Hi Frank, I think the way how you have implemented is almost correct. You query server for supported attributes. As result client will get all attributes supported bu the server and if FATTR4_XATTR_SUPPORT is returned, then client adds xattr capability. This the way how I read rfc8276. Do you have a different opinion? Regards, Tigran. ----- Original Message ----- > From: "Frank van der Linden" <fllinden@xxxxxxxxxx> > To: "Tigran Mkrtchyan" <tigran.mkrtchyan@xxxxxxx> > Cc: "Trond Myklebust" <trond.myklebust@xxxxxxxxxxxxxxx>, "Anna Schumaker" <anna.schumaker@xxxxxxxxxx>, "linux-nfs" > <linux-nfs@xxxxxxxxxxxxxxx> > Sent: Thursday, March 12, 2020 10:15:55 PM > Subject: Re: [PATCH 03/13] NFSv4.2: query the server for extended attribute support > On Thu, Mar 12, 2020 at 08:51:39PM +0000, Frank van der Linden wrote: >> 1) The xattr_support attribute exists >> 2) The xattr support attribute exists *and* it's true for the root fh >> >> Currently the code does 2) in one operation. That might not be 100% >> correct - the RFC does mention that (section 8.2): >> >> "Before interrogating this attribute using GETATTR, a client should >> determine whether it is a supported attribute by interrogating the >> supported_attrs attribute." >> >> That's a "should", not a "MUST", but it's still waving its finger >> at you not to do this. >> >> Since 8.2.1 says: >> >> "However, a client may reasonably assume that a server >> (or file system) that does not support the xattr_support attribute >> does not provide xattr support, and it acts on that basis." >> >> ..I think you're right, and the code should just use the existence >> of the attribute as a signal that the server knows about xattrs - >> operations should still error out correctly if it doesn't. >> >> I'll make that change, thanks. > > ..or, alternatively, only query xattr_support in nfs4_server_capabilities, > and then its actual value, if it exists, in nfs4_fs_info. > > Any opinions on this? > > - Frank
