NFS: Add mount options to enable local caching on NFS
Add NFS mount options to allow the local caching support to be enabled.
The attached patch makes it possible for the NFS filesystem to be told to make
use of the network filesystem local caching service (FS-Cache).
To be able to use this, a recent nfsutils package is required.
There are three variant NFS mount options that can be added to a mount command
to control caching for a mount. Only the last one specified takes effect:
(*) Adding "fsc" will request caching.
(*) Adding "fsc=<string>" will request caching and also specify a uniquifier.
(*) Adding "nofsc" will disable caching.
For example:
mount warthog:/ /a -o fsc
The cache of a particular superblock (NFS FSID) will be shared between all
mounts of that volume, provided they have the same connection parameters and
are not marked 'nosharecache'.
Where it is otherwise impossible to distinguish superblocks because all the
parameters are identical, but the 'nosharecache' option is supplied, a
uniquifying string must be supplied, else only the first mount will be
permitted to use the cache.
If there's a key collision, then the second mount will disable caching and give
a warning into the kernel log.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 0130700..e4d6a83 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -39,6 +39,7 @@
int acregmin, acregmax,
acdirmin, acdirmax;
int namlen;
+ unsigned int options;
unsigned int bsize;
unsigned int auth_flavor_len;
rpc_authflavor_t auth_flavors[1];