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SubjectRe: nfs stale filehandle issues with 2.6.10-rc1 in-kernel server
Jeff V. Merkey wrote:

> Trond Myklebust wrote:
>
>>
>>>> Connect 2.4.18 and 2.6.9 with NFS 3 enabled. I am seeing problems
>>>> connecting and file size mismatches. I also see errors with zero
>>>> length files (host side) that get opened and populated with data
>>>> and the remote side is unable to read them -- keeps seeing them as
>>>> zero length.
>>>
>>
>> That's entirely expected. NFS has always been forced to use a polling
>> model for attribute cache consistency. "man 5 nfs" and read all about
>> the "actimeo" mount options that control this behaviour.
>>
>> Cheers,
>> Trond
>>
>>
>>
> Trond,
>
> Thanks for the update. I noticed from another post on this thread
> that the problems with
> /etc/exports are being addressed. This was the other problem I was
> seeing but it appears
> to be getting fixed.
>
> Jeff
>
>
>
Trond,

While you are running down this problem, I've located another odd
behavior you
may (or may not) chose to address. In my dsfs file system, I use sector
runs (large ones)
that can sometimes return odd sizes during running down a file for
reading.

i.e. I can return 4096,4096,4096,512,1024,4096,4096 block sizes on size
returns
from vfs_read() for 512 or 4096 block requests when the file is read
sequentially.
Under NTFS and other OS architectures, unless the final read attempt
returns 0 size
denoting end of file, this seems to be allowed. I noticed that all of
the linux code with
the exception of NFS also handles this situation quite nicely. NFS does
not. I have
noted that if NFS receives a read size smaller than the requested block,
it always assumes
end of file and terminates the next read. I hace modified dsfs to
always return
block sizes in a uniform manner so NFS will work properly, even though
the rest
of the Linux apps work just fine without assuming the end of file has
been reached.

I personally think this is a broken behavior, but perhaps it's in line
with some NFS
spec somewhere. I have coded around it, but thout I would mention it to
you.

Jeff



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