NFSv4: Ensure change attribute returned by GETATTR callback conforms to spec

 According to RFC3530 we're supposed to cache the change attribute
 at the time the client receives a write delegation.
 If the inode is clean, a CB_GETATTR callback by the server to the
 client is supposed to return the cached change attribute.
 If, OTOH, the inode is dirty, the client should bump the cached
 change attribute by 1.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 65f1e19e4d19..462cfceb50c5 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -35,7 +35,9 @@ unsigned nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres
         if (delegation == NULL || (delegation->type & FMODE_WRITE) == 0)
                 goto out_iput;
         res->size = i_size_read(inode);
-        res->change_attr = NFS_CHANGE_ATTR(inode);
+        res->change_attr = delegation->change_attr;
+        if (nfsi->npages != 0)
+                res->change_attr++;
         res->ctime = inode->i_ctime;
         res->mtime = inode->i_mtime;
         res->bitmap[0] = (FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE) &