: Wed Sep 12 2012 - 13:38:10 EST

"J. Bruce Fields" <bfields@xxxxxxxxxxxx> writes:

>> On other view (as server side solution), we are thinking there is
>> possible to make the stable filehandle on FAT if we disabled some
>> operations (e.g. rename(), unlink()) which change inode location in FAT.
>> Yes, it would be stable, but supporting limited operations.
>> This is server side solution, and we comparing it with client solution.
> Is that useful to anyone?

Good question. I'm not sure though, Namjae is asking. And I was asked
about stable read-only export in past.

>> >> LOOKUP return NFS FH->[inode number changed at NFS Server] ->
>> >> But we still use old NFS FH returned from LOOKUP for any file
>> >> operation(write,read,etc..)
>> >> -> ESTALE will be returned.
>> Yes. And I'm expecting as client side solution,
>> -> ESTALE will be returned -> discard old FH -> restart from LOOKUP ->
>> make cached inode -> use returned new FH.
>> Yeah, I know this is unstable (there is no perfect solution for now),
> You may end up with a totally different file, of course:
> client: server:
> open "/foo/bar"
> rename "/foo/baz"->"/foo/bar"
> write to file
> And now we're writing to the file that was originally named /foo/baz
> when we should have gotten ESTALE.

I see. So, client can't solve the ESTALE if inode cache was evicted,
right? (without application changes)
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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