Re: FS-Cache: Duplicate cookie detected

[Christian Kujau]

Hi David,

On Tue, 12 Mar 2019, David Howells wrote:
> > My /usr/local/src mount was mounted with vers=4.2 (default), while 
> > nfstest_cache was mounting its test-mount with vers=4.1! Apart from the 
> > different rsize/wsize values, the version number stood out. And indeed, 
> > when I mount my regular NFS mount /usr/local/src with vers=4.1, the 
> > "duplicate cookie" is no longer printed.
> 
> Yeah - NFS superblocks are differentiated by a whole host of parameters,
> including protocol version number, and caches aren't shared between
> superblocks because this introduces a tricky coherency problem.
> 
> The issue is that NFS superblocks to the same place do not currently manage
> coherency (inode attributes, data) between themselves, except via the server.
> 
> However, if "fsc" isn't given on the mount commandline, the superblock
> probably shouldn't get a server-level cookie if we can avoid it.

Just checking - are you waiting for new results from me, should I test 
something that I missed? Or are new patches in the works? :-D

Thanks,
Christian.
-- 
BOFH excuse #139:

UBNC (user brain not connected)