> -----Original Message----- > From: J. Bruce Fields [mailto:bfields@xxxxxxxxxxxx] > Sent: Wednesday, February 13, 2013 4:34 PM > To: Myklebust, Trond > Cc: Theodore Ts'o; linux-ext4@xxxxxxxxxxxxxxx; sandeen@xxxxxxxxxx; > Bernd Schubert; gluster-devel@xxxxxxxxxx; linux-nfs@xxxxxxxxxxxxxxx > Subject: Re: regressions due to 64-bit ext4 directory cookies > > On Wed, Feb 13, 2013 at 04:43:05PM +0000, Myklebust, Trond wrote: > > On Wed, 2013-02-13 at 11:20 -0500, J. Bruce Fields wrote: > > > Oops, probably should have cc'd linux-nfs. > > > > > > On Wed, Feb 13, 2013 at 10:36:54AM -0500, Theodore Ts'o wrote: > > > > The other thing that I'd note is that the readdir cookie has been > > > > 64-bit since NFSv3, which was released in June ***1995***. And > > > > the explicit, stated purpose of making it be a 64-bit value (as > > > > stated in RFC 1813) was to reduce interoperability problems. If > > > > that were the case, are you telling me that Sun (who has > > > > traditionally been pretty good worrying about interoperability > > > > concerns, and in fact employed the editors of RFC 1813) didn't get > > > > this right? This seems quite.... surprising to me. > > > > > > > > I thought this was the whole point of the various NFS > > > > interoperability testing done at Connectathon, for which Sun was a > > > > major sponsor?!? No one noticed?!? > > > > > > Beats me. But it's not necessarily easy to replace clients running > > > legacy applications, so we're stuck working with the clients we have.... > > > > > > The linux client does remap the server-provided cookies to small > > > integers, I believe exactly because older applications had trouble > > > with servers returning "large" cookies. So presumably > > > ext4-exporting-Linux servers aren't the first to do this. > > > > > > I don't know which client versions are affected--Connectathon's next > > > week and I'll talk to people and make sure there's an ext4 export > > > with this turned on to test against. > > > > Actually, one of the main reasons for the Linux client not exporting > > raw readdir cookies is because the glibc-2 folks in their infinite > > wisdom declared that telldir()/seekdir() use an off_t. They then went > > yet one further and decided to declare negative offsets to be illegal > > so that they could use the negative values internally in their syscall > wrappers. > > > > The POSIX definition has none of the above rubbish > > (http://pubs.opengroup.org/onlinepubs/009695399/functions/telldir.html > > ) and so glibc brilliantly saddled Linux with a crippled readdir > > implementation that is _not_ POSIX compatible. > > > > No, I'm not at all bitter... > > Oh, right, I knew I'd forgotten part of the story.... > > But then you must have actually been testing against servers that were using > that 32nd bit? > > I think ext4 actually only uses 31 bits even in the 32-bit case. And for a server > that was literally using an offset inside a directory file, that would be a > colossal directory. > > So I'm wondering how you ran across it. > > Partly just pure curiosity. IIRC, XFS on IRIX used 0xFFFFF as the readdir eof marker, which caused us to generate an EIO... Cheers Trond
