Re: Case sensitivity in NFS files

["J. Bruce Fields" <bfields@fieldses.org>]

On Thu, Oct 09, 2008 at 06:39:49PM +0200, Michal Sojka wrote:
> I'm experiencing strange problem with case sensitivity of files on NFS3 
> filesystem. I want to backup my server to a NAS device. The server is:
> Linux rtime 2.6.25-gentoo-r8 #6 SMP Thu Oct 9 13:00:08 CEST 2008 i686
> and NAS is:
> Linux RtimeBackup 2.6.15 #722 Fri Sep 19 20:23:15 CST 2008 armv5tejl unknown

Do you know which filesystem it exports?  I haven't played with exports
of case-insensitive filesystems, but the behavior you saw would seem
consistent with that:

> On NFS, I sometimes get the following (neither "A" nor "a" files existed 
> before execution):
> 
> 1. open(A): Success
> 2. lstat(A): Success
> 3. lstat(a): Success

So we looked up "a" on the filesystem, and it found "A", since it
considers the two names the same.

> 4. unlink(a): Success

And the unlink worked too.

> 5. lstat(A): Stale NFS file handle

But we don't know that it resulted in deleting "A", so we send this stat
with the old filehandle and find the file's gone....

> 6. lstat(a): No such file or directory
> 
> This happens when the program is run for the first time. When I run it for the 
> second time, I get the expected output and file "A" is created.

The second time it's probably cached the non-existance of "a", so just
returns -ENOENT on lstat(a) instead of asking the server about it.

--b.

> After I 
> remove the A file, I get the "wrong" output again.
> 
> Does anybody know, what is causing this behavior?
> 
> Thanks
> Michal
> 
> P.S.: Please CC me when replying.
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