On Mon, May 23, 2011 at 1:07 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > On Mon, 23 May 2011 12:52:36 -0500 > Steve French <smfrench@xxxxxxxxx> wrote: > >> On Mon, May 23, 2011 at 12:45 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: >> > On Mon, 23 May 2011 11:58:50 -0500 >> > Steve French <smfrench@xxxxxxxxx> wrote: >> > >> >> On Mon, May 23, 2011 at 11:31 AM, Gerald Carter <jerry@xxxxxxxxxxxx> wrote: >> >> > On 05/23/2011 08:42 AM, Steve French wrote: >> >> > >> >> >> Shirish had done some experiments (and AFAIK has a small patch >> >> >> that fixed NFS export over CIFS which works, with the usual restrictions >> >> >> about having to return ESTALE if the NFS client tries to access >> >> >> an inode which has been flushed from the cache on the server side). >> >> >> >> >> >>>> For nfs v3 clients that can't handle ESTALE, we are probably >> >> >>>> stuck with having to wait for Samba to implement the flag >> >> >>> Flag? >> >> >> >> >> >> NTCreateX: FILE_OPEN_BY_FILE_ID >> >> >> >> >> >> IIRC Shirish verified that the Windows client will emit this flag, but their >> >> >> server had not gotten around to implementing it (although Samba could >> >> >> implement it now that their is an open-by-handle syscall). >> >> > >> >> > Hey Jeff/Steve, >> >> > >> >> > I found in [MS-CIFS] that says a server MUST return STATUS_NOT_SUPPORTED >> >> > for this option. >> >> Yes - Microsoft has said that their servers do return >> >> STATUS_NOT_SUPPORTED but this is not "MUST" in exactly the same sense >> >> as in an IETF RFC, and the discussion I had with JRA was about servers >> >> which support the Unix/POSIX extensions allowing this. >> >> >> > >> > Reality check -- this is only going to be useful iff: >> > >> > 1) such a thing were to materialize on the server side (and that will >> > probably be in samba only) >> > >> > ...and... >> > >> > 2) someone writes the code to take advantage of it >> > >> > ...and that still won't fix the aforementioned problem with >> > directories. >> >> Hang on - it is useful already. With Shirish's patch he was able to >> back up a Windows or Samba server via NFS. For running more >> complicated applications for long periods of time - it depends on the >> NFS client whether ESTALE is handled or not - but at least ESTALE is a >> documented return code and that the Linux NFS implementation did not >> yet merge Peter Staubach's fix for ESTALE is a bug in Linux NFS (some >> OS do handle ESTALE properly). >> > > Again, this is not reliable. Your backup in this case might work if > you're lucky, or it might not if the server happens to crash and reboot > or an inode gets pushed out of the cache. A NFS server that doesn't > work after a reboot is worse than useless -- it's risky. Until Peter's Linux NFS fix is in - aren't we in that situation already with other fs. -- Thanks, Steve -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
